#!/bin/sh
# Tcl ignores the next line -*- tcl -*- \
exec wish "$0" -- "$@"

# Copyright © 2005-2008 Paul Mackerras.  All rights reserved.
# This program is free software; it may be used, copied, modified
# and distributed under the terms of the GNU General Public Licence,
# either version 2, or (at your option) any later version.

proc gitdir {} {
    global env
    if {[info exists env(GIT_DIR)]} {
        return $env(GIT_DIR)
    } else {
        return [exec git rev-parse --git-dir]
    }
}

# A simple scheduler for compute-intensive stuff.
# The aim is to make sure that event handlers for GUI actions can
# run at least every 50-100 ms.  Unfortunately fileevent handlers are
# run before X event handlers, so reading from a fast source can
# make the GUI completely unresponsive.
proc run args {
    global isonrunq runq

    set script $args
    if {[info exists isonrunq($script)]} return
    if {$runq eq {}} {
        after idle dorunq
    }
    lappend runq [list {} $script]
    set isonrunq($script) 1
}

proc filerun {fd script} {
    fileevent $fd readable [list filereadable $fd $script]
}

proc filereadable {fd script} {
    global runq

    fileevent $fd readable {}
    if {$runq eq {}} {
        after idle dorunq
    }
    lappend runq [list $fd $script]
}

proc nukefile {fd} {
    global runq

    for {set i 0} {$i < [llength $runq]} {} {
        if {[lindex $runq $i 0] eq $fd} {
            set runq [lreplace $runq $i $i]
        } else {
            incr i
        }
    }
}

proc dorunq {} {
    global isonrunq runq

    set tstart [clock clicks -milliseconds]
    set t0 $tstart
    while {[llength $runq] > 0} {
        set fd [lindex $runq 0 0]
        set script [lindex $runq 0 1]
        set repeat [eval $script]
        set t1 [clock clicks -milliseconds]
        set t [expr {$t1 - $t0}]
        set runq [lrange $runq 1 end]
        if {$repeat ne {} && $repeat} {
            if {$fd eq {} || $repeat == 2} {
                # script returns 1 if it wants to be readded
                # file readers return 2 if they could do more straight away
                lappend runq [list $fd $script]
            } else {
                fileevent $fd readable [list filereadable $fd $script]
            }
        } elseif {$fd eq {}} {
            unset isonrunq($script)
        }
        set t0 $t1
        if {$t1 - $tstart >= 80} break
    }
    if {$runq ne {}} {
        after idle dorunq
    }
}

proc reg_instance {fd} {
    global commfd leftover loginstance

    set i [incr loginstance]
    set commfd($i) $fd
    set leftover($i) {}
    return $i
}

proc unmerged_files {files} {
    global nr_unmerged

    # find the list of unmerged files
    set mlist {}
    set nr_unmerged 0
    if {[catch {
        set fd [open "| git ls-files -u" r]
    } err]} {
        show_error {} . "[mc "Couldn't get list of unmerged files:"] $err"
        exit 1
    }
    while {[gets $fd line] >= 0} {
        set i [string first "\t" $line]
        if {$i < 0} continue
        set fname [string range $line [expr {$i+1}] end]
        if {[lsearch -exact $mlist $fname] >= 0} continue
        incr nr_unmerged
        if {$files eq {} || [path_filter $files $fname]} {
            lappend mlist $fname
        }
    }
    catch {close $fd}
    return $mlist
}

proc parseviewargs {n arglist} {
    global vdatemode vmergeonly vflags vdflags vrevs vfiltered vorigargs

    set vdatemode($n) 0
    set vmergeonly($n) 0
    set glflags {}
    set diffargs {}
    set nextisval 0
    set revargs {}
    set origargs $arglist
    set allknown 1
    set filtered 0
    set i -1
    foreach arg $arglist {
        incr i
        if {$nextisval} {
            lappend glflags $arg
            set nextisval 0
            continue
        }
        switch -glob -- $arg {
            "-d" -
            "--date-order" {
                set vdatemode($n) 1
                # remove from origargs in case we hit an unknown option
                set origargs [lreplace $origargs $i $i]
                incr i -1
            }
            # These request or affect diff output, which we don't want.
            # Some could be used to set our defaults for diff display.
            "-[puabwcrRBMC]" -
            "--no-renames" - "--full-index" - "--binary" - "--abbrev=*" -
            "--find-copies-harder" - "-l*" - "--ext-diff" - "--no-ext-diff" -
            "--src-prefix=*" - "--dst-prefix=*" - "--no-prefix" -
            "-O*" - "--text" - "--full-diff" - "--ignore-space-at-eol" -
            "--ignore-space-change" - "-U*" - "--unified=*" {
                lappend diffargs $arg
            }
            # These cause our parsing of git log's output to fail, or else
            # they're options we want to set ourselves, so ignore them.
            "--raw" - "--patch-with-raw" - "--patch-with-stat" -
            "--name-only" - "--name-status" - "--color" - "--color-words" -
            "--log-size" - "--pretty=*" - "--decorate" - "--abbrev-commit" -
            "--cc" - "-z" - "--header" - "--parents" - "--boundary" -
            "--no-color" - "-g" - "--walk-reflogs" - "--no-walk" -
            "--timestamp" - "relative-date" - "--date=*" - "--stdin" -
            "--objects" - "--objects-edge" - "--reverse" {
            }
            # These are harmless, and some are even useful
            "--stat=*" - "--numstat" - "--shortstat" - "--summary" -
            "--check" - "--exit-code" - "--quiet" - "--topo-order" -
            "--full-history" - "--dense" - "--sparse" -
            "--follow" - "--left-right" - "--encoding=*" {
                lappend glflags $arg
            }
            # These mean that we get a subset of the commits
            "--diff-filter=*" - "--no-merges" - "--unpacked" -
            "--max-count=*" - "--skip=*" - "--since=*" - "--after=*" -
            "--until=*" - "--before=*" - "--max-age=*" - "--min-age=*" -
            "--author=*" - "--committer=*" - "--grep=*" - "-[iE]" -
            "--remove-empty" - "--first-parent" - "--cherry-pick" -
            "-S*" - "--pickaxe-all" - "--pickaxe-regex" - {
                set filtered 1
                lappend glflags $arg
            }
            # This appears to be the only one that has a value as a
            # separate word following it
            "-n" {
                set filtered 1
                set nextisval 1
                lappend glflags $arg
            }
            "--not" {
                set notflag [expr {!$notflag}]
                lappend revargs $arg
            }
            "--all" {
                lappend revargs $arg
            }
            "--merge" {
                set vmergeonly($n) 1
                # git rev-parse doesn't understand --merge
                lappend revargs --gitk-symmetric-diff-marker MERGE_HEAD...HEAD
            }
            # Other flag arguments including -<n>
            "-*" {
                if {[string is digit -strict [string range $arg 1 end]]} {
                    set filtered 1
                } else {
                    # a flag argument that we don't recognize;
                    # that means we can't optimize
                    set allknown 0
                }
                lappend glflags $arg
            }
            # Non-flag arguments specify commits or ranges of commits
            default {
                if {[string match "*...*" $arg]} {
                    lappend revargs --gitk-symmetric-diff-marker
                }
                lappend revargs $arg
            }
        }
    }
    set vdflags($n) $diffargs
    set vflags($n) $glflags
    set vrevs($n) $revargs
    set vfiltered($n) $filtered
    set vorigargs($n) $origargs
    return $allknown
}

proc parseviewrevs {view revs} {
    global vposids vnegids

    if {$revs eq {}} {
        set revs HEAD
    }
    if {[catch {set ids [eval exec git rev-parse $revs]} err]} {
        # we get stdout followed by stderr in $err
        # for an unknown rev, git rev-parse echoes it and then errors out
        set errlines [split $err "\n"]
        set badrev {}
        for {set l 0} {$l < [llength $errlines]} {incr l} {
            set line [lindex $errlines $l]
            if {!([string length $line] == 40 && [string is xdigit $line])} {
                if {[string match "fatal:*" $line]} {
                    if {[string match "fatal: ambiguous argument*" $line]
                        && $badrev ne {}} {
                        if {[llength $badrev] == 1} {
                            set err "unknown revision $badrev"
                        } else {
                            set err "unknown revisions: [join $badrev ", "]"
                        }
                    } else {
                        set err [join [lrange $errlines $l end] "\n"]
                    }
                    break
                }
                lappend badrev $line
            }
        }                   
        error_popup "Error parsing revisions: $err"
        return {}
    }
    set ret {}
    set pos {}
    set neg {}
    set sdm 0
    foreach id [split $ids "\n"] {
        if {$id eq "--gitk-symmetric-diff-marker"} {
            set sdm 4
        } elseif {[string match "^*" $id]} {
            if {$sdm != 1} {
                lappend ret $id
                if {$sdm == 3} {
                    set sdm 0
                }
            }
            lappend neg [string range $id 1 end]
        } else {
            if {$sdm != 2} {
                lappend ret $id
            } else {
                lset ret end [lindex $ret end]...$id
            }
            lappend pos $id
        }
        incr sdm -1
    }
    set vposids($view) $pos
    set vnegids($view) $neg
    return $ret
}

# Start off a git log process and arrange to read its output
proc start_rev_list {view} {
    global startmsecs commitidx viewcomplete curview
    global tclencoding
    global viewargs viewargscmd viewfiles vfilelimit
    global showlocalchanges commitinterest
    global viewactive viewinstances vmergeonly
    global mainheadid
    global vcanopt vflags vrevs vorigargs

    set startmsecs [clock clicks -milliseconds]
    set commitidx($view) 0
    # these are set this way for the error exits
    set viewcomplete($view) 1
    set viewactive($view) 0
    varcinit $view

    set args $viewargs($view)
    if {$viewargscmd($view) ne {}} {
        if {[catch {
            set str [exec sh -c $viewargscmd($view)]
        } err]} {
            error_popup "Error executing --argscmd command: $err"
            return 0
        }
        set args [concat $args [split $str "\n"]]
    }
    set vcanopt($view) [parseviewargs $view $args]

    set files $viewfiles($view)
    if {$vmergeonly($view)} {
        set files [unmerged_files $files]
        if {$files eq {}} {
            global nr_unmerged
            if {$nr_unmerged == 0} {
                error_popup [mc "No files selected: --merge specified but\
                             no files are unmerged."]
            } else {
                error_popup [mc "No files selected: --merge specified but\
                             no unmerged files are within file limit."]
            }
            return 0
        }
    }
    set vfilelimit($view) $files

    if {$vcanopt($view)} {
        set revs [parseviewrevs $view $vrevs($view)]
        if {$revs eq {}} {
            return 0
        }
        set args [concat $vflags($view) $revs]
    } else {
        set args $vorigargs($view)
    }

    if {[catch {
        set fd [open [concat | git log --no-color -z --pretty=raw --parents \
                         --boundary $args "--" $files] r]
    } err]} {
        error_popup "[mc "Error executing git log:"] $err"
        return 0
    }
    set i [reg_instance $fd]
    set viewinstances($view) [list $i]
    if {$showlocalchanges && $mainheadid ne {}} {
        lappend commitinterest($mainheadid) {dodiffindex}
    }
    fconfigure $fd -blocking 0 -translation lf -eofchar {}
    if {$tclencoding != {}} {
        fconfigure $fd -encoding $tclencoding
    }
    filerun $fd [list getcommitlines $fd $i $view 0]
    nowbusy $view [mc "Reading"]
    set viewcomplete($view) 0
    set viewactive($view) 1
    return 1
}

proc stop_instance {inst} {
    global commfd leftover

    set fd $commfd($inst)
    catch {
        set pid [pid $fd]

        if {$::tcl_platform(platform) eq {windows}} {
            exec kill -f $pid
        } else {
            exec kill $pid
        }
    }
    catch {close $fd}
    nukefile $fd
    unset commfd($inst)
    unset leftover($inst)
}

proc stop_backends {} {
    global commfd

    foreach inst [array names commfd] {
        stop_instance $inst
    }
}

proc stop_rev_list {view} {
    global viewinstances

    foreach inst $viewinstances($view) {
        stop_instance $inst
    }
    set viewinstances($view) {}
}

proc reset_pending_select {selid} {
    global pending_select mainheadid

    if {$selid ne {}} {
        set pending_select $selid
    } else {
        set pending_select $mainheadid
    }
}

proc getcommits {selid} {
    global canv curview need_redisplay viewactive

    initlayout
    if {[start_rev_list $curview]} {
        reset_pending_select $selid
        show_status [mc "Reading commits..."]
        set need_redisplay 1
    } else {
        show_status [mc "No commits selected"]
    }
}

proc updatecommits {} {
    global curview vcanopt vorigargs vfilelimit viewinstances
    global viewactive viewcomplete tclencoding
    global startmsecs showneartags showlocalchanges
    global mainheadid pending_select
    global isworktree
    global varcid vposids vnegids vflags vrevs

    set isworktree [expr {[exec git rev-parse --is-inside-work-tree] == "true"}]
    set oldmainid $mainheadid
    rereadrefs
    if {$showlocalchanges} {
        if {$mainheadid ne $oldmainid} {
            dohidelocalchanges
        }
        if {[commitinview $mainheadid $curview]} {
            dodiffindex
        }
    }
    set view $curview
    if {$vcanopt($view)} {
        set oldpos $vposids($view)
        set oldneg $vnegids($view)
        set revs [parseviewrevs $view $vrevs($view)]
        if {$revs eq {}} {
            return
        }
        # note: getting the delta when negative refs change is hard,
        # and could require multiple git log invocations, so in that
        # case we ask git log for all the commits (not just the delta)
        if {$oldneg eq $vnegids($view)} {
            set newrevs {}
            set npos 0
            # take out positive refs that we asked for before or
            # that we have already seen
            foreach rev $revs {
                if {[string length $rev] == 40} {
                    if {[lsearch -exact $oldpos $rev] < 0
                        && ![info exists varcid($view,$rev)]} {
                        lappend newrevs $rev
                        incr npos
                    }
                } else {
                    lappend $newrevs $rev
                }
            }
            if {$npos == 0} return
            set revs $newrevs
            set vposids($view) [lsort -unique [concat $oldpos $vposids($view)]]
        }
        set args [concat $vflags($view) $revs --not $oldpos]
    } else {
        set args $vorigargs($view)
    }
    if {[catch {
        set fd [open [concat | git log --no-color -z --pretty=raw --parents \
                          --boundary $args "--" $vfilelimit($view)] r]
    } err]} {
        error_popup "Error executing git log: $err"
        return
    }
    if {$viewactive($view) == 0} {
        set startmsecs [clock clicks -milliseconds]
    }
    set i [reg_instance $fd]
    lappend viewinstances($view) $i
    fconfigure $fd -blocking 0 -translation lf -eofchar {}
    if {$tclencoding != {}} {
        fconfigure $fd -encoding $tclencoding
    }
    filerun $fd [list getcommitlines $fd $i $view 1]
    incr viewactive($view)
    set viewcomplete($view) 0
    reset_pending_select {}
    nowbusy $view "Reading"
    if {$showneartags} {
        getallcommits
    }
}

proc reloadcommits {} {
    global curview viewcomplete selectedline currentid thickerline
    global showneartags treediffs commitinterest cached_commitrow
    global targetid

    set selid {}
    if {$selectedline ne {}} {
        set selid $currentid
    }

    if {!$viewcomplete($curview)} {
        stop_rev_list $curview
    }
    resetvarcs $curview
    set selectedline {}
    catch {unset currentid}
    catch {unset thickerline}
    catch {unset treediffs}
    readrefs
    changedrefs
    if {$showneartags} {
        getallcommits
    }
    clear_display
    catch {unset commitinterest}
    catch {unset cached_commitrow}
    catch {unset targetid}
    setcanvscroll
    getcommits $selid
    return 0
}

# This makes a string representation of a positive integer which
# sorts as a string in numerical order
proc strrep {n} {
    if {$n < 16} {
        return [format "%x" $n]
    } elseif {$n < 256} {
        return [format "x%.2x" $n]
    } elseif {$n < 65536} {
        return [format "y%.4x" $n]
    }
    return [format "z%.8x" $n]
}

# Procedures used in reordering commits from git log (without
# --topo-order) into the order for display.

proc varcinit {view} {
    global varcstart vupptr vdownptr vleftptr vbackptr varctok varcrow
    global vtokmod varcmod vrowmod varcix vlastins

    set varcstart($view) {{}}
    set vupptr($view) {0}
    set vdownptr($view) {0}
    set vleftptr($view) {0}
    set vbackptr($view) {0}
    set varctok($view) {{}}
    set varcrow($view) {{}}
    set vtokmod($view) {}
    set varcmod($view) 0
    set vrowmod($view) 0
    set varcix($view) {{}}
    set vlastins($view) {0}
}

proc resetvarcs {view} {
    global varcid varccommits parents children vseedcount ordertok

    foreach vid [array names varcid $view,*] {
        unset varcid($vid)
        unset children($vid)
        unset parents($vid)
    }
    # some commits might have children but haven't been seen yet
    foreach vid [array names children $view,*] {
        unset children($vid)
    }
    foreach va [array names varccommits $view,*] {
        unset varccommits($va)
    }
    foreach vd [array names vseedcount $view,*] {
        unset vseedcount($vd)
    }
    catch {unset ordertok}
}

# returns a list of the commits with no children
proc seeds {v} {
    global vdownptr vleftptr varcstart

    set ret {}
    set a [lindex $vdownptr($v) 0]
    while {$a != 0} {
        lappend ret [lindex $varcstart($v) $a]
        set a [lindex $vleftptr($v) $a]
    }
    return $ret
}

proc newvarc {view id} {
    global varcid varctok parents children vdatemode
    global vupptr vdownptr vleftptr vbackptr varcrow varcix varcstart
    global commitdata commitinfo vseedcount varccommits vlastins

    set a [llength $varctok($view)]
    set vid $view,$id
    if {[llength $children($vid)] == 0 || $vdatemode($view)} {
        if {![info exists commitinfo($id)]} {
            parsecommit $id $commitdata($id) 1
        }
        set cdate [lindex $commitinfo($id) 4]
        if {![string is integer -strict $cdate]} {
            set cdate 0
        }
        if {![info exists vseedcount($view,$cdate)]} {
            set vseedcount($view,$cdate) -1
        }
        set c [incr vseedcount($view,$cdate)]
        set cdate [expr {$cdate ^ 0xffffffff}]
        set tok "s[strrep $cdate][strrep $c]"
    } else {
        set tok {}
    }
    set ka 0
    if {[llength $children($vid)] > 0} {
        set kid [lindex $children($vid) end]
        set k $varcid($view,$kid)
        if {[string compare [lindex $varctok($view) $k] $tok] > 0} {
            set ki $kid
            set ka $k
            set tok [lindex $varctok($view) $k]
        }
    }
    if {$ka != 0} {
        set i [lsearch -exact $parents($view,$ki) $id]
        set j [expr {[llength $parents($view,$ki)] - 1 - $i}]
        append tok [strrep $j]
    }
    set c [lindex $vlastins($view) $ka]
    if {$c == 0 || [string compare $tok [lindex $varctok($view) $c]] < 0} {
        set c $ka
        set b [lindex $vdownptr($view) $ka]
    } else {
        set b [lindex $vleftptr($view) $c]
    }
    while {$b != 0 && [string compare $tok [lindex $varctok($view) $b]] >= 0} {
        set c $b
        set b [lindex $vleftptr($view) $c]
    }
    if {$c == $ka} {
        lset vdownptr($view) $ka $a
        lappend vbackptr($view) 0
    } else {
        lset vleftptr($view) $c $a
        lappend vbackptr($view) $c
    }
    lset vlastins($view) $ka $a
    lappend vupptr($view) $ka
    lappend vleftptr($view) $b
    if {$b != 0} {
        lset vbackptr($view) $b $a
    }
    lappend varctok($view) $tok
    lappend varcstart($view) $id
    lappend vdownptr($view) 0
    lappend varcrow($view) {}
    lappend varcix($view) {}
    set varccommits($view,$a) {}
    lappend vlastins($view) 0
    return $a
}

proc splitvarc {p v} {
    global varcid varcstart varccommits varctok
    global vupptr vdownptr vleftptr vbackptr varcix varcrow vlastins

    set oa $varcid($v,$p)
    set ac $varccommits($v,$oa)
    set i [lsearch -exact $varccommits($v,$oa) $p]
    if {$i <= 0} return
    set na [llength $varctok($v)]
    # "%" sorts before "0"...
    set tok "[lindex $varctok($v) $oa]%[strrep $i]"
    lappend varctok($v) $tok
    lappend varcrow($v) {}
    lappend varcix($v) {}
    set varccommits($v,$oa) [lrange $ac 0 [expr {$i - 1}]]
    set varccommits($v,$na) [lrange $ac $i end]
    lappend varcstart($v) $p
    foreach id $varccommits($v,$na) {
        set varcid($v,$id) $na
    }
    lappend vdownptr($v) [lindex $vdownptr($v) $oa]
    lappend vlastins($v) [lindex $vlastins($v) $oa]
    lset vdownptr($v) $oa $na
    lset vlastins($v) $oa 0
    lappend vupptr($v) $oa
    lappend vleftptr($v) 0
    lappend vbackptr($v) 0
    for {set b [lindex $vdownptr($v) $na]} {$b != 0} {set b [lindex $vleftptr($v) $b]} {
        lset vupptr($v) $b $na
    }
}

proc renumbervarc {a v} {
    global parents children varctok varcstart varccommits
    global vupptr vdownptr vleftptr vbackptr vlastins varcid vtokmod vdatemode

    set t1 [clock clicks -milliseconds]
    set todo {}
    set isrelated($a) 1
    set kidchanged($a) 1
    set ntot 0
    while {$a != 0} {
        if {[info exists isrelated($a)]} {
            lappend todo $a
            set id [lindex $varccommits($v,$a) end]
            foreach p $parents($v,$id) {
                if {[info exists varcid($v,$p)]} {
                    set isrelated($varcid($v,$p)) 1
                }
            }
        }
        incr ntot
        set b [lindex $vdownptr($v) $a]
        if {$b == 0} {
            while {$a != 0} {
                set b [lindex $vleftptr($v) $a]
                if {$b != 0} break
                set a [lindex $vupptr($v) $a]
            }
        }
        set a $b
    }
    foreach a $todo {
        if {![info exists kidchanged($a)]} continue
        set id [lindex $varcstart($v) $a]
        if {[llength $children($v,$id)] > 1} {
            set children($v,$id) [lsort -command [list vtokcmp $v] \
                                      $children($v,$id)]
        }
        set oldtok [lindex $varctok($v) $a]
        if {!$vdatemode($v)} {
            set tok {}
        } else {
            set tok $oldtok
        }
        set ka 0
        set kid [last_real_child $v,$id]
        if {$kid ne {}} {
            set k $varcid($v,$kid)
            if {[string compare [lindex $varctok($v) $k] $tok] > 0} {
                set ki $kid
                set ka $k
                set tok [lindex $varctok($v) $k]
            }
        }
        if {$ka != 0} {
            set i [lsearch -exact $parents($v,$ki) $id]
            set j [expr {[llength $parents($v,$ki)] - 1 - $i}]
            append tok [strrep $j]
        }
        if {$tok eq $oldtok} {
            continue
        }
        set id [lindex $varccommits($v,$a) end]
        foreach p $parents($v,$id) {
            if {[info exists varcid($v,$p)]} {
                set kidchanged($varcid($v,$p)) 1
            } else {
                set sortkids($p) 1
            }
        }
        lset varctok($v) $a $tok
        set b [lindex $vupptr($v) $a]
        if {$b != $ka} {
            if {[string compare [lindex $varctok($v) $ka] $vtokmod($v)] < 0} {
                modify_arc $v $ka
            }
            if {[string compare [lindex $varctok($v) $b] $vtokmod($v)] < 0} {
                modify_arc $v $b
            }
            set c [lindex $vbackptr($v) $a]
            set d [lindex $vleftptr($v) $a]
            if {$c == 0} {
                lset vdownptr($v) $b $d
            } else {
                lset vleftptr($v) $c $d
            }
            if {$d != 0} {
                lset vbackptr($v) $d $c
            }
            if {[lindex $vlastins($v) $b] == $a} {
                lset vlastins($v) $b $c
            }
            lset vupptr($v) $a $ka
            set c [lindex $vlastins($v) $ka]
            if {$c == 0 || \
                    [string compare $tok [lindex $varctok($v) $c]] < 0} {
                set c $ka
                set b [lindex $vdownptr($v) $ka]
            } else {
                set b [lindex $vleftptr($v) $c]
            }
            while {$b != 0 && \
                      [string compare $tok [lindex $varctok($v) $b]] >= 0} {
                set c $b
                set b [lindex $vleftptr($v) $c]
            }
            if {$c == $ka} {
                lset vdownptr($v) $ka $a
                lset vbackptr($v) $a 0
            } else {
                lset vleftptr($v) $c $a
                lset vbackptr($v) $a $c
            }
            lset vleftptr($v) $a $b
            if {$b != 0} {
                lset vbackptr($v) $b $a
            }
            lset vlastins($v) $ka $a
        }
    }
    foreach id [array names sortkids] {
        if {[llength $children($v,$id)] > 1} {
            set children($v,$id) [lsort -command [list vtokcmp $v] \
                                      $children($v,$id)]
        }
    }
    set t2 [clock clicks -milliseconds]
    #puts "renumbervarc did [llength $todo] of $ntot arcs in [expr {$t2-$t1}]ms"
}

# Fix up the graph after we have found out that in view $v,
# $p (a commit that we have already seen) is actually the parent
# of the last commit in arc $a.
proc fix_reversal {p a v} {
    global varcid varcstart varctok vupptr

    set pa $varcid($v,$p)
    if {$p ne [lindex $varcstart($v) $pa]} {
        splitvarc $p $v
        set pa $varcid($v,$p)
    }
    # seeds always need to be renumbered
    if {[lindex $vupptr($v) $pa] == 0 ||
        [string compare [lindex $varctok($v) $a] \
             [lindex $varctok($v) $pa]] > 0} {
        renumbervarc $pa $v
    }
}

proc insertrow {id p v} {
    global cmitlisted children parents varcid varctok vtokmod
    global varccommits ordertok commitidx numcommits curview
    global targetid targetrow

    readcommit $id
    set vid $v,$id
    set cmitlisted($vid) 1
    set children($vid) {}
    set parents($vid) [list $p]
    set a [newvarc $v $id]
    set varcid($vid) $a
    if {[string compare [lindex $varctok($v) $a] $vtokmod($v)] < 0} {
        modify_arc $v $a
    }
    lappend varccommits($v,$a) $id
    set vp $v,$p
    if {[llength [lappend children($vp) $id]] > 1} {
        set children($vp) [lsort -command [list vtokcmp $v] $children($vp)]
        catch {unset ordertok}
    }
    fix_reversal $p $a $v
    incr commitidx($v)
    if {$v == $curview} {
        set numcommits $commitidx($v)
        setcanvscroll
        if {[info exists targetid]} {
            if {![comes_before $targetid $p]} {
                incr targetrow
            }
        }
    }
}

proc insertfakerow {id p} {
    global varcid varccommits parents children cmitlisted
    global commitidx varctok vtokmod targetid targetrow curview numcommits

    set v $curview
    set a $varcid($v,$p)
    set i [lsearch -exact $varccommits($v,$a) $p]
    if {$i < 0} {
        puts "oops: insertfakerow can't find [shortids $p] on arc $a"
        return
    }
    set children($v,$id) {}
    set parents($v,$id) [list $p]
    set varcid($v,$id) $a
    lappend children($v,$p) $id
    set cmitlisted($v,$id) 1
    set numcommits [incr commitidx($v)]
    # note we deliberately don't update varcstart($v) even if $i == 0
    set varccommits($v,$a) [linsert $varccommits($v,$a) $i $id]
    modify_arc $v $a $i
    if {[info exists targetid]} {
        if {![comes_before $targetid $p]} {
            incr targetrow
        }
    }
    setcanvscroll
    drawvisible
}

proc removefakerow {id} {
    global varcid varccommits parents children commitidx
    global varctok vtokmod cmitlisted currentid selectedline
    global targetid curview numcommits

    set v $curview
    if {[llength $parents($v,$id)] != 1} {
        puts "oops: removefakerow [shortids $id] has [llength $parents($v,$id)] parents"
        return
    }
    set p [lindex $parents($v,$id) 0]
    set a $varcid($v,$id)
    set i [lsearch -exact $varccommits($v,$a) $id]
    if {$i < 0} {
        puts "oops: removefakerow can't find [shortids $id] on arc $a"
        return
    }
    unset varcid($v,$id)
    set varccommits($v,$a) [lreplace $varccommits($v,$a) $i $i]
    unset parents($v,$id)
    unset children($v,$id)
    unset cmitlisted($v,$id)
    set numcommits [incr commitidx($v) -1]
    set j [lsearch -exact $children($v,$p) $id]
    if {$j >= 0} {
        set children($v,$p) [lreplace $children($v,$p) $j $j]
    }
    modify_arc $v $a $i
    if {[info exist currentid] && $id eq $currentid} {
        unset currentid
        set selectedline {}
    }
    if {[info exists targetid] && $targetid eq $id} {
        set targetid $p
    }
    setcanvscroll
    drawvisible
}

proc first_real_child {vp} {
    global children nullid nullid2

    foreach id $children($vp) {
        if {$id ne $nullid && $id ne $nullid2} {
            return $id
        }
    }
    return {}
}

proc last_real_child {vp} {
    global children nullid nullid2

    set kids $children($vp)
    for {set i [llength $kids]} {[incr i -1] >= 0} {} {
        set id [lindex $kids $i]
        if {$id ne $nullid && $id ne $nullid2} {
            return $id
        }
    }
    return {}
}

proc vtokcmp {v a b} {
    global varctok varcid

    return [string compare [lindex $varctok($v) $varcid($v,$a)] \
                [lindex $varctok($v) $varcid($v,$b)]]
}

# This assumes that if lim is not given, the caller has checked that
# arc a's token is less than $vtokmod($v)
proc modify_arc {v a {lim {}}} {
    global varctok vtokmod varcmod varcrow vupptr curview vrowmod varccommits

    if {$lim ne {}} {
        set c [string compare [lindex $varctok($v) $a] $vtokmod($v)]
        if {$c > 0} return
        if {$c == 0} {
            set r [lindex $varcrow($v) $a]
            if {$r ne {} && $vrowmod($v) <= $r + $lim} return
        }
    }
    set vtokmod($v) [lindex $varctok($v) $a]
    set varcmod($v) $a
    if {$v == $curview} {
        while {$a != 0 && [lindex $varcrow($v) $a] eq {}} {
            set a [lindex $vupptr($v) $a]
            set lim {}
        }
        set r 0
        if {$a != 0} {
            if {$lim eq {}} {
                set lim [llength $varccommits($v,$a)]
            }
            set r [expr {[lindex $varcrow($v) $a] + $lim}]
        }
        set vrowmod($v) $r
        undolayout $r
    }
}

proc update_arcrows {v} {
    global vtokmod varcmod vrowmod varcrow commitidx currentid selectedline
    global varcid vrownum varcorder varcix varccommits
    global vupptr vdownptr vleftptr varctok
    global displayorder parentlist curview cached_commitrow

    if {$vrowmod($v) == $commitidx($v)} return
    if {$v == $curview} {
        if {[llength $displayorder] > $vrowmod($v)} {
            set displayorder [lrange $displayorder 0 [expr {$vrowmod($v) - 1}]]
            set parentlist [lrange $parentlist 0 [expr {$vrowmod($v) - 1}]]
        }
        catch {unset cached_commitrow}
    }
    set narctot [expr {[llength $varctok($v)] - 1}]
    set a $varcmod($v)
    while {$a != 0 && [lindex $varcix($v) $a] eq {}} {
        # go up the tree until we find something that has a row number,
        # or we get to a seed
        set a [lindex $vupptr($v) $a]
    }
    if {$a == 0} {
        set a [lindex $vdownptr($v) 0]
        if {$a == 0} return
        set vrownum($v) {0}
        set varcorder($v) [list $a]
        lset varcix($v) $a 0
        lset varcrow($v) $a 0
        set arcn 0
        set row 0
    } else {
        set arcn [lindex $varcix($v) $a]
        if {[llength $vrownum($v)] > $arcn + 1} {
            set vrownum($v) [lrange $vrownum($v) 0 $arcn]
            set varcorder($v) [lrange $varcorder($v) 0 $arcn]
        }
        set row [lindex $varcrow($v) $a]
    }
    while {1} {
        set p $a
        incr row [llength $varccommits($v,$a)]
        # go down if possible
        set b [lindex $vdownptr($v) $a]
        if {$b == 0} {
            # if not, go left, or go up until we can go left
            while {$a != 0} {
                set b [lindex $vleftptr($v) $a]
                if {$b != 0} break
                set a [lindex $vupptr($v) $a]
            }
            if {$a == 0} break
        }
        set a $b
        incr arcn
        lappend vrownum($v) $row
        lappend varcorder($v) $a
        lset varcix($v) $a $arcn
        lset varcrow($v) $a $row
    }
    set vtokmod($v) [lindex $varctok($v) $p]
    set varcmod($v) $p
    set vrowmod($v) $row
    if {[info exists currentid]} {
        set selectedline [rowofcommit $currentid]
    }
}

# Test whether view $v contains commit $id
proc commitinview {id v} {
    global varcid

    return [info exists varcid($v,$id)]
}

# Return the row number for commit $id in the current view
proc rowofcommit {id} {
    global varcid varccommits varcrow curview cached_commitrow
    global varctok vtokmod

    set v $curview
    if {![info exists varcid($v,$id)]} {
        puts "oops rowofcommit no arc for [shortids $id]"
        return {}
    }
    set a $varcid($v,$id)
    if {[string compare [lindex $varctok($v) $a] $vtokmod($v)] >= 0} {
        update_arcrows $v
    }
    if {[info exists cached_commitrow($id)]} {
        return $cached_commitrow($id)
    }
    set i [lsearch -exact $varccommits($v,$a) $id]
    if {$i < 0} {
        puts "oops didn't find commit [shortids $id] in arc $a"
        return {}
    }
    incr i [lindex $varcrow($v) $a]
    set cached_commitrow($id) $i
    return $i
}

# Returns 1 if a is on an earlier row than b, otherwise 0
proc comes_before {a b} {
    global varcid varctok curview

    set v $curview
    if {$a eq $b || ![info exists varcid($v,$a)] || \
            ![info exists varcid($v,$b)]} {
        return 0
    }
    if {$varcid($v,$a) != $varcid($v,$b)} {
        return [expr {[string compare [lindex $varctok($v) $varcid($v,$a)] \
                           [lindex $varctok($v) $varcid($v,$b)]] < 0}]
    }
    return [expr {[rowofcommit $a] < [rowofcommit $b]}]
}

proc bsearch {l elt} {
    if {[llength $l] == 0 || $elt <= [lindex $l 0]} {
        return 0
    }
    set lo 0
    set hi [llength $l]
    while {$hi - $lo > 1} {
        set mid [expr {int(($lo + $hi) / 2)}]
        set t [lindex $l $mid]
        if {$elt < $t} {
            set hi $mid
        } elseif {$elt > $t} {
            set lo $mid
        } else {
            return $mid
        }
    }
    return $lo
}

# Make sure rows $start..$end-1 are valid in displayorder and parentlist
proc make_disporder {start end} {
    global vrownum curview commitidx displayorder parentlist
    global varccommits varcorder parents vrowmod varcrow
    global d_valid_start d_valid_end

    if {$end > $vrowmod($curview)} {
        update_arcrows $curview
    }
    set ai [bsearch $vrownum($curview) $start]
    set start [lindex $vrownum($curview) $ai]
    set narc [llength $vrownum($curview)]
    for {set r $start} {$ai < $narc && $r < $end} {incr ai} {
        set a [lindex $varcorder($curview) $ai]
        set l [llength $displayorder]
        set al [llength $varccommits($curview,$a)]
        if {$l < $r + $al} {
            if {$l < $r} {
                set pad [ntimes [expr {$r - $l}] {}]
                set displayorder [concat $displayorder $pad]
                set parentlist [concat $parentlist $pad]
            } elseif {$l > $r} {
                set displayorder [lrange $displayorder 0 [expr {$r - 1}]]
                set parentlist [lrange $parentlist 0 [expr {$r - 1}]]
            }
            foreach id $varccommits($curview,$a) {
                lappend displayorder $id
                lappend parentlist $parents($curview,$id)
            }
        } elseif {[lindex $displayorder [expr {$r + $al - 1}]] eq {}} {
            set i $r
            foreach id $varccommits($curview,$a) {
                lset displayorder $i $id
                lset parentlist $i $parents($curview,$id)
                incr i
            }
        }
        incr r $al
    }
}

proc commitonrow {row} {
    global displayorder

    set id [lindex $displayorder $row]
    if {$id eq {}} {
        make_disporder $row [expr {$row + 1}]
        set id [lindex $displayorder $row]
    }
    return $id
}

proc closevarcs {v} {
    global varctok varccommits varcid parents children
    global cmitlisted commitidx commitinterest vtokmod

    set missing_parents 0
    set scripts {}
    set narcs [llength $varctok($v)]
    for {set a 1} {$a < $narcs} {incr a} {
        set id [lindex $varccommits($v,$a) end]
        foreach p $parents($v,$id) {
            if {[info exists varcid($v,$p)]} continue
            # add p as a new commit
            incr missing_parents
            set cmitlisted($v,$p) 0
            set parents($v,$p) {}
            if {[llength $children($v,$p)] == 1 &&
                [llength $parents($v,$id)] == 1} {
                set b $a
            } else {
                set b [newvarc $v $p]
            }
            set varcid($v,$p) $b
            if {[string compare [lindex $varctok($v) $b] $vtokmod($v)] < 0} {
                modify_arc $v $b
            }
            lappend varccommits($v,$b) $p
            incr commitidx($v)
            if {[info exists commitinterest($p)]} {
                foreach script $commitinterest($p) {
                    lappend scripts [string map [list "%I" $p] $script]
                }
                unset commitinterest($id)
            }
        }
    }
    if {$missing_parents > 0} {
        foreach s $scripts {
            eval $s
        }
    }
}

# Use $rwid as a substitute for $id, i.e. reparent $id's children to $rwid
# Assumes we already have an arc for $rwid.
proc rewrite_commit {v id rwid} {
    global children parents varcid varctok vtokmod varccommits

    foreach ch $children($v,$id) {
        # make $rwid be $ch's parent in place of $id
        set i [lsearch -exact $parents($v,$ch) $id]
        if {$i < 0} {
            puts "oops rewrite_commit didn't find $id in parent list for $ch"
        }
        set parents($v,$ch) [lreplace $parents($v,$ch) $i $i $rwid]
        # add $ch to $rwid's children and sort the list if necessary
        if {[llength [lappend children($v,$rwid) $ch]] > 1} {
            set children($v,$rwid) [lsort -command [list vtokcmp $v] \
                                        $children($v,$rwid)]
        }
        # fix the graph after joining $id to $rwid
        set a $varcid($v,$ch)
        fix_reversal $rwid $a $v
        # parentlist is wrong for the last element of arc $a
        # even if displayorder is right, hence the 3rd arg here
        modify_arc $v $a [expr {[llength $varccommits($v,$a)] - 1}]
    }
}

proc getcommitlines {fd inst view updating}  {
    global cmitlisted commitinterest leftover
    global commitidx commitdata vdatemode
    global parents children curview hlview
    global idpending ordertok
    global varccommits varcid varctok vtokmod vfilelimit

    set stuff [read $fd 500000]
    # git log doesn't terminate the last commit with a null...
    if {$stuff == {} && $leftover($inst) ne {} && [eof $fd]} {
        set stuff "\0"
    }
    if {$stuff == {}} {
        if {![eof $fd]} {
            return 1
        }
        global commfd viewcomplete viewactive viewname
        global viewinstances
        unset commfd($inst)
        set i [lsearch -exact $viewinstances($view) $inst]
        if {$i >= 0} {
            set viewinstances($view) [lreplace $viewinstances($view) $i $i]
        }
        # set it blocking so we wait for the process to terminate
        fconfigure $fd -blocking 1
        if {[catch {close $fd} err]} {
            set fv {}
            if {$view != $curview} {
                set fv " for the \"$viewname($view)\" view"
            }
            if {[string range $err 0 4] == "usage"} {
                set err "Gitk: error reading commits$fv:\
                        bad arguments to git log."
                if {$viewname($view) eq "Command line"} {
                    append err \
                        "  (Note: arguments to gitk are passed to git log\
                         to allow selection of commits to be displayed.)"
                }
            } else {
                set err "Error reading commits$fv: $err"
            }
            error_popup $err
        }
        if {[incr viewactive($view) -1] <= 0} {
            set viewcomplete($view) 1
            # Check if we have seen any ids listed as parents that haven't
            # appeared in the list
            closevarcs $view
            notbusy $view
        }
        if {$view == $curview} {
            run chewcommits
        }
        return 0
    }
    set start 0
    set gotsome 0
    set scripts {}
    while 1 {
        set i [string first "\0" $stuff $start]
        if {$i < 0} {
            append leftover($inst) [string range $stuff $start end]
            break
        }
        if {$start == 0} {
            set cmit $leftover($inst)
            append cmit [string range $stuff 0 [expr {$i - 1}]]
            set leftover($inst) {}
        } else {
            set cmit [string range $stuff $start [expr {$i - 1}]]
        }
        set start [expr {$i + 1}]
        set j [string first "\n" $cmit]
        set ok 0
        set listed 1
        if {$j >= 0 && [string match "commit *" $cmit]} {
            set ids [string range $cmit 7 [expr {$j - 1}]]
            if {[string match {[-^<>]*} $ids]} {
                switch -- [string index $ids 0] {
                    "-" {set listed 0}
                    "^" {set listed 2}
                    "<" {set listed 3}
                    ">" {set listed 4}
                }
                set ids [string range $ids 1 end]
            }
            set ok 1
            foreach id $ids {
                if {[string length $id] != 40} {
                    set ok 0
                    break
                }
            }
        }
        if {!$ok} {
            set shortcmit $cmit
            if {[string length $shortcmit] > 80} {
                set shortcmit "[string range $shortcmit 0 80]..."
            }
            error_popup "[mc "Can't parse git log output:"] {$shortcmit}"
            exit 1
        }
        set id [lindex $ids 0]
        set vid $view,$id

        if {!$listed && $updating && ![info exists varcid($vid)] &&
            $vfilelimit($view) ne {}} {
            # git log doesn't rewrite parents for unlisted commits
            # when doing path limiting, so work around that here
            # by working out the rewritten parent with git rev-list
            # and if we already know about it, using the rewritten
            # parent as a substitute parent for $id's children.
            if {![catch {
                set rwid [exec git rev-list --first-parent --max-count=1 \
                              $id -- $vfilelimit($view)]
            }]} {
                if {$rwid ne {} && [info exists varcid($view,$rwid)]} {
                    # use $rwid in place of $id
                    rewrite_commit $view $id $rwid
                    continue
                }
            }
        }

        set a 0
        if {[info exists varcid($vid)]} {
            if {$cmitlisted($vid) || !$listed} continue
            set a $varcid($vid)
        }
        if {$listed} {
            set olds [lrange $ids 1 end]
        } else {
            set olds {}
        }
        set commitdata($id) [string range $cmit [expr {$j + 1}] end]
        set cmitlisted($vid) $listed
        set parents($vid) $olds
        if {![info exists children($vid)]} {
            set children($vid) {}
        } elseif {$a == 0 && [llength $children($vid)] == 1} {
            set k [lindex $children($vid) 0]
            if {[llength $parents($view,$k)] == 1 &&
                (!$vdatemode($view) ||
                 $varcid($view,$k) == [llength $varctok($view)] - 1)} {
                set a $varcid($view,$k)
            }
        }
        if {$a == 0} {
            # new arc
            set a [newvarc $view $id]
        }
        if {[string compare [lindex $varctok($view) $a] $vtokmod($view)] < 0} {
            modify_arc $view $a
        }
        if {![info exists varcid($vid)]} {
            set varcid($vid) $a
            lappend varccommits($view,$a) $id
            incr commitidx($view)
        }

        set i 0
        foreach p $olds {
            if {$i == 0 || [lsearch -exact $olds $p] >= $i} {
                set vp $view,$p
                if {[llength [lappend children($vp) $id]] > 1 &&
                    [vtokcmp $view [lindex $children($vp) end-1] $id] > 0} {
                    set children($vp) [lsort -command [list vtokcmp $view] \
                                           $children($vp)]
                    catch {unset ordertok}
                }
                if {[info exists varcid($view,$p)]} {
                    fix_reversal $p $a $view
                }
            }
            incr i
        }

        if {[info exists commitinterest($id)]} {
            foreach script $commitinterest($id) {
                lappend scripts [string map [list "%I" $id] $script]
            }
            unset commitinterest($id)
        }
        set gotsome 1
    }
    if {$gotsome} {
        global numcommits hlview

        if {$view == $curview} {
            set numcommits $commitidx($view)
            run chewcommits
        }
        if {[info exists hlview] && $view == $hlview} {
            # we never actually get here...
            run vhighlightmore
        }
        foreach s $scripts {
            eval $s
        }
    }
    return 2
}

proc chewcommits {} {
    global curview hlview viewcomplete
    global pending_select

    layoutmore
    if {$viewcomplete($curview)} {
        global commitidx varctok
        global numcommits startmsecs

        if {[info exists pending_select]} {
            update
            reset_pending_select {}

            if {[commitinview $pending_select $curview]} {
                selectline [rowofcommit $pending_select] 1
            } else {
                set row [first_real_row]
                selectline $row 1
            }
        }
        if {$commitidx($curview) > 0} {
            #set ms [expr {[clock clicks -milliseconds] - $startmsecs}]
            #puts "overall $ms ms for $numcommits commits"
            #puts "[llength $varctok($view)] arcs, $commitidx($view) commits"
        } else {
            show_status [mc "No commits selected"]
        }
        notbusy layout
    }
    return 0
}

proc readcommit {id} {
    if {[catch {set contents [exec git cat-file commit $id]}]} return
    parsecommit $id $contents 0
}

proc parsecommit {id contents listed} {
    global commitinfo cdate

    set inhdr 1
    set comment {}
    set headline {}
    set auname {}
    set audate {}
    set comname {}
    set comdate {}
    set hdrend [string first "\n\n" $contents]
    if {$hdrend < 0} {
        # should never happen...
        set hdrend [string length $contents]
    }
    set header [string range $contents 0 [expr {$hdrend - 1}]]
    set comment [string range $contents [expr {$hdrend + 2}] end]
    foreach line [split $header "\n"] {
        set tag [lindex $line 0]
        if {$tag == "author"} {
            set audate [lindex $line end-1]
            set auname [lrange $line 1 end-2]
        } elseif {$tag == "committer"} {
            set comdate [lindex $line end-1]
            set comname [lrange $line 1 end-2]
        }
    }
    set headline {}
    # take the first non-blank line of the comment as the headline
    set headline [string trimleft $comment]
    set i [string first "\n" $headline]
    if {$i >= 0} {
        set headline [string range $headline 0 $i]
    }
    set headline [string trimright $headline]
    set i [string first "\r" $headline]
    if {$i >= 0} {
        set headline [string trimright [string range $headline 0 $i]]
    }
    if {!$listed} {
        # git log indents the comment by 4 spaces;
        # if we got this via git cat-file, add the indentation
        set newcomment {}
        foreach line [split $comment "\n"] {
            append newcomment "    "
            append newcomment $line
            append newcomment "\n"
        }
        set comment $newcomment
    }
    if {$comdate != {}} {
        set cdate($id) $comdate
    }
    set commitinfo($id) [list $headline $auname $audate \
                             $comname $comdate $comment]
}

proc getcommit {id} {
    global commitdata commitinfo

    if {[info exists commitdata($id)]} {
        parsecommit $id $commitdata($id) 1
    } else {
        readcommit $id
        if {![info exists commitinfo($id)]} {
            set commitinfo($id) [list [mc "No commit information available"]]
        }
    }
    return 1
}

proc readrefs {} {
    global tagids idtags headids idheads tagobjid
    global otherrefids idotherrefs mainhead mainheadid

    foreach v {tagids idtags headids idheads otherrefids idotherrefs} {
        catch {unset $v}
    }
    set refd [open [list | git show-ref -d] r]
    while {[gets $refd line] >= 0} {
        if {[string index $line 40] ne " "} continue
        set id [string range $line 0 39]
        set ref [string range $line 41 end]
        if {![string match "refs/*" $ref]} continue
        set name [string range $ref 5 end]
        if {[string match "remotes/*" $name]} {
            if {![string match "*/HEAD" $name]} {
                set headids($name) $id
                lappend idheads($id) $name
            }
        } elseif {[string match "heads/*" $name]} {
            set name [string range $name 6 end]
            set headids($name) $id
            lappend idheads($id) $name
        } elseif {[string match "tags/*" $name]} {
            # this lets refs/tags/foo^{} overwrite refs/tags/foo,
            # which is what we want since the former is the commit ID
            set name [string range $name 5 end]
            if {[string match "*^{}" $name]} {
                set name [string range $name 0 end-3]
            } else {
                set tagobjid($name) $id
            }
            set tagids($name) $id
            lappend idtags($id) $name
        } else {
            set otherrefids($name) $id
            lappend idotherrefs($id) $name
        }
    }
    catch {close $refd}
    set mainhead {}
    set mainheadid {}
    catch {
        set mainheadid [exec git rev-parse HEAD]
        set thehead [exec git symbolic-ref HEAD]
        if {[string match "refs/heads/*" $thehead]} {
            set mainhead [string range $thehead 11 end]
        }
    }
}

# skip over fake commits
proc first_real_row {} {
    global nullid nullid2 numcommits

    for {set row 0} {$row < $numcommits} {incr row} {
        set id [commitonrow $row]
        if {$id ne $nullid && $id ne $nullid2} {
            break
        }
    }
    return $row
}

# update things for a head moved to a child of its previous location
proc movehead {id name} {
    global headids idheads

    removehead $headids($name) $name
    set headids($name) $id
    lappend idheads($id) $name
}

# update things when a head has been removed
proc removehead {id name} {
    global headids idheads

    if {$idheads($id) eq $name} {
        unset idheads($id)
    } else {
        set i [lsearch -exact $idheads($id) $name]
        if {$i >= 0} {
            set idheads($id) [lreplace $idheads($id) $i $i]
        }
    }
    unset headids($name)
}

proc show_error {w top msg} {
    message $w.m -text $msg -justify center -aspect 400
    pack $w.m -side top -fill x -padx 20 -pady 20
    button $w.ok -text [mc OK] -command "destroy $top"
    pack $w.ok -side bottom -fill x
    bind $top <Visibility> "grab $top; focus $top"
    bind $top <Key-Return> "destroy $top"
    tkwait window $top
}

proc error_popup msg {
    set w .error
    toplevel $w
    wm transient $w .
    show_error $w $w $msg
}

proc confirm_popup msg {
    global confirm_ok
    set confirm_ok 0
    set w .confirm
    toplevel $w
    wm transient $w .
    message $w.m -text $msg -justify center -aspect 400
    pack $w.m -side top -fill x -padx 20 -pady 20
    button $w.ok -text [mc OK] -command "set confirm_ok 1; destroy $w"
    pack $w.ok -side left -fill x
    button $w.cancel -text [mc Cancel] -command "destroy $w"
    pack $w.cancel -side right -fill x
    bind $w <Visibility> "grab $w; focus $w"
    tkwait window $w
    return $confirm_ok
}

proc setoptions {} {
    option add *Panedwindow.showHandle 1 startupFile
    option add *Panedwindow.sashRelief raised startupFile
    option add *Button.font uifont startupFile
    option add *Checkbutton.font uifont startupFile
    option add *Radiobutton.font uifont startupFile
    option add *Menu.font uifont startupFile
    option add *Menubutton.font uifont startupFile
    option add *Label.font uifont startupFile
    option add *Message.font uifont startupFile
    option add *Entry.font uifont startupFile
}

proc makewindow {} {
    global canv canv2 canv3 linespc charspc ctext cflist cscroll
    global tabstop
    global findtype findtypemenu findloc findstring fstring geometry
    global entries sha1entry sha1string sha1but
    global diffcontextstring diffcontext
    global ignorespace
    global maincursor textcursor curtextcursor
    global rowctxmenu fakerowmenu mergemax wrapcomment
    global highlight_files gdttype
    global searchstring sstring
    global bgcolor fgcolor bglist fglist diffcolors selectbgcolor
    global headctxmenu progresscanv progressitem progresscoords statusw
    global fprogitem fprogcoord lastprogupdate progupdatepending
    global rprogitem rprogcoord rownumsel numcommits
    global have_tk85

    menu .bar
    .bar add cascade -label [mc "File"] -menu .bar.file
    menu .bar.file
    .bar.file add command -label [mc "Update"] -command updatecommits
    .bar.file add command -label [mc "Reload"] -command reloadcommits
    .bar.file add command -label [mc "Reread references"] -command rereadrefs
    .bar.file add command -label [mc "List references"] -command showrefs
    .bar.file add command -label [mc "Quit"] -command doquit
    menu .bar.edit
    .bar add cascade -label [mc "Edit"] -menu .bar.edit
    .bar.edit add command -label [mc "Preferences"] -command doprefs

    menu .bar.view
    .bar add cascade -label [mc "View"] -menu .bar.view
    .bar.view add command -label [mc "New view..."] -command {newview 0}
    .bar.view add command -label [mc "Edit view..."] -command editview \
        -state disabled
    .bar.view add command -label [mc "Delete view"] -command delview -state disabled
    .bar.view add separator
    .bar.view add radiobutton -label [mc "All files"] -command {showview 0} \
        -variable selectedview -value 0

    menu .bar.help
    .bar add cascade -label [mc "Help"] -menu .bar.help
    .bar.help add command -label [mc "About gitk"] -command about
    .bar.help add command -label [mc "Key bindings"] -command keys
    .bar.help configure
    . configure -menu .bar

    # the gui has upper and lower half, parts of a paned window.
    panedwindow .ctop -orient vertical

    # possibly use assumed geometry
    if {![info exists geometry(pwsash0)]} {
        set geometry(topheight) [expr {15 * $linespc}]
        set geometry(topwidth) [expr {80 * $charspc}]
        set geometry(botheight) [expr {15 * $linespc}]
        set geometry(botwidth) [expr {50 * $charspc}]
        set geometry(pwsash0) "[expr {40 * $charspc}] 2"
        set geometry(pwsash1) "[expr {60 * $charspc}] 2"
    }

    # the upper half will have a paned window, a scroll bar to the right, and some stuff below
    frame .tf -height $geometry(topheight) -width $geometry(topwidth)
    frame .tf.histframe
    panedwindow .tf.histframe.pwclist -orient horizontal -sashpad 0 -handlesize 4

    # create three canvases
    set cscroll .tf.histframe.csb
    set canv .tf.histframe.pwclist.canv
    canvas $canv \
        -selectbackground $selectbgcolor \
        -background $bgcolor -bd 0 \
        -yscrollincr $linespc -yscrollcommand "scrollcanv $cscroll"
    .tf.histframe.pwclist add $canv
    set canv2 .tf.histframe.pwclist.canv2
    canvas $canv2 \
        -selectbackground $selectbgcolor \
        -background $bgcolor -bd 0 -yscrollincr $linespc
    .tf.histframe.pwclist add $canv2
    set canv3 .tf.histframe.pwclist.canv3
    canvas $canv3 \
        -selectbackground $selectbgcolor \
        -background $bgcolor -bd 0 -yscrollincr $linespc
    .tf.histframe.pwclist add $canv3
    eval .tf.histframe.pwclist sash place 0 $geometry(pwsash0)
    eval .tf.histframe.pwclist sash place 1 $geometry(pwsash1)

    # a scroll bar to rule them
    scrollbar $cscroll -command {allcanvs yview} -highlightthickness 0
    pack $cscroll -side right -fill y
    bind .tf.histframe.pwclist <Configure> {resizeclistpanes %W %w}
    lappend bglist $canv $canv2 $canv3
    pack .tf.histframe.pwclist -fill both -expand 1 -side left

    # we have two button bars at bottom of top frame. Bar 1
    frame .tf.bar
    frame .tf.lbar -height 15

    set sha1entry .tf.bar.sha1
    set entries $sha1entry
    set sha1but .tf.bar.sha1label
    button $sha1but -text [mc "SHA1 ID: "] -state disabled -relief flat \
        -command gotocommit -width 8
    $sha1but conf -disabledforeground [$sha1but cget -foreground]
    pack .tf.bar.sha1label -side left
    entry $sha1entry -width 40 -font textfont -textvariable sha1string
    trace add variable sha1string write sha1change
    pack $sha1entry -side left -pady 2

    image create bitmap bm-left -data {
        #define left_width 16
        #define left_height 16
        static unsigned char left_bits[] = {
        0x00, 0x00, 0xc0, 0x01, 0xe0, 0x00, 0x70, 0x00, 0x38, 0x00, 0x1c, 0x00,
        0x0e, 0x00, 0xff, 0x7f, 0xff, 0x7f, 0xff, 0x7f, 0x0e, 0x00, 0x1c, 0x00,
        0x38, 0x00, 0x70, 0x00, 0xe0, 0x00, 0xc0, 0x01};
    }
    image create bitmap bm-right -data {
        #define right_width 16
        #define right_height 16
        static unsigned char right_bits[] = {
        0x00, 0x00, 0xc0, 0x01, 0x80, 0x03, 0x00, 0x07, 0x00, 0x0e, 0x00, 0x1c,
        0x00, 0x38, 0xff, 0x7f, 0xff, 0x7f, 0xff, 0x7f, 0x00, 0x38, 0x00, 0x1c,
        0x00, 0x0e, 0x00, 0x07, 0x80, 0x03, 0xc0, 0x01};
    }
    button .tf.bar.leftbut -image bm-left -command goback \
        -state disabled -width 26
    pack .tf.bar.leftbut -side left -fill y
    button .tf.bar.rightbut -image bm-right -command goforw \
        -state disabled -width 26
    pack .tf.bar.rightbut -side left -fill y

    label .tf.bar.rowlabel -text [mc "Row"]
    set rownumsel {}
    label .tf.bar.rownum -width 7 -font textfont -textvariable rownumsel \
        -relief sunken -anchor e
    label .tf.bar.rowlabel2 -text "/"
    label .tf.bar.numcommits -width 7 -font textfont -textvariable numcommits \
        -relief sunken -anchor e
    pack .tf.bar.rowlabel .tf.bar.rownum .tf.bar.rowlabel2 .tf.bar.numcommits \
        -side left
    global selectedline
    trace add variable selectedline write selectedline_change

    # Status label and progress bar
    set statusw .tf.bar.status
    label $statusw -width 15 -relief sunken
    pack $statusw -side left -padx 5
    set h [expr {[font metrics uifont -linespace] + 2}]
    set progresscanv .tf.bar.progress
    canvas $progresscanv -relief sunken -height $h -borderwidth 2
    set progressitem [$progresscanv create rect -1 0 0 $h -fill green]
    set fprogitem [$progresscanv create rect -1 0 0 $h -fill yellow]
    set rprogitem [$progresscanv create rect -1 0 0 $h -fill red]
    pack $progresscanv -side right -expand 1 -fill x
    set progresscoords {0 0}
    set fprogcoord 0
    set rprogcoord 0
    bind $progresscanv <Configure> adjustprogress
    set lastprogupdate [clock clicks -milliseconds]
    set progupdatepending 0

    # build up the bottom bar of upper window
    label .tf.lbar.flabel -text "[mc "Find"] "
    button .tf.lbar.fnext -text [mc "next"] -command {dofind 1 1}
    button .tf.lbar.fprev -text [mc "prev"] -command {dofind -1 1}
    label .tf.lbar.flab2 -text " [mc "commit"] "
    pack .tf.lbar.flabel .tf.lbar.fnext .tf.lbar.fprev .tf.lbar.flab2 \
        -side left -fill y
    set gdttype [mc "containing:"]
    set gm [tk_optionMenu .tf.lbar.gdttype gdttype \
                [mc "containing:"] \
                [mc "touching paths:"] \
                [mc "adding/removing string:"]]
    trace add variable gdttype write gdttype_change
    pack .tf.lbar.gdttype -side left -fill y

    set findstring {}
    set fstring .tf.lbar.findstring
    lappend entries $fstring
    entry $fstring -width 30 -font textfont -textvariable findstring
    trace add variable findstring write find_change
    set findtype [mc "Exact"]
    set findtypemenu [tk_optionMenu .tf.lbar.findtype \
                      findtype [mc "Exact"] [mc "IgnCase"] [mc "Regexp"]]
    trace add variable findtype write findcom_change
    set findloc [mc "All fields"]
    tk_optionMenu .tf.lbar.findloc findloc [mc "All fields"] [mc "Headline"] \
        [mc "Comments"] [mc "Author"] [mc "Committer"]
    trace add variable findloc write find_change
    pack .tf.lbar.findloc -side right
    pack .tf.lbar.findtype -side right
    pack $fstring -side left -expand 1 -fill x

    # Finish putting the upper half of the viewer together
    pack .tf.lbar -in .tf -side bottom -fill x
    pack .tf.bar -in .tf -side bottom -fill x
    pack .tf.histframe -fill both -side top -expand 1
    .ctop add .tf
    .ctop paneconfigure .tf -height $geometry(topheight)
    .ctop paneconfigure .tf -width $geometry(topwidth)

    # now build up the bottom
    panedwindow .pwbottom -orient horizontal

    # lower left, a text box over search bar, scroll bar to the right
    # if we know window height, then that will set the lower text height, otherwise
    # we set lower text height which will drive window height
    if {[info exists geometry(main)]} {
        frame .bleft -width $geometry(botwidth)
    } else {
        frame .bleft -width $geometry(botwidth) -height $geometry(botheight)
    }
    frame .bleft.top
    frame .bleft.mid
    frame .bleft.bottom

    button .bleft.top.search -text [mc "Search"] -command dosearch
    pack .bleft.top.search -side left -padx 5
    set sstring .bleft.top.sstring
    entry $sstring -width 20 -font textfont -textvariable searchstring
    lappend entries $sstring
    trace add variable searchstring write incrsearch
    pack $sstring -side left -expand 1 -fill x
    radiobutton .bleft.mid.diff -text [mc "Diff"] \
        -command changediffdisp -variable diffelide -value {0 0}
    radiobutton .bleft.mid.old -text [mc "Old version"] \
        -command changediffdisp -variable diffelide -value {0 1}
    radiobutton .bleft.mid.new -text [mc "New version"] \
        -command changediffdisp -variable diffelide -value {1 0}
    label .bleft.mid.labeldiffcontext -text "      [mc "Lines of context"]: "
    pack .bleft.mid.diff .bleft.mid.old .bleft.mid.new -side left
    spinbox .bleft.mid.diffcontext -width 5 -font textfont \
        -from 1 -increment 1 -to 10000000 \
        -validate all -validatecommand "diffcontextvalidate %P" \
        -textvariable diffcontextstring
    .bleft.mid.diffcontext set $diffcontext
    trace add variable diffcontextstring write diffcontextchange
    lappend entries .bleft.mid.diffcontext
    pack .bleft.mid.labeldiffcontext .bleft.mid.diffcontext -side left
    checkbutton .bleft.mid.ignspace -text [mc "Ignore space change"] \
        -command changeignorespace -variable ignorespace
    pack .bleft.mid.ignspace -side left -padx 5
    set ctext .bleft.bottom.ctext
    text $ctext -background $bgcolor -foreground $fgcolor \
        -state disabled -font textfont \
        -yscrollcommand scrolltext -wrap none \
        -xscrollcommand ".bleft.bottom.sbhorizontal set"
    if {$have_tk85} {
        $ctext conf -tabstyle wordprocessor
    }
    scrollbar .bleft.bottom.sb -command "$ctext yview"
    scrollbar .bleft.bottom.sbhorizontal -command "$ctext xview" -orient h \
        -width 10
    pack .bleft.top -side top -fill x
    pack .bleft.mid -side top -fill x
    grid $ctext .bleft.bottom.sb -sticky nsew
    grid .bleft.bottom.sbhorizontal -sticky ew
    grid columnconfigure .bleft.bottom 0 -weight 1
    grid rowconfigure .bleft.bottom 0 -weight 1
    grid rowconfigure .bleft.bottom 1 -weight 0
    pack .bleft.bottom -side top -fill both -expand 1
    lappend bglist $ctext
    lappend fglist $ctext

    $ctext tag conf comment -wrap $wrapcomment
    $ctext tag conf filesep -font textfontbold -back "#aaaaaa"
    $ctext tag conf hunksep -fore [lindex $diffcolors 2]
    $ctext tag conf d0 -fore [lindex $diffcolors 0]
    $ctext tag conf d1 -fore [lindex $diffcolors 1]
    $ctext tag conf m0 -fore red
    $ctext tag conf m1 -fore blue
    $ctext tag conf m2 -fore green
    $ctext tag conf m3 -fore purple
    $ctext tag conf m4 -fore brown
    $ctext tag conf m5 -fore "#009090"
    $ctext tag conf m6 -fore magenta
    $ctext tag conf m7 -fore "#808000"
    $ctext tag conf m8 -fore "#009000"
    $ctext tag conf m9 -fore "#ff0080"
    $ctext tag conf m10 -fore cyan
    $ctext tag conf m11 -fore "#b07070"
    $ctext tag conf m12 -fore "#70b0f0"
    $ctext tag conf m13 -fore "#70f0b0"
    $ctext tag conf m14 -fore "#f0b070"
    $ctext tag conf m15 -fore "#ff70b0"
    $ctext tag conf mmax -fore darkgrey
    set mergemax 16
    $ctext tag conf mresult -font textfontbold
    $ctext tag conf msep -font textfontbold
    $ctext tag conf found -back yellow

    .pwbottom add .bleft
    .pwbottom paneconfigure .bleft -width $geometry(botwidth)

    # lower right
    frame .bright
    frame .bright.mode
    radiobutton .bright.mode.patch -text [mc "Patch"] \
        -command reselectline -variable cmitmode -value "patch"
    radiobutton .bright.mode.tree -text [mc "Tree"] \
        -command reselectline -variable cmitmode -value "tree"
    grid .bright.mode.patch .bright.mode.tree -sticky ew
    pack .bright.mode -side top -fill x
    set cflist .bright.cfiles
    set indent [font measure mainfont "nn"]
    text $cflist \
        -selectbackground $selectbgcolor \
        -background $bgcolor -foreground $fgcolor \
        -font mainfont \
        -tabs [list $indent [expr {2 * $indent}]] \
        -yscrollcommand ".bright.sb set" \
        -cursor [. cget -cursor] \
        -spacing1 1 -spacing3 1
    lappend bglist $cflist
    lappend fglist $cflist
    scrollbar .bright.sb -command "$cflist yview"
    pack .bright.sb -side right -fill y
    pack $cflist -side left -fill both -expand 1
    $cflist tag configure highlight \
        -background [$cflist cget -selectbackground]
    $cflist tag configure bold -font mainfontbold

    .pwbottom add .bright
    .ctop add .pwbottom

    # restore window width & height if known
    if {[info exists geometry(main)]} {
        if {[scan $geometry(main) "%dx%d" w h] >= 2} {
            if {$w > [winfo screenwidth .]} {
                set w [winfo screenwidth .]
            }
            if {$h > [winfo screenheight .]} {
                set h [winfo screenheight .]
            }
            wm geometry . "${w}x$h"
        }
    }

    if {[tk windowingsystem] eq {aqua}} {
        set M1B M1
    } else {
        set M1B Control
    }

    bind .pwbottom <Configure> {resizecdetpanes %W %w}
    pack .ctop -fill both -expand 1
    bindall <1> {selcanvline %W %x %y}
    #bindall <B1-Motion> {selcanvline %W %x %y}
    if {[tk windowingsystem] == "win32"} {
        bind . <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D }
        bind $ctext <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D ; break }
    } else {
        bindall <ButtonRelease-4> "allcanvs yview scroll -5 units"
        bindall <ButtonRelease-5> "allcanvs yview scroll 5 units"
        if {[tk windowingsystem] eq "aqua"} {
            bindall <MouseWheel> {
                set delta [expr {- (%D)}]
                allcanvs yview scroll $delta units
            }
        }
    }
    bindall <2> "canvscan mark %W %x %y"
    bindall <B2-Motion> "canvscan dragto %W %x %y"
    bindkey <Home> selfirstline
    bindkey <End> sellastline
    bind . <Key-Up> "selnextline -1"
    bind . <Key-Down> "selnextline 1"
    bind . <Shift-Key-Up> "dofind -1 0"
    bind . <Shift-Key-Down> "dofind 1 0"
    bindkey <Key-Right> "goforw"
    bindkey <Key-Left> "goback"
    bind . <Key-Prior> "selnextpage -1"
    bind . <Key-Next> "selnextpage 1"
    bind . <$M1B-Home> "allcanvs yview moveto 0.0"
    bind . <$M1B-End> "allcanvs yview moveto 1.0"
    bind . <$M1B-Key-Up> "allcanvs yview scroll -1 units"
    bind . <$M1B-Key-Down> "allcanvs yview scroll 1 units"
    bind . <$M1B-Key-Prior> "allcanvs yview scroll -1 pages"
    bind . <$M1B-Key-Next> "allcanvs yview scroll 1 pages"
    bindkey <Key-Delete> "$ctext yview scroll -1 pages"
    bindkey <Key-BackSpace> "$ctext yview scroll -1 pages"
    bindkey <Key-space> "$ctext yview scroll 1 pages"
    bindkey p "selnextline -1"
    bindkey n "selnextline 1"
    bindkey z "goback"
    bindkey x "goforw"
    bindkey i "selnextline -1"
    bindkey k "selnextline 1"
    bindkey j "goback"
    bindkey l "goforw"
    bindkey b prevfile
    bindkey d "$ctext yview scroll 18 units"
    bindkey u "$ctext yview scroll -18 units"
    bindkey / {dofind 1 1}
    bindkey <Key-Return> {dofind 1 1}
    bindkey ? {dofind -1 1}
    bindkey f nextfile
    bindkey <F5> updatecommits
    bind . <$M1B-q> doquit
    bind . <$M1B-f> {dofind 1 1}
    bind . <$M1B-g> {dofind 1 0}
    bind . <$M1B-r> dosearchback
    bind . <$M1B-s> dosearch
    bind . <$M1B-equal> {incrfont 1}
    bind . <$M1B-plus> {incrfont 1}
    bind . <$M1B-KP_Add> {incrfont 1}
    bind . <$M1B-minus> {incrfont -1}
    bind . <$M1B-KP_Subtract> {incrfont -1}
    wm protocol . WM_DELETE_WINDOW doquit
    bind . <Destroy> {stop_backends}
    bind . <Button-1> "click %W"
    bind $fstring <Key-Return> {dofind 1 1}
    bind $sha1entry <Key-Return> gotocommit
    bind $sha1entry <<PasteSelection>> clearsha1
    bind $cflist <1> {sel_flist %W %x %y; break}
    bind $cflist <B1-Motion> {sel_flist %W %x %y; break}
    bind $cflist <ButtonRelease-1> {treeclick %W %x %y}
    bind $cflist <Button-3> {pop_flist_menu %W %X %Y %x %y}

    set maincursor [. cget -cursor]
    set textcursor [$ctext cget -cursor]
    set curtextcursor $textcursor

    set rowctxmenu .rowctxmenu
    menu $rowctxmenu -tearoff 0
    $rowctxmenu add command -label [mc "Diff this -> selected"] \
        -command {diffvssel 0}
    $rowctxmenu add command -label [mc "Diff selected -> this"] \
        -command {diffvssel 1}
    $rowctxmenu add command -label [mc "Make patch"] -command mkpatch
    $rowctxmenu add command -label [mc "Create tag"] -command mktag
    $rowctxmenu add command -label [mc "Write commit to file"] -command writecommit
    $rowctxmenu add command -label [mc "Create new branch"] -command mkbranch
    $rowctxmenu add command -label [mc "Cherry-pick this commit"] \
        -command cherrypick
    $rowctxmenu add command -label [mc "Reset HEAD branch to here"] \
        -command resethead

    set fakerowmenu .fakerowmenu
    menu $fakerowmenu -tearoff 0
    $fakerowmenu add command -label [mc "Diff this -> selected"] \
        -command {diffvssel 0}
    $fakerowmenu add command -label [mc "Diff selected -> this"] \
        -command {diffvssel 1}
    $fakerowmenu add command -label [mc "Make patch"] -command mkpatch
#    $fakerowmenu add command -label [mc "Commit"] -command {mkcommit 0}
#    $fakerowmenu add command -label [mc "Commit all"] -command {mkcommit 1}
#    $fakerowmenu add command -label [mc "Revert local changes"] -command revertlocal

    set headctxmenu .headctxmenu
    menu $headctxmenu -tearoff 0
    $headctxmenu add command -label [mc "Check out this branch"] \
        -command cobranch
    $headctxmenu add command -label [mc "Remove this branch"] \
        -command rmbranch

    global flist_menu
    set flist_menu .flistctxmenu
    menu $flist_menu -tearoff 0
    $flist_menu add command -label [mc "Highlight this too"] \
        -command {flist_hl 0}
    $flist_menu add command -label [mc "Highlight this only"] \
        -command {flist_hl 1}
    $flist_menu add command -label [mc "External diff"] \
        -command {external_diff}
}

# Windows sends all mouse wheel events to the current focused window, not
# the one where the mouse hovers, so bind those events here and redirect
# to the correct window
proc windows_mousewheel_redirector {W X Y D} {
    global canv canv2 canv3
    set w [winfo containing -displayof $W $X $Y]
    if {$w ne ""} {
        set u [expr {$D < 0 ? 5 : -5}]
        if {$w == $canv || $w == $canv2 || $w == $canv3} {
            allcanvs yview scroll $u units
        } else {
            catch {
                $w yview scroll $u units
            }
        }
    }
}

# Update row number label when selectedline changes
proc selectedline_change {n1 n2 op} {
    global selectedline rownumsel

    if {$selectedline eq {}} {
        set rownumsel {}
    } else {
        set rownumsel [expr {$selectedline + 1}]
    }
}

# mouse-2 makes all windows scan vertically, but only the one
# the cursor is in scans horizontally
proc canvscan {op w x y} {
    global canv canv2 canv3
    foreach c [list $canv $canv2 $canv3] {
        if {$c == $w} {
            $c scan $op $x $y
        } else {
            $c scan $op 0 $y
        }
    }
}

proc scrollcanv {cscroll f0 f1} {
    $cscroll set $f0 $f1
    drawvisible
    flushhighlights
}

# when we make a key binding for the toplevel, make sure
# it doesn't get triggered when that key is pressed in the
# find string entry widget.
proc bindkey {ev script} {
    global entries
    bind . $ev $script
    set escript [bind Entry $ev]
    if {$escript == {}} {
        set escript [bind Entry <Key>]
    }
    foreach e $entries {
        bind $e $ev "$escript; break"
    }
}

# set the focus back to the toplevel for any click outside
# the entry widgets
proc click {w} {
    global ctext entries
    foreach e [concat $entries $ctext] {
        if {$w == $e} return
    }
    focus .
}

# Adjust the progress bar for a change in requested extent or canvas size
proc adjustprogress {} {
    global progresscanv progressitem progresscoords
    global fprogitem fprogcoord lastprogupdate progupdatepending
    global rprogitem rprogcoord

    set w [expr {[winfo width $progresscanv] - 4}]
    set x0 [expr {$w * [lindex $progresscoords 0]}]
    set x1 [expr {$w * [lindex $progresscoords 1]}]
    set h [winfo height $progresscanv]
    $progresscanv coords $progressitem $x0 0 $x1 $h
    $progresscanv coords $fprogitem 0 0 [expr {$w * $fprogcoord}] $h
    $progresscanv coords $rprogitem 0 0 [expr {$w * $rprogcoord}] $h
    set now [clock clicks -milliseconds]
    if {$now >= $lastprogupdate + 100} {
        set progupdatepending 0
        update
    } elseif {!$progupdatepending} {
        set progupdatepending 1
        after [expr {$lastprogupdate + 100 - $now}] doprogupdate
    }
}

proc doprogupdate {} {
    global lastprogupdate progupdatepending

    if {$progupdatepending} {
        set progupdatepending 0
        set lastprogupdate [clock clicks -milliseconds]
        update
    }
}

proc savestuff {w} {
    global canv canv2 canv3 mainfont textfont uifont tabstop
    global stuffsaved findmergefiles maxgraphpct
    global maxwidth showneartags showlocalchanges
    global viewname viewfiles viewargs viewargscmd viewperm nextviewnum
    global cmitmode wrapcomment datetimeformat limitdiffs
    global colors bgcolor fgcolor diffcolors diffcontext selectbgcolor
    global autoselect extdifftool

    if {$stuffsaved} return
    if {![winfo viewable .]} return
    catch {
        set f [open "~/.gitk-new" w]
        puts $f [list set mainfont $mainfont]
        puts $f [list set textfont $textfont]
        puts $f [list set uifont $uifont]
        puts $f [list set tabstop $tabstop]
        puts $f [list set findmergefiles $findmergefiles]
        puts $f [list set maxgraphpct $maxgraphpct]
        puts $f [list set maxwidth $maxwidth]
        puts $f [list set cmitmode $cmitmode]
        puts $f [list set wrapcomment $wrapcomment]
        puts $f [list set autoselect $autoselect]
        puts $f [list set showneartags $showneartags]
        puts $f [list set showlocalchanges $showlocalchanges]
        puts $f [list set datetimeformat $datetimeformat]
        puts $f [list set limitdiffs $limitdiffs]
        puts $f [list set bgcolor $bgcolor]
        puts $f [list set fgcolor $fgcolor]
        puts $f [list set colors $colors]
        puts $f [list set diffcolors $diffcolors]
        puts $f [list set diffcontext $diffcontext]
        puts $f [list set selectbgcolor $selectbgcolor]
        puts $f [list set extdifftool $extdifftool]

        puts $f "set geometry(main) [wm geometry .]"
        puts $f "set geometry(topwidth) [winfo width .tf]"
        puts $f "set geometry(topheight) [winfo height .tf]"
        puts $f "set geometry(pwsash0) \"[.tf.histframe.pwclist sash coord 0]\""
        puts $f "set geometry(pwsash1) \"[.tf.histframe.pwclist sash coord 1]\""
        puts $f "set geometry(botwidth) [winfo width .bleft]"
        puts $f "set geometry(botheight) [winfo height .bleft]"

        puts -nonewline $f "set permviews {"
        for {set v 0} {$v < $nextviewnum} {incr v} {
            if {$viewperm($v)} {
                puts $f "{[list $viewname($v) $viewfiles($v) $viewargs($v) $viewargscmd($v)]}"
            }
        }
        puts $f "}"
        close $f
        file rename -force "~/.gitk-new" "~/.gitk"
    }
    set stuffsaved 1
}

proc resizeclistpanes {win w} {
    global oldwidth
    if {[info exists oldwidth($win)]} {
        set s0 [$win sash coord 0]
        set s1 [$win sash coord 1]
        if {$w < 60} {
            set sash0 [expr {int($w/2 - 2)}]
            set sash1 [expr {int($w*5/6 - 2)}]
        } else {
            set factor [expr {1.0 * $w / $oldwidth($win)}]
            set sash0 [expr {int($factor * [lindex $s0 0])}]
            set sash1 [expr {int($factor * [lindex $s1 0])}]
            if {$sash0 < 30} {
                set sash0 30
            }
            if {$sash1 < $sash0 + 20} {
                set sash1 [expr {$sash0 + 20}]
            }
            if {$sash1 > $w - 10} {
                set sash1 [expr {$w - 10}]
                if {$sash0 > $sash1 - 20} {
                    set sash0 [expr {$sash1 - 20}]
                }
            }
        }
        $win sash place 0 $sash0 [lindex $s0 1]
        $win sash place 1 $sash1 [lindex $s1 1]
    }
    set oldwidth($win) $w
}

proc resizecdetpanes {win w} {
    global oldwidth
    if {[info exists oldwidth($win)]} {
        set s0 [$win sash coord 0]
        if {$w < 60} {
            set sash0 [expr {int($w*3/4 - 2)}]
        } else {
            set factor [expr {1.0 * $w / $oldwidth($win)}]
            set sash0 [expr {int($factor * [lindex $s0 0])}]
            if {$sash0 < 45} {
                set sash0 45
            }
            if {$sash0 > $w - 15} {
                set sash0 [expr {$w - 15}]
            }
        }
        $win sash place 0 $sash0 [lindex $s0 1]
    }
    set oldwidth($win) $w
}

proc allcanvs args {
    global canv canv2 canv3
    eval $canv $args
    eval $canv2 $args
    eval $canv3 $args
}

proc bindall {event action} {
    global canv canv2 canv3
    bind $canv $event $action
    bind $canv2 $event $action
    bind $canv3 $event $action
}

proc about {} {
    global uifont
    set w .about
    if {[winfo exists $w]} {
        raise $w
        return
    }
    toplevel $w
    wm title $w [mc "About gitk"]
    message $w.m -text [mc "
Gitk - a commit viewer for git

Copyright © 2005-2008 Paul Mackerras

Use and redistribute under the terms of the GNU General Public License"] \
            -justify center -aspect 400 -border 2 -bg white -relief groove
    pack $w.m -side top -fill x -padx 2 -pady 2
    button $w.ok -text [mc "Close"] -command "destroy $w" -default active
    pack $w.ok -side bottom
    bind $w <Visibility> "focus $w.ok"
    bind $w <Key-Escape> "destroy $w"
    bind $w <Key-Return> "destroy $w"
}

proc keys {} {
    set w .keys
    if {[winfo exists $w]} {
        raise $w
        return
    }
    if {[tk windowingsystem] eq {aqua}} {
        set M1T Cmd
    } else {
        set M1T Ctrl
    }
    toplevel $w
    wm title $w [mc "Gitk key bindings"]
    message $w.m -text "
[mc "Gitk key bindings:"]

[mc "<%s-Q>             Quit" $M1T]
[mc "<Home>             Move to first commit"]
[mc "<End>              Move to last commit"]
[mc "<Up>, p, i Move up one commit"]
[mc "<Down>, n, k       Move down one commit"]
[mc "<Left>, z, j       Go back in history list"]
[mc "<Right>, x, l      Go forward in history list"]
[mc "<PageUp>   Move up one page in commit list"]
[mc "<PageDown> Move down one page in commit list"]
[mc "<%s-Home>  Scroll to top of commit list" $M1T]
[mc "<%s-End>   Scroll to bottom of commit list" $M1T]
[mc "<%s-Up>    Scroll commit list up one line" $M1T]
[mc "<%s-Down>  Scroll commit list down one line" $M1T]
[mc "<%s-PageUp>        Scroll commit list up one page" $M1T]
[mc "<%s-PageDown>      Scroll commit list down one page" $M1T]
[mc "<Shift-Up> Find backwards (upwards, later commits)"]
[mc "<Shift-Down>       Find forwards (downwards, earlier commits)"]
[mc "<Delete>, b        Scroll diff view up one page"]
[mc "<Backspace>        Scroll diff view up one page"]
[mc "<Space>            Scroll diff view down one page"]
[mc "u          Scroll diff view up 18 lines"]
[mc "d          Scroll diff view down 18 lines"]
[mc "<%s-F>             Find" $M1T]
[mc "<%s-G>             Move to next find hit" $M1T]
[mc "<Return>   Move to next find hit"]
[mc "/          Move to next find hit, or redo find"]
[mc "?          Move to previous find hit"]
[mc "f          Scroll diff view to next file"]
[mc "<%s-S>             Search for next hit in diff view" $M1T]
[mc "<%s-R>             Search for previous hit in diff view" $M1T]
[mc "<%s-KP+>   Increase font size" $M1T]
[mc "<%s-plus>  Increase font size" $M1T]
[mc "<%s-KP->   Decrease font size" $M1T]
[mc "<%s-minus> Decrease font size" $M1T]
[mc "<F5>               Update"]
" \
            -justify left -bg white -border 2 -relief groove
    pack $w.m -side top -fill both -padx 2 -pady 2
    button $w.ok -text [mc "Close"] -command "destroy $w" -default active
    pack $w.ok -side bottom
    bind $w <Visibility> "focus $w.ok"
    bind $w <Key-Escape> "destroy $w"
    bind $w <Key-Return> "destroy $w"
}

# Procedures for manipulating the file list window at the
# bottom right of the overall window.

proc treeview {w l openlevs} {
    global treecontents treediropen treeheight treeparent treeindex

    set ix 0
    set treeindex() 0
    set lev 0
    set prefix {}
    set prefixend -1
    set prefendstack {}
    set htstack {}
    set ht 0
    set treecontents() {}
    $w conf -state normal
    foreach f $l {
        while {[string range $f 0 $prefixend] ne $prefix} {
            if {$lev <= $openlevs} {
                $w mark set e:$treeindex($prefix) "end -1c"
                $w mark gravity e:$treeindex($prefix) left
            }
            set treeheight($prefix) $ht
            incr ht [lindex $htstack end]
            set htstack [lreplace $htstack end end]
            set prefixend [lindex $prefendstack end]
            set prefendstack [lreplace $prefendstack end end]
            set prefix [string range $prefix 0 $prefixend]
            incr lev -1
        }
        set tail [string range $f [expr {$prefixend+1}] end]
        while {[set slash [string first "/" $tail]] >= 0} {
            lappend htstack $ht
            set ht 0
            lappend prefendstack $prefixend
            incr prefixend [expr {$slash + 1}]
            set d [string range $tail 0 $slash]
            lappend treecontents($prefix) $d
            set oldprefix $prefix
            append prefix $d
            set treecontents($prefix) {}
            set treeindex($prefix) [incr ix]
            set treeparent($prefix) $oldprefix
            set tail [string range $tail [expr {$slash+1}] end]
            if {$lev <= $openlevs} {
                set ht 1
                set treediropen($prefix) [expr {$lev < $openlevs}]
                set bm [expr {$lev == $openlevs? "tri-rt": "tri-dn"}]
                $w mark set d:$ix "end -1c"
                $w mark gravity d:$ix left
                set str "\n"
                for {set i 0} {$i < $lev} {incr i} {append str "\t"}
                $w insert end $str
                $w image create end -align center -image $bm -padx 1 \
                    -name a:$ix
                $w insert end $d [highlight_tag $prefix]
                $w mark set s:$ix "end -1c"
                $w mark gravity s:$ix left
            }
            incr lev
        }
        if {$tail ne {}} {
            if {$lev <= $openlevs} {
                incr ht
                set str "\n"
                for {set i 0} {$i < $lev} {incr i} {append str "\t"}
                $w insert end $str
                $w insert end $tail [highlight_tag $f]
            }
            lappend treecontents($prefix) $tail
        }
    }
    while {$htstack ne {}} {
        set treeheight($prefix) $ht
        incr ht [lindex $htstack end]
        set htstack [lreplace $htstack end end]
        set prefixend [lindex $prefendstack end]
        set prefendstack [lreplace $prefendstack end end]
        set prefix [string range $prefix 0 $prefixend]
    }
    $w conf -state disabled
}

proc linetoelt {l} {
    global treeheight treecontents

    set y 2
    set prefix {}
    while {1} {
        foreach e $treecontents($prefix) {
            if {$y == $l} {
                return "$prefix$e"
            }
            set n 1
            if {[string index $e end] eq "/"} {
                set n $treeheight($prefix$e)
                if {$y + $n > $l} {
                    append prefix $e
                    incr y
                    break
                }
            }
            incr y $n
        }
    }
}

proc highlight_tree {y prefix} {
    global treeheight treecontents cflist

    foreach e $treecontents($prefix) {
        set path $prefix$e
        if {[highlight_tag $path] ne {}} {
            $cflist tag add bold $y.0 "$y.0 lineend"
        }
        incr y
        if {[string index $e end] eq "/" && $treeheight($path) > 1} {
            set y [highlight_tree $y $path]
        }
    }
    return $y
}

proc treeclosedir {w dir} {
    global treediropen treeheight treeparent treeindex

    set ix $treeindex($dir)
    $w conf -state normal
    $w delete s:$ix e:$ix
    set treediropen($dir) 0
    $w image configure a:$ix -image tri-rt
    $w conf -state disabled
    set n [expr {1 - $treeheight($dir)}]
    while {$dir ne {}} {
        incr treeheight($dir) $n
        set dir $treeparent($dir)
    }
}

proc treeopendir {w dir} {
    global treediropen treeheight treeparent treecontents treeindex

    set ix $treeindex($dir)
    $w conf -state normal
    $w image configure a:$ix -image tri-dn
    $w mark set e:$ix s:$ix
    $w mark gravity e:$ix right
    set lev 0
    set str "\n"
    set n [llength $treecontents($dir)]
    for {set x $dir} {$x ne {}} {set x $treeparent($x)} {
        incr lev
        append str "\t"
        incr treeheight($x) $n
    }
    foreach e $treecontents($dir) {
        set de $dir$e
        if {[string index $e end] eq "/"} {
            set iy $treeindex($de)
            $w mark set d:$iy e:$ix
            $w mark gravity d:$iy left
            $w insert e:$ix $str
            set treediropen($de) 0
            $w image create e:$ix -align center -image tri-rt -padx 1 \
                -name a:$iy
            $w insert e:$ix $e [highlight_tag $de]
            $w mark set s:$iy e:$ix
            $w mark gravity s:$iy left
            set treeheight($de) 1
        } else {
            $w insert e:$ix $str
            $w insert e:$ix $e [highlight_tag $de]
        }
    }
    $w mark gravity e:$ix left
    $w conf -state disabled
    set treediropen($dir) 1
    set top [lindex [split [$w index @0,0] .] 0]
    set ht [$w cget -height]
    set l [lindex [split [$w index s:$ix] .] 0]
    if {$l < $top} {
        $w yview $l.0
    } elseif {$l + $n + 1 > $top + $ht} {
        set top [expr {$l + $n + 2 - $ht}]
        if {$l < $top} {
            set top $l
        }
        $w yview $top.0
    }
}

proc treeclick {w x y} {
    global treediropen cmitmode ctext cflist cflist_top

    if {$cmitmode ne "tree"} return
    if {![info exists cflist_top]} return
    set l [lindex [split [$w index "@$x,$y"] "."] 0]
    $cflist tag remove highlight $cflist_top.0 "$cflist_top.0 lineend"
    $cflist tag add highlight $l.0 "$l.0 lineend"
    set cflist_top $l
    if {$l == 1} {
        $ctext yview 1.0
        return
    }
    set e [linetoelt $l]
    if {[string index $e end] ne "/"} {
        showfile $e
    } elseif {$treediropen($e)} {
        treeclosedir $w $e
    } else {
        treeopendir $w $e
    }
}

proc setfilelist {id} {
    global treefilelist cflist

    treeview $cflist $treefilelist($id) 0
}

image create bitmap tri-rt -background black -foreground blue -data {
    #define tri-rt_width 13
    #define tri-rt_height 13
    static unsigned char tri-rt_bits[] = {
       0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x30, 0x00, 0x70, 0x00, 0xf0, 0x00,
       0xf0, 0x01, 0xf0, 0x00, 0x70, 0x00, 0x30, 0x00, 0x10, 0x00, 0x00, 0x00,
       0x00, 0x00};
} -maskdata {
    #define tri-rt-mask_width 13
    #define tri-rt-mask_height 13
    static unsigned char tri-rt-mask_bits[] = {
       0x08, 0x00, 0x18, 0x00, 0x38, 0x00, 0x78, 0x00, 0xf8, 0x00, 0xf8, 0x01,
       0xf8, 0x03, 0xf8, 0x01, 0xf8, 0x00, 0x78, 0x00, 0x38, 0x00, 0x18, 0x00,
       0x08, 0x00};
}
image create bitmap tri-dn -background black -foreground blue -data {
    #define tri-dn_width 13
    #define tri-dn_height 13
    static unsigned char tri-dn_bits[] = {
       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfc, 0x07, 0xf8, 0x03,
       0xf0, 0x01, 0xe0, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
       0x00, 0x00};
} -maskdata {
    #define tri-dn-mask_width 13
    #define tri-dn-mask_height 13
    static unsigned char tri-dn-mask_bits[] = {
       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0x1f, 0xfe, 0x0f, 0xfc, 0x07,
       0xf8, 0x03, 0xf0, 0x01, 0xe0, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
       0x00, 0x00};
}

image create bitmap reficon-T -background black -foreground yellow -data {
    #define tagicon_width 13
    #define tagicon_height 9
    static unsigned char tagicon_bits[] = {
       0x00, 0x00, 0x00, 0x00, 0xf0, 0x07, 0xf8, 0x07,
       0xfc, 0x07, 0xf8, 0x07, 0xf0, 0x07, 0x00, 0x00, 0x00, 0x00};
} -maskdata {
    #define tagicon-mask_width 13
    #define tagicon-mask_height 9
    static unsigned char tagicon-mask_bits[] = {
       0x00, 0x00, 0xf0, 0x0f, 0xf8, 0x0f, 0xfc, 0x0f,
       0xfe, 0x0f, 0xfc, 0x0f, 0xf8, 0x0f, 0xf0, 0x0f, 0x00, 0x00};
}
set rectdata {
    #define headicon_width 13
    #define headicon_height 9
    static unsigned char headicon_bits[] = {
       0x00, 0x00, 0x00, 0x00, 0xf8, 0x07, 0xf8, 0x07,
       0xf8, 0x07, 0xf8, 0x07, 0xf8, 0x07, 0x00, 0x00, 0x00, 0x00};
}
set rectmask {
    #define headicon-mask_width 13
    #define headicon-mask_height 9
    static unsigned char headicon-mask_bits[] = {
       0x00, 0x00, 0xfc, 0x0f, 0xfc, 0x0f, 0xfc, 0x0f,
       0xfc, 0x0f, 0xfc, 0x0f, 0xfc, 0x0f, 0xfc, 0x0f, 0x00, 0x00};
}
image create bitmap reficon-H -background black -foreground green \
    -data $rectdata -maskdata $rectmask
image create bitmap reficon-o -background black -foreground "#ddddff" \
    -data $rectdata -maskdata $rectmask

proc init_flist {first} {
    global cflist cflist_top difffilestart

    $cflist conf -state normal
    $cflist delete 0.0 end
    if {$first ne {}} {
        $cflist insert end $first
        set cflist_top 1
        $cflist tag add highlight 1.0 "1.0 lineend"
    } else {
        catch {unset cflist_top}
    }
    $cflist conf -state disabled
    set difffilestart {}
}

proc highlight_tag {f} {
    global highlight_paths

    foreach p $highlight_paths {
        if {[string match $p $f]} {
            return "bold"
        }
    }
    return {}
}

proc highlight_filelist {} {
    global cmitmode cflist

    $cflist conf -state normal
    if {$cmitmode ne "tree"} {
        set end [lindex [split [$cflist index end] .] 0]
        for {set l 2} {$l < $end} {incr l} {
            set line [$cflist get $l.0 "$l.0 lineend"]
            if {[highlight_tag $line] ne {}} {
                $cflist tag add bold $l.0 "$l.0 lineend"
            }
        }
    } else {
        highlight_tree 2 {}
    }
    $cflist conf -state disabled
}

proc unhighlight_filelist {} {
    global cflist

    $cflist conf -state normal
    $cflist tag remove bold 1.0 end
    $cflist conf -state disabled
}

proc add_flist {fl} {
    global cflist

    $cflist conf -state normal
    foreach f $fl {
        $cflist insert end "\n"
        $cflist insert end $f [highlight_tag $f]
    }
    $cflist conf -state disabled
}

proc sel_flist {w x y} {
    global ctext difffilestart cflist cflist_top cmitmode

    if {$cmitmode eq "tree"} return
    if {![info exists cflist_top]} return
    set l [lindex [split [$w index "@$x,$y"] "."] 0]
    $cflist tag remove highlight $cflist_top.0 "$cflist_top.0 lineend"
    $cflist tag add highlight $l.0 "$l.0 lineend"
    set cflist_top $l
    if {$l == 1} {
        $ctext yview 1.0
    } else {
        catch {$ctext yview [lindex $difffilestart [expr {$l - 2}]]}
    }
}

proc pop_flist_menu {w X Y x y} {
    global ctext cflist cmitmode flist_menu flist_menu_file
    global treediffs diffids

    stopfinding
    set l [lindex [split [$w index "@$x,$y"] "."] 0]
    if {$l <= 1} return
    if {$cmitmode eq "tree"} {
        set e [linetoelt $l]
        if {[string index $e end] eq "/"} return
    } else {
        set e [lindex $treediffs($diffids) [expr {$l-2}]]
    }
    set flist_menu_file $e
    set xdiffstate "normal"
    if {$cmitmode eq "tree"} {
        set xdiffstate "disabled"
    }
    # Disable "External diff" item in tree mode
    $flist_menu entryconf 2 -state $xdiffstate
    tk_popup $flist_menu $X $Y
}

proc flist_hl {only} {
    global flist_menu_file findstring gdttype

    set x [shellquote $flist_menu_file]
    if {$only || $findstring eq {} || $gdttype ne [mc "touching paths:"]} {
        set findstring $x
    } else {
        append findstring " " $x
    }
    set gdttype [mc "touching paths:"]
}

proc save_file_from_commit {filename output what} {
    global nullfile

    if {[catch {exec git show $filename -- > $output} err]} {
        if {[string match "fatal: bad revision *" $err]} {
            return $nullfile
        }
        error_popup "Error getting \"$filename\" from $what: $err"
        return {}
    }
    return $output
}

proc external_diff_get_one_file {diffid filename diffdir} {
    global nullid nullid2 nullfile
    global gitdir

    if {$diffid == $nullid} {
        set difffile [file join [file dirname $gitdir] $filename]
        if {[file exists $difffile]} {
            return $difffile
        }
        return $nullfile
    }
    if {$diffid == $nullid2} {
        set difffile [file join $diffdir "\[index\] [file tail $filename]"]
        return [save_file_from_commit :$filename $difffile index]
    }
    set difffile [file join $diffdir "\[$diffid\] [file tail $filename]"]
    return [save_file_from_commit $diffid:$filename $difffile \
               "revision $diffid"]
}

proc external_diff {} {
    global gitktmpdir nullid nullid2
    global flist_menu_file
    global diffids
    global diffnum
    global gitdir extdifftool

    if {[llength $diffids] == 1} {
        # no reference commit given
        set diffidto [lindex $diffids 0]
        if {$diffidto eq $nullid} {
            # diffing working copy with index
            set diffidfrom $nullid2
        } elseif {$diffidto eq $nullid2} {
            # diffing index with HEAD
            set diffidfrom "HEAD"
        } else {
            # use first parent commit
            global parentlist selectedline
            set diffidfrom [lindex $parentlist $selectedline 0]
        }
    } else {
        set diffidfrom [lindex $diffids 0]
        set diffidto [lindex $diffids 1]
    }

    # make sure that several diffs wont collide
    if {![info exists gitktmpdir]} {
        set gitktmpdir [file join [file dirname $gitdir] \
                            [format ".gitk-tmp.%s" [pid]]]
        if {[catch {file mkdir $gitktmpdir} err]} {
            error_popup "Error creating temporary directory $gitktmpdir: $err"
            unset gitktmpdir
            return
        }
        set diffnum 0
    }
    incr diffnum
    set diffdir [file join $gitktmpdir $diffnum]
    if {[catch {file mkdir $diffdir} err]} {
        error_popup "Error creating temporary directory $diffdir: $err"
        return
    }

    # gather files to diff
    set difffromfile [external_diff_get_one_file $diffidfrom $flist_menu_file $diffdir]
    set difftofile [external_diff_get_one_file $diffidto $flist_menu_file $diffdir]

    if {$difffromfile ne {} && $difftofile ne {}} {
        set cmd [concat | [shellsplit $extdifftool] \
                     [list $difffromfile $difftofile]]
        if {[catch {set fl [open $cmd r]} err]} {
            file delete -force $diffdir
            error_popup [mc "$extdifftool: command failed: $err"]
        } else {
            fconfigure $fl -blocking 0
            filerun $fl [list delete_at_eof $fl $diffdir]
        }
    }
}

# delete $dir when we see eof on $f (presumably because the child has exited)
proc delete_at_eof {f dir} {
    while {[gets $f line] >= 0} {}
    if {[eof $f]} {
        if {[catch {close $f} err]} {
            error_popup "External diff viewer failed: $err"
        }
        file delete -force $dir
        return 0
    }
    return 1
}

# Functions for adding and removing shell-type quoting

proc shellquote {str} {
    if {![string match "*\['\"\\ \t]*" $str]} {
        return $str
    }
    if {![string match "*\['\"\\]*" $str]} {
        return "\"$str\""
    }
    if {![string match "*'*" $str]} {
        return "'$str'"
    }
    return "\"[string map {\" \\\" \\ \\\\} $str]\""
}

proc shellarglist {l} {
    set str {}
    foreach a $l {
        if {$str ne {}} {
            append str " "
        }
        append str [shellquote $a]
    }
    return $str
}

proc shelldequote {str} {
    set ret {}
    set used -1
    while {1} {
        incr used
        if {![regexp -start $used -indices "\['\"\\\\ \t]" $str first]} {
            append ret [string range $str $used end]
            set used [string length $str]
            break
        }
        set first [lindex $first 0]
        set ch [string index $str $first]
        if {$first > $used} {
            append ret [string range $str $used [expr {$first - 1}]]
            set used $first
        }
        if {$ch eq " " || $ch eq "\t"} break
        incr used
        if {$ch eq "'"} {
            set first [string first "'" $str $used]
            if {$first < 0} {
                error "unmatched single-quote"
            }
            append ret [string range $str $used [expr {$first - 1}]]
            set used $first
            continue
        }
        if {$ch eq "\\"} {
            if {$used >= [string length $str]} {
                error "trailing backslash"
            }
            append ret [string index $str $used]
            continue
        }
        # here ch == "\""
        while {1} {
            if {![regexp -start $used -indices "\[\"\\\\]" $str first]} {
                error "unmatched double-quote"
            }
            set first [lindex $first 0]
            set ch [string index $str $first]
            if {$first > $used} {
                append ret [string range $str $used [expr {$first - 1}]]
                set used $first
            }
            if {$ch eq "\""} break
            incr used
            append ret [string index $str $used]
            incr used
        }
    }
    return [list $used $ret]
}

proc shellsplit {str} {
    set l {}
    while {1} {
        set str [string trimleft $str]
        if {$str eq {}} break
        set dq [shelldequote $str]
        set n [lindex $dq 0]
        set word [lindex $dq 1]
        set str [string range $str $n end]
        lappend l $word
    }
    return $l
}

# Code to implement multiple views

proc newview {ishighlight} {
    global nextviewnum newviewname newviewperm newishighlight
    global newviewargs revtreeargs viewargscmd newviewargscmd curview

    set newishighlight $ishighlight
    set top .gitkview
    if {[winfo exists $top]} {
        raise $top
        return
    }
    set newviewname($nextviewnum) "[mc "View"] $nextviewnum"
    set newviewperm($nextviewnum) 0
    set newviewargs($nextviewnum) [shellarglist $revtreeargs]
    set newviewargscmd($nextviewnum) $viewargscmd($curview)
    vieweditor $top $nextviewnum [mc "Gitk view definition"]
}

proc editview {} {
    global curview
    global viewname viewperm newviewname newviewperm
    global viewargs newviewargs viewargscmd newviewargscmd

    set top .gitkvedit-$curview
    if {[winfo exists $top]} {
        raise $top
        return
    }
    set newviewname($curview) $viewname($curview)
    set newviewperm($curview) $viewperm($curview)
    set newviewargs($curview) [shellarglist $viewargs($curview)]
    set newviewargscmd($curview) $viewargscmd($curview)
    vieweditor $top $curview "Gitk: edit view $viewname($curview)"
}

proc vieweditor {top n title} {
    global newviewname newviewperm viewfiles bgcolor

    toplevel $top
    wm title $top $title
    label $top.nl -text [mc "Name"]
    entry $top.name -width 20 -textvariable newviewname($n)
    grid $top.nl $top.name -sticky w -pady 5
    checkbutton $top.perm -text [mc "Remember this view"] \
        -variable newviewperm($n)
    grid $top.perm - -pady 5 -sticky w
    message $top.al -aspect 1000 \
        -text [mc "Commits to include (arguments to git log):"]
    grid $top.al - -sticky w -pady 5
    entry $top.args -width 50 -textvariable newviewargs($n) \
        -background $bgcolor
    grid $top.args - -sticky ew -padx 5

    message $top.ac -aspect 1000 \
        -text [mc "Command to generate more commits to include:"]
    grid $top.ac - -sticky w -pady 5
    entry $top.argscmd -width 50 -textvariable newviewargscmd($n) \
        -background white
    grid $top.argscmd - -sticky ew -padx 5

    message $top.l -aspect 1000 \
        -text [mc "Enter files and directories to include, one per line:"]
    grid $top.l - -sticky w
    text $top.t -width 40 -height 10 -background $bgcolor -font uifont
    if {[info exists viewfiles($n)]} {
        foreach f $viewfiles($n) {
            $top.t insert end $f
            $top.t insert end "\n"
        }
        $top.t delete {end - 1c} end
        $top.t mark set insert 0.0
    }
    grid $top.t - -sticky ew -padx 5
    frame $top.buts
    button $top.buts.ok -text [mc "OK"] -command [list newviewok $top $n]
    button $top.buts.can -text [mc "Cancel"] -command [list destroy $top]
    grid $top.buts.ok $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - -pady 10 -sticky ew
    focus $top.t
}

proc doviewmenu {m first cmd op argv} {
    set nmenu [$m index end]
    for {set i $first} {$i <= $nmenu} {incr i} {
        if {[$m entrycget $i -command] eq $cmd} {
            eval $m $op $i $argv
            break
        }
    }
}

proc allviewmenus {n op args} {
    # global viewhlmenu

    doviewmenu .bar.view 5 [list showview $n] $op $args
    # doviewmenu $viewhlmenu 1 [list addvhighlight $n] $op $args
}

proc newviewok {top n} {
    global nextviewnum newviewperm newviewname newishighlight
    global viewname viewfiles viewperm selectedview curview
    global viewargs newviewargs viewargscmd newviewargscmd viewhlmenu

    if {[catch {
        set newargs [shellsplit $newviewargs($n)]
    } err]} {
        error_popup "[mc "Error in commit selection arguments:"] $err"
        wm raise $top
        focus $top
        return
    }
    set files {}
    foreach f [split [$top.t get 0.0 end] "\n"] {
        set ft [string trim $f]
        if {$ft ne {}} {
            lappend files $ft
        }
    }
    if {![info exists viewfiles($n)]} {
        # creating a new view
        incr nextviewnum
        set viewname($n) $newviewname($n)
        set viewperm($n) $newviewperm($n)
        set viewfiles($n) $files
        set viewargs($n) $newargs
        set viewargscmd($n) $newviewargscmd($n)
        addviewmenu $n
        if {!$newishighlight} {
            run showview $n
        } else {
            run addvhighlight $n
        }
    } else {
        # editing an existing view
        set viewperm($n) $newviewperm($n)
        if {$newviewname($n) ne $viewname($n)} {
            set viewname($n) $newviewname($n)
            doviewmenu .bar.view 5 [list showview $n] \
                entryconf [list -label $viewname($n)]
            # doviewmenu $viewhlmenu 1 [list addvhighlight $n] \
                # entryconf [list -label $viewname($n) -value $viewname($n)]
        }
        if {$files ne $viewfiles($n) || $newargs ne $viewargs($n) || \
                $newviewargscmd($n) ne $viewargscmd($n)} {
            set viewfiles($n) $files
            set viewargs($n) $newargs
            set viewargscmd($n) $newviewargscmd($n)
            if {$curview == $n} {
                run reloadcommits
            }
        }
    }
    catch {destroy $top}
}

proc delview {} {
    global curview viewperm hlview selectedhlview

    if {$curview == 0} return
    if {[info exists hlview] && $hlview == $curview} {
        set selectedhlview [mc "None"]
        unset hlview
    }
    allviewmenus $curview delete
    set viewperm($curview) 0
    showview 0
}

proc addviewmenu {n} {
    global viewname viewhlmenu

    .bar.view add radiobutton -label $viewname($n) \
        -command [list showview $n] -variable selectedview -value $n
    #$viewhlmenu add radiobutton -label $viewname($n) \
    #   -command [list addvhighlight $n] -variable selectedhlview
}

proc showview {n} {
    global curview cached_commitrow ordertok
    global displayorder parentlist rowidlist rowisopt rowfinal
    global colormap rowtextx nextcolor canvxmax
    global numcommits viewcomplete
    global selectedline currentid canv canvy0
    global treediffs
    global pending_select mainheadid
    global commitidx
    global selectedview
    global hlview selectedhlview commitinterest

    if {$n == $curview} return
    set selid {}
    set ymax [lindex [$canv cget -scrollregion] 3]
    set span [$canv yview]
    set ytop [expr {[lindex $span 0] * $ymax}]
    set ybot [expr {[lindex $span 1] * $ymax}]
    set yscreen [expr {($ybot - $ytop) / 2}]
    if {$selectedline ne {}} {
        set selid $currentid
        set y [yc $selectedline]
        if {$ytop < $y && $y < $ybot} {
            set yscreen [expr {$y - $ytop}]
        }
    } elseif {[info exists pending_select]} {
        set selid $pending_select
        unset pending_select
    }
    unselectline
    normalline
    catch {unset treediffs}
    clear_display
    if {[info exists hlview] && $hlview == $n} {
        unset hlview
        set selectedhlview [mc "None"]
    }
    catch {unset commitinterest}
    catch {unset cached_commitrow}
    catch {unset ordertok}

    set curview $n
    set selectedview $n
    .bar.view entryconf [mc "Edit view..."] -state [expr {$n == 0? "disabled": "normal"}]
    .bar.view entryconf [mc "Delete view"] -state [expr {$n == 0? "disabled": "normal"}]

    run refill_reflist
    if {![info exists viewcomplete($n)]} {
        getcommits $selid
        return
    }

    set displayorder {}
    set parentlist {}
    set rowidlist {}
    set rowisopt {}
    set rowfinal {}
    set numcommits $commitidx($n)

    catch {unset colormap}
    catch {unset rowtextx}
    set nextcolor 0
    set canvxmax [$canv cget -width]
    set curview $n
    set row 0
    setcanvscroll
    set yf 0
    set row {}
    if {$selid ne {} && [commitinview $selid $n]} {
        set row [rowofcommit $selid]
        # try to get the selected row in the same position on the screen
        set ymax [lindex [$canv cget -scrollregion] 3]
        set ytop [expr {[yc $row] - $yscreen}]
        if {$ytop < 0} {
            set ytop 0
        }
        set yf [expr {$ytop * 1.0 / $ymax}]
    }
    allcanvs yview moveto $yf
    drawvisible
    if {$row ne {}} {
        selectline $row 0
    } elseif {!$viewcomplete($n)} {
        reset_pending_select $selid
    } else {
        reset_pending_select {}

        if {[commitinview $pending_select $curview]} {
            selectline [rowofcommit $pending_select] 1
        } else {
            set row [first_real_row]
            if {$row < $numcommits} {
                selectline $row 0
            }
        }
    }
    if {!$viewcomplete($n)} {
        if {$numcommits == 0} {
            show_status [mc "Reading commits..."]
        }
    } elseif {$numcommits == 0} {
        show_status [mc "No commits selected"]
    }
}

# Stuff relating to the highlighting facility

proc ishighlighted {id} {
    global vhighlights fhighlights nhighlights rhighlights

    if {[info exists nhighlights($id)] && $nhighlights($id) > 0} {
        return $nhighlights($id)
    }
    if {[info exists vhighlights($id)] && $vhighlights($id) > 0} {
        return $vhighlights($id)
    }
    if {[info exists fhighlights($id)] && $fhighlights($id) > 0} {
        return $fhighlights($id)
    }
    if {[info exists rhighlights($id)] && $rhighlights($id) > 0} {
        return $rhighlights($id)
    }
    return 0
}

proc bolden {row font} {
    global canv linehtag selectedline boldrows

    lappend boldrows $row
    $canv itemconf $linehtag($row) -font $font
    if {$row == $selectedline} {
        $canv delete secsel
        set t [eval $canv create rect [$canv bbox $linehtag($row)] \
                   -outline {{}} -tags secsel \
                   -fill [$canv cget -selectbackground]]
        $canv lower $t
    }
}

proc bolden_name {row font} {
    global canv2 linentag selectedline boldnamerows

    lappend boldnamerows $row
    $canv2 itemconf $linentag($row) -font $font
    if {$row == $selectedline} {
        $canv2 delete secsel
        set t [eval $canv2 create rect [$canv2 bbox $linentag($row)] \
                   -outline {{}} -tags secsel \
                   -fill [$canv2 cget -selectbackground]]
        $canv2 lower $t
    }
}

proc unbolden {} {
    global boldrows

    set stillbold {}
    foreach row $boldrows {
        if {![ishighlighted [commitonrow $row]]} {
            bolden $row mainfont
        } else {
            lappend stillbold $row
        }
    }
    set boldrows $stillbold
}

proc addvhighlight {n} {
    global hlview viewcomplete curview vhl_done commitidx

    if {[info exists hlview]} {
        delvhighlight
    }
    set hlview $n
    if {$n != $curview && ![info exists viewcomplete($n)]} {
        start_rev_list $n
    }
    set vhl_done $commitidx($hlview)
    if {$vhl_done > 0} {
        drawvisible
    }
}

proc delvhighlight {} {
    global hlview vhighlights

    if {![info exists hlview]} return
    unset hlview
    catch {unset vhighlights}
    unbolden
}

proc vhighlightmore {} {
    global hlview vhl_done commitidx vhighlights curview

    set max $commitidx($hlview)
    set vr [visiblerows]
    set r0 [lindex $vr 0]
    set r1 [lindex $vr 1]
    for {set i $vhl_done} {$i < $max} {incr i} {
        set id [commitonrow $i $hlview]
        if {[commitinview $id $curview]} {
            set row [rowofcommit $id]
            if {$r0 <= $row && $row <= $r1} {
                if {![highlighted $row]} {
                    bolden $row mainfontbold
                }
                set vhighlights($id) 1
            }
        }
    }
    set vhl_done $max
    return 0
}

proc askvhighlight {row id} {
    global hlview vhighlights iddrawn

    if {[commitinview $id $hlview]} {
        if {[info exists iddrawn($id)] && ![ishighlighted $id]} {
            bolden $row mainfontbold
        }
        set vhighlights($id) 1
    } else {
        set vhighlights($id) 0
    }
}

proc hfiles_change {} {
    global highlight_files filehighlight fhighlights fh_serial
    global highlight_paths gdttype

    if {[info exists filehighlight]} {
        # delete previous highlights
        catch {close $filehighlight}
        unset filehighlight
        catch {unset fhighlights}
        unbolden
        unhighlight_filelist
    }
    set highlight_paths {}
    after cancel do_file_hl $fh_serial
    incr fh_serial
    if {$highlight_files ne {}} {
        after 300 do_file_hl $fh_serial
    }
}

proc gdttype_change {name ix op} {
    global gdttype highlight_files findstring findpattern

    stopfinding
    if {$findstring ne {}} {
        if {$gdttype eq [mc "containing:"]} {
            if {$highlight_files ne {}} {
                set highlight_files {}
                hfiles_change
            }
            findcom_change
        } else {
            if {$findpattern ne {}} {
                set findpattern {}
                findcom_change
            }
            set highlight_files $findstring
            hfiles_change
        }
        drawvisible
    }
    # enable/disable findtype/findloc menus too
}

proc find_change {name ix op} {
    global gdttype findstring highlight_files

    stopfinding
    if {$gdttype eq [mc "containing:"]} {
        findcom_change
    } else {
        if {$highlight_files ne $findstring} {
            set highlight_files $findstring
            hfiles_change
        }
    }
    drawvisible
}

proc findcom_change args {
    global nhighlights boldnamerows
    global findpattern findtype findstring gdttype

    stopfinding
    # delete previous highlights, if any
    foreach row $boldnamerows {
        bolden_name $row mainfont
    }
    set boldnamerows {}
    catch {unset nhighlights}
    unbolden
    unmarkmatches
    if {$gdttype ne [mc "containing:"] || $findstring eq {}} {
        set findpattern {}
    } elseif {$findtype eq [mc "Regexp"]} {
        set findpattern $findstring
    } else {
        set e [string map {"*" "\\*" "?" "\\?" "\[" "\\\[" "\\" "\\\\"} \
                   $findstring]
        set findpattern "*$e*"
    }
}

proc makepatterns {l} {
    set ret {}
    foreach e $l {
        set ee [string map {"*" "\\*" "?" "\\?" "\[" "\\\[" "\\" "\\\\"} $e]
        if {[string index $ee end] eq "/"} {
            lappend ret "$ee*"
        } else {
            lappend ret $ee
            lappend ret "$ee/*"
        }
    }
    return $ret
}

proc do_file_hl {serial} {
    global highlight_files filehighlight highlight_paths gdttype fhl_list

    if {$gdttype eq [mc "touching paths:"]} {
        if {[catch {set paths [shellsplit $highlight_files]}]} return
        set highlight_paths [makepatterns $paths]
        highlight_filelist
        set gdtargs [concat -- $paths]
    } elseif {$gdttype eq [mc "adding/removing string:"]} {
        set gdtargs [list "-S$highlight_files"]
    } else {
        # must be "containing:", i.e. we're searching commit info
        return
    }
    set cmd [concat | git diff-tree -r -s --stdin $gdtargs]
    set filehighlight [open $cmd r+]
    fconfigure $filehighlight -blocking 0
    filerun $filehighlight readfhighlight
    set fhl_list {}
    drawvisible
    flushhighlights
}

proc flushhighlights {} {
    global filehighlight fhl_list

    if {[info exists filehighlight]} {
        lappend fhl_list {}
        puts $filehighlight ""
        flush $filehighlight
    }
}

proc askfilehighlight {row id} {
    global filehighlight fhighlights fhl_list

    lappend fhl_list $id
    set fhighlights($id) -1
    puts $filehighlight $id
}

proc readfhighlight {} {
    global filehighlight fhighlights curview iddrawn
    global fhl_list find_dirn

    if {![info exists filehighlight]} {
        return 0
    }
    set nr 0
    while {[incr nr] <= 100 && [gets $filehighlight line] >= 0} {
        set line [string trim $line]
        set i [lsearch -exact $fhl_list $line]
        if {$i < 0} continue
        for {set j 0} {$j < $i} {incr j} {
            set id [lindex $fhl_list $j]
            set fhighlights($id) 0
        }
        set fhl_list [lrange $fhl_list [expr {$i+1}] end]
        if {$line eq {}} continue
        if {![commitinview $line $curview]} continue
        set row [rowofcommit $line]
        if {[info exists iddrawn($line)] && ![ishighlighted $line]} {
            bolden $row mainfontbold
        }
        set fhighlights($line) 1
    }
    if {[eof $filehighlight]} {
        # strange...
        puts "oops, git diff-tree died"
        catch {close $filehighlight}
        unset filehighlight
        return 0
    }
    if {[info exists find_dirn]} {
        run findmore
    }
    return 1
}

proc doesmatch {f} {
    global findtype findpattern

    if {$findtype eq [mc "Regexp"]} {
        return [regexp $findpattern $f]
    } elseif {$findtype eq [mc "IgnCase"]} {
        return [string match -nocase $findpattern $f]
    } else {
        return [string match $findpattern $f]
    }
}

proc askfindhighlight {row id} {
    global nhighlights commitinfo iddrawn
    global findloc
    global markingmatches

    if {![info exists commitinfo($id)]} {
        getcommit $id
    }
    set info $commitinfo($id)
    set isbold 0
    set fldtypes [list [mc Headline] [mc Author] [mc Date] [mc Committer] [mc CDate] [mc Comments]]
    foreach f $info ty $fldtypes {
        if {($findloc eq [mc "All fields"] || $findloc eq $ty) &&
            [doesmatch $f]} {
            if {$ty eq [mc "Author"]} {
                set isbold 2
                break
            }
            set isbold 1
        }
    }
    if {$isbold && [info exists iddrawn($id)]} {
        if {![ishighlighted $id]} {
            bolden $row mainfontbold
            if {$isbold > 1} {
                bolden_name $row mainfontbold
            }
        }
        if {$markingmatches} {
            markrowmatches $row $id
        }
    }
    set nhighlights($id) $isbold
}

proc markrowmatches {row id} {
    global canv canv2 linehtag linentag commitinfo findloc

    set headline [lindex $commitinfo($id) 0]
    set author [lindex $commitinfo($id) 1]
    $canv delete match$row
    $canv2 delete match$row
    if {$findloc eq [mc "All fields"] || $findloc eq [mc "Headline"]} {
        set m [findmatches $headline]
        if {$m ne {}} {
            markmatches $canv $row $headline $linehtag($row) $m \
                [$canv itemcget $linehtag($row) -font] $row
        }
    }
    if {$findloc eq [mc "All fields"] || $findloc eq [mc "Author"]} {
        set m [findmatches $author]
        if {$m ne {}} {
            markmatches $canv2 $row $author $linentag($row) $m \
                [$canv2 itemcget $linentag($row) -font] $row
        }
    }
}

proc vrel_change {name ix op} {
    global highlight_related

    rhighlight_none
    if {$highlight_related ne [mc "None"]} {
        run drawvisible
    }
}

# prepare for testing whether commits are descendents or ancestors of a
proc rhighlight_sel {a} {
    global descendent desc_todo ancestor anc_todo
    global highlight_related

    catch {unset descendent}
    set desc_todo [list $a]
    catch {unset ancestor}
    set anc_todo [list $a]
    if {$highlight_related ne [mc "None"]} {
        rhighlight_none
        run drawvisible
    }
}

proc rhighlight_none {} {
    global rhighlights

    catch {unset rhighlights}
    unbolden
}

proc is_descendent {a} {
    global curview children descendent desc_todo

    set v $curview
    set la [rowofcommit $a]
    set todo $desc_todo
    set leftover {}
    set done 0
    for {set i 0} {$i < [llength $todo]} {incr i} {
        set do [lindex $todo $i]
        if {[rowofcommit $do] < $la} {
            lappend leftover $do
            continue
        }
        foreach nk $children($v,$do) {
            if {![info exists descendent($nk)]} {
                set descendent($nk) 1
                lappend todo $nk
                if {$nk eq $a} {
                    set done 1
                }
            }
        }
        if {$done} {
            set desc_todo [concat $leftover [lrange $todo [expr {$i+1}] end]]
            return
        }
    }
    set descendent($a) 0
    set desc_todo $leftover
}

proc is_ancestor {a} {
    global curview parents ancestor anc_todo

    set v $curview
    set la [rowofcommit $a]
    set todo $anc_todo
    set leftover {}
    set done 0
    for {set i 0} {$i < [llength $todo]} {incr i} {
        set do [lindex $todo $i]
        if {![commitinview $do $v] || [rowofcommit $do] > $la} {
            lappend leftover $do
            continue
        }
        foreach np $parents($v,$do) {
            if {![info exists ancestor($np)]} {
                set ancestor($np) 1
                lappend todo $np
                if {$np eq $a} {
                    set done 1
                }
            }
        }
        if {$done} {
            set anc_todo [concat $leftover [lrange $todo [expr {$i+1}] end]]
            return
        }
    }
    set ancestor($a) 0
    set anc_todo $leftover
}

proc askrelhighlight {row id} {
    global descendent highlight_related iddrawn rhighlights
    global selectedline ancestor

    if {$selectedline eq {}} return
    set isbold 0
    if {$highlight_related eq [mc "Descendant"] ||
        $highlight_related eq [mc "Not descendant"]} {
        if {![info exists descendent($id)]} {
            is_descendent $id
        }
        if {$descendent($id) == ($highlight_related eq [mc "Descendant"])} {
            set isbold 1
        }
    } elseif {$highlight_related eq [mc "Ancestor"] ||
              $highlight_related eq [mc "Not ancestor"]} {
        if {![info exists ancestor($id)]} {
            is_ancestor $id
        }
        if {$ancestor($id) == ($highlight_related eq [mc "Ancestor"])} {
            set isbold 1
        }
    }
    if {[info exists iddrawn($id)]} {
        if {$isbold && ![ishighlighted $id]} {
            bolden $row mainfontbold
        }
    }
    set rhighlights($id) $isbold
}

# Graph layout functions

proc shortids {ids} {
    set res {}
    foreach id $ids {
        if {[llength $id] > 1} {
            lappend res [shortids $id]
        } elseif {[regexp {^[0-9a-f]{40}$} $id]} {
            lappend res [string range $id 0 7]
        } else {
            lappend res $id
        }
    }
    return $res
}

proc ntimes {n o} {
    set ret {}
    set o [list $o]
    for {set mask 1} {$mask <= $n} {incr mask $mask} {
        if {($n & $mask) != 0} {
            set ret [concat $ret $o]
        }
        set o [concat $o $o]
    }
    return $ret
}

proc ordertoken {id} {
    global ordertok curview varcid varcstart varctok curview parents children
    global nullid nullid2

    if {[info exists ordertok($id)]} {
        return $ordertok($id)
    }
    set origid $id
    set todo {}
    while {1} {
        if {[info exists varcid($curview,$id)]} {
            set a $varcid($curview,$id)
            set p [lindex $varcstart($curview) $a]
        } else {
            set p [lindex $children($curview,$id) 0]
        }
        if {[info exists ordertok($p)]} {
            set tok $ordertok($p)
            break
        }
        set id [first_real_child $curview,$p]
        if {$id eq {}} {
            # it's a root
            set tok [lindex $varctok($curview) $varcid($curview,$p)]
            break
        }
        if {[llength $parents($curview,$id)] == 1} {
            lappend todo [list $p {}]
        } else {
            set j [lsearch -exact $parents($curview,$id) $p]
            if {$j < 0} {
                puts "oops didn't find [shortids $p] in parents of [shortids $id]"
            }
            lappend todo [list $p [strrep $j]]
        }
    }
    for {set i [llength $todo]} {[incr i -1] >= 0} {} {
        set p [lindex $todo $i 0]
        append tok [lindex $todo $i 1]
        set ordertok($p) $tok
    }
    set ordertok($origid) $tok
    return $tok
}

# Work out where id should go in idlist so that order-token
# values increase from left to right
proc idcol {idlist id {i 0}} {
    set t [ordertoken $id]
    if {$i < 0} {
        set i 0
    }
    if {$i >= [llength $idlist] || $t < [ordertoken [lindex $idlist $i]]} {
        if {$i > [llength $idlist]} {
            set i [llength $idlist]
        }
        while {[incr i -1] >= 0 && $t < [ordertoken [lindex $idlist $i]]} {}
        incr i
    } else {
        if {$t > [ordertoken [lindex $idlist $i]]} {
            while {[incr i] < [llength $idlist] &&
                   $t >= [ordertoken [lindex $idlist $i]]} {}
        }
    }
    return $i
}

proc initlayout {} {
    global rowidlist rowisopt rowfinal displayorder parentlist
    global numcommits canvxmax canv
    global nextcolor
    global colormap rowtextx

    set numcommits 0
    set displayorder {}
    set parentlist {}
    set nextcolor 0
    set rowidlist {}
    set rowisopt {}
    set rowfinal {}
    set canvxmax [$canv cget -width]
    catch {unset colormap}
    catch {unset rowtextx}
    setcanvscroll
}

proc setcanvscroll {} {
    global canv canv2 canv3 numcommits linespc canvxmax canvy0
    global lastscrollset lastscrollrows

    set ymax [expr {$canvy0 + ($numcommits - 0.5) * $linespc + 2}]
    $canv conf -scrollregion [list 0 0 $canvxmax $ymax]
    $canv2 conf -scrollregion [list 0 0 0 $ymax]
    $canv3 conf -scrollregion [list 0 0 0 $ymax]
    set lastscrollset [clock clicks -milliseconds]
    set lastscrollrows $numcommits
}

proc visiblerows {} {
    global canv numcommits linespc

    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax == 0} return
    set f [$canv yview]
    set y0 [expr {int([lindex $f 0] * $ymax)}]
    set r0 [expr {int(($y0 - 3) / $linespc) - 1}]
    if {$r0 < 0} {
        set r0 0
    }
    set y1 [expr {int([lindex $f 1] * $ymax)}]
    set r1 [expr {int(($y1 - 3) / $linespc) + 1}]
    if {$r1 >= $numcommits} {
        set r1 [expr {$numcommits - 1}]
    }
    return [list $r0 $r1]
}

proc layoutmore {} {
    global commitidx viewcomplete curview
    global numcommits pending_select curview
    global lastscrollset lastscrollrows commitinterest

    if {$lastscrollrows < 100 || $viewcomplete($curview) ||
        [clock clicks -milliseconds] - $lastscrollset > 500} {
        setcanvscroll
    }
    if {[info exists pending_select] &&
        [commitinview $pending_select $curview]} {
        update
        selectline [rowofcommit $pending_select] 1
    }
    drawvisible
}

proc doshowlocalchanges {} {
    global curview mainheadid

    if {$mainheadid eq {}} return
    if {[commitinview $mainheadid $curview]} {
        dodiffindex
    } else {
        lappend commitinterest($mainheadid) {dodiffindex}
    }
}

proc dohidelocalchanges {} {
    global nullid nullid2 lserial curview

    if {[commitinview $nullid $curview]} {
        removefakerow $nullid
    }
    if {[commitinview $nullid2 $curview]} {
        removefakerow $nullid2
    }
    incr lserial
}

# spawn off a process to do git diff-index --cached HEAD
proc dodiffindex {} {
    global lserial showlocalchanges
    global isworktree

    if {!$showlocalchanges || !$isworktree} return
    incr lserial
    set fd [open "|git diff-index --cached HEAD" r]
    fconfigure $fd -blocking 0
    set i [reg_instance $fd]
    filerun $fd [list readdiffindex $fd $lserial $i]
}

proc readdiffindex {fd serial inst} {
    global mainheadid nullid nullid2 curview commitinfo commitdata lserial

    set isdiff 1
    if {[gets $fd line] < 0} {
        if {![eof $fd]} {
            return 1
        }
        set isdiff 0
    }
    # we only need to see one line and we don't really care what it says...
    stop_instance $inst

    if {$serial != $lserial} {
        return 0
    }

    # now see if there are any local changes not checked in to the index
    set fd [open "|git diff-files" r]
    fconfigure $fd -blocking 0
    set i [reg_instance $fd]
    filerun $fd [list readdifffiles $fd $serial $i]

    if {$isdiff && ![commitinview $nullid2 $curview]} {
        # add the line for the changes in the index to the graph
        set hl [mc "Local changes checked in to index but not committed"]
        set commitinfo($nullid2) [list  $hl {} {} {} {} "    $hl\n"]
        set commitdata($nullid2) "\n    $hl\n"
        if {[commitinview $nullid $curview]} {
            removefakerow $nullid
        }
        insertfakerow $nullid2 $mainheadid
    } elseif {!$isdiff && [commitinview $nullid2 $curview]} {
        removefakerow $nullid2
    }
    return 0
}

proc readdifffiles {fd serial inst} {
    global mainheadid nullid nullid2 curview
    global commitinfo commitdata lserial

    set isdiff 1
    if {[gets $fd line] < 0} {
        if {![eof $fd]} {
            return 1
        }
        set isdiff 0
    }
    # we only need to see one line and we don't really care what it says...
    stop_instance $inst

    if {$serial != $lserial} {
        return 0
    }

    if {$isdiff && ![commitinview $nullid $curview]} {
        # add the line for the local diff to the graph
        set hl [mc "Local uncommitted changes, not checked in to index"]
        set commitinfo($nullid) [list  $hl {} {} {} {} "    $hl\n"]
        set commitdata($nullid) "\n    $hl\n"
        if {[commitinview $nullid2 $curview]} {
            set p $nullid2
        } else {
            set p $mainheadid
        }
        insertfakerow $nullid $p
    } elseif {!$isdiff && [commitinview $nullid $curview]} {
        removefakerow $nullid
    }
    return 0
}

proc nextuse {id row} {
    global curview children

    if {[info exists children($curview,$id)]} {
        foreach kid $children($curview,$id) {
            if {![commitinview $kid $curview]} {
                return -1
            }
            if {[rowofcommit $kid] > $row} {
                return [rowofcommit $kid]
            }
        }
    }
    if {[commitinview $id $curview]} {
        return [rowofcommit $id]
    }
    return -1
}

proc prevuse {id row} {
    global curview children

    set ret -1
    if {[info exists children($curview,$id)]} {
        foreach kid $children($curview,$id) {
            if {![commitinview $kid $curview]} break
            if {[rowofcommit $kid] < $row} {
                set ret [rowofcommit $kid]
            }
        }
    }
    return $ret
}

proc make_idlist {row} {
    global displayorder parentlist uparrowlen downarrowlen mingaplen
    global commitidx curview children

    set r [expr {$row - $mingaplen - $downarrowlen - 1}]
    if {$r < 0} {
        set r 0
    }
    set ra [expr {$row - $downarrowlen}]
    if {$ra < 0} {
        set ra 0
    }
    set rb [expr {$row + $uparrowlen}]
    if {$rb > $commitidx($curview)} {
        set rb $commitidx($curview)
    }
    make_disporder $r [expr {$rb + 1}]
    set ids {}
    for {} {$r < $ra} {incr r} {
        set nextid [lindex $displayorder [expr {$r + 1}]]
        foreach p [lindex $parentlist $r] {
            if {$p eq $nextid} continue
            set rn [nextuse $p $r]
            if {$rn >= $row &&
                $rn <= $r + $downarrowlen + $mingaplen + $uparrowlen} {
                lappend ids [list [ordertoken $p] $p]
            }
        }
    }
    for {} {$r < $row} {incr r} {
        set nextid [lindex $displayorder [expr {$r + 1}]]
        foreach p [lindex $parentlist $r] {
            if {$p eq $nextid} continue
            set rn [nextuse $p $r]
            if {$rn < 0 || $rn >= $row} {
                lappend ids [list [ordertoken $p] $p]
            }
        }
    }
    set id [lindex $displayorder $row]
    lappend ids [list [ordertoken $id] $id]
    while {$r < $rb} {
        foreach p [lindex $parentlist $r] {
            set firstkid [lindex $children($curview,$p) 0]
            if {[rowofcommit $firstkid] < $row} {
                lappend ids [list [ordertoken $p] $p]
            }
        }
        incr r
        set id [lindex $displayorder $r]
        if {$id ne {}} {
            set firstkid [lindex $children($curview,$id) 0]
            if {$firstkid ne {} && [rowofcommit $firstkid] < $row} {
                lappend ids [list [ordertoken $id] $id]
            }
        }
    }
    set idlist {}
    foreach idx [lsort -unique $ids] {
        lappend idlist [lindex $idx 1]
    }
    return $idlist
}

proc rowsequal {a b} {
    while {[set i [lsearch -exact $a {}]] >= 0} {
        set a [lreplace $a $i $i]
    }
    while {[set i [lsearch -exact $b {}]] >= 0} {
        set b [lreplace $b $i $i]
    }
    return [expr {$a eq $b}]
}

proc makeupline {id row rend col} {
    global rowidlist uparrowlen downarrowlen mingaplen

    for {set r $rend} {1} {set r $rstart} {
        set rstart [prevuse $id $r]
        if {$rstart < 0} return
        if {$rstart < $row} break
    }
    if {$rstart + $uparrowlen + $mingaplen + $downarrowlen < $rend} {
        set rstart [expr {$rend - $uparrowlen - 1}]
    }
    for {set r $rstart} {[incr r] <= $row} {} {
        set idlist [lindex $rowidlist $r]
        if {$idlist ne {} && [lsearch -exact $idlist $id] < 0} {
            set col [idcol $idlist $id $col]
            lset rowidlist $r [linsert $idlist $col $id]
            changedrow $r
        }
    }
}

proc layoutrows {row endrow} {
    global rowidlist rowisopt rowfinal displayorder
    global uparrowlen downarrowlen maxwidth mingaplen
    global children parentlist
    global commitidx viewcomplete curview

    make_disporder [expr {$row - 1}] [expr {$endrow + $uparrowlen}]
    set idlist {}
    if {$row > 0} {
        set rm1 [expr {$row - 1}]
        foreach id [lindex $rowidlist $rm1] {
            if {$id ne {}} {
                lappend idlist $id
            }
        }
        set final [lindex $rowfinal $rm1]
    }
    for {} {$row < $endrow} {incr row} {
        set rm1 [expr {$row - 1}]
        if {$rm1 < 0 || $idlist eq {}} {
            set idlist [make_idlist $row]
            set final 1
        } else {
            set id [lindex $displayorder $rm1]
            set col [lsearch -exact $idlist $id]
            set idlist [lreplace $idlist $col $col]
            foreach p [lindex $parentlist $rm1] {
                if {[lsearch -exact $idlist $p] < 0} {
                    set col [idcol $idlist $p $col]
                    set idlist [linsert $idlist $col $p]
                    # if not the first child, we have to insert a line going up
                    if {$id ne [lindex $children($curview,$p) 0]} {
                        makeupline $p $rm1 $row $col
                    }
                }
            }
            set id [lindex $displayorder $row]
            if {$row > $downarrowlen} {
                set termrow [expr {$row - $downarrowlen - 1}]
                foreach p [lindex $parentlist $termrow] {
                    set i [lsearch -exact $idlist $p]
                    if {$i < 0} continue
                    set nr [nextuse $p $termrow]
                    if {$nr < 0 || $nr >= $row + $mingaplen + $uparrowlen} {
                        set idlist [lreplace $idlist $i $i]
                    }
                }
            }
            set col [lsearch -exact $idlist $id]
            if {$col < 0} {
                set col [idcol $idlist $id]
                set idlist [linsert $idlist $col $id]
                if {$children($curview,$id) ne {}} {
                    makeupline $id $rm1 $row $col
                }
            }
            set r [expr {$row + $uparrowlen - 1}]
            if {$r < $commitidx($curview)} {
                set x $col
                foreach p [lindex $parentlist $r] {
                    if {[lsearch -exact $idlist $p] >= 0} continue
                    set fk [lindex $children($curview,$p) 0]
                    if {[rowofcommit $fk] < $row} {
                        set x [idcol $idlist $p $x]
                        set idlist [linsert $idlist $x $p]
                    }
                }
                if {[incr r] < $commitidx($curview)} {
                    set p [lindex $displayorder $r]
                    if {[lsearch -exact $idlist $p] < 0} {
                        set fk [lindex $children($curview,$p) 0]
                        if {$fk ne {} && [rowofcommit $fk] < $row} {
                            set x [idcol $idlist $p $x]
                            set idlist [linsert $idlist $x $p]
                        }
                    }
                }
            }
        }
        if {$final && !$viewcomplete($curview) &&
            $row + $uparrowlen + $mingaplen + $downarrowlen
                >= $commitidx($curview)} {
            set final 0
        }
        set l [llength $rowidlist]
        if {$row == $l} {
            lappend rowidlist $idlist
            lappend rowisopt 0
            lappend rowfinal $final
        } elseif {$row < $l} {
            if {![rowsequal $idlist [lindex $rowidlist $row]]} {
                lset rowidlist $row $idlist
                changedrow $row
            }
            lset rowfinal $row $final
        } else {
            set pad [ntimes [expr {$row - $l}] {}]
            set rowidlist [concat $rowidlist $pad]
            lappend rowidlist $idlist
            set rowfinal [concat $rowfinal $pad]
            lappend rowfinal $final
            set rowisopt [concat $rowisopt [ntimes [expr {$row - $l + 1}] 0]]
        }
    }
    return $row
}

proc changedrow {row} {
    global displayorder iddrawn rowisopt need_redisplay

    set l [llength $rowisopt]
    if {$row < $l} {
        lset rowisopt $row 0
        if {$row + 1 < $l} {
            lset rowisopt [expr {$row + 1}] 0
            if {$row + 2 < $l} {
                lset rowisopt [expr {$row + 2}] 0
            }
        }
    }
    set id [lindex $displayorder $row]
    if {[info exists iddrawn($id)]} {
        set need_redisplay 1
    }
}

proc insert_pad {row col npad} {
    global rowidlist

    set pad [ntimes $npad {}]
    set idlist [lindex $rowidlist $row]
    set bef [lrange $idlist 0 [expr {$col - 1}]]
    set aft [lrange $idlist $col end]
    set i [lsearch -exact $aft {}]
    if {$i > 0} {
        set aft [lreplace $aft $i $i]
    }
    lset rowidlist $row [concat $bef $pad $aft]
    changedrow $row
}

proc optimize_rows {row col endrow} {
    global rowidlist rowisopt displayorder curview children

    if {$row < 1} {
        set row 1
    }
    for {} {$row < $endrow} {incr row; set col 0} {
        if {[lindex $rowisopt $row]} continue
        set haspad 0
        set y0 [expr {$row - 1}]
        set ym [expr {$row - 2}]
        set idlist [lindex $rowidlist $row]
        set previdlist [lindex $rowidlist $y0]
        if {$idlist eq {} || $previdlist eq {}} continue
        if {$ym >= 0} {
            set pprevidlist [lindex $rowidlist $ym]
            if {$pprevidlist eq {}} continue
        } else {
            set pprevidlist {}
        }
        set x0 -1
        set xm -1
        for {} {$col < [llength $idlist]} {incr col} {
            set id [lindex $idlist $col]
            if {[lindex $previdlist $col] eq $id} continue
            if {$id eq {}} {
                set haspad 1
                continue
            }
            set x0 [lsearch -exact $previdlist $id]
            if {$x0 < 0} continue
            set z [expr {$x0 - $col}]
            set isarrow 0
            set z0 {}
            if {$ym >= 0} {
                set xm [lsearch -exact $pprevidlist $id]
                if {$xm >= 0} {
                    set z0 [expr {$xm - $x0}]
                }
            }
            if {$z0 eq {}} {
                # if row y0 is the first child of $id then it's not an arrow
                if {[lindex $children($curview,$id) 0] ne
                    [lindex $displayorder $y0]} {
                    set isarrow 1
                }
            }
            if {!$isarrow && $id ne [lindex $displayorder $row] &&
                [lsearch -exact [lindex $rowidlist [expr {$row+1}]] $id] < 0} {
                set isarrow 1
            }
            # Looking at lines from this row to the previous row,
            # make them go straight up if they end in an arrow on
            # the previous row; otherwise make them go straight up
            # or at 45 degrees.
            if {$z < -1 || ($z < 0 && $isarrow)} {
                # Line currently goes left too much;
                # insert pads in the previous row, then optimize it
                set npad [expr {-1 - $z + $isarrow}]
                insert_pad $y0 $x0 $npad
                if {$y0 > 0} {
                    optimize_rows $y0 $x0 $row
                }
                set previdlist [lindex $rowidlist $y0]
                set x0 [lsearch -exact $previdlist $id]
                set z [expr {$x0 - $col}]
                if {$z0 ne {}} {
                    set pprevidlist [lindex $rowidlist $ym]
                    set xm [lsearch -exact $pprevidlist $id]
                    set z0 [expr {$xm - $x0}]
                }
            } elseif {$z > 1 || ($z > 0 && $isarrow)} {
                # Line currently goes right too much;
                # insert pads in this line
                set npad [expr {$z - 1 + $isarrow}]
                insert_pad $row $col $npad
                set idlist [lindex $rowidlist $row]
                incr col $npad
                set z [expr {$x0 - $col}]
                set haspad 1
            }
            if {$z0 eq {} && !$isarrow && $ym >= 0} {
                # this line links to its first child on row $row-2
                set id [lindex $displayorder $ym]
                set xc [lsearch -exact $pprevidlist $id]
                if {$xc >= 0} {
                    set z0 [expr {$xc - $x0}]
                }
            }
            # avoid lines jigging left then immediately right
            if {$z0 ne {} && $z < 0 && $z0 > 0} {
                insert_pad $y0 $x0 1
                incr x0
                optimize_rows $y0 $x0 $row
                set previdlist [lindex $rowidlist $y0]
            }
        }
        if {!$haspad} {
            # Find the first column that doesn't have a line going right
            for {set col [llength $idlist]} {[incr col -1] >= 0} {} {
                set id [lindex $idlist $col]
                if {$id eq {}} break
                set x0 [lsearch -exact $previdlist $id]
                if {$x0 < 0} {
                    # check if this is the link to the first child
                    set kid [lindex $displayorder $y0]
                    if {[lindex $children($curview,$id) 0] eq $kid} {
                        # it is, work out offset to child
                        set x0 [lsearch -exact $previdlist $kid]
                    }
                }
                if {$x0 <= $col} break
            }
            # Insert a pad at that column as long as it has a line and
            # isn't the last column
            if {$x0 >= 0 && [incr col] < [llength $idlist]} {
                set idlist [linsert $idlist $col {}]
                lset rowidlist $row $idlist
                changedrow $row
            }
        }
    }
}

proc xc {row col} {
    global canvx0 linespc
    return [expr {$canvx0 + $col * $linespc}]
}

proc yc {row} {
    global canvy0 linespc
    return [expr {$canvy0 + $row * $linespc}]
}

proc linewidth {id} {
    global thickerline lthickness

    set wid $lthickness
    if {[info exists thickerline] && $id eq $thickerline} {
        set wid [expr {2 * $lthickness}]
    }
    return $wid
}

proc rowranges {id} {
    global curview children uparrowlen downarrowlen
    global rowidlist

    set kids $children($curview,$id)
    if {$kids eq {}} {
        return {}
    }
    set ret {}
    lappend kids $id
    foreach child $kids {
        if {![commitinview $child $curview]} break
        set row [rowofcommit $child]
        if {![info exists prev]} {
            lappend ret [expr {$row + 1}]
        } else {
            if {$row <= $prevrow} {
                puts "oops children of [shortids $id] out of order [shortids $child] $row <= [shortids $prev] $prevrow"
            }
            # see if the line extends the whole way from prevrow to row
            if {$row > $prevrow + $uparrowlen + $downarrowlen &&
                [lsearch -exact [lindex $rowidlist \
                            [expr {int(($row + $prevrow) / 2)}]] $id] < 0} {
                # it doesn't, see where it ends
                set r [expr {$prevrow + $downarrowlen}]
                if {[lsearch -exact [lindex $rowidlist $r] $id] < 0} {
                    while {[incr r -1] > $prevrow &&
                           [lsearch -exact [lindex $rowidlist $r] $id] < 0} {}
                } else {
                    while {[incr r] <= $row &&
                           [lsearch -exact [lindex $rowidlist $r] $id] >= 0} {}
                    incr r -1
                }
                lappend ret $r
                # see where it starts up again
                set r [expr {$row - $uparrowlen}]
                if {[lsearch -exact [lindex $rowidlist $r] $id] < 0} {
                    while {[incr r] < $row &&
                           [lsearch -exact [lindex $rowidlist $r] $id] < 0} {}
                } else {
                    while {[incr r -1] >= $prevrow &&
                           [lsearch -exact [lindex $rowidlist $r] $id] >= 0} {}
                    incr r
                }
                lappend ret $r
            }
        }
        if {$child eq $id} {
            lappend ret $row
        }
        set prev $child
        set prevrow $row
    }
    return $ret
}

proc drawlineseg {id row endrow arrowlow} {
    global rowidlist displayorder iddrawn linesegs
    global canv colormap linespc curview maxlinelen parentlist

    set cols [list [lsearch -exact [lindex $rowidlist $row] $id]]
    set le [expr {$row + 1}]
    set arrowhigh 1
    while {1} {
        set c [lsearch -exact [lindex $rowidlist $le] $id]
        if {$c < 0} {
            incr le -1
            break
        }
        lappend cols $c
        set x [lindex $displayorder $le]
        if {$x eq $id} {
            set arrowhigh 0
            break
        }
        if {[info exists iddrawn($x)] || $le == $endrow} {
            set c [lsearch -exact [lindex $rowidlist [expr {$le+1}]] $id]
            if {$c >= 0} {
                lappend cols $c
                set arrowhigh 0
            }
            break
        }
        incr le
    }
    if {$le <= $row} {
        return $row
    }

    set lines {}
    set i 0
    set joinhigh 0
    if {[info exists linesegs($id)]} {
        set lines $linesegs($id)
        foreach li $lines {
            set r0 [lindex $li 0]
            if {$r0 > $row} {
                if {$r0 == $le && [lindex $li 1] - $row <= $maxlinelen} {
                    set joinhigh 1
                }
                break
            }
            incr i
        }
    }
    set joinlow 0
    if {$i > 0} {
        set li [lindex $lines [expr {$i-1}]]
        set r1 [lindex $li 1]
        if {$r1 == $row && $le - [lindex $li 0] <= $maxlinelen} {
            set joinlow 1
        }
    }

    set x [lindex $cols [expr {$le - $row}]]
    set xp [lindex $cols [expr {$le - 1 - $row}]]
    set dir [expr {$xp - $x}]
    if {$joinhigh} {
        set ith [lindex $lines $i 2]
        set coords [$canv coords $ith]
        set ah [$canv itemcget $ith -arrow]
        set arrowhigh [expr {$ah eq "first" || $ah eq "both"}]
        set x2 [lindex $cols [expr {$le + 1 - $row}]]
        if {$x2 ne {} && $x - $x2 == $dir} {
            set coords [lrange $coords 0 end-2]
        }
    } else {
        set coords [list [xc $le $x] [yc $le]]
    }
    if {$joinlow} {
        set itl [lindex $lines [expr {$i-1}] 2]
        set al [$canv itemcget $itl -arrow]
        set arrowlow [expr {$al eq "last" || $al eq "both"}]
    } elseif {$arrowlow} {
        if {[lsearch -exact [lindex $rowidlist [expr {$row-1}]] $id] >= 0 ||
            [lsearch -exact [lindex $parentlist [expr {$row-1}]] $id] >= 0} {
            set arrowlow 0
        }
    }
    set arrow [lindex {none first last both} [expr {$arrowhigh + 2*$arrowlow}]]
    for {set y $le} {[incr y -1] > $row} {} {
        set x $xp
        set xp [lindex $cols [expr {$y - 1 - $row}]]
        set ndir [expr {$xp - $x}]
        if {$dir != $ndir || $xp < 0} {
            lappend coords [xc $y $x] [yc $y]
        }
        set dir $ndir
    }
    if {!$joinlow} {
        if {$xp < 0} {
            # join parent line to first child
            set ch [lindex $displayorder $row]
            set xc [lsearch -exact [lindex $rowidlist $row] $ch]
            if {$xc < 0} {
                puts "oops: drawlineseg: child $ch not on row $row"
            } elseif {$xc != $x} {
                if {($arrowhigh && $le == $row + 1) || $dir == 0} {
                    set d [expr {int(0.5 * $linespc)}]
                    set x1 [xc $row $x]
                    if {$xc < $x} {
                        set x2 [expr {$x1 - $d}]
                    } else {
                        set x2 [expr {$x1 + $d}]
                    }
                    set y2 [yc $row]
                    set y1 [expr {$y2 + $d}]
                    lappend coords $x1 $y1 $x2 $y2
                } elseif {$xc < $x - 1} {
                    lappend coords [xc $row [expr {$x-1}]] [yc $row]
                } elseif {$xc > $x + 1} {
                    lappend coords [xc $row [expr {$x+1}]] [yc $row]
                }
                set x $xc
            }
            lappend coords [xc $row $x] [yc $row]
        } else {
            set xn [xc $row $xp]
            set yn [yc $row]
            lappend coords $xn $yn
        }
        if {!$joinhigh} {
            assigncolor $id
            set t [$canv create line $coords -width [linewidth $id] \
                       -fill $colormap($id) -tags lines.$id -arrow $arrow]
            $canv lower $t
            bindline $t $id
            set lines [linsert $lines $i [list $row $le $t]]
        } else {
            $canv coords $ith $coords
            if {$arrow ne $ah} {
                $canv itemconf $ith -arrow $arrow
            }
            lset lines $i 0 $row
        }
    } else {
        set xo [lsearch -exact [lindex $rowidlist [expr {$row - 1}]] $id]
        set ndir [expr {$xo - $xp}]
        set clow [$canv coords $itl]
        if {$dir == $ndir} {
            set clow [lrange $clow 2 end]
        }
        set coords [concat $coords $clow]
        if {!$joinhigh} {
            lset lines [expr {$i-1}] 1 $le
        } else {
            # coalesce two pieces
            $canv delete $ith
            set b [lindex $lines [expr {$i-1}] 0]
            set e [lindex $lines $i 1]
            set lines [lreplace $lines [expr {$i-1}] $i [list $b $e $itl]]
        }
        $canv coords $itl $coords
        if {$arrow ne $al} {
            $canv itemconf $itl -arrow $arrow
        }
    }

    set linesegs($id) $lines
    return $le
}

proc drawparentlinks {id row} {
    global rowidlist canv colormap curview parentlist
    global idpos linespc

    set rowids [lindex $rowidlist $row]
    set col [lsearch -exact $rowids $id]
    if {$col < 0} return
    set olds [lindex $parentlist $row]
    set row2 [expr {$row + 1}]
    set x [xc $row $col]
    set y [yc $row]
    set y2 [yc $row2]
    set d [expr {int(0.5 * $linespc)}]
    set ymid [expr {$y + $d}]
    set ids [lindex $rowidlist $row2]
    # rmx = right-most X coord used
    set rmx 0
    foreach p $olds {
        set i [lsearch -exact $ids $p]
        if {$i < 0} {
            puts "oops, parent $p of $id not in list"
            continue
        }
        set x2 [xc $row2 $i]
        if {$x2 > $rmx} {
            set rmx $x2
        }
        set j [lsearch -exact $rowids $p]
        if {$j < 0} {
            # drawlineseg will do this one for us
            continue
        }
        assigncolor $p
        # should handle duplicated parents here...
        set coords [list $x $y]
        if {$i != $col} {
            # if attaching to a vertical segment, draw a smaller
            # slant for visual distinctness
            if {$i == $j} {
                if {$i < $col} {
                    lappend coords [expr {$x2 + $d}] $y $x2 $ymid
                } else {
                    lappend coords [expr {$x2 - $d}] $y $x2 $ymid
                }
            } elseif {$i < $col && $i < $j} {
                # segment slants towards us already
                lappend coords [xc $row $j] $y
            } else {
                if {$i < $col - 1} {
                    lappend coords [expr {$x2 + $linespc}] $y
                } elseif {$i > $col + 1} {
                    lappend coords [expr {$x2 - $linespc}] $y
                }
                lappend coords $x2 $y2
            }
        } else {
            lappend coords $x2 $y2
        }
        set t [$canv create line $coords -width [linewidth $p] \
                   -fill $colormap($p) -tags lines.$p]
        $canv lower $t
        bindline $t $p
    }
    if {$rmx > [lindex $idpos($id) 1]} {
        lset idpos($id) 1 $rmx
        redrawtags $id
    }
}

proc drawlines {id} {
    global canv

    $canv itemconf lines.$id -width [linewidth $id]
}

proc drawcmittext {id row col} {
    global linespc canv canv2 canv3 fgcolor curview
    global cmitlisted commitinfo rowidlist parentlist
    global rowtextx idpos idtags idheads idotherrefs
    global linehtag linentag linedtag selectedline
    global canvxmax boldrows boldnamerows fgcolor
    global mainheadid nullid nullid2 circleitem circlecolors

    # listed is 0 for boundary, 1 for normal, 2 for negative, 3 for left, 4 for right
    set listed $cmitlisted($curview,$id)
    if {$id eq $nullid} {
        set ofill red
    } elseif {$id eq $nullid2} {
        set ofill green
    } elseif {$id eq $mainheadid} {
        set ofill yellow
    } else {
        set ofill [lindex $circlecolors $listed]
    }
    set x [xc $row $col]
    set y [yc $row]
    set orad [expr {$linespc / 3}]
    if {$listed <= 2} {
        set t [$canv create oval [expr {$x - $orad}] [expr {$y - $orad}] \
                   [expr {$x + $orad - 1}] [expr {$y + $orad - 1}] \
                   -fill $ofill -outline $fgcolor -width 1 -tags circle]
    } elseif {$listed == 3} {
        # triangle pointing left for left-side commits
        set t [$canv create polygon \
                   [expr {$x - $orad}] $y \
                   [expr {$x + $orad - 1}] [expr {$y - $orad}] \
                   [expr {$x + $orad - 1}] [expr {$y + $orad - 1}] \
                   -fill $ofill -outline $fgcolor -width 1 -tags circle]
    } else {
        # triangle pointing right for right-side commits
        set t [$canv create polygon \
                   [expr {$x + $orad - 1}] $y \
                   [expr {$x - $orad}] [expr {$y - $orad}] \
                   [expr {$x - $orad}] [expr {$y + $orad - 1}] \
                   -fill $ofill -outline $fgcolor -width 1 -tags circle]
    }
    set circleitem($row) $t
    $canv raise $t
    $canv bind $t <1> {selcanvline {} %x %y}
    set rmx [llength [lindex $rowidlist $row]]
    set olds [lindex $parentlist $row]
    if {$olds ne {}} {
        set nextids [lindex $rowidlist [expr {$row + 1}]]
        foreach p $olds {
            set i [lsearch -exact $nextids $p]
            if {$i > $rmx} {
                set rmx $i
            }
        }
    }
    set xt [xc $row $rmx]
    set rowtextx($row) $xt
    set idpos($id) [list $x $xt $y]
    if {[info exists idtags($id)] || [info exists idheads($id)]
        || [info exists idotherrefs($id)]} {
        set xt [drawtags $id $x $xt $y]
    }
    set headline [lindex $commitinfo($id) 0]
    set name [lindex $commitinfo($id) 1]
    set date [lindex $commitinfo($id) 2]
    set date [formatdate $date]
    set font mainfont
    set nfont mainfont
    set isbold [ishighlighted $id]
    if {$isbold > 0} {
        lappend boldrows $row
        set font mainfontbold
        if {$isbold > 1} {
            lappend boldnamerows $row
            set nfont mainfontbold
        }
    }
    set linehtag($row) [$canv create text $xt $y -anchor w -fill $fgcolor \
                            -text $headline -font $font -tags text]
    $canv bind $linehtag($row) <Button-3> "rowmenu %X %Y $id"
    set linentag($row) [$canv2 create text 3 $y -anchor w -fill $fgcolor \
                            -text $name -font $nfont -tags text]
    set linedtag($row) [$canv3 create text 3 $y -anchor w -fill $fgcolor \
                            -text $date -font mainfont -tags text]
    if {$selectedline == $row} {
        make_secsel $row
    }
    set xr [expr {$xt + [font measure $font $headline]}]
    if {$xr > $canvxmax} {
        set canvxmax $xr
        setcanvscroll
    }
}

proc drawcmitrow {row} {
    global displayorder rowidlist nrows_drawn
    global iddrawn markingmatches
    global commitinfo numcommits
    global filehighlight fhighlights findpattern nhighlights
    global hlview vhighlights
    global highlight_related rhighlights

    if {$row >= $numcommits} return

    set id [lindex $displayorder $row]
    if {[info exists hlview] && ![info exists vhighlights($id)]} {
        askvhighlight $row $id
    }
    if {[info exists filehighlight] && ![info exists fhighlights($id)]} {
        askfilehighlight $row $id
    }
    if {$findpattern ne {} && ![info exists nhighlights($id)]} {
        askfindhighlight $row $id
    }
    if {$highlight_related ne [mc "None"] && ![info exists rhighlights($id)]} {
        askrelhighlight $row $id
    }
    if {![info exists iddrawn($id)]} {
        set col [lsearch -exact [lindex $rowidlist $row] $id]
        if {$col < 0} {
            puts "oops, row $row id $id not in list"
            return
        }
        if {![info exists commitinfo($id)]} {
            getcommit $id
        }
        assigncolor $id
        drawcmittext $id $row $col
        set iddrawn($id) 1
        incr nrows_drawn
    }
    if {$markingmatches} {
        markrowmatches $row $id
    }
}

proc drawcommits {row {endrow {}}} {
    global numcommits iddrawn displayorder curview need_redisplay
    global parentlist rowidlist rowfinal uparrowlen downarrowlen nrows_drawn

    if {$row < 0} {
        set row 0
    }
    if {$endrow eq {}} {
        set endrow $row
    }
    if {$endrow >= $numcommits} {
        set endrow [expr {$numcommits - 1}]
    }

    set rl1 [expr {$row - $downarrowlen - 3}]
    if {$rl1 < 0} {
        set rl1 0
    }
    set ro1 [expr {$row - 3}]
    if {$ro1 < 0} {
        set ro1 0
    }
    set r2 [expr {$endrow + $uparrowlen + 3}]
    if {$r2 > $numcommits} {
        set r2 $numcommits
    }
    for {set r $rl1} {$r < $r2} {incr r} {
        if {[lindex $rowidlist $r] ne {} && [lindex $rowfinal $r]} {
            if {$rl1 < $r} {
                layoutrows $rl1 $r
            }
            set rl1 [expr {$r + 1}]
        }
    }
    if {$rl1 < $r} {
        layoutrows $rl1 $r
    }
    optimize_rows $ro1 0 $r2
    if {$need_redisplay || $nrows_drawn > 2000} {
        clear_display
        drawvisible
    }

    # make the lines join to already-drawn rows either side
    set r [expr {$row - 1}]
    if {$r < 0 || ![info exists iddrawn([lindex $displayorder $r])]} {
        set r $row
    }
    set er [expr {$endrow + 1}]
    if {$er >= $numcommits ||
        ![info exists iddrawn([lindex $displayorder $er])]} {
        set er $endrow
    }
    for {} {$r <= $er} {incr r} {
        set id [lindex $displayorder $r]
        set wasdrawn [info exists iddrawn($id)]
        drawcmitrow $r
        if {$r == $er} break
        set nextid [lindex $displayorder [expr {$r + 1}]]
        if {$wasdrawn && [info exists iddrawn($nextid)]} continue
        drawparentlinks $id $r

        set rowids [lindex $rowidlist $r]
        foreach lid $rowids {
            if {$lid eq {}} continue
            if {[info exists lineend($lid)] && $lineend($lid) > $r} continue
            if {$lid eq $id} {
                # see if this is the first child of any of its parents
                foreach p [lindex $parentlist $r] {
                    if {[lsearch -exact $rowids $p] < 0} {
                        # make this line extend up to the child
                        set lineend($p) [drawlineseg $p $r $er 0]
                    }
                }
            } else {
                set lineend($lid) [drawlineseg $lid $r $er 1]
            }
        }
    }
}

proc undolayout {row} {
    global uparrowlen mingaplen downarrowlen
    global rowidlist rowisopt rowfinal need_redisplay

    set r [expr {$row - ($uparrowlen + $mingaplen + $downarrowlen)}]
    if {$r < 0} {
        set r 0
    }
    if {[llength $rowidlist] > $r} {
        incr r -1
        set rowidlist [lrange $rowidlist 0 $r]
        set rowfinal [lrange $rowfinal 0 $r]
        set rowisopt [lrange $rowisopt 0 $r]
        set need_redisplay 1
        run drawvisible
    }
}

proc drawvisible {} {
    global canv linespc curview vrowmod selectedline targetrow targetid
    global need_redisplay cscroll numcommits

    set fs [$canv yview]
    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax == 0 || $numcommits == 0} return
    set f0 [lindex $fs 0]
    set f1 [lindex $fs 1]
    set y0 [expr {int($f0 * $ymax)}]
    set y1 [expr {int($f1 * $ymax)}]

    if {[info exists targetid]} {
        if {[commitinview $targetid $curview]} {
            set r [rowofcommit $targetid]
            if {$r != $targetrow} {
                # Fix up the scrollregion and change the scrolling position
                # now that our target row has moved.
                set diff [expr {($r - $targetrow) * $linespc}]
                set targetrow $r
                setcanvscroll
                set ymax [lindex [$canv cget -scrollregion] 3]
                incr y0 $diff
                incr y1 $diff
                set f0 [expr {$y0 / $ymax}]
                set f1 [expr {$y1 / $ymax}]
                allcanvs yview moveto $f0
                $cscroll set $f0 $f1
                set need_redisplay 1
            }
        } else {
            unset targetid
        }
    }

    set row [expr {int(($y0 - 3) / $linespc) - 1}]
    set endrow [expr {int(($y1 - 3) / $linespc) + 1}]
    if {$endrow >= $vrowmod($curview)} {
        update_arcrows $curview
    }
    if {$selectedline ne {} &&
        $row <= $selectedline && $selectedline <= $endrow} {
        set targetrow $selectedline
    } elseif {[info exists targetid]} {
        set targetrow [expr {int(($row + $endrow) / 2)}]
    }
    if {[info exists targetrow]} {
        if {$targetrow >= $numcommits} {
            set targetrow [expr {$numcommits - 1}]
        }
        set targetid [commitonrow $targetrow]
    }
    drawcommits $row $endrow
}

proc clear_display {} {
    global iddrawn linesegs need_redisplay nrows_drawn
    global vhighlights fhighlights nhighlights rhighlights
    global linehtag linentag linedtag boldrows boldnamerows

    allcanvs delete all
    catch {unset iddrawn}
    catch {unset linesegs}
    catch {unset linehtag}
    catch {unset linentag}
    catch {unset linedtag}
    set boldrows {}
    set boldnamerows {}
    catch {unset vhighlights}
    catch {unset fhighlights}
    catch {unset nhighlights}
    catch {unset rhighlights}
    set need_redisplay 0
    set nrows_drawn 0
}

proc findcrossings {id} {
    global rowidlist parentlist numcommits displayorder

    set cross {}
    set ccross {}
    foreach {s e} [rowranges $id] {
        if {$e >= $numcommits} {
            set e [expr {$numcommits - 1}]
        }
        if {$e <= $s} continue
        for {set row $e} {[incr row -1] >= $s} {} {
            set x [lsearch -exact [lindex $rowidlist $row] $id]
            if {$x < 0} break
            set olds [lindex $parentlist $row]
            set kid [lindex $displayorder $row]
            set kidx [lsearch -exact [lindex $rowidlist $row] $kid]
            if {$kidx < 0} continue
            set nextrow [lindex $rowidlist [expr {$row + 1}]]
            foreach p $olds {
                set px [lsearch -exact $nextrow $p]
                if {$px < 0} continue
                if {($kidx < $x && $x < $px) || ($px < $x && $x < $kidx)} {
                    if {[lsearch -exact $ccross $p] >= 0} continue
                    if {$x == $px + ($kidx < $px? -1: 1)} {
                        lappend ccross $p
                    } elseif {[lsearch -exact $cross $p] < 0} {
                        lappend cross $p
                    }
                }
            }
        }
    }
    return [concat $ccross {{}} $cross]
}

proc assigncolor {id} {
    global colormap colors nextcolor
    global parents children children curview

    if {[info exists colormap($id)]} return
    set ncolors [llength $colors]
    if {[info exists children($curview,$id)]} {
        set kids $children($curview,$id)
    } else {
        set kids {}
    }
    if {[llength $kids] == 1} {
        set child [lindex $kids 0]
        if {[info exists colormap($child)]
            && [llength $parents($curview,$child)] == 1} {
            set colormap($id) $colormap($child)
            return
        }
    }
    set badcolors {}
    set origbad {}
    foreach x [findcrossings $id] {
        if {$x eq {}} {
            # delimiter between corner crossings and other crossings
            if {[llength $badcolors] >= $ncolors - 1} break
            set origbad $badcolors
        }
        if {[info exists colormap($x)]
            && [lsearch -exact $badcolors $colormap($x)] < 0} {
            lappend badcolors $colormap($x)
        }
    }
    if {[llength $badcolors] >= $ncolors} {
        set badcolors $origbad
    }
    set origbad $badcolors
    if {[llength $badcolors] < $ncolors - 1} {
        foreach child $kids {
            if {[info exists colormap($child)]
                && [lsearch -exact $badcolors $colormap($child)] < 0} {
                lappend badcolors $colormap($child)
            }
            foreach p $parents($curview,$child) {
                if {[info exists colormap($p)]
                    && [lsearch -exact $badcolors $colormap($p)] < 0} {
                    lappend badcolors $colormap($p)
                }
            }
        }
        if {[llength $badcolors] >= $ncolors} {
            set badcolors $origbad
        }
    }
    for {set i 0} {$i <= $ncolors} {incr i} {
        set c [lindex $colors $nextcolor]
        if {[incr nextcolor] >= $ncolors} {
            set nextcolor 0
        }
        if {[lsearch -exact $badcolors $c]} break
    }
    set colormap($id) $c
}

proc bindline {t id} {
    global canv

    $canv bind $t <Enter> "lineenter %x %y $id"
    $canv bind $t <Motion> "linemotion %x %y $id"
    $canv bind $t <Leave> "lineleave $id"
    $canv bind $t <Button-1> "lineclick %x %y $id 1"
}

proc drawtags {id x xt y1} {
    global idtags idheads idotherrefs mainhead
    global linespc lthickness
    global canv rowtextx curview fgcolor bgcolor

    set marks {}
    set ntags 0
    set nheads 0
    if {[info exists idtags($id)]} {
        set marks $idtags($id)
        set ntags [llength $marks]
    }
    if {[info exists idheads($id)]} {
        set marks [concat $marks $idheads($id)]
        set nheads [llength $idheads($id)]
    }
    if {[info exists idotherrefs($id)]} {
        set marks [concat $marks $idotherrefs($id)]
    }
    if {$marks eq {}} {
        return $xt
    }

    set delta [expr {int(0.5 * ($linespc - $lthickness))}]
    set yt [expr {$y1 - 0.5 * $linespc}]
    set yb [expr {$yt + $linespc - 1}]
    set xvals {}
    set wvals {}
    set i -1
    foreach tag $marks {
        incr i
        if {$i >= $ntags && $i < $ntags + $nheads && $tag eq $mainhead} {
            set wid [font measure mainfontbold $tag]
        } else {
            set wid [font measure mainfont $tag]
        }
        lappend xvals $xt
        lappend wvals $wid
        set xt [expr {$xt + $delta + $wid + $lthickness + $linespc}]
    }
    set t [$canv create line $x $y1 [lindex $xvals end] $y1 \
               -width $lthickness -fill black -tags tag.$id]
    $canv lower $t
    foreach tag $marks x $xvals wid $wvals {
        set xl [expr {$x + $delta}]
        set xr [expr {$x + $delta + $wid + $lthickness}]
        set font mainfont
        if {[incr ntags -1] >= 0} {
            # draw a tag
            set t [$canv create polygon $x [expr {$yt + $delta}] $xl $yt \
                       $xr $yt $xr $yb $xl $yb $x [expr {$yb - $delta}] \
                       -width 1 -outline black -fill yellow -tags tag.$id]
            $canv bind $t <1> [list showtag $tag 1]
            set rowtextx([rowofcommit $id]) [expr {$xr + $linespc}]
        } else {
            # draw a head or other ref
            if {[incr nheads -1] >= 0} {
                set col green
                if {$tag eq $mainhead} {
                    set font mainfontbold
                }
            } else {
                set col "#ddddff"
            }
            set xl [expr {$xl - $delta/2}]
            $canv create polygon $x $yt $xr $yt $xr $yb $x $yb \
                -width 1 -outline black -fill $col -tags tag.$id
            if {[regexp {^(remotes/.*/|remotes/)} $tag match remoteprefix]} {
                set rwid [font measure mainfont $remoteprefix]
                set xi [expr {$x + 1}]
                set yti [expr {$yt + 1}]
                set xri [expr {$x + $rwid}]
                $canv create polygon $xi $yti $xri $yti $xri $yb $xi $yb \
                        -width 0 -fill "#ffddaa" -tags tag.$id
            }
        }
        set t [$canv create text $xl $y1 -anchor w -text $tag -fill $fgcolor \
                   -font $font -tags [list tag.$id text]]
        if {$ntags >= 0} {
            $canv bind $t <1> [list showtag $tag 1]
        } elseif {$nheads >= 0} {
            $canv bind $t <Button-3> [list headmenu %X %Y $id $tag]
        }
    }
    return $xt
}

proc xcoord {i level ln} {
    global canvx0 xspc1 xspc2

    set x [expr {$canvx0 + $i * $xspc1($ln)}]
    if {$i > 0 && $i == $level} {
        set x [expr {$x + 0.5 * ($xspc2 - $xspc1($ln))}]
    } elseif {$i > $level} {
        set x [expr {$x + $xspc2 - $xspc1($ln)}]
    }
    return $x
}

proc show_status {msg} {
    global canv fgcolor

    clear_display
    $canv create text 3 3 -anchor nw -text $msg -font mainfont \
        -tags text -fill $fgcolor
}

# Don't change the text pane cursor if it is currently the hand cursor,
# showing that we are over a sha1 ID link.
proc settextcursor {c} {
    global ctext curtextcursor

    if {[$ctext cget -cursor] == $curtextcursor} {
        $ctext config -cursor $c
    }
    set curtextcursor $c
}

proc nowbusy {what {name {}}} {
    global isbusy busyname statusw

    if {[array names isbusy] eq {}} {
        . config -cursor watch
        settextcursor watch
    }
    set isbusy($what) 1
    set busyname($what) $name
    if {$name ne {}} {
        $statusw conf -text $name
    }
}

proc notbusy {what} {
    global isbusy maincursor textcursor busyname statusw

    catch {
        unset isbusy($what)
        if {$busyname($what) ne {} &&
            [$statusw cget -text] eq $busyname($what)} {
            $statusw conf -text {}
        }
    }
    if {[array names isbusy] eq {}} {
        . config -cursor $maincursor
        settextcursor $textcursor
    }
}

proc findmatches {f} {
    global findtype findstring
    if {$findtype == [mc "Regexp"]} {
        set matches [regexp -indices -all -inline $findstring $f]
    } else {
        set fs $findstring
        if {$findtype == [mc "IgnCase"]} {
            set f [string tolower $f]
            set fs [string tolower $fs]
        }
        set matches {}
        set i 0
        set l [string length $fs]
        while {[set j [string first $fs $f $i]] >= 0} {
            lappend matches [list $j [expr {$j+$l-1}]]
            set i [expr {$j + $l}]
        }
    }
    return $matches
}

proc dofind {{dirn 1} {wrap 1}} {
    global findstring findstartline findcurline selectedline numcommits
    global gdttype filehighlight fh_serial find_dirn findallowwrap

    if {[info exists find_dirn]} {
        if {$find_dirn == $dirn} return
        stopfinding
    }
    focus .
    if {$findstring eq {} || $numcommits == 0} return
    if {$selectedline eq {}} {
        set findstartline [lindex [visiblerows] [expr {$dirn < 0}]]
    } else {
        set findstartline $selectedline
    }
    set findcurline $findstartline
    nowbusy finding [mc "Searching"]
    if {$gdttype ne [mc "containing:"] && ![info exists filehighlight]} {
        after cancel do_file_hl $fh_serial
        do_file_hl $fh_serial
    }
    set find_dirn $dirn
    set findallowwrap $wrap
    run findmore
}

proc stopfinding {} {
    global find_dirn findcurline fprogcoord

    if {[info exists find_dirn]} {
        unset find_dirn
        unset findcurline
        notbusy finding
        set fprogcoord 0
        adjustprogress
    }
}

proc findmore {} {
    global commitdata commitinfo numcommits findpattern findloc
    global findstartline findcurline findallowwrap
    global find_dirn gdttype fhighlights fprogcoord
    global curview varcorder vrownum varccommits vrowmod

    if {![info exists find_dirn]} {
        return 0
    }
    set fldtypes [list [mc "Headline"] [mc "Author"] [mc "Date"] [mc "Committer"] [mc "CDate"] [mc "Comments"]]
    set l $findcurline
    set moretodo 0
    if {$find_dirn > 0} {
        incr l
        if {$l >= $numcommits} {
            set l 0
        }
        if {$l <= $findstartline} {
            set lim [expr {$findstartline + 1}]
        } else {
            set lim $numcommits
            set moretodo $findallowwrap
        }
    } else {
        if {$l == 0} {
            set l $numcommits
        }
        incr l -1
        if {$l >= $findstartline} {
            set lim [expr {$findstartline - 1}]
        } else {
            set lim -1
            set moretodo $findallowwrap
        }
    }
    set n [expr {($lim - $l) * $find_dirn}]
    if {$n > 500} {
        set n 500
        set moretodo 1
    }
    if {$l + ($find_dirn > 0? $n: 1) > $vrowmod($curview)} {
        update_arcrows $curview
    }
    set found 0
    set domore 1
    set ai [bsearch $vrownum($curview) $l]
    set a [lindex $varcorder($curview) $ai]
    set arow [lindex $vrownum($curview) $ai]
    set ids [lindex $varccommits($curview,$a)]
    set arowend [expr {$arow + [llength $ids]}]
    if {$gdttype eq [mc "containing:"]} {
        for {} {$n > 0} {incr n -1; incr l $find_dirn} {
            if {$l < $arow || $l >= $arowend} {
                incr ai $find_dirn
                set a [lindex $varcorder($curview) $ai]
                set arow [lindex $vrownum($curview) $ai]
                set ids [lindex $varccommits($curview,$a)]
                set arowend [expr {$arow + [llength $ids]}]
            }
            set id [lindex $ids [expr {$l - $arow}]]
            # shouldn't happen unless git log doesn't give all the commits...
            if {![info exists commitdata($id)] ||
                ![doesmatch $commitdata($id)]} {
                continue
            }
            if {![info exists commitinfo($id)]} {
                getcommit $id
            }
            set info $commitinfo($id)
            foreach f $info ty $fldtypes {
                if {($findloc eq [mc "All fields"] || $findloc eq $ty) &&
                    [doesmatch $f]} {
                    set found 1
                    break
                }
            }
            if {$found} break
        }
    } else {
        for {} {$n > 0} {incr n -1; incr l $find_dirn} {
            if {$l < $arow || $l >= $arowend} {
                incr ai $find_dirn
                set a [lindex $varcorder($curview) $ai]
                set arow [lindex $vrownum($curview) $ai]
                set ids [lindex $varccommits($curview,$a)]
                set arowend [expr {$arow + [llength $ids]}]
            }
            set id [lindex $ids [expr {$l - $arow}]]
            if {![info exists fhighlights($id)]} {
                # this sets fhighlights($id) to -1
                askfilehighlight $l $id
            }
            if {$fhighlights($id) > 0} {
                set found $domore
                break
            }
            if {$fhighlights($id) < 0} {
                if {$domore} {
                    set domore 0
                    set findcurline [expr {$l - $find_dirn}]
                }
            }
        }
    }
    if {$found || ($domore && !$moretodo)} {
        unset findcurline
        unset find_dirn
        notbusy finding
        set fprogcoord 0
        adjustprogress
        if {$found} {
            findselectline $l
        } else {
            bell
        }
        return 0
    }
    if {!$domore} {
        flushhighlights
    } else {
        set findcurline [expr {$l - $find_dirn}]
    }
    set n [expr {($findcurline - $findstartline) * $find_dirn - 1}]
    if {$n < 0} {
        incr n $numcommits
    }
    set fprogcoord [expr {$n * 1.0 / $numcommits}]
    adjustprogress
    return $domore
}

proc findselectline {l} {
    global findloc commentend ctext findcurline markingmatches gdttype

    set markingmatches 1
    set findcurline $l
    selectline $l 1
    if {$findloc == [mc "All fields"] || $findloc == [mc "Comments"]} {
        # highlight the matches in the comments
        set f [$ctext get 1.0 $commentend]
        set matches [findmatches $f]
        foreach match $matches {
            set start [lindex $match 0]
            set end [expr {[lindex $match 1] + 1}]
            $ctext tag add found "1.0 + $start c" "1.0 + $end c"
        }
    }
    drawvisible
}

# mark the bits of a headline or author that match a find string
proc markmatches {canv l str tag matches font row} {
    global selectedline

    set bbox [$canv bbox $tag]
    set x0 [lindex $bbox 0]
    set y0 [lindex $bbox 1]
    set y1 [lindex $bbox 3]
    foreach match $matches {
        set start [lindex $match 0]
        set end [lindex $match 1]
        if {$start > $end} continue
        set xoff [font measure $font [string range $str 0 [expr {$start-1}]]]
        set xlen [font measure $font [string range $str 0 [expr {$end}]]]
        set t [$canv create rect [expr {$x0+$xoff}] $y0 \
                   [expr {$x0+$xlen+2}] $y1 \
                   -outline {} -tags [list match$l matches] -fill yellow]
        $canv lower $t
        if {$row == $selectedline} {
            $canv raise $t secsel
        }
    }
}

proc unmarkmatches {} {
    global markingmatches

    allcanvs delete matches
    set markingmatches 0
    stopfinding
}

proc selcanvline {w x y} {
    global canv canvy0 ctext linespc
    global rowtextx
    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax == {}} return
    set yfrac [lindex [$canv yview] 0]
    set y [expr {$y + $yfrac * $ymax}]
    set l [expr {int(($y - $canvy0) / $linespc + 0.5)}]
    if {$l < 0} {
        set l 0
    }
    if {$w eq $canv} {
        set xmax [lindex [$canv cget -scrollregion] 2]
        set xleft [expr {[lindex [$canv xview] 0] * $xmax}]
        if {![info exists rowtextx($l)] || $xleft + $x < $rowtextx($l)} return
    }
    unmarkmatches
    selectline $l 1
}

proc commit_descriptor {p} {
    global commitinfo
    if {![info exists commitinfo($p)]} {
        getcommit $p
    }
    set l "..."
    if {[llength $commitinfo($p)] > 1} {
        set l [lindex $commitinfo($p) 0]
    }
    return "$p ($l)\n"
}

# append some text to the ctext widget, and make any SHA1 ID
# that we know about be a clickable link.
proc appendwithlinks {text tags} {
    global ctext linknum curview pendinglinks

    set start [$ctext index "end - 1c"]
    $ctext insert end $text $tags
    set links [regexp -indices -all -inline {[0-9a-f]{40}} $text]
    foreach l $links {
        set s [lindex $l 0]
        set e [lindex $l 1]
        set linkid [string range $text $s $e]
        incr e
        $ctext tag delete link$linknum
        $ctext tag add link$linknum "$start + $s c" "$start + $e c"
        setlink $linkid link$linknum
        incr linknum
    }
}

proc setlink {id lk} {
    global curview ctext pendinglinks commitinterest

    if {[commitinview $id $curview]} {
        $ctext tag conf $lk -foreground blue -underline 1
        $ctext tag bind $lk <1> [list selectline [rowofcommit $id] 1]
        $ctext tag bind $lk <Enter> {linkcursor %W 1}
        $ctext tag bind $lk <Leave> {linkcursor %W -1}
    } else {
        lappend pendinglinks($id) $lk
        lappend commitinterest($id) {makelink %I}
    }
}

proc makelink {id} {
    global pendinglinks

    if {![info exists pendinglinks($id)]} return
    foreach lk $pendinglinks($id) {
        setlink $id $lk
    }
    unset pendinglinks($id)
}

proc linkcursor {w inc} {
    global linkentercount curtextcursor

    if {[incr linkentercount $inc] > 0} {
        $w configure -cursor hand2
    } else {
        $w configure -cursor $curtextcursor
        if {$linkentercount < 0} {
            set linkentercount 0
        }
    }
}

proc viewnextline {dir} {
    global canv linespc

    $canv delete hover
    set ymax [lindex [$canv cget -scrollregion] 3]
    set wnow [$canv yview]
    set wtop [expr {[lindex $wnow 0] * $ymax}]
    set newtop [expr {$wtop + $dir * $linespc}]
    if {$newtop < 0} {
        set newtop 0
    } elseif {$newtop > $ymax} {
        set newtop $ymax
    }
    allcanvs yview moveto [expr {$newtop * 1.0 / $ymax}]
}

# add a list of tag or branch names at position pos
# returns the number of names inserted
proc appendrefs {pos ids var} {
    global ctext linknum curview $var maxrefs

    if {[catch {$ctext index $pos}]} {
        return 0
    }
    $ctext conf -state normal
    $ctext delete $pos "$pos lineend"
    set tags {}
    foreach id $ids {
        foreach tag [set $var\($id\)] {
            lappend tags [list $tag $id]
        }
    }
    if {[llength $tags] > $maxrefs} {
        $ctext insert $pos "many ([llength $tags])"
    } else {
        set tags [lsort -index 0 -decreasing $tags]
        set sep {}
        foreach ti $tags {
            set id [lindex $ti 1]
            set lk link$linknum
            incr linknum
            $ctext tag delete $lk
            $ctext insert $pos $sep
            $ctext insert $pos [lindex $ti 0] $lk
            setlink $id $lk
            set sep ", "
        }
    }
    $ctext conf -state disabled
    return [llength $tags]
}

# called when we have finished computing the nearby tags
proc dispneartags {delay} {
    global selectedline currentid showneartags tagphase

    if {$selectedline eq {} || !$showneartags} return
    after cancel dispnexttag
    if {$delay} {
        after 200 dispnexttag
        set tagphase -1
    } else {
        after idle dispnexttag
        set tagphase 0
    }
}

proc dispnexttag {} {
    global selectedline currentid showneartags tagphase ctext

    if {$selectedline eq {} || !$showneartags} return
    switch -- $tagphase {
        0 {
            set dtags [desctags $currentid]
            if {$dtags ne {}} {
                appendrefs precedes $dtags idtags
            }
        }
        1 {
            set atags [anctags $currentid]
            if {$atags ne {}} {
                appendrefs follows $atags idtags
            }
        }
        2 {
            set dheads [descheads $currentid]
            if {$dheads ne {}} {
                if {[appendrefs branch $dheads idheads] > 1
                    && [$ctext get "branch -3c"] eq "h"} {
                    # turn "Branch" into "Branches"
                    $ctext conf -state normal
                    $ctext insert "branch -2c" "es"
                    $ctext conf -state disabled
                }
            }
        }
    }
    if {[incr tagphase] <= 2} {
        after idle dispnexttag
    }
}

proc make_secsel {l} {
    global linehtag linentag linedtag canv canv2 canv3

    if {![info exists linehtag($l)]} return
    $canv delete secsel
    set t [eval $canv create rect [$canv bbox $linehtag($l)] -outline {{}} \
               -tags secsel -fill [$canv cget -selectbackground]]
    $canv lower $t
    $canv2 delete secsel
    set t [eval $canv2 create rect [$canv2 bbox $linentag($l)] -outline {{}} \
               -tags secsel -fill [$canv2 cget -selectbackground]]
    $canv2 lower $t
    $canv3 delete secsel
    set t [eval $canv3 create rect [$canv3 bbox $linedtag($l)] -outline {{}} \
               -tags secsel -fill [$canv3 cget -selectbackground]]
    $canv3 lower $t
}

proc selectline {l isnew} {
    global canv ctext commitinfo selectedline
    global canvy0 linespc parents children curview
    global currentid sha1entry
    global commentend idtags linknum
    global mergemax numcommits pending_select
    global cmitmode showneartags allcommits
    global targetrow targetid lastscrollrows
    global autoselect

    catch {unset pending_select}
    $canv delete hover
    normalline
    unsel_reflist
    stopfinding
    if {$l < 0 || $l >= $numcommits} return
    set id [commitonrow $l]
    set targetid $id
    set targetrow $l
    set selectedline $l
    set currentid $id
    if {$lastscrollrows < $numcommits} {
        setcanvscroll
    }

    set y [expr {$canvy0 + $l * $linespc}]
    set ymax [lindex [$canv cget -scrollregion] 3]
    set ytop [expr {$y - $linespc - 1}]
    set ybot [expr {$y + $linespc + 1}]
    set wnow [$canv yview]
    set wtop [expr {[lindex $wnow 0] * $ymax}]
    set wbot [expr {[lindex $wnow 1] * $ymax}]
    set wh [expr {$wbot - $wtop}]
    set newtop $wtop
    if {$ytop < $wtop} {
        if {$ybot < $wtop} {
            set newtop [expr {$y - $wh / 2.0}]
        } else {
            set newtop $ytop
            if {$newtop > $wtop - $linespc} {
                set newtop [expr {$wtop - $linespc}]
            }
        }
    } elseif {$ybot > $wbot} {
        if {$ytop > $wbot} {
            set newtop [expr {$y - $wh / 2.0}]
        } else {
            set newtop [expr {$ybot - $wh}]
            if {$newtop < $wtop + $linespc} {
                set newtop [expr {$wtop + $linespc}]
            }
        }
    }
    if {$newtop != $wtop} {
        if {$newtop < 0} {
            set newtop 0
        }
        allcanvs yview moveto [expr {$newtop * 1.0 / $ymax}]
        drawvisible
    }

    make_secsel $l

    if {$isnew} {
        addtohistory [list selbyid $id]
    }

    $sha1entry delete 0 end
    $sha1entry insert 0 $id
    if {$autoselect} {
        $sha1entry selection from 0
        $sha1entry selection to end
    }
    rhighlight_sel $id

    $ctext conf -state normal
    clear_ctext
    set linknum 0
    if {![info exists commitinfo($id)]} {
        getcommit $id
    }
    set info $commitinfo($id)
    set date [formatdate [lindex $info 2]]
    $ctext insert end "[mc "Author"]: [lindex $info 1]  $date\n"
    set date [formatdate [lindex $info 4]]
    $ctext insert end "[mc "Committer"]: [lindex $info 3]  $date\n"
    if {[info exists idtags($id)]} {
        $ctext insert end [mc "Tags:"]
        foreach tag $idtags($id) {
            $ctext insert end " $tag"
        }
        $ctext insert end "\n"
    }

    set headers {}
    set olds $parents($curview,$id)
    if {[llength $olds] > 1} {
        set np 0
        foreach p $olds {
            if {$np >= $mergemax} {
                set tag mmax
            } else {
                set tag m$np
            }
            $ctext insert end "[mc "Parent"]: " $tag
            appendwithlinks [commit_descriptor $p] {}
            incr np
        }
    } else {
        foreach p $olds {
            append headers "[mc "Parent"]: [commit_descriptor $p]"
        }
    }

    foreach c $children($curview,$id) {
        append headers "[mc "Child"]:  [commit_descriptor $c]"
    }

    # make anything that looks like a SHA1 ID be a clickable link
    appendwithlinks $headers {}
    if {$showneartags} {
        if {![info exists allcommits]} {
            getallcommits
        }
        $ctext insert end "[mc "Branch"]: "
        $ctext mark set branch "end -1c"
        $ctext mark gravity branch left
        $ctext insert end "\n[mc "Follows"]: "
        $ctext mark set follows "end -1c"
        $ctext mark gravity follows left
        $ctext insert end "\n[mc "Precedes"]: "
        $ctext mark set precedes "end -1c"
        $ctext mark gravity precedes left
        $ctext insert end "\n"
        dispneartags 1
    }
    $ctext insert end "\n"
    set comment [lindex $info 5]
    if {[string first "\r" $comment] >= 0} {
        set comment [string map {"\r" "\n    "} $comment]
    }
    appendwithlinks $comment {comment}

    $ctext tag remove found 1.0 end
    $ctext conf -state disabled
    set commentend [$ctext index "end - 1c"]

    init_flist [mc "Comments"]
    if {$cmitmode eq "tree"} {
        gettree $id
    } elseif {[llength $olds] <= 1} {
        startdiff $id
    } else {
        mergediff $id
    }
}

proc selfirstline {} {
    unmarkmatches
    selectline 0 1
}

proc sellastline {} {
    global numcommits
    unmarkmatches
    set l [expr {$numcommits - 1}]
    selectline $l 1
}

proc selnextline {dir} {
    global selectedline
    focus .
    if {$selectedline eq {}} return
    set l [expr {$selectedline + $dir}]
    unmarkmatches
    selectline $l 1
}

proc selnextpage {dir} {
    global canv linespc selectedline numcommits

    set lpp [expr {([winfo height $canv] - 2) / $linespc}]
    if {$lpp < 1} {
        set lpp 1
    }
    allcanvs yview scroll [expr {$dir * $lpp}] units
    drawvisible
    if {$selectedline eq {}} return
    set l [expr {$selectedline + $dir * $lpp}]
    if {$l < 0} {
        set l 0
    } elseif {$l >= $numcommits} {
        set l [expr $numcommits - 1]
    }
    unmarkmatches
    selectline $l 1
}

proc unselectline {} {
    global selectedline currentid

    set selectedline {}
    catch {unset currentid}
    allcanvs delete secsel
    rhighlight_none
}

proc reselectline {} {
    global selectedline

    if {$selectedline ne {}} {
        selectline $selectedline 0
    }
}

proc addtohistory {cmd} {
    global history historyindex curview

    set elt [list $curview $cmd]
    if {$historyindex > 0
        && [lindex $history [expr {$historyindex - 1}]] == $elt} {
        return
    }

    if {$historyindex < [llength $history]} {
        set history [lreplace $history $historyindex end $elt]
    } else {
        lappend history $elt
    }
    incr historyindex
    if {$historyindex > 1} {
        .tf.bar.leftbut conf -state normal
    } else {
        .tf.bar.leftbut conf -state disabled
    }
    .tf.bar.rightbut conf -state disabled
}

proc godo {elt} {
    global curview

    set view [lindex $elt 0]
    set cmd [lindex $elt 1]
    if {$curview != $view} {
        showview $view
    }
    eval $cmd
}

proc goback {} {
    global history historyindex
    focus .

    if {$historyindex > 1} {
        incr historyindex -1
        godo [lindex $history [expr {$historyindex - 1}]]
        .tf.bar.rightbut conf -state normal
    }
    if {$historyindex <= 1} {
        .tf.bar.leftbut conf -state disabled
    }
}

proc goforw {} {
    global history historyindex
    focus .

    if {$historyindex < [llength $history]} {
        set cmd [lindex $history $historyindex]
        incr historyindex
        godo $cmd
        .tf.bar.leftbut conf -state normal
    }
    if {$historyindex >= [llength $history]} {
        .tf.bar.rightbut conf -state disabled
    }
}

proc gettree {id} {
    global treefilelist treeidlist diffids diffmergeid treepending
    global nullid nullid2

    set diffids $id
    catch {unset diffmergeid}
    if {![info exists treefilelist($id)]} {
        if {![info exists treepending]} {
            if {$id eq $nullid} {
                set cmd [list | git ls-files]
            } elseif {$id eq $nullid2} {
                set cmd [list | git ls-files --stage -t]
            } else {
                set cmd [list | git ls-tree -r $id]
            }
            if {[catch {set gtf [open $cmd r]}]} {
                return
            }
            set treepending $id
            set treefilelist($id) {}
            set treeidlist($id) {}
            fconfigure $gtf -blocking 0
            filerun $gtf [list gettreeline $gtf $id]
        }
    } else {
        setfilelist $id
    }
}

proc gettreeline {gtf id} {
    global treefilelist treeidlist treepending cmitmode diffids nullid nullid2

    set nl 0
    while {[incr nl] <= 1000 && [gets $gtf line] >= 0} {
        if {$diffids eq $nullid} {
            set fname $line
        } else {
            set i [string first "\t" $line]
            if {$i < 0} continue
            set fname [string range $line [expr {$i+1}] end]
            set line [string range $line 0 [expr {$i-1}]]
            if {$diffids ne $nullid2 && [lindex $line 1] ne "blob"} continue
            set sha1 [lindex $line 2]
            if {[string index $fname 0] eq "\""} {
                set fname [lindex $fname 0]
            }
            lappend treeidlist($id) $sha1
        }
        lappend treefilelist($id) $fname
    }
    if {![eof $gtf]} {
        return [expr {$nl >= 1000? 2: 1}]
    }
    close $gtf
    unset treepending
    if {$cmitmode ne "tree"} {
        if {![info exists diffmergeid]} {
            gettreediffs $diffids
        }
    } elseif {$id ne $diffids} {
        gettree $diffids
    } else {
        setfilelist $id
    }
    return 0
}

proc showfile {f} {
    global treefilelist treeidlist diffids nullid nullid2
    global ctext commentend

    set i [lsearch -exact $treefilelist($diffids) $f]
    if {$i < 0} {
        puts "oops, $f not in list for id $diffids"
        return
    }
    if {$diffids eq $nullid} {
        if {[catch {set bf [open $f r]} err]} {
            puts "oops, can't read $f: $err"
            return
        }
    } else {
        set blob [lindex $treeidlist($diffids) $i]
        if {[catch {set bf [open [concat | git cat-file blob $blob] r]} err]} {
            puts "oops, error reading blob $blob: $err"
            return
        }
    }
    fconfigure $bf -blocking 0
    filerun $bf [list getblobline $bf $diffids]
    $ctext config -state normal
    clear_ctext $commentend
    $ctext insert end "\n"
    $ctext insert end "$f\n" filesep
    $ctext config -state disabled
    $ctext yview $commentend
    settabs 0
}

proc getblobline {bf id} {
    global diffids cmitmode ctext

    if {$id ne $diffids || $cmitmode ne "tree"} {
        catch {close $bf}
        return 0
    }
    $ctext config -state normal
    set nl 0
    while {[incr nl] <= 1000 && [gets $bf line] >= 0} {
        $ctext insert end "$line\n"
    }
    if {[eof $bf]} {
        # delete last newline
        $ctext delete "end - 2c" "end - 1c"
        close $bf
        return 0
    }
    $ctext config -state disabled
    return [expr {$nl >= 1000? 2: 1}]
}

proc mergediff {id} {
    global diffmergeid mdifffd
    global diffids
    global parents
    global diffcontext
    global limitdiffs vfilelimit curview

    set diffmergeid $id
    set diffids $id
    # this doesn't seem to actually affect anything...
    set cmd [concat | git diff-tree --no-commit-id --cc -U$diffcontext $id]
    if {$limitdiffs && $vfilelimit($curview) ne {}} {
        set cmd [concat $cmd -- $vfilelimit($curview)]
    }
    if {[catch {set mdf [open $cmd r]} err]} {
        error_popup "[mc "Error getting merge diffs:"] $err"
        return
    }
    fconfigure $mdf -blocking 0
    set mdifffd($id) $mdf
    set np [llength $parents($curview,$id)]
    settabs $np
    filerun $mdf [list getmergediffline $mdf $id $np]
}

proc getmergediffline {mdf id np} {
    global diffmergeid ctext cflist mergemax
    global difffilestart mdifffd

    $ctext conf -state normal
    set nr 0
    while {[incr nr] <= 1000 && [gets $mdf line] >= 0} {
        if {![info exists diffmergeid] || $id != $diffmergeid
            || $mdf != $mdifffd($id)} {
            close $mdf
            return 0
        }
        if {[regexp {^diff --cc (.*)} $line match fname]} {
            # start of a new file
            $ctext insert end "\n"
            set here [$ctext index "end - 1c"]
            lappend difffilestart $here
            add_flist [list $fname]
            set l [expr {(78 - [string length $fname]) / 2}]
            set pad [string range "----------------------------------------" 1 $l]
            $ctext insert end "$pad $fname $pad\n" filesep
        } elseif {[regexp {^@@} $line]} {
            $ctext insert end "$line\n" hunksep
        } elseif {[regexp {^[0-9a-f]{40}$} $line] || [regexp {^index} $line]} {
            # do nothing
        } else {
            # parse the prefix - one ' ', '-' or '+' for each parent
            set spaces {}
            set minuses {}
            set pluses {}
            set isbad 0
            for {set j 0} {$j < $np} {incr j} {
                set c [string range $line $j $j]
                if {$c == " "} {
                    lappend spaces $j
                } elseif {$c == "-"} {
                    lappend minuses $j
                } elseif {$c == "+"} {
                    lappend pluses $j
                } else {
                    set isbad 1
                    break
                }
            }
            set tags {}
            set num {}
            if {!$isbad && $minuses ne {} && $pluses eq {}} {
                # line doesn't appear in result, parents in $minuses have the line
                set num [lindex $minuses 0]
            } elseif {!$isbad && $pluses ne {} && $minuses eq {}} {
                # line appears in result, parents in $pluses don't have the line
                lappend tags mresult
                set num [lindex $spaces 0]
            }
            if {$num ne {}} {
                if {$num >= $mergemax} {
                    set num "max"
                }
                lappend tags m$num
            }
            $ctext insert end "$line\n" $tags
        }
    }
    $ctext conf -state disabled
    if {[eof $mdf]} {
        close $mdf
        return 0
    }
    return [expr {$nr >= 1000? 2: 1}]
}

proc startdiff {ids} {
    global treediffs diffids treepending diffmergeid nullid nullid2

    settabs 1
    set diffids $ids
    catch {unset diffmergeid}
    if {![info exists treediffs($ids)] ||
        [lsearch -exact $ids $nullid] >= 0 ||
        [lsearch -exact $ids $nullid2] >= 0} {
        if {![info exists treepending]} {
            gettreediffs $ids
        }
    } else {
        addtocflist $ids
    }
}

proc path_filter {filter name} {
    foreach p $filter {
        set l [string length $p]
        if {[string index $p end] eq "/"} {
            if {[string compare -length $l $p $name] == 0} {
                return 1
            }
        } else {
            if {[string compare -length $l $p $name] == 0 &&
                ([string length $name] == $l ||
                 [string index $name $l] eq "/")} {
                return 1
            }
        }
    }
    return 0
}

proc addtocflist {ids} {
    global treediffs

    add_flist $treediffs($ids)
    getblobdiffs $ids
}

proc diffcmd {ids flags} {
    global nullid nullid2

    set i [lsearch -exact $ids $nullid]
    set j [lsearch -exact $ids $nullid2]
    if {$i >= 0} {
        if {[llength $ids] > 1 && $j < 0} {
            # comparing working directory with some specific revision
            set cmd [concat | git diff-index $flags]
            if {$i == 0} {
                lappend cmd -R [lindex $ids 1]
            } else {
                lappend cmd [lindex $ids 0]
            }
        } else {
            # comparing working directory with index
            set cmd [concat | git diff-files $flags]
            if {$j == 1} {
                lappend cmd -R
            }
        }
    } elseif {$j >= 0} {
        set cmd [concat | git diff-index --cached $flags]
        if {[llength $ids] > 1} {
            # comparing index with specific revision
            if {$i == 0} {
                lappend cmd -R [lindex $ids 1]
            } else {
                lappend cmd [lindex $ids 0]
            }
        } else {
            # comparing index with HEAD
            lappend cmd HEAD
        }
    } else {
        set cmd [concat | git diff-tree -r $flags $ids]
    }
    return $cmd
}

proc gettreediffs {ids} {
    global treediff treepending

    if {[catch {set gdtf [open [diffcmd $ids {--no-commit-id}] r]}]} return

    set treepending $ids
    set treediff {}
    fconfigure $gdtf -blocking 0
    filerun $gdtf [list gettreediffline $gdtf $ids]
}

proc gettreediffline {gdtf ids} {
    global treediff treediffs treepending diffids diffmergeid
    global cmitmode vfilelimit curview limitdiffs

    set nr 0
    while {[incr nr] <= 1000 && [gets $gdtf line] >= 0} {
        set i [string first "\t" $line]
        if {$i >= 0} {
            set file [string range $line [expr {$i+1}] end]
            if {[string index $file 0] eq "\""} {
                set file [lindex $file 0]
            }
            lappend treediff $file
        }
    }
    if {![eof $gdtf]} {
        return [expr {$nr >= 1000? 2: 1}]
    }
    close $gdtf
    if {$limitdiffs && $vfilelimit($curview) ne {}} {
        set flist {}
        foreach f $treediff {
            if {[path_filter $vfilelimit($curview) $f]} {
                lappend flist $f
            }
        }
        set treediffs($ids) $flist
    } else {
        set treediffs($ids) $treediff
    }
    unset treepending
    if {$cmitmode eq "tree"} {
        gettree $diffids
    } elseif {$ids != $diffids} {
        if {![info exists diffmergeid]} {
            gettreediffs $diffids
        }
    } else {
        addtocflist $ids
    }
    return 0
}

# empty string or positive integer
proc diffcontextvalidate {v} {
    return [regexp {^(|[1-9][0-9]*)$} $v]
}

proc diffcontextchange {n1 n2 op} {
    global diffcontextstring diffcontext

    if {[string is integer -strict $diffcontextstring]} {
        if {$diffcontextstring > 0} {
            set diffcontext $diffcontextstring
            reselectline
        }
    }
}

proc changeignorespace {} {
    reselectline
}

proc getblobdiffs {ids} {
    global blobdifffd diffids env
    global diffinhdr treediffs
    global diffcontext
    global ignorespace
    global limitdiffs vfilelimit curview

    set cmd [diffcmd $ids "-p -C --no-commit-id -U$diffcontext"]
    if {$ignorespace} {
        append cmd " -w"
    }
    if {$limitdiffs && $vfilelimit($curview) ne {}} {
        set cmd [concat $cmd -- $vfilelimit($curview)]
    }
    if {[catch {set bdf [open $cmd r]} err]} {
        puts "error getting diffs: $err"
        return
    }
    set diffinhdr 0
    fconfigure $bdf -blocking 0
    set blobdifffd($ids) $bdf
    filerun $bdf [list getblobdiffline $bdf $diffids]
}

proc setinlist {var i val} {
    global $var

    while {[llength [set $var]] < $i} {
        lappend $var {}
    }
    if {[llength [set $var]] == $i} {
        lappend $var $val
    } else {
        lset $var $i $val
    }
}

proc makediffhdr {fname ids} {
    global ctext curdiffstart treediffs

    set i [lsearch -exact $treediffs($ids) $fname]
    if {$i >= 0} {
        setinlist difffilestart $i $curdiffstart
    }
    set l [expr {(78 - [string length $fname]) / 2}]
    set pad [string range "----------------------------------------" 1 $l]
    $ctext insert $curdiffstart "$pad $fname $pad" filesep
}

proc getblobdiffline {bdf ids} {
    global diffids blobdifffd ctext curdiffstart
    global diffnexthead diffnextnote difffilestart
    global diffinhdr treediffs

    set nr 0
    $ctext conf -state normal
    while {[incr nr] <= 1000 && [gets $bdf line] >= 0} {
        if {$ids != $diffids || $bdf != $blobdifffd($ids)} {
            close $bdf
            return 0
        }
        if {![string compare -length 11 "diff --git " $line]} {
            # trim off "diff --git "
            set line [string range $line 11 end]
            set diffinhdr 1
            # start of a new file
            $ctext insert end "\n"
            set curdiffstart [$ctext index "end - 1c"]
            $ctext insert end "\n" filesep
            # If the name hasn't changed the length will be odd,
            # the middle char will be a space, and the two bits either
            # side will be a/name and b/name, or "a/name" and "b/name".
            # If the name has changed we'll get "rename from" and
            # "rename to" or "copy from" and "copy to" lines following this,
            # and we'll use them to get the filenames.
            # This complexity is necessary because spaces in the filename(s)
            # don't get escaped.
            set l [string length $line]
            set i [expr {$l / 2}]
            if {!(($l & 1) && [string index $line $i] eq " " &&
                  [string range $line 2 [expr {$i - 1}]] eq \
                      [string range $line [expr {$i + 3}] end])} {
                continue
            }
            # unescape if quoted and chop off the a/ from the front
            if {[string index $line 0] eq "\""} {
                set fname [string range [lindex $line 0] 2 end]
            } else {
                set fname [string range $line 2 [expr {$i - 1}]]
            }
            makediffhdr $fname $ids

        } elseif {[regexp {^@@ -([0-9]+)(,[0-9]+)? \+([0-9]+)(,[0-9]+)? @@(.*)} \
                       $line match f1l f1c f2l f2c rest]} {
            $ctext insert end "$line\n" hunksep
            set diffinhdr 0

        } elseif {$diffinhdr} {
            if {![string compare -length 12 "rename from " $line]} {
                set fname [string range $line [expr 6 + [string first " from " $line] ] end]
                if {[string index $fname 0] eq "\""} {
                    set fname [lindex $fname 0]
                }
                set i [lsearch -exact $treediffs($ids) $fname]
                if {$i >= 0} {
                    setinlist difffilestart $i $curdiffstart
                }
            } elseif {![string compare -length 10 $line "rename to "] ||
                      ![string compare -length 8 $line "copy to "]} {
                set fname [string range $line [expr 4 + [string first " to " $line] ] end]
                if {[string index $fname 0] eq "\""} {
                    set fname [lindex $fname 0]
                }
                makediffhdr $fname $ids
            } elseif {[string compare -length 3 $line "---"] == 0} {
                # do nothing
                continue
            } elseif {[string compare -length 3 $line "+++"] == 0} {
                set diffinhdr 0
                continue
            }
            $ctext insert end "$line\n" filesep

        } else {
            set x [string range $line 0 0]
            if {$x == "-" || $x == "+"} {
                set tag [expr {$x == "+"}]
                $ctext insert end "$line\n" d$tag
            } elseif {$x == " "} {
                $ctext insert end "$line\n"
            } else {
                # "\ No newline at end of file",
                # or something else we don't recognize
                $ctext insert end "$line\n" hunksep
            }
        }
    }
    $ctext conf -state disabled
    if {[eof $bdf]} {
        close $bdf
        return 0
    }
    return [expr {$nr >= 1000? 2: 1}]
}

proc changediffdisp {} {
    global ctext diffelide

    $ctext tag conf d0 -elide [lindex $diffelide 0]
    $ctext tag conf d1 -elide [lindex $diffelide 1]
}

proc highlightfile {loc cline} {
    global ctext cflist cflist_top

    $ctext yview $loc
    $cflist tag remove highlight $cflist_top.0 "$cflist_top.0 lineend"
    $cflist tag add highlight $cline.0 "$cline.0 lineend"
    $cflist see $cline.0
    set cflist_top $cline
}

proc prevfile {} {
    global difffilestart ctext cmitmode

    if {$cmitmode eq "tree"} return
    set prev 0.0
    set prevline 1
    set here [$ctext index @0,0]
    foreach loc $difffilestart {
        if {[$ctext compare $loc >= $here]} {
            highlightfile $prev $prevline
            return
        }
        set prev $loc
        incr prevline
    }
    highlightfile $prev $prevline
}

proc nextfile {} {
    global difffilestart ctext cmitmode

    if {$cmitmode eq "tree"} return
    set here [$ctext index @0,0]
    set line 1
    foreach loc $difffilestart {
        incr line
        if {[$ctext compare $loc > $here]} {
            highlightfile $loc $line
            return
        }
    }
}

proc clear_ctext {{first 1.0}} {
    global ctext smarktop smarkbot
    global pendinglinks

    set l [lindex [split $first .] 0]
    if {![info exists smarktop] || [$ctext compare $first < $smarktop.0]} {
        set smarktop $l
    }
    if {![info exists smarkbot] || [$ctext compare $first < $smarkbot.0]} {
        set smarkbot $l
    }
    $ctext delete $first end
    if {$first eq "1.0"} {
        catch {unset pendinglinks}
    }
}

proc settabs {{firstab {}}} {
    global firsttabstop tabstop ctext have_tk85

    if {$firstab ne {} && $have_tk85} {
        set firsttabstop $firstab
    }
    set w [font measure textfont "0"]
    if {$firsttabstop != 0} {
        $ctext conf -tabs [list [expr {($firsttabstop + $tabstop) * $w}] \
                               [expr {($firsttabstop + 2 * $tabstop) * $w}]]
    } elseif {$have_tk85 || $tabstop != 8} {
        $ctext conf -tabs [expr {$tabstop * $w}]
    } else {
        $ctext conf -tabs {}
    }
}

proc incrsearch {name ix op} {
    global ctext searchstring searchdirn

    $ctext tag remove found 1.0 end
    if {[catch {$ctext index anchor}]} {
        # no anchor set, use start of selection, or of visible area
        set sel [$ctext tag ranges sel]
        if {$sel ne {}} {
            $ctext mark set anchor [lindex $sel 0]
        } elseif {$searchdirn eq "-forwards"} {
            $ctext mark set anchor @0,0
        } else {
            $ctext mark set anchor @0,[winfo height $ctext]
        }
    }
    if {$searchstring ne {}} {
        set here [$ctext search $searchdirn -- $searchstring anchor]
        if {$here ne {}} {
            $ctext see $here
        }
        searchmarkvisible 1
    }
}

proc dosearch {} {
    global sstring ctext searchstring searchdirn

    focus $sstring
    $sstring icursor end
    set searchdirn -forwards
    if {$searchstring ne {}} {
        set sel [$ctext tag ranges sel]
        if {$sel ne {}} {
            set start "[lindex $sel 0] + 1c"
        } elseif {[catch {set start [$ctext index anchor]}]} {
            set start "@0,0"
        }
        set match [$ctext search -count mlen -- $searchstring $start]
        $ctext tag remove sel 1.0 end
        if {$match eq {}} {
            bell
            return
        }
        $ctext see $match
        set mend "$match + $mlen c"
        $ctext tag add sel $match $mend
        $ctext mark unset anchor
    }
}

proc dosearchback {} {
    global sstring ctext searchstring searchdirn

    focus $sstring
    $sstring icursor end
    set searchdirn -backwards
    if {$searchstring ne {}} {
        set sel [$ctext tag ranges sel]
        if {$sel ne {}} {
            set start [lindex $sel 0]
        } elseif {[catch {set start [$ctext index anchor]}]} {
            set start @0,[winfo height $ctext]
        }
        set match [$ctext search -backwards -count ml -- $searchstring $start]
        $ctext tag remove sel 1.0 end
        if {$match eq {}} {
            bell
            return
        }
        $ctext see $match
        set mend "$match + $ml c"
        $ctext tag add sel $match $mend
        $ctext mark unset anchor
    }
}

proc searchmark {first last} {
    global ctext searchstring

    set mend $first.0
    while {1} {
        set match [$ctext search -count mlen -- $searchstring $mend $last.end]
        if {$match eq {}} break
        set mend "$match + $mlen c"
        $ctext tag add found $match $mend
    }
}

proc searchmarkvisible {doall} {
    global ctext smarktop smarkbot

    set topline [lindex [split [$ctext index @0,0] .] 0]
    set botline [lindex [split [$ctext index @0,[winfo height $ctext]] .] 0]
    if {$doall || $botline < $smarktop || $topline > $smarkbot} {
        # no overlap with previous
        searchmark $topline $botline
        set smarktop $topline
        set smarkbot $botline
    } else {
        if {$topline < $smarktop} {
            searchmark $topline [expr {$smarktop-1}]
            set smarktop $topline
        }
        if {$botline > $smarkbot} {
            searchmark [expr {$smarkbot+1}] $botline
            set smarkbot $botline
        }
    }
}

proc scrolltext {f0 f1} {
    global searchstring

    .bleft.bottom.sb set $f0 $f1
    if {$searchstring ne {}} {
        searchmarkvisible 0
    }
}

proc setcoords {} {
    global linespc charspc canvx0 canvy0
    global xspc1 xspc2 lthickness

    set linespc [font metrics mainfont -linespace]
    set charspc [font measure mainfont "m"]
    set canvy0 [expr {int(3 + 0.5 * $linespc)}]
    set canvx0 [expr {int(3 + 0.5 * $linespc)}]
    set lthickness [expr {int($linespc / 9) + 1}]
    set xspc1(0) $linespc
    set xspc2 $linespc
}

proc redisplay {} {
    global canv
    global selectedline

    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax == 0} return
    set span [$canv yview]
    clear_display
    setcanvscroll
    allcanvs yview moveto [lindex $span 0]
    drawvisible
    if {$selectedline ne {}} {
        selectline $selectedline 0
        allcanvs yview moveto [lindex $span 0]
    }
}

proc parsefont {f n} {
    global fontattr

    set fontattr($f,family) [lindex $n 0]
    set s [lindex $n 1]
    if {$s eq {} || $s == 0} {
        set s 10
    } elseif {$s < 0} {
        set s [expr {int(-$s / [winfo fpixels . 1p] + 0.5)}]
    }
    set fontattr($f,size) $s
    set fontattr($f,weight) normal
    set fontattr($f,slant) roman
    foreach style [lrange $n 2 end] {
        switch -- $style {
            "normal" -
            "bold"   {set fontattr($f,weight) $style}
            "roman" -
            "italic" {set fontattr($f,slant) $style}
        }
    }
}

proc fontflags {f {isbold 0}} {
    global fontattr

    return [list -family $fontattr($f,family) -size $fontattr($f,size) \
                -weight [expr {$isbold? "bold": $fontattr($f,weight)}] \
                -slant $fontattr($f,slant)]
}

proc fontname {f} {
    global fontattr

    set n [list $fontattr($f,family) $fontattr($f,size)]
    if {$fontattr($f,weight) eq "bold"} {
        lappend n "bold"
    }
    if {$fontattr($f,slant) eq "italic"} {
        lappend n "italic"
    }
    return $n
}

proc incrfont {inc} {
    global mainfont textfont ctext canv cflist showrefstop
    global stopped entries fontattr

    unmarkmatches
    set s $fontattr(mainfont,size)
    incr s $inc
    if {$s < 1} {
        set s 1
    }
    set fontattr(mainfont,size) $s
    font config mainfont -size $s
    font config mainfontbold -size $s
    set mainfont [fontname mainfont]
    set s $fontattr(textfont,size)
    incr s $inc
    if {$s < 1} {
        set s 1
    }
    set fontattr(textfont,size) $s
    font config textfont -size $s
    font config textfontbold -size $s
    set textfont [fontname textfont]
    setcoords
    settabs
    redisplay
}

proc clearsha1 {} {
    global sha1entry sha1string
    if {[string length $sha1string] == 40} {
        $sha1entry delete 0 end
    }
}

proc sha1change {n1 n2 op} {
    global sha1string currentid sha1but
    if {$sha1string == {}
        || ([info exists currentid] && $sha1string == $currentid)} {
        set state disabled
    } else {
        set state normal
    }
    if {[$sha1but cget -state] == $state} return
    if {$state == "normal"} {
        $sha1but conf -state normal -relief raised -text "[mc "Goto:"] "
    } else {
        $sha1but conf -state disabled -relief flat -text "[mc "SHA1 ID:"] "
    }
}

proc gotocommit {} {
    global sha1string tagids headids curview varcid

    if {$sha1string == {}
        || ([info exists currentid] && $sha1string == $currentid)} return
    if {[info exists tagids($sha1string)]} {
        set id $tagids($sha1string)
    } elseif {[info exists headids($sha1string)]} {
        set id $headids($sha1string)
    } else {
        set id [string tolower $sha1string]
        if {[regexp {^[0-9a-f]{4,39}$} $id]} {
            set matches [array names varcid "$curview,$id*"]
            if {$matches ne {}} {
                if {[llength $matches] > 1} {
                    error_popup [mc "Short SHA1 id %s is ambiguous" $id]
                    return
                }
                set id [lindex [split [lindex $matches 0] ","] 1]
            }
        }
    }
    if {[commitinview $id $curview]} {
        selectline [rowofcommit $id] 1
        return
    }
    if {[regexp {^[0-9a-fA-F]{4,}$} $sha1string]} {
        set msg [mc "SHA1 id %s is not known" $sha1string]
    } else {
        set msg [mc "Tag/Head %s is not known" $sha1string]
    }
    error_popup $msg
}

proc lineenter {x y id} {
    global hoverx hovery hoverid hovertimer
    global commitinfo canv

    if {![info exists commitinfo($id)] && ![getcommit $id]} return
    set hoverx $x
    set hovery $y
    set hoverid $id
    if {[info exists hovertimer]} {
        after cancel $hovertimer
    }
    set hovertimer [after 500 linehover]
    $canv delete hover
}

proc linemotion {x y id} {
    global hoverx hovery hoverid hovertimer

    if {[info exists hoverid] && $id == $hoverid} {
        set hoverx $x
        set hovery $y
        if {[info exists hovertimer]} {
            after cancel $hovertimer
        }
        set hovertimer [after 500 linehover]
    }
}

proc lineleave {id} {
    global hoverid hovertimer canv

    if {[info exists hoverid] && $id == $hoverid} {
        $canv delete hover
        if {[info exists hovertimer]} {
            after cancel $hovertimer
            unset hovertimer
        }
        unset hoverid
    }
}

proc linehover {} {
    global hoverx hovery hoverid hovertimer
    global canv linespc lthickness
    global commitinfo

    set text [lindex $commitinfo($hoverid) 0]
    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax == {}} return
    set yfrac [lindex [$canv yview] 0]
    set x [expr {$hoverx + 2 * $linespc}]
    set y [expr {$hovery + $yfrac * $ymax - $linespc / 2}]
    set x0 [expr {$x - 2 * $lthickness}]
    set y0 [expr {$y - 2 * $lthickness}]
    set x1 [expr {$x + [font measure mainfont $text] + 2 * $lthickness}]
    set y1 [expr {$y + $linespc + 2 * $lthickness}]
    set t [$canv create rectangle $x0 $y0 $x1 $y1 \
               -fill \#ffff80 -outline black -width 1 -tags hover]
    $canv raise $t
    set t [$canv create text $x $y -anchor nw -text $text -tags hover \
               -font mainfont]
    $canv raise $t
}

proc clickisonarrow {id y} {
    global lthickness

    set ranges [rowranges $id]
    set thresh [expr {2 * $lthickness + 6}]
    set n [expr {[llength $ranges] - 1}]
    for {set i 1} {$i < $n} {incr i} {
        set row [lindex $ranges $i]
        if {abs([yc $row] - $y) < $thresh} {
            return $i
        }
    }
    return {}
}

proc arrowjump {id n y} {
    global canv

    # 1 <-> 2, 3 <-> 4, etc...
    set n [expr {(($n - 1) ^ 1) + 1}]
    set row [lindex [rowranges $id] $n]
    set yt [yc $row]
    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax <= 0} return
    set view [$canv yview]
    set yspan [expr {[lindex $view 1] - [lindex $view 0]}]
    set yfrac [expr {$yt / $ymax - $yspan / 2}]
    if {$yfrac < 0} {
        set yfrac 0
    }
    allcanvs yview moveto $yfrac
}

proc lineclick {x y id isnew} {
    global ctext commitinfo children canv thickerline curview

    if {![info exists commitinfo($id)] && ![getcommit $id]} return
    unmarkmatches
    unselectline
    normalline
    $canv delete hover
    # draw this line thicker than normal
    set thickerline $id
    drawlines $id
    if {$isnew} {
        set ymax [lindex [$canv cget -scrollregion] 3]
        if {$ymax eq {}} return
        set yfrac [lindex [$canv yview] 0]
        set y [expr {$y + $yfrac * $ymax}]
    }
    set dirn [clickisonarrow $id $y]
    if {$dirn ne {}} {
        arrowjump $id $dirn $y
        return
    }

    if {$isnew} {
        addtohistory [list lineclick $x $y $id 0]
    }
    # fill the details pane with info about this line
    $ctext conf -state normal
    clear_ctext
    settabs 0
    $ctext insert end "[mc "Parent"]:\t"
    $ctext insert end $id link0
    setlink $id link0
    set info $commitinfo($id)
    $ctext insert end "\n\t[lindex $info 0]\n"
    $ctext insert end "\t[mc "Author"]:\t[lindex $info 1]\n"
    set date [formatdate [lindex $info 2]]
    $ctext insert end "\t[mc "Date"]:\t$date\n"
    set kids $children($curview,$id)
    if {$kids ne {}} {
        $ctext insert end "\n[mc "Children"]:"
        set i 0
        foreach child $kids {
            incr i
            if {![info exists commitinfo($child)] && ![getcommit $child]} continue
            set info $commitinfo($child)
            $ctext insert end "\n\t"
            $ctext insert end $child link$i
            setlink $child link$i
            $ctext insert end "\n\t[lindex $info 0]"
            $ctext insert end "\n\t[mc "Author"]:\t[lindex $info 1]"
            set date [formatdate [lindex $info 2]]
            $ctext insert end "\n\t[mc "Date"]:\t$date\n"
        }
    }
    $ctext conf -state disabled
    init_flist {}
}

proc normalline {} {
    global thickerline
    if {[info exists thickerline]} {
        set id $thickerline
        unset thickerline
        drawlines $id
    }
}

proc selbyid {id} {
    global curview
    if {[commitinview $id $curview]} {
        selectline [rowofcommit $id] 1
    }
}

proc mstime {} {
    global startmstime
    if {![info exists startmstime]} {
        set startmstime [clock clicks -milliseconds]
    }
    return [format "%.3f" [expr {([clock click -milliseconds] - $startmstime) / 1000.0}]]
}

proc rowmenu {x y id} {
    global rowctxmenu selectedline rowmenuid curview
    global nullid nullid2 fakerowmenu mainhead

    stopfinding
    set rowmenuid $id
    if {$selectedline eq {} || [rowofcommit $id] eq $selectedline} {
        set state disabled
    } else {
        set state normal
    }
    if {$id ne $nullid && $id ne $nullid2} {
        set menu $rowctxmenu
        if {$mainhead ne {}} {
            $menu entryconfigure 7 -label [mc "Reset %s branch to here" $mainhead]
        } else {
            $menu entryconfigure 7 -label [mc "Detached head: can't reset" $mainhead] -state disabled
        }
    } else {
        set menu $fakerowmenu
    }
    $menu entryconfigure [mc "Diff this -> selected"] -state $state
    $menu entryconfigure [mc "Diff selected -> this"] -state $state
    $menu entryconfigure [mc "Make patch"] -state $state
    tk_popup $menu $x $y
}

proc diffvssel {dirn} {
    global rowmenuid selectedline

    if {$selectedline eq {}} return
    if {$dirn} {
        set oldid [commitonrow $selectedline]
        set newid $rowmenuid
    } else {
        set oldid $rowmenuid
        set newid [commitonrow $selectedline]
    }
    addtohistory [list doseldiff $oldid $newid]
    doseldiff $oldid $newid
}

proc doseldiff {oldid newid} {
    global ctext
    global commitinfo

    $ctext conf -state normal
    clear_ctext
    init_flist [mc "Top"]
    $ctext insert end "[mc "From"] "
    $ctext insert end $oldid link0
    setlink $oldid link0
    $ctext insert end "\n     "
    $ctext insert end [lindex $commitinfo($oldid) 0]
    $ctext insert end "\n\n[mc "To"]   "
    $ctext insert end $newid link1
    setlink $newid link1
    $ctext insert end "\n     "
    $ctext insert end [lindex $commitinfo($newid) 0]
    $ctext insert end "\n"
    $ctext conf -state disabled
    $ctext tag remove found 1.0 end
    startdiff [list $oldid $newid]
}

proc mkpatch {} {
    global rowmenuid currentid commitinfo patchtop patchnum

    if {![info exists currentid]} return
    set oldid $currentid
    set oldhead [lindex $commitinfo($oldid) 0]
    set newid $rowmenuid
    set newhead [lindex $commitinfo($newid) 0]
    set top .patch
    set patchtop $top
    catch {destroy $top}
    toplevel $top
    label $top.title -text [mc "Generate patch"]
    grid $top.title - -pady 10
    label $top.from -text [mc "From:"]
    entry $top.fromsha1 -width 40 -relief flat
    $top.fromsha1 insert 0 $oldid
    $top.fromsha1 conf -state readonly
    grid $top.from $top.fromsha1 -sticky w
    entry $top.fromhead -width 60 -relief flat
    $top.fromhead insert 0 $oldhead
    $top.fromhead conf -state readonly
    grid x $top.fromhead -sticky w
    label $top.to -text [mc "To:"]
    entry $top.tosha1 -width 40 -relief flat
    $top.tosha1 insert 0 $newid
    $top.tosha1 conf -state readonly
    grid $top.to $top.tosha1 -sticky w
    entry $top.tohead -width 60 -relief flat
    $top.tohead insert 0 $newhead
    $top.tohead conf -state readonly
    grid x $top.tohead -sticky w
    button $top.rev -text [mc "Reverse"] -command mkpatchrev -padx 5
    grid $top.rev x -pady 10
    label $top.flab -text [mc "Output file:"]
    entry $top.fname -width 60
    $top.fname insert 0 [file normalize "patch$patchnum.patch"]
    incr patchnum
    grid $top.flab $top.fname -sticky w
    frame $top.buts
    button $top.buts.gen -text [mc "Generate"] -command mkpatchgo
    button $top.buts.can -text [mc "Cancel"] -command mkpatchcan
    grid $top.buts.gen $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - -pady 10 -sticky ew
    focus $top.fname
}

proc mkpatchrev {} {
    global patchtop

    set oldid [$patchtop.fromsha1 get]
    set oldhead [$patchtop.fromhead get]
    set newid [$patchtop.tosha1 get]
    set newhead [$patchtop.tohead get]
    foreach e [list fromsha1 fromhead tosha1 tohead] \
            v [list $newid $newhead $oldid $oldhead] {
        $patchtop.$e conf -state normal
        $patchtop.$e delete 0 end
        $patchtop.$e insert 0 $v
        $patchtop.$e conf -state readonly
    }
}

proc mkpatchgo {} {
    global patchtop nullid nullid2

    set oldid [$patchtop.fromsha1 get]
    set newid [$patchtop.tosha1 get]
    set fname [$patchtop.fname get]
    set cmd [diffcmd [list $oldid $newid] -p]
    # trim off the initial "|"
    set cmd [lrange $cmd 1 end]
    lappend cmd >$fname &
    if {[catch {eval exec $cmd} err]} {
        error_popup "[mc "Error creating patch:"] $err"
    }
    catch {destroy $patchtop}
    unset patchtop
}

proc mkpatchcan {} {
    global patchtop

    catch {destroy $patchtop}
    unset patchtop
}

proc mktag {} {
    global rowmenuid mktagtop commitinfo

    set top .maketag
    set mktagtop $top
    catch {destroy $top}
    toplevel $top
    label $top.title -text [mc "Create tag"]
    grid $top.title - -pady 10
    label $top.id -text [mc "ID:"]
    entry $top.sha1 -width 40 -relief flat
    $top.sha1 insert 0 $rowmenuid
    $top.sha1 conf -state readonly
    grid $top.id $top.sha1 -sticky w
    entry $top.head -width 60 -relief flat
    $top.head insert 0 [lindex $commitinfo($rowmenuid) 0]
    $top.head conf -state readonly
    grid x $top.head -sticky w
    label $top.tlab -text [mc "Tag name:"]
    entry $top.tag -width 60
    grid $top.tlab $top.tag -sticky w
    frame $top.buts
    button $top.buts.gen -text [mc "Create"] -command mktaggo
    button $top.buts.can -text [mc "Cancel"] -command mktagcan
    grid $top.buts.gen $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - -pady 10 -sticky ew
    focus $top.tag
}

proc domktag {} {
    global mktagtop env tagids idtags

    set id [$mktagtop.sha1 get]
    set tag [$mktagtop.tag get]
    if {$tag == {}} {
        error_popup [mc "No tag name specified"]
        return
    }
    if {[info exists tagids($tag)]} {
        error_popup [mc "Tag \"%s\" already exists" $tag]
        return
    }
    if {[catch {
        exec git tag $tag $id
    } err]} {
        error_popup "[mc "Error creating tag:"] $err"
        return
    }

    set tagids($tag) $id
    lappend idtags($id) $tag
    redrawtags $id
    addedtag $id
    dispneartags 0
    run refill_reflist
}

proc redrawtags {id} {
    global canv linehtag idpos currentid curview cmitlisted
    global canvxmax iddrawn circleitem mainheadid circlecolors

    if {![commitinview $id $curview]} return
    if {![info exists iddrawn($id)]} return
    set row [rowofcommit $id]
    if {$id eq $mainheadid} {
        set ofill yellow
    } else {
        set ofill [lindex $circlecolors $cmitlisted($curview,$id)]
    }
    $canv itemconf $circleitem($row) -fill $ofill
    $canv delete tag.$id
    set xt [eval drawtags $id $idpos($id)]
    $canv coords $linehtag($row) $xt [lindex $idpos($id) 2]
    set text [$canv itemcget $linehtag($row) -text]
    set font [$canv itemcget $linehtag($row) -font]
    set xr [expr {$xt + [font measure $font $text]}]
    if {$xr > $canvxmax} {
        set canvxmax $xr
        setcanvscroll
    }
    if {[info exists currentid] && $currentid == $id} {
        make_secsel $row
    }
}

proc mktagcan {} {
    global mktagtop

    catch {destroy $mktagtop}
    unset mktagtop
}

proc mktaggo {} {
    domktag
    mktagcan
}

proc writecommit {} {
    global rowmenuid wrcomtop commitinfo wrcomcmd

    set top .writecommit
    set wrcomtop $top
    catch {destroy $top}
    toplevel $top
    label $top.title -text [mc "Write commit to file"]
    grid $top.title - -pady 10
    label $top.id -text [mc "ID:"]
    entry $top.sha1 -width 40 -relief flat
    $top.sha1 insert 0 $rowmenuid
    $top.sha1 conf -state readonly
    grid $top.id $top.sha1 -sticky w
    entry $top.head -width 60 -relief flat
    $top.head insert 0 [lindex $commitinfo($rowmenuid) 0]
    $top.head conf -state readonly
    grid x $top.head -sticky w
    label $top.clab -text [mc "Command:"]
    entry $top.cmd -width 60 -textvariable wrcomcmd
    grid $top.clab $top.cmd -sticky w -pady 10
    label $top.flab -text [mc "Output file:"]
    entry $top.fname -width 60
    $top.fname insert 0 [file normalize "commit-[string range $rowmenuid 0 6]"]
    grid $top.flab $top.fname -sticky w
    frame $top.buts
    button $top.buts.gen -text [mc "Write"] -command wrcomgo
    button $top.buts.can -text [mc "Cancel"] -command wrcomcan
    grid $top.buts.gen $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - -pady 10 -sticky ew
    focus $top.fname
}

proc wrcomgo {} {
    global wrcomtop

    set id [$wrcomtop.sha1 get]
    set cmd "echo $id | [$wrcomtop.cmd get]"
    set fname [$wrcomtop.fname get]
    if {[catch {exec sh -c $cmd >$fname &} err]} {
        error_popup "[mc "Error writing commit:"] $err"
    }
    catch {destroy $wrcomtop}
    unset wrcomtop
}

proc wrcomcan {} {
    global wrcomtop

    catch {destroy $wrcomtop}
    unset wrcomtop
}

proc mkbranch {} {
    global rowmenuid mkbrtop

    set top .makebranch
    catch {destroy $top}
    toplevel $top
    label $top.title -text [mc "Create new branch"]
    grid $top.title - -pady 10
    label $top.id -text [mc "ID:"]
    entry $top.sha1 -width 40 -relief flat
    $top.sha1 insert 0 $rowmenuid
    $top.sha1 conf -state readonly
    grid $top.id $top.sha1 -sticky w
    label $top.nlab -text [mc "Name:"]
    entry $top.name -width 40
    grid $top.nlab $top.name -sticky w
    frame $top.buts
    button $top.buts.go -text [mc "Create"] -command [list mkbrgo $top]
    button $top.buts.can -text [mc "Cancel"] -command "catch {destroy $top}"
    grid $top.buts.go $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - -pady 10 -sticky ew
    focus $top.name
}

proc mkbrgo {top} {
    global headids idheads

    set name [$top.name get]
    set id [$top.sha1 get]
    if {$name eq {}} {
        error_popup [mc "Please specify a name for the new branch"]
        return
    }
    catch {destroy $top}
    nowbusy newbranch
    update
    if {[catch {
        exec git branch $name $id
    } err]} {
        notbusy newbranch
        error_popup $err
    } else {
        set headids($name) $id
        lappend idheads($id) $name
        addedhead $id $name
        notbusy newbranch
        redrawtags $id
        dispneartags 0
        run refill_reflist
    }
}

proc cherrypick {} {
    global rowmenuid curview
    global mainhead mainheadid

    set oldhead [exec git rev-parse HEAD]
    set dheads [descheads $rowmenuid]
    if {$dheads ne {} && [lsearch -exact $dheads $oldhead] >= 0} {
        set ok [confirm_popup [mc "Commit %s is already\
                included in branch %s -- really re-apply it?" \
                                   [string range $rowmenuid 0 7] $mainhead]]
        if {!$ok} return
    }
    nowbusy cherrypick [mc "Cherry-picking"]
    update
    # Unfortunately git-cherry-pick writes stuff to stderr even when
    # no error occurs, and exec takes that as an indication of error...
    if {[catch {exec sh -c "git cherry-pick -r $rowmenuid 2>&1"} err]} {
        notbusy cherrypick
        error_popup $err
        return
    }
    set newhead [exec git rev-parse HEAD]
    if {$newhead eq $oldhead} {
        notbusy cherrypick
        error_popup [mc "No changes committed"]
        return
    }
    addnewchild $newhead $oldhead
    if {[commitinview $oldhead $curview]} {
        insertrow $newhead $oldhead $curview
        if {$mainhead ne {}} {
            movehead $newhead $mainhead
            movedhead $newhead $mainhead
        }
        set mainheadid $newhead
        redrawtags $oldhead
        redrawtags $newhead
        selbyid $newhead
    }
    notbusy cherrypick
}

proc resethead {} {
    global mainhead rowmenuid confirm_ok resettype

    set confirm_ok 0
    set w ".confirmreset"
    toplevel $w
    wm transient $w .
    wm title $w [mc "Confirm reset"]
    message $w.m -text \
        [mc "Reset branch %s to %s?" $mainhead [string range $rowmenuid 0 7]] \
        -justify center -aspect 1000
    pack $w.m -side top -fill x -padx 20 -pady 20
    frame $w.f -relief sunken -border 2
    message $w.f.rt -text [mc "Reset type:"] -aspect 1000
    grid $w.f.rt -sticky w
    set resettype mixed
    radiobutton $w.f.soft -value soft -variable resettype -justify left \
        -text [mc "Soft: Leave working tree and index untouched"]
    grid $w.f.soft -sticky w
    radiobutton $w.f.mixed -value mixed -variable resettype -justify left \
        -text [mc "Mixed: Leave working tree untouched, reset index"]
    grid $w.f.mixed -sticky w
    radiobutton $w.f.hard -value hard -variable resettype -justify left \
        -text [mc "Hard: Reset working tree and index\n(discard ALL local changes)"]
    grid $w.f.hard -sticky w
    pack $w.f -side top -fill x
    button $w.ok -text [mc OK] -command "set confirm_ok 1; destroy $w"
    pack $w.ok -side left -fill x -padx 20 -pady 20
    button $w.cancel -text [mc Cancel] -command "destroy $w"
    pack $w.cancel -side right -fill x -padx 20 -pady 20
    bind $w <Visibility> "grab $w; focus $w"
    tkwait window $w
    if {!$confirm_ok} return
    if {[catch {set fd [open \
            [list | git reset --$resettype $rowmenuid 2>@1] r]} err]} {
        error_popup $err
    } else {
        dohidelocalchanges
        filerun $fd [list readresetstat $fd]
        nowbusy reset [mc "Resetting"]
        selbyid $rowmenuid
    }
}

proc readresetstat {fd} {
    global mainhead mainheadid showlocalchanges rprogcoord

    if {[gets $fd line] >= 0} {
        if {[regexp {([0-9]+)% \(([0-9]+)/([0-9]+)\)} $line match p m n]} {
            set rprogcoord [expr {1.0 * $m / $n}]
            adjustprogress
        }
        return 1
    }
    set rprogcoord 0
    adjustprogress
    notbusy reset
    if {[catch {close $fd} err]} {
        error_popup $err
    }
    set oldhead $mainheadid
    set newhead [exec git rev-parse HEAD]
    if {$newhead ne $oldhead} {
        movehead $newhead $mainhead
        movedhead $newhead $mainhead
        set mainheadid $newhead
        redrawtags $oldhead
        redrawtags $newhead
    }
    if {$showlocalchanges} {
        doshowlocalchanges
    }
    return 0
}

# context menu for a head
proc headmenu {x y id head} {
    global headmenuid headmenuhead headctxmenu mainhead

    stopfinding
    set headmenuid $id
    set headmenuhead $head
    set state normal
    if {$head eq $mainhead} {
        set state disabled
    }
    $headctxmenu entryconfigure 0 -state $state
    $headctxmenu entryconfigure 1 -state $state
    tk_popup $headctxmenu $x $y
}

proc cobranch {} {
    global headmenuid headmenuhead headids
    global showlocalchanges mainheadid

    # check the tree is clean first??
    nowbusy checkout [mc "Checking out"]
    update
    dohidelocalchanges
    if {[catch {
        set fd [open [list | git checkout $headmenuhead 2>@1] r]
    } err]} {
        notbusy checkout
        error_popup $err
        if {$showlocalchanges} {
            dodiffindex
        }
    } else {
        filerun $fd [list readcheckoutstat $fd $headmenuhead $headmenuid]
    }
}

proc readcheckoutstat {fd newhead newheadid} {
    global mainhead mainheadid headids showlocalchanges progresscoords

    if {[gets $fd line] >= 0} {
        if {[regexp {([0-9]+)% \(([0-9]+)/([0-9]+)\)} $line match p m n]} {
            set progresscoords [list 0 [expr {1.0 * $m / $n}]]
            adjustprogress
        }
        return 1
    }
    set progresscoords {0 0}
    adjustprogress
    notbusy checkout
    if {[catch {close $fd} err]} {
        error_popup $err
    }
    set oldmainid $mainheadid
    set mainhead $newhead
    set mainheadid $newheadid
    redrawtags $oldmainid
    redrawtags $newheadid
    selbyid $newheadid
    if {$showlocalchanges} {
        dodiffindex
    }
}

proc rmbranch {} {
    global headmenuid headmenuhead mainhead
    global idheads

    set head $headmenuhead
    set id $headmenuid
    # this check shouldn't be needed any more...
    if {$head eq $mainhead} {
        error_popup [mc "Cannot delete the currently checked-out branch"]
        return
    }
    set dheads [descheads $id]
    if {[llength $dheads] == 1 && $idheads($dheads) eq $head} {
        # the stuff on this branch isn't on any other branch
        if {![confirm_popup [mc "The commits on branch %s aren't on any other\
                        branch.\nReally delete branch %s?" $head $head]]} return
    }
    nowbusy rmbranch
    update
    if {[catch {exec git branch -D $head} err]} {
        notbusy rmbranch
        error_popup $err
        return
    }
    removehead $id $head
    removedhead $id $head
    redrawtags $id
    notbusy rmbranch
    dispneartags 0
    run refill_reflist
}

# Display a list of tags and heads
proc showrefs {} {
    global showrefstop bgcolor fgcolor selectbgcolor
    global bglist fglist reflistfilter reflist maincursor

    set top .showrefs
    set showrefstop $top
    if {[winfo exists $top]} {
        raise $top
        refill_reflist
        return
    }
    toplevel $top
    wm title $top [mc "Tags and heads: %s" [file tail [pwd]]]
    text $top.list -background $bgcolor -foreground $fgcolor \
        -selectbackground $selectbgcolor -font mainfont \
        -xscrollcommand "$top.xsb set" -yscrollcommand "$top.ysb set" \
        -width 30 -height 20 -cursor $maincursor \
        -spacing1 1 -spacing3 1 -state disabled
    $top.list tag configure highlight -background $selectbgcolor
    lappend bglist $top.list
    lappend fglist $top.list
    scrollbar $top.ysb -command "$top.list yview" -orient vertical
    scrollbar $top.xsb -command "$top.list xview" -orient horizontal
    grid $top.list $top.ysb -sticky nsew
    grid $top.xsb x -sticky ew
    frame $top.f
    label $top.f.l -text "[mc "Filter"]: "
    entry $top.f.e -width 20 -textvariable reflistfilter
    set reflistfilter "*"
    trace add variable reflistfilter write reflistfilter_change
    pack $top.f.e -side right -fill x -expand 1
    pack $top.f.l -side left
    grid $top.f - -sticky ew -pady 2
    button $top.close -command [list destroy $top] -text [mc "Close"]
    grid $top.close -
    grid columnconfigure $top 0 -weight 1
    grid rowconfigure $top 0 -weight 1
    bind $top.list <1> {break}
    bind $top.list <B1-Motion> {break}
    bind $top.list <ButtonRelease-1> {sel_reflist %W %x %y; break}
    set reflist {}
    refill_reflist
}

proc sel_reflist {w x y} {
    global showrefstop reflist headids tagids otherrefids

    if {![winfo exists $showrefstop]} return
    set l [lindex [split [$w index "@$x,$y"] "."] 0]
    set ref [lindex $reflist [expr {$l-1}]]
    set n [lindex $ref 0]
    switch -- [lindex $ref 1] {
        "H" {selbyid $headids($n)}
        "T" {selbyid $tagids($n)}
        "o" {selbyid $otherrefids($n)}
    }
    $showrefstop.list tag add highlight $l.0 "$l.0 lineend"
}

proc unsel_reflist {} {
    global showrefstop

    if {![info exists showrefstop] || ![winfo exists $showrefstop]} return
    $showrefstop.list tag remove highlight 0.0 end
}

proc reflistfilter_change {n1 n2 op} {
    global reflistfilter

    after cancel refill_reflist
    after 200 refill_reflist
}

proc refill_reflist {} {
    global reflist reflistfilter showrefstop headids tagids otherrefids
    global curview commitinterest

    if {![info exists showrefstop] || ![winfo exists $showrefstop]} return
    set refs {}
    foreach n [array names headids] {
        if {[string match $reflistfilter $n]} {
            if {[commitinview $headids($n) $curview]} {
                lappend refs [list $n H]
            } else {
                set commitinterest($headids($n)) {run refill_reflist}
            }
        }
    }
    foreach n [array names tagids] {
        if {[string match $reflistfilter $n]} {
            if {[commitinview $tagids($n) $curview]} {
                lappend refs [list $n T]
            } else {
                set commitinterest($tagids($n)) {run refill_reflist}
            }
        }
    }
    foreach n [array names otherrefids] {
        if {[string match $reflistfilter $n]} {
            if {[commitinview $otherrefids($n) $curview]} {
                lappend refs [list $n o]
            } else {
                set commitinterest($otherrefids($n)) {run refill_reflist}
            }
        }
    }
    set refs [lsort -index 0 $refs]
    if {$refs eq $reflist} return

    # Update the contents of $showrefstop.list according to the
    # differences between $reflist (old) and $refs (new)
    $showrefstop.list conf -state normal
    $showrefstop.list insert end "\n"
    set i 0
    set j 0
    while {$i < [llength $reflist] || $j < [llength $refs]} {
        if {$i < [llength $reflist]} {
            if {$j < [llength $refs]} {
                set cmp [string compare [lindex $reflist $i 0] \
                             [lindex $refs $j 0]]
                if {$cmp == 0} {
                    set cmp [string compare [lindex $reflist $i 1] \
                                 [lindex $refs $j 1]]
                }
            } else {
                set cmp -1
            }
        } else {
            set cmp 1
        }
        switch -- $cmp {
            -1 {
                $showrefstop.list delete "[expr {$j+1}].0" "[expr {$j+2}].0"
                incr i
            }
            0 {
                incr i
                incr j
            }
            1 {
                set l [expr {$j + 1}]
                $showrefstop.list image create $l.0 -align baseline \
                    -image reficon-[lindex $refs $j 1] -padx 2
                $showrefstop.list insert $l.1 "[lindex $refs $j 0]\n"
                incr j
            }
        }
    }
    set reflist $refs
    # delete last newline
    $showrefstop.list delete end-2c end-1c
    $showrefstop.list conf -state disabled
}

# Stuff for finding nearby tags
proc getallcommits {} {
    global allcommits nextarc seeds allccache allcwait cachedarcs allcupdate
    global idheads idtags idotherrefs allparents tagobjid

    if {![info exists allcommits]} {
        set nextarc 0
        set allcommits 0
        set seeds {}
        set allcwait 0
        set cachedarcs 0
        set allccache [file join [gitdir] "gitk.cache"]
        if {![catch {
            set f [open $allccache r]
            set allcwait 1
            getcache $f
        }]} return
    }

    if {$allcwait} {
        return
    }
    set cmd [list | git rev-list --parents]
    set allcupdate [expr {$seeds ne {}}]
    if {!$allcupdate} {
        set ids "--all"
    } else {
        set refs [concat [array names idheads] [array names idtags] \
                      [array names idotherrefs]]
        set ids {}
        set tagobjs {}
        foreach name [array names tagobjid] {
            lappend tagobjs $tagobjid($name)
        }
        foreach id [lsort -unique $refs] {
            if {![info exists allparents($id)] &&
                [lsearch -exact $tagobjs $id] < 0} {
                lappend ids $id
            }
        }
        if {$ids ne {}} {
            foreach id $seeds {
                lappend ids "^$id"
            }
        }
    }
    if {$ids ne {}} {
        set fd [open [concat $cmd $ids] r]
        fconfigure $fd -blocking 0
        incr allcommits
        nowbusy allcommits
        filerun $fd [list getallclines $fd]
    } else {
        dispneartags 0
    }
}

# Since most commits have 1 parent and 1 child, we group strings of
# such commits into "arcs" joining branch/merge points (BMPs), which
# are commits that either don't have 1 parent or don't have 1 child.
#
# arcnos(id) - incoming arcs for BMP, arc we're on for other nodes
# arcout(id) - outgoing arcs for BMP
# arcids(a) - list of IDs on arc including end but not start
# arcstart(a) - BMP ID at start of arc
# arcend(a) - BMP ID at end of arc
# growing(a) - arc a is still growing
# arctags(a) - IDs out of arcids (excluding end) that have tags
# archeads(a) - IDs out of arcids (excluding end) that have heads
# The start of an arc is at the descendent end, so "incoming" means
# coming from descendents, and "outgoing" means going towards ancestors.

proc getallclines {fd} {
    global allparents allchildren idtags idheads nextarc
    global arcnos arcids arctags arcout arcend arcstart archeads growing
    global seeds allcommits cachedarcs allcupdate
    
    set nid 0
    while {[incr nid] <= 1000 && [gets $fd line] >= 0} {
        set id [lindex $line 0]
        if {[info exists allparents($id)]} {
            # seen it already
            continue
        }
        set cachedarcs 0
        set olds [lrange $line 1 end]
        set allparents($id) $olds
        if {![info exists allchildren($id)]} {
            set allchildren($id) {}
            set arcnos($id) {}
            lappend seeds $id
        } else {
            set a $arcnos($id)
            if {[llength $olds] == 1 && [llength $a] == 1} {
                lappend arcids($a) $id
                if {[info exists idtags($id)]} {
                    lappend arctags($a) $id
                }
                if {[info exists idheads($id)]} {
                    lappend archeads($a) $id
                }
                if {[info exists allparents($olds)]} {
                    # seen parent already
                    if {![info exists arcout($olds)]} {
                        splitarc $olds
                    }
                    lappend arcids($a) $olds
                    set arcend($a) $olds
                    unset growing($a)
                }
                lappend allchildren($olds) $id
                lappend arcnos($olds) $a
                continue
            }
        }
        foreach a $arcnos($id) {
            lappend arcids($a) $id
            set arcend($a) $id
            unset growing($a)
        }

        set ao {}
        foreach p $olds {
            lappend allchildren($p) $id
            set a [incr nextarc]
            set arcstart($a) $id
            set archeads($a) {}
            set arctags($a) {}
            set archeads($a) {}
            set arcids($a) {}
            lappend ao $a
            set growing($a) 1
            if {[info exists allparents($p)]} {
                # seen it already, may need to make a new branch
                if {![info exists arcout($p)]} {
                    splitarc $p
                }
                lappend arcids($a) $p
                set arcend($a) $p
                unset growing($a)
            }
            lappend arcnos($p) $a
        }
        set arcout($id) $ao
    }
    if {$nid > 0} {
        global cached_dheads cached_dtags cached_atags
        catch {unset cached_dheads}
        catch {unset cached_dtags}
        catch {unset cached_atags}
    }
    if {![eof $fd]} {
        return [expr {$nid >= 1000? 2: 1}]
    }
    set cacheok 1
    if {[catch {
        fconfigure $fd -blocking 1
        close $fd
    } err]} {
        # got an error reading the list of commits
        # if we were updating, try rereading the whole thing again
        if {$allcupdate} {
            incr allcommits -1
            dropcache $err
            return
        }
        error_popup "[mc "Error reading commit topology information;\
                branch and preceding/following tag information\
                will be incomplete."]\n($err)"
        set cacheok 0
    }
    if {[incr allcommits -1] == 0} {
        notbusy allcommits
        if {$cacheok} {
            run savecache
        }
    }
    dispneartags 0
    return 0
}

proc recalcarc {a} {
    global arctags archeads arcids idtags idheads

    set at {}
    set ah {}
    foreach id [lrange $arcids($a) 0 end-1] {
        if {[info exists idtags($id)]} {
            lappend at $id
        }
        if {[info exists idheads($id)]} {
            lappend ah $id
        }
    }
    set arctags($a) $at
    set archeads($a) $ah
}

proc splitarc {p} {
    global arcnos arcids nextarc arctags archeads idtags idheads
    global arcstart arcend arcout allparents growing

    set a $arcnos($p)
    if {[llength $a] != 1} {
        puts "oops splitarc called but [llength $a] arcs already"
        return
    }
    set a [lindex $a 0]
    set i [lsearch -exact $arcids($a) $p]
    if {$i < 0} {
        puts "oops splitarc $p not in arc $a"
        return
    }
    set na [incr nextarc]
    if {[info exists arcend($a)]} {
        set arcend($na) $arcend($a)
    } else {
        set l [lindex $allparents([lindex $arcids($a) end]) 0]
        set j [lsearch -exact $arcnos($l) $a]
        set arcnos($l) [lreplace $arcnos($l) $j $j $na]
    }
    set tail [lrange $arcids($a) [expr {$i+1}] end]
    set arcids($a) [lrange $arcids($a) 0 $i]
    set arcend($a) $p
    set arcstart($na) $p
    set arcout($p) $na
    set arcids($na) $tail
    if {[info exists growing($a)]} {
        set growing($na) 1
        unset growing($a)
    }

    foreach id $tail {
        if {[llength $arcnos($id)] == 1} {
            set arcnos($id) $na
        } else {
            set j [lsearch -exact $arcnos($id) $a]
            set arcnos($id) [lreplace $arcnos($id) $j $j $na]
        }
    }

    # reconstruct tags and heads lists
    if {$arctags($a) ne {} || $archeads($a) ne {}} {
        recalcarc $a
        recalcarc $na
    } else {
        set arctags($na) {}
        set archeads($na) {}
    }
}

# Update things for a new commit added that is a child of one
# existing commit.  Used when cherry-picking.
proc addnewchild {id p} {
    global allparents allchildren idtags nextarc
    global arcnos arcids arctags arcout arcend arcstart archeads growing
    global seeds allcommits

    if {![info exists allcommits] || ![info exists arcnos($p)]} return
    set allparents($id) [list $p]
    set allchildren($id) {}
    set arcnos($id) {}
    lappend seeds $id
    lappend allchildren($p) $id
    set a [incr nextarc]
    set arcstart($a) $id
    set archeads($a) {}
    set arctags($a) {}
    set arcids($a) [list $p]
    set arcend($a) $p
    if {![info exists arcout($p)]} {
        splitarc $p
    }
    lappend arcnos($p) $a
    set arcout($id) [list $a]
}

# This implements a cache for the topology information.
# The cache saves, for each arc, the start and end of the arc,
# the ids on the arc, and the outgoing arcs from the end.
proc readcache {f} {
    global arcnos arcids arcout arcstart arcend arctags archeads nextarc
    global idtags idheads allparents cachedarcs possible_seeds seeds growing
    global allcwait

    set a $nextarc
    set lim $cachedarcs
    if {$lim - $a > 500} {
        set lim [expr {$a + 500}]
    }
    if {[catch {
        if {$a == $lim} {
            # finish reading the cache and setting up arctags, etc.
            set line [gets $f]
            if {$line ne "1"} {error "bad final version"}
            close $f
            foreach id [array names idtags] {
                if {[info exists arcnos($id)] && [llength $arcnos($id)] == 1 &&
                    [llength $allparents($id)] == 1} {
                    set a [lindex $arcnos($id) 0]
                    if {$arctags($a) eq {}} {
                        recalcarc $a
                    }
                }
            }
            foreach id [array names idheads] {
                if {[info exists arcnos($id)] && [llength $arcnos($id)] == 1 &&
                    [llength $allparents($id)] == 1} {
                    set a [lindex $arcnos($id) 0]
                    if {$archeads($a) eq {}} {
                        recalcarc $a
                    }
                }
            }
            foreach id [lsort -unique $possible_seeds] {
                if {$arcnos($id) eq {}} {
                    lappend seeds $id
                }
            }
            set allcwait 0
        } else {
            while {[incr a] <= $lim} {
                set line [gets $f]
                if {[llength $line] != 3} {error "bad line"}
                set s [lindex $line 0]
                set arcstart($a) $s
                lappend arcout($s) $a
                if {![info exists arcnos($s)]} {
                    lappend possible_seeds $s
                    set arcnos($s) {}
                }
                set e [lindex $line 1]
                if {$e eq {}} {
                    set growing($a) 1
                } else {
                    set arcend($a) $e
                    if {![info exists arcout($e)]} {
                        set arcout($e) {}
                    }
                }
                set arcids($a) [lindex $line 2]
                foreach id $arcids($a) {
                    lappend allparents($s) $id
                    set s $id
                    lappend arcnos($id) $a
                }
                if {![info exists allparents($s)]} {
                    set allparents($s) {}
                }
                set arctags($a) {}
                set archeads($a) {}
            }
            set nextarc [expr {$a - 1}]
        }
    } err]} {
        dropcache $err
        return 0
    }
    if {!$allcwait} {
        getallcommits
    }
    return $allcwait
}

proc getcache {f} {
    global nextarc cachedarcs possible_seeds

    if {[catch {
        set line [gets $f]
        if {[llength $line] != 2 || [lindex $line 0] ne "1"} {error "bad version"}
        # make sure it's an integer
        set cachedarcs [expr {int([lindex $line 1])}]
        if {$cachedarcs < 0} {error "bad number of arcs"}
        set nextarc 0
        set possible_seeds {}
        run readcache $f
    } err]} {
        dropcache $err
    }
    return 0
}

proc dropcache {err} {
    global allcwait nextarc cachedarcs seeds

    #puts "dropping cache ($err)"
    foreach v {arcnos arcout arcids arcstart arcend growing \
                   arctags archeads allparents allchildren} {
        global $v
        catch {unset $v}
    }
    set allcwait 0
    set nextarc 0
    set cachedarcs 0
    set seeds {}
    getallcommits
}

proc writecache {f} {
    global cachearc cachedarcs allccache
    global arcstart arcend arcnos arcids arcout

    set a $cachearc
    set lim $cachedarcs
    if {$lim - $a > 1000} {
        set lim [expr {$a + 1000}]
    }
    if {[catch {
        while {[incr a] <= $lim} {
            if {[info exists arcend($a)]} {
                puts $f [list $arcstart($a) $arcend($a) $arcids($a)]
            } else {
                puts $f [list $arcstart($a) {} $arcids($a)]
            }
        }
    } err]} {
        catch {close $f}
        catch {file delete $allccache}
        #puts "writing cache failed ($err)"
        return 0
    }
    set cachearc [expr {$a - 1}]
    if {$a > $cachedarcs} {
        puts $f "1"
        close $f
        return 0
    }
    return 1
}

proc savecache {} {
    global nextarc cachedarcs cachearc allccache

    if {$nextarc == $cachedarcs} return
    set cachearc 0
    set cachedarcs $nextarc
    catch {
        set f [open $allccache w]
        puts $f [list 1 $cachedarcs]
        run writecache $f
    }
}

# Returns 1 if a is an ancestor of b, -1 if b is an ancestor of a,
# or 0 if neither is true.
proc anc_or_desc {a b} {
    global arcout arcstart arcend arcnos cached_isanc

    if {$arcnos($a) eq $arcnos($b)} {
        # Both are on the same arc(s); either both are the same BMP,
        # or if one is not a BMP, the other is also not a BMP or is
        # the BMP at end of the arc (and it only has 1 incoming arc).
        # Or both can be BMPs with no incoming arcs.
        if {$a eq $b || $arcnos($a) eq {}} {
            return 0
        }
        # assert {[llength $arcnos($a)] == 1}
        set arc [lindex $arcnos($a) 0]
        set i [lsearch -exact $arcids($arc) $a]
        set j [lsearch -exact $arcids($arc) $b]
        if {$i < 0 || $i > $j} {
            return 1
        } else {
            return -1
        }
    }

    if {![info exists arcout($a)]} {
        set arc [lindex $arcnos($a) 0]
        if {[info exists arcend($arc)]} {
            set aend $arcend($arc)
        } else {
            set aend {}
        }
        set a $arcstart($arc)
    } else {
        set aend $a
    }
    if {![info exists arcout($b)]} {
        set arc [lindex $arcnos($b) 0]
        if {[info exists arcend($arc)]} {
            set bend $arcend($arc)
        } else {
            set bend {}
        }
        set b $arcstart($arc)
    } else {
        set bend $b
    }
    if {$a eq $bend} {
        return 1
    }
    if {$b eq $aend} {
        return -1
    }
    if {[info exists cached_isanc($a,$bend)]} {
        if {$cached_isanc($a,$bend)} {
            return 1
        }
    }
    if {[info exists cached_isanc($b,$aend)]} {
        if {$cached_isanc($b,$aend)} {
            return -1
        }
        if {[info exists cached_isanc($a,$bend)]} {
            return 0
        }
    }

    set todo [list $a $b]
    set anc($a) a
    set anc($b) b
    for {set i 0} {$i < [llength $todo]} {incr i} {
        set x [lindex $todo $i]
        if {$anc($x) eq {}} {
            continue
        }
        foreach arc $arcnos($x) {
            set xd $arcstart($arc)
            if {$xd eq $bend} {
                set cached_isanc($a,$bend) 1
                set cached_isanc($b,$aend) 0
                return 1
            } elseif {$xd eq $aend} {
                set cached_isanc($b,$aend) 1
                set cached_isanc($a,$bend) 0
                return -1
            }
            if {![info exists anc($xd)]} {
                set anc($xd) $anc($x)
                lappend todo $xd
            } elseif {$anc($xd) ne $anc($x)} {
                set anc($xd) {}
            }
        }
    }
    set cached_isanc($a,$bend) 0
    set cached_isanc($b,$aend) 0
    return 0
}

# This identifies whether $desc has an ancestor that is
# a growing tip of the graph and which is not an ancestor of $anc
# and returns 0 if so and 1 if not.
# If we subsequently discover a tag on such a growing tip, and that
# turns out to be a descendent of $anc (which it could, since we
# don't necessarily see children before parents), then $desc
# isn't a good choice to display as a descendent tag of
# $anc (since it is the descendent of another tag which is
# a descendent of $anc).  Similarly, $anc isn't a good choice to
# display as a ancestor tag of $desc.
#
proc is_certain {desc anc} {
    global arcnos arcout arcstart arcend growing problems

    set certain {}
    if {[llength $arcnos($anc)] == 1} {
        # tags on the same arc are certain
        if {$arcnos($desc) eq $arcnos($anc)} {
            return 1
        }
        if {![info exists arcout($anc)]} {
            # if $anc is partway along an arc, use the start of the arc instead
            set a [lindex $arcnos($anc) 0]
            set anc $arcstart($a)
        }
    }
    if {[llength $arcnos($desc)] > 1 || [info exists arcout($desc)]} {
        set x $desc
    } else {
        set a [lindex $arcnos($desc) 0]
        set x $arcend($a)
    }
    if {$x == $anc} {
        return 1
    }
    set anclist [list $x]
    set dl($x) 1
    set nnh 1
    set ngrowanc 0
    for {set i 0} {$i < [llength $anclist] && ($nnh > 0 || $ngrowanc > 0)} {incr i} {
        set x [lindex $anclist $i]
        if {$dl($x)} {
            incr nnh -1
        }
        set done($x) 1
        foreach a $arcout($x) {
            if {[info exists growing($a)]} {
                if {![info exists growanc($x)] && $dl($x)} {
                    set growanc($x) 1
                    incr ngrowanc
                }
            } else {
                set y $arcend($a)
                if {[info exists dl($y)]} {
                    if {$dl($y)} {
                        if {!$dl($x)} {
                            set dl($y) 0
                            if {![info exists done($y)]} {
                                incr nnh -1
                            }
                            if {[info exists growanc($x)]} {
                                incr ngrowanc -1
                            }
                            set xl [list $y]
                            for {set k 0} {$k < [llength $xl]} {incr k} {
                                set z [lindex $xl $k]
                                foreach c $arcout($z) {
                                    if {[info exists arcend($c)]} {
                                        set v $arcend($c)
                                        if {[info exists dl($v)] && $dl($v)} {
                                            set dl($v) 0
                                            if {![info exists done($v)]} {
                                                incr nnh -1
                                            }
                                            if {[info exists growanc($v)]} {
                                                incr ngrowanc -1
                                            }
                                            lappend xl $v
                                        }
                                    }
                                }
                            }
                        }
                    }
                } elseif {$y eq $anc || !$dl($x)} {
                    set dl($y) 0
                    lappend anclist $y
                } else {
                    set dl($y) 1
                    lappend anclist $y
                    incr nnh
                }
            }
        }
    }
    foreach x [array names growanc] {
        if {$dl($x)} {
            return 0
        }
        return 0
    }
    return 1
}

proc validate_arctags {a} {
    global arctags idtags

    set i -1
    set na $arctags($a)
    foreach id $arctags($a) {
        incr i
        if {![info exists idtags($id)]} {
            set na [lreplace $na $i $i]
            incr i -1
        }
    }
    set arctags($a) $na
}

proc validate_archeads {a} {
    global archeads idheads

    set i -1
    set na $archeads($a)
    foreach id $archeads($a) {
        incr i
        if {![info exists idheads($id)]} {
            set na [lreplace $na $i $i]
            incr i -1
        }
    }
    set archeads($a) $na
}

# Return the list of IDs that have tags that are descendents of id,
# ignoring IDs that are descendents of IDs already reported.
proc desctags {id} {
    global arcnos arcstart arcids arctags idtags allparents
    global growing cached_dtags

    if {![info exists allparents($id)]} {
        return {}
    }
    set t1 [clock clicks -milliseconds]
    set argid $id
    if {[llength $arcnos($id)] == 1 && [llength $allparents($id)] == 1} {
        # part-way along an arc; check that arc first
        set a [lindex $arcnos($id) 0]
        if {$arctags($a) ne {}} {
            validate_arctags $a
            set i [lsearch -exact $arcids($a) $id]
            set tid {}
            foreach t $arctags($a) {
                set j [lsearch -exact $arcids($a) $t]
                if {$j >= $i} break
                set tid $t
            }
            if {$tid ne {}} {
                return $tid
            }
        }
        set id $arcstart($a)
        if {[info exists idtags($id)]} {
            return $id
        }
    }
    if {[info exists cached_dtags($id)]} {
        return $cached_dtags($id)
    }

    set origid $id
    set todo [list $id]
    set queued($id) 1
    set nc 1
    for {set i 0} {$i < [llength $todo] && $nc > 0} {incr i} {
        set id [lindex $todo $i]
        set done($id) 1
        set ta [info exists hastaggedancestor($id)]
        if {!$ta} {
            incr nc -1
        }
        # ignore tags on starting node
        if {!$ta && $i > 0} {
            if {[info exists idtags($id)]} {
                set tagloc($id) $id
                set ta 1
            } elseif {[info exists cached_dtags($id)]} {
                set tagloc($id) $cached_dtags($id)
                set ta 1
            }
        }
        foreach a $arcnos($id) {
            set d $arcstart($a)
            if {!$ta && $arctags($a) ne {}} {
                validate_arctags $a
                if {$arctags($a) ne {}} {
                    lappend tagloc($id) [lindex $arctags($a) end]
                }
            }
            if {$ta || $arctags($a) ne {}} {
                set tomark [list $d]
                for {set j 0} {$j < [llength $tomark]} {incr j} {
                    set dd [lindex $tomark $j]
                    if {![info exists hastaggedancestor($dd)]} {
                        if {[info exists done($dd)]} {
                            foreach b $arcnos($dd) {
                                lappend tomark $arcstart($b)
                            }
                            if {[info exists tagloc($dd)]} {
                                unset tagloc($dd)
                            }
                        } elseif {[info exists queued($dd)]} {
                            incr nc -1
                        }
                        set hastaggedancestor($dd) 1
                    }
                }
            }
            if {![info exists queued($d)]} {
                lappend todo $d
                set queued($d) 1
                if {![info exists hastaggedancestor($d)]} {
                    incr nc
                }
            }
        }
    }
    set tags {}
    foreach id [array names tagloc] {
        if {![info exists hastaggedancestor($id)]} {
            foreach t $tagloc($id) {
                if {[lsearch -exact $tags $t] < 0} {
                    lappend tags $t
                }
            }
        }
    }
    set t2 [clock clicks -milliseconds]
    set loopix $i

    # remove tags that are descendents of other tags
    for {set i 0} {$i < [llength $tags]} {incr i} {
        set a [lindex $tags $i]
        for {set j 0} {$j < $i} {incr j} {
            set b [lindex $tags $j]
            set r [anc_or_desc $a $b]
            if {$r == 1} {
                set tags [lreplace $tags $j $j]
                incr j -1
                incr i -1
            } elseif {$r == -1} {
                set tags [lreplace $tags $i $i]
                incr i -1
                break
            }
        }
    }

    if {[array names growing] ne {}} {
        # graph isn't finished, need to check if any tag could get
        # eclipsed by another tag coming later.  Simply ignore any
        # tags that could later get eclipsed.
        set ctags {}
        foreach t $tags {
            if {[is_certain $t $origid]} {
                lappend ctags $t
            }
        }
        if {$tags eq $ctags} {
            set cached_dtags($origid) $tags
        } else {
            set tags $ctags
        }
    } else {
        set cached_dtags($origid) $tags
    }
    set t3 [clock clicks -milliseconds]
    if {0 && $t3 - $t1 >= 100} {
        puts "iterating descendents ($loopix/[llength $todo] nodes) took\
            [expr {$t2-$t1}]+[expr {$t3-$t2}]ms, $nc candidates left"
    }
    return $tags
}

proc anctags {id} {
    global arcnos arcids arcout arcend arctags idtags allparents
    global growing cached_atags

    if {![info exists allparents($id)]} {
        return {}
    }
    set t1 [clock clicks -milliseconds]
    set argid $id
    if {[llength $arcnos($id)] == 1 && [llength $allparents($id)] == 1} {
        # part-way along an arc; check that arc first
        set a [lindex $arcnos($id) 0]
        if {$arctags($a) ne {}} {
            validate_arctags $a
            set i [lsearch -exact $arcids($a) $id]
            foreach t $arctags($a) {
                set j [lsearch -exact $arcids($a) $t]
                if {$j > $i} {
                    return $t
                }
            }
        }
        if {![info exists arcend($a)]} {
            return {}
        }
        set id $arcend($a)
        if {[info exists idtags($id)]} {
            return $id
        }
    }
    if {[info exists cached_atags($id)]} {
        return $cached_atags($id)
    }

    set origid $id
    set todo [list $id]
    set queued($id) 1
    set taglist {}
    set nc 1
    for {set i 0} {$i < [llength $todo] && $nc > 0} {incr i} {
        set id [lindex $todo $i]
        set done($id) 1
        set td [info exists hastaggeddescendent($id)]
        if {!$td} {
            incr nc -1
        }
        # ignore tags on starting node
        if {!$td && $i > 0} {
            if {[info exists idtags($id)]} {
                set tagloc($id) $id
                set td 1
            } elseif {[info exists cached_atags($id)]} {
                set tagloc($id) $cached_atags($id)
                set td 1
            }
        }
        foreach a $arcout($id) {
            if {!$td && $arctags($a) ne {}} {
                validate_arctags $a
                if {$arctags($a) ne {}} {
                    lappend tagloc($id) [lindex $arctags($a) 0]
                }
            }
            if {![info exists arcend($a)]} continue
            set d $arcend($a)
            if {$td || $arctags($a) ne {}} {
                set tomark [list $d]
                for {set j 0} {$j < [llength $tomark]} {incr j} {
                    set dd [lindex $tomark $j]
                    if {![info exists hastaggeddescendent($dd)]} {
                        if {[info exists done($dd)]} {
                            foreach b $arcout($dd) {
                                if {[info exists arcend($b)]} {
                                    lappend tomark $arcend($b)
                                }
                            }
                            if {[info exists tagloc($dd)]} {
                                unset tagloc($dd)
                            }
                        } elseif {[info exists queued($dd)]} {
                            incr nc -1
                        }
                        set hastaggeddescendent($dd) 1
                    }
                }
            }
            if {![info exists queued($d)]} {
                lappend todo $d
                set queued($d) 1
                if {![info exists hastaggeddescendent($d)]} {
                    incr nc
                }
            }
        }
    }
    set t2 [clock clicks -milliseconds]
    set loopix $i
    set tags {}
    foreach id [array names tagloc] {
        if {![info exists hastaggeddescendent($id)]} {
            foreach t $tagloc($id) {
                if {[lsearch -exact $tags $t] < 0} {
                    lappend tags $t
                }
            }
        }
    }

    # remove tags that are ancestors of other tags
    for {set i 0} {$i < [llength $tags]} {incr i} {
        set a [lindex $tags $i]
        for {set j 0} {$j < $i} {incr j} {
            set b [lindex $tags $j]
            set r [anc_or_desc $a $b]
            if {$r == -1} {
                set tags [lreplace $tags $j $j]
                incr j -1
                incr i -1
            } elseif {$r == 1} {
                set tags [lreplace $tags $i $i]
                incr i -1
                break
            }
        }
    }

    if {[array names growing] ne {}} {
        # graph isn't finished, need to check if any tag could get
        # eclipsed by another tag coming later.  Simply ignore any
        # tags that could later get eclipsed.
        set ctags {}
        foreach t $tags {
            if {[is_certain $origid $t]} {
                lappend ctags $t
            }
        }
        if {$tags eq $ctags} {
            set cached_atags($origid) $tags
        } else {
            set tags $ctags
        }
    } else {
        set cached_atags($origid) $tags
    }
    set t3 [clock clicks -milliseconds]
    if {0 && $t3 - $t1 >= 100} {
        puts "iterating ancestors ($loopix/[llength $todo] nodes) took\
            [expr {$t2-$t1}]+[expr {$t3-$t2}]ms, $nc candidates left"
    }
    return $tags
}

# Return the list of IDs that have heads that are descendents of id,
# including id itself if it has a head.
proc descheads {id} {
    global arcnos arcstart arcids archeads idheads cached_dheads
    global allparents

    if {![info exists allparents($id)]} {
        return {}
    }
    set aret {}
    if {[llength $arcnos($id)] == 1 && [llength $allparents($id)] == 1} {
        # part-way along an arc; check it first
        set a [lindex $arcnos($id) 0]
        if {$archeads($a) ne {}} {
            validate_archeads $a
            set i [lsearch -exact $arcids($a) $id]
            foreach t $archeads($a) {
                set j [lsearch -exact $arcids($a) $t]
                if {$j > $i} break
                lappend aret $t
            }
        }
        set id $arcstart($a)
    }
    set origid $id
    set todo [list $id]
    set seen($id) 1
    set ret {}
    for {set i 0} {$i < [llength $todo]} {incr i} {
        set id [lindex $todo $i]
        if {[info exists cached_dheads($id)]} {
            set ret [concat $ret $cached_dheads($id)]
        } else {
            if {[info exists idheads($id)]} {
                lappend ret $id
            }
            foreach a $arcnos($id) {
                if {$archeads($a) ne {}} {
                    validate_archeads $a
                    if {$archeads($a) ne {}} {
                        set ret [concat $ret $archeads($a)]
                    }
                }
                set d $arcstart($a)
                if {![info exists seen($d)]} {
                    lappend todo $d
                    set seen($d) 1
                }
            }
        }
    }
    set ret [lsort -unique $ret]
    set cached_dheads($origid) $ret
    return [concat $ret $aret]
}

proc addedtag {id} {
    global arcnos arcout cached_dtags cached_atags

    if {![info exists arcnos($id)]} return
    if {![info exists arcout($id)]} {
        recalcarc [lindex $arcnos($id) 0]
    }
    catch {unset cached_dtags}
    catch {unset cached_atags}
}

proc addedhead {hid head} {
    global arcnos arcout cached_dheads

    if {![info exists arcnos($hid)]} return
    if {![info exists arcout($hid)]} {
        recalcarc [lindex $arcnos($hid) 0]
    }
    catch {unset cached_dheads}
}

proc removedhead {hid head} {
    global cached_dheads

    catch {unset cached_dheads}
}

proc movedhead {hid head} {
    global arcnos arcout cached_dheads

    if {![info exists arcnos($hid)]} return
    if {![info exists arcout($hid)]} {
        recalcarc [lindex $arcnos($hid) 0]
    }
    catch {unset cached_dheads}
}

proc changedrefs {} {
    global cached_dheads cached_dtags cached_atags
    global arctags archeads arcnos arcout idheads idtags

    foreach id [concat [array names idheads] [array names idtags]] {
        if {[info exists arcnos($id)] && ![info exists arcout($id)]} {
            set a [lindex $arcnos($id) 0]
            if {![info exists donearc($a)]} {
                recalcarc $a
                set donearc($a) 1
            }
        }
    }
    catch {unset cached_dtags}
    catch {unset cached_atags}
    catch {unset cached_dheads}
}

proc rereadrefs {} {
    global idtags idheads idotherrefs mainheadid

    set refids [concat [array names idtags] \
                    [array names idheads] [array names idotherrefs]]
    foreach id $refids {
        if {![info exists ref($id)]} {
            set ref($id) [listrefs $id]
        }
    }
    set oldmainhead $mainheadid
    readrefs
    changedrefs
    set refids [lsort -unique [concat $refids [array names idtags] \
                        [array names idheads] [array names idotherrefs]]]
    foreach id $refids {
        set v [listrefs $id]
        if {![info exists ref($id)] || $ref($id) != $v} {
            redrawtags $id
        }
    }
    if {$oldmainhead ne $mainheadid} {
        redrawtags $oldmainhead
        redrawtags $mainheadid
    }
    run refill_reflist
}

proc listrefs {id} {
    global idtags idheads idotherrefs

    set x {}
    if {[info exists idtags($id)]} {
        set x $idtags($id)
    }
    set y {}
    if {[info exists idheads($id)]} {
        set y $idheads($id)
    }
    set z {}
    if {[info exists idotherrefs($id)]} {
        set z $idotherrefs($id)
    }
    return [list $x $y $z]
}

proc showtag {tag isnew} {
    global ctext tagcontents tagids linknum tagobjid

    if {$isnew} {
        addtohistory [list showtag $tag 0]
    }
    $ctext conf -state normal
    clear_ctext
    settabs 0
    set linknum 0
    if {![info exists tagcontents($tag)]} {
        catch {
            set tagcontents($tag) [exec git cat-file tag $tagobjid($tag)]
        }
    }
    if {[info exists tagcontents($tag)]} {
        set text $tagcontents($tag)
    } else {
        set text "[mc "Tag"]: $tag\n[mc "Id"]:  $tagids($tag)"
    }
    appendwithlinks $text {}
    $ctext conf -state disabled
    init_flist {}
}

proc doquit {} {
    global stopped
    global gitktmpdir

    set stopped 100
    savestuff .
    destroy .

    if {[info exists gitktmpdir]} {
        catch {file delete -force $gitktmpdir}
    }
}

proc mkfontdisp {font top which} {
    global fontattr fontpref $font

    set fontpref($font) [set $font]
    button $top.${font}but -text $which -font optionfont \
        -command [list choosefont $font $which]
    label $top.$font -relief flat -font $font \
        -text $fontattr($font,family) -justify left
    grid x $top.${font}but $top.$font -sticky w
}

proc choosefont {font which} {
    global fontparam fontlist fonttop fontattr

    set fontparam(which) $which
    set fontparam(font) $font
    set fontparam(family) [font actual $font -family]
    set fontparam(size) $fontattr($font,size)
    set fontparam(weight) $fontattr($font,weight)
    set fontparam(slant) $fontattr($font,slant)
    set top .gitkfont
    set fonttop $top
    if {![winfo exists $top]} {
        font create sample
        eval font config sample [font actual $font]
        toplevel $top
        wm title $top [mc "Gitk font chooser"]
        label $top.l -textvariable fontparam(which)
        pack $top.l -side top
        set fontlist [lsort [font families]]
        frame $top.f
        listbox $top.f.fam -listvariable fontlist \
            -yscrollcommand [list $top.f.sb set]
        bind $top.f.fam <<ListboxSelect>> selfontfam
        scrollbar $top.f.sb -command [list $top.f.fam yview]
        pack $top.f.sb -side right -fill y
        pack $top.f.fam -side left -fill both -expand 1
        pack $top.f -side top -fill both -expand 1
        frame $top.g
        spinbox $top.g.size -from 4 -to 40 -width 4 \
            -textvariable fontparam(size) \
            -validatecommand {string is integer -strict %s}
        checkbutton $top.g.bold -padx 5 \
            -font {{Times New Roman} 12 bold} -text [mc "B"] -indicatoron 0 \
            -variable fontparam(weight) -onvalue bold -offvalue normal
        checkbutton $top.g.ital -padx 5 \
            -font {{Times New Roman} 12 italic} -text [mc "I"] -indicatoron 0  \
            -variable fontparam(slant) -onvalue italic -offvalue roman
        pack $top.g.size $top.g.bold $top.g.ital -side left
        pack $top.g -side top
        canvas $top.c -width 150 -height 50 -border 2 -relief sunk \
            -background white
        $top.c create text 100 25 -anchor center -text $which -font sample \
            -fill black -tags text
        bind $top.c <Configure> [list centertext $top.c]
        pack $top.c -side top -fill x
        frame $top.buts
        button $top.buts.ok -text [mc "OK"] -command fontok -default active
        button $top.buts.can -text [mc "Cancel"] -command fontcan -default normal
        grid $top.buts.ok $top.buts.can
        grid columnconfigure $top.buts 0 -weight 1 -uniform a
        grid columnconfigure $top.buts 1 -weight 1 -uniform a
        pack $top.buts -side bottom -fill x
        trace add variable fontparam write chg_fontparam
    } else {
        raise $top
        $top.c itemconf text -text $which
    }
    set i [lsearch -exact $fontlist $fontparam(family)]
    if {$i >= 0} {
        $top.f.fam selection set $i
        $top.f.fam see $i
    }
}

proc centertext {w} {
    $w coords text [expr {[winfo width $w] / 2}] [expr {[winfo height $w] / 2}]
}

proc fontok {} {
    global fontparam fontpref prefstop

    set f $fontparam(font)
    set fontpref($f) [list $fontparam(family) $fontparam(size)]
    if {$fontparam(weight) eq "bold"} {
        lappend fontpref($f) "bold"
    }
    if {$fontparam(slant) eq "italic"} {
        lappend fontpref($f) "italic"
    }
    set w $prefstop.$f
    $w conf -text $fontparam(family) -font $fontpref($f)
        
    fontcan
}

proc fontcan {} {
    global fonttop fontparam

    if {[info exists fonttop]} {
        catch {destroy $fonttop}
        catch {font delete sample}
        unset fonttop
        unset fontparam
    }
}

proc selfontfam {} {
    global fonttop fontparam

    set i [$fonttop.f.fam curselection]
    if {$i ne {}} {
        set fontparam(family) [$fonttop.f.fam get $i]
    }
}

proc chg_fontparam {v sub op} {
    global fontparam

    font config sample -$sub $fontparam($sub)
}

proc doprefs {} {
    global maxwidth maxgraphpct
    global oldprefs prefstop showneartags showlocalchanges
    global bgcolor fgcolor ctext diffcolors selectbgcolor
    global tabstop limitdiffs autoselect extdifftool

    set top .gitkprefs
    set prefstop $top
    if {[winfo exists $top]} {
        raise $top
        return
    }
    foreach v {maxwidth maxgraphpct showneartags showlocalchanges \
                   limitdiffs tabstop} {
        set oldprefs($v) [set $v]
    }
    toplevel $top
    wm title $top [mc "Gitk preferences"]
    label $top.ldisp -text [mc "Commit list display options"]
    grid $top.ldisp - -sticky w -pady 10
    label $top.spacer -text " "
    label $top.maxwidthl -text [mc "Maximum graph width (lines)"] \
        -font optionfont
    spinbox $top.maxwidth -from 0 -to 100 -width 4 -textvariable maxwidth
    grid $top.spacer $top.maxwidthl $top.maxwidth -sticky w
    label $top.maxpctl -text [mc "Maximum graph width (% of pane)"] \
        -font optionfont
    spinbox $top.maxpct -from 1 -to 100 -width 4 -textvariable maxgraphpct
    grid x $top.maxpctl $top.maxpct -sticky w
    frame $top.showlocal
    label $top.showlocal.l -text [mc "Show local changes"] -font optionfont
    checkbutton $top.showlocal.b -variable showlocalchanges
    pack $top.showlocal.b $top.showlocal.l -side left
    grid x $top.showlocal -sticky w
    frame $top.autoselect
    label $top.autoselect.l -text [mc "Auto-select SHA1"] -font optionfont
    checkbutton $top.autoselect.b -variable autoselect
    pack $top.autoselect.b $top.autoselect.l -side left
    grid x $top.autoselect -sticky w

    label $top.ddisp -text [mc "Diff display options"]
    grid $top.ddisp - -sticky w -pady 10
    label $top.tabstopl -text [mc "Tab spacing"] -font optionfont
    spinbox $top.tabstop -from 1 -to 20 -width 4 -textvariable tabstop
    grid x $top.tabstopl $top.tabstop -sticky w
    frame $top.ntag
    label $top.ntag.l -text [mc "Display nearby tags"] -font optionfont
    checkbutton $top.ntag.b -variable showneartags
    pack $top.ntag.b $top.ntag.l -side left
    grid x $top.ntag -sticky w
    frame $top.ldiff
    label $top.ldiff.l -text [mc "Limit diffs to listed paths"] -font optionfont
    checkbutton $top.ldiff.b -variable limitdiffs
    pack $top.ldiff.b $top.ldiff.l -side left
    grid x $top.ldiff -sticky w

    entry $top.extdifft -textvariable extdifftool
    frame $top.extdifff
    label $top.extdifff.l -text [mc "External diff tool" ] -font optionfont \
        -padx 10
    button $top.extdifff.b -text [mc "Choose..."] -font optionfont \
        -command choose_extdiff
    pack $top.extdifff.l $top.extdifff.b -side left
    grid x $top.extdifff $top.extdifft -sticky w

    label $top.cdisp -text [mc "Colors: press to choose"]
    grid $top.cdisp - -sticky w -pady 10
    label $top.bg -padx 40 -relief sunk -background $bgcolor
    button $top.bgbut -text [mc "Background"] -font optionfont \
        -command [list choosecolor bgcolor {} $top.bg background setbg]
    grid x $top.bgbut $top.bg -sticky w
    label $top.fg -padx 40 -relief sunk -background $fgcolor
    button $top.fgbut -text [mc "Foreground"] -font optionfont \
        -command [list choosecolor fgcolor {} $top.fg foreground setfg]
    grid x $top.fgbut $top.fg -sticky w
    label $top.diffold -padx 40 -relief sunk -background [lindex $diffcolors 0]
    button $top.diffoldbut -text [mc "Diff: old lines"] -font optionfont \
        -command [list choosecolor diffcolors 0 $top.diffold "diff old lines" \
                      [list $ctext tag conf d0 -foreground]]
    grid x $top.diffoldbut $top.diffold -sticky w
    label $top.diffnew -padx 40 -relief sunk -background [lindex $diffcolors 1]
    button $top.diffnewbut -text [mc "Diff: new lines"] -font optionfont \
        -command [list choosecolor diffcolors 1 $top.diffnew "diff new lines" \
                      [list $ctext tag conf d1 -foreground]]
    grid x $top.diffnewbut $top.diffnew -sticky w
    label $top.hunksep -padx 40 -relief sunk -background [lindex $diffcolors 2]
    button $top.hunksepbut -text [mc "Diff: hunk header"] -font optionfont \
        -command [list choosecolor diffcolors 2 $top.hunksep \
                      "diff hunk header" \
                      [list $ctext tag conf hunksep -foreground]]
    grid x $top.hunksepbut $top.hunksep -sticky w
    label $top.selbgsep -padx 40 -relief sunk -background $selectbgcolor
    button $top.selbgbut -text [mc "Select bg"] -font optionfont \
        -command [list choosecolor selectbgcolor {} $top.selbgsep background setselbg]
    grid x $top.selbgbut $top.selbgsep -sticky w

    label $top.cfont -text [mc "Fonts: press to choose"]
    grid $top.cfont - -sticky w -pady 10
    mkfontdisp mainfont $top [mc "Main font"]
    mkfontdisp textfont $top [mc "Diff display font"]
    mkfontdisp uifont $top [mc "User interface font"]

    frame $top.buts
    button $top.buts.ok -text [mc "OK"] -command prefsok -default active
    button $top.buts.can -text [mc "Cancel"] -command prefscan -default normal
    grid $top.buts.ok $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - - -pady 10 -sticky ew
    bind $top <Visibility> "focus $top.buts.ok"
}

proc choose_extdiff {} {
    global extdifftool

    set prog [tk_getOpenFile -title "External diff tool" -multiple false]
    if {$prog ne {}} {
        set extdifftool $prog
    }
}

proc choosecolor {v vi w x cmd} {
    global $v

    set c [tk_chooseColor -initialcolor [lindex [set $v] $vi] \
               -title [mc "Gitk: choose color for %s" $x]]
    if {$c eq {}} return
    $w conf -background $c
    lset $v $vi $c
    eval $cmd $c
}

proc setselbg {c} {
    global bglist cflist
    foreach w $bglist {
        $w configure -selectbackground $c
    }
    $cflist tag configure highlight \
        -background [$cflist cget -selectbackground]
    allcanvs itemconf secsel -fill $c
}

proc setbg {c} {
    global bglist

    foreach w $bglist {
        $w conf -background $c
    }
}

proc setfg {c} {
    global fglist canv

    foreach w $fglist {
        $w conf -foreground $c
    }
    allcanvs itemconf text -fill $c
    $canv itemconf circle -outline $c
}

proc prefscan {} {
    global oldprefs prefstop

    foreach v {maxwidth maxgraphpct showneartags showlocalchanges \
                   limitdiffs tabstop} {
        global $v
        set $v $oldprefs($v)
    }
    catch {destroy $prefstop}
    unset prefstop
    fontcan
}

proc prefsok {} {
    global maxwidth maxgraphpct
    global oldprefs prefstop showneartags showlocalchanges
    global fontpref mainfont textfont uifont
    global limitdiffs treediffs

    catch {destroy $prefstop}
    unset prefstop
    fontcan
    set fontchanged 0
    if {$mainfont ne $fontpref(mainfont)} {
        set mainfont $fontpref(mainfont)
        parsefont mainfont $mainfont
        eval font configure mainfont [fontflags mainfont]
        eval font configure mainfontbold [fontflags mainfont 1]
        setcoords
        set fontchanged 1
    }
    if {$textfont ne $fontpref(textfont)} {
        set textfont $fontpref(textfont)
        parsefont textfont $textfont
        eval font configure textfont [fontflags textfont]
        eval font configure textfontbold [fontflags textfont 1]
    }
    if {$uifont ne $fontpref(uifont)} {
        set uifont $fontpref(uifont)
        parsefont uifont $uifont
        eval font configure uifont [fontflags uifont]
    }
    settabs
    if {$showlocalchanges != $oldprefs(showlocalchanges)} {
        if {$showlocalchanges} {
            doshowlocalchanges
        } else {
            dohidelocalchanges
        }
    }
    if {$limitdiffs != $oldprefs(limitdiffs)} {
        # treediffs elements are limited by path
        catch {unset treediffs}
    }
    if {$fontchanged || $maxwidth != $oldprefs(maxwidth)
        || $maxgraphpct != $oldprefs(maxgraphpct)} {
        redisplay
    } elseif {$showneartags != $oldprefs(showneartags) ||
          $limitdiffs != $oldprefs(limitdiffs)} {
        reselectline
    }
}

proc formatdate {d} {
    global datetimeformat
    if {$d ne {}} {
        set d [clock format $d -format $datetimeformat]
    }
    return $d
}

# This list of encoding names and aliases is distilled from
# http://www.iana.org/assignments/character-sets.
# Not all of them are supported by Tcl.
set encoding_aliases {
    { ANSI_X3.4-1968 iso-ir-6 ANSI_X3.4-1986 ISO_646.irv:1991 ASCII
      ISO646-US US-ASCII us IBM367 cp367 csASCII }
    { ISO-10646-UTF-1 csISO10646UTF1 }
    { ISO_646.basic:1983 ref csISO646basic1983 }
    { INVARIANT csINVARIANT }
    { ISO_646.irv:1983 iso-ir-2 irv csISO2IntlRefVersion }
    { BS_4730 iso-ir-4 ISO646-GB gb uk csISO4UnitedKingdom }
    { NATS-SEFI iso-ir-8-1 csNATSSEFI }
    { NATS-SEFI-ADD iso-ir-8-2 csNATSSEFIADD }
    { NATS-DANO iso-ir-9-1 csNATSDANO }
    { NATS-DANO-ADD iso-ir-9-2 csNATSDANOADD }
    { SEN_850200_B iso-ir-10 FI ISO646-FI ISO646-SE se csISO10Swedish }
    { SEN_850200_C iso-ir-11 ISO646-SE2 se2 csISO11SwedishForNames }
    { KS_C_5601-1987 iso-ir-149 KS_C_5601-1989 KSC_5601 korean csKSC56011987 }
    { ISO-2022-KR csISO2022KR }
    { EUC-KR csEUCKR }
    { ISO-2022-JP csISO2022JP }
    { ISO-2022-JP-2 csISO2022JP2 }
    { JIS_C6220-1969-jp JIS_C6220-1969 iso-ir-13 katakana x0201-7
      csISO13JISC6220jp }
    { JIS_C6220-1969-ro iso-ir-14 jp ISO646-JP csISO14JISC6220ro }
    { IT iso-ir-15 ISO646-IT csISO15Italian }
    { PT iso-ir-16 ISO646-PT csISO16Portuguese }
    { ES iso-ir-17 ISO646-ES csISO17Spanish }
    { greek7-old iso-ir-18 csISO18Greek7Old }
    { latin-greek iso-ir-19 csISO19LatinGreek }
    { DIN_66003 iso-ir-21 de ISO646-DE csISO21German }
    { NF_Z_62-010_(1973) iso-ir-25 ISO646-FR1 csISO25French }
    { Latin-greek-1 iso-ir-27 csISO27LatinGreek1 }
    { ISO_5427 iso-ir-37 csISO5427Cyrillic }
    { JIS_C6226-1978 iso-ir-42 csISO42JISC62261978 }
    { BS_viewdata iso-ir-47 csISO47BSViewdata }
    { INIS iso-ir-49 csISO49INIS }
    { INIS-8 iso-ir-50 csISO50INIS8 }
    { INIS-cyrillic iso-ir-51 csISO51INISCyrillic }
    { ISO_5427:1981 iso-ir-54 ISO5427Cyrillic1981 }
    { ISO_5428:1980 iso-ir-55 csISO5428Greek }
    { GB_1988-80 iso-ir-57 cn ISO646-CN csISO57GB1988 }
    { GB_2312-80 iso-ir-58 chinese csISO58GB231280 }
    { NS_4551-1 iso-ir-60 ISO646-NO no csISO60DanishNorwegian
      csISO60Norwegian1 }
    { NS_4551-2 ISO646-NO2 iso-ir-61 no2 csISO61Norwegian2 }
    { NF_Z_62-010 iso-ir-69 ISO646-FR fr csISO69French }
    { videotex-suppl iso-ir-70 csISO70VideotexSupp1 }
    { PT2 iso-ir-84 ISO646-PT2 csISO84Portuguese2 }
    { ES2 iso-ir-85 ISO646-ES2 csISO85Spanish2 }
    { MSZ_7795.3 iso-ir-86 ISO646-HU hu csISO86Hungarian }
    { JIS_C6226-1983 iso-ir-87 x0208 JIS_X0208-1983 csISO87JISX0208 }
    { greek7 iso-ir-88 csISO88Greek7 }
    { ASMO_449 ISO_9036 arabic7 iso-ir-89 csISO89ASMO449 }
    { iso-ir-90 csISO90 }
    { JIS_C6229-1984-a iso-ir-91 jp-ocr-a csISO91JISC62291984a }
    { JIS_C6229-1984-b iso-ir-92 ISO646-JP-OCR-B jp-ocr-b
      csISO92JISC62991984b }
    { JIS_C6229-1984-b-add iso-ir-93 jp-ocr-b-add csISO93JIS62291984badd }
    { JIS_C6229-1984-hand iso-ir-94 jp-ocr-hand csISO94JIS62291984hand }
    { JIS_C6229-1984-hand-add iso-ir-95 jp-ocr-hand-add
      csISO95JIS62291984handadd }
    { JIS_C6229-1984-kana iso-ir-96 csISO96JISC62291984kana }
    { ISO_2033-1983 iso-ir-98 e13b csISO2033 }
    { ANSI_X3.110-1983 iso-ir-99 CSA_T500-1983 NAPLPS csISO99NAPLPS }
    { ISO_8859-1:1987 iso-ir-100 ISO_8859-1 ISO-8859-1 latin1 l1 IBM819
      CP819 csISOLatin1 }
    { ISO_8859-2:1987 iso-ir-101 ISO_8859-2 ISO-8859-2 latin2 l2 csISOLatin2 }
    { T.61-7bit iso-ir-102 csISO102T617bit }
    { T.61-8bit T.61 iso-ir-103 csISO103T618bit }
    { ISO_8859-3:1988 iso-ir-109 ISO_8859-3 ISO-8859-3 latin3 l3 csISOLatin3 }
    { ISO_8859-4:1988 iso-ir-110 ISO_8859-4 ISO-8859-4 latin4 l4 csISOLatin4 }
    { ECMA-cyrillic iso-ir-111 KOI8-E csISO111ECMACyrillic }
    { CSA_Z243.4-1985-1 iso-ir-121 ISO646-CA csa7-1 ca csISO121Canadian1 }
    { CSA_Z243.4-1985-2 iso-ir-122 ISO646-CA2 csa7-2 csISO122Canadian2 }
    { CSA_Z243.4-1985-gr iso-ir-123 csISO123CSAZ24341985gr }
    { ISO_8859-6:1987 iso-ir-127 ISO_8859-6 ISO-8859-6 ECMA-114 ASMO-708
      arabic csISOLatinArabic }
    { ISO_8859-6-E csISO88596E ISO-8859-6-E }
    { ISO_8859-6-I csISO88596I ISO-8859-6-I }
    { ISO_8859-7:1987 iso-ir-126 ISO_8859-7 ISO-8859-7 ELOT_928 ECMA-118
      greek greek8 csISOLatinGreek }
    { T.101-G2 iso-ir-128 csISO128T101G2 }
    { ISO_8859-8:1988 iso-ir-138 ISO_8859-8 ISO-8859-8 hebrew
      csISOLatinHebrew }
    { ISO_8859-8-E csISO88598E ISO-8859-8-E }
    { ISO_8859-8-I csISO88598I ISO-8859-8-I }
    { CSN_369103 iso-ir-139 csISO139CSN369103 }
    { JUS_I.B1.002 iso-ir-141 ISO646-YU js yu csISO141JUSIB1002 }
    { ISO_6937-2-add iso-ir-142 csISOTextComm }
    { IEC_P27-1 iso-ir-143 csISO143IECP271 }
    { ISO_8859-5:1988 iso-ir-144 ISO_8859-5 ISO-8859-5 cyrillic
      csISOLatinCyrillic }
    { JUS_I.B1.003-serb iso-ir-146 serbian csISO146Serbian }
    { JUS_I.B1.003-mac macedonian iso-ir-147 csISO147Macedonian }
    { ISO_8859-9:1989 iso-ir-148 ISO_8859-9 ISO-8859-9 latin5 l5 csISOLatin5 }
    { greek-ccitt iso-ir-150 csISO150 csISO150GreekCCITT }
    { NC_NC00-10:81 cuba iso-ir-151 ISO646-CU csISO151Cuba }
    { ISO_6937-2-25 iso-ir-152 csISO6937Add }
    { GOST_19768-74 ST_SEV_358-88 iso-ir-153 csISO153GOST1976874 }
    { ISO_8859-supp iso-ir-154 latin1-2-5 csISO8859Supp }
    { ISO_10367-box iso-ir-155 csISO10367Box }
    { ISO-8859-10 iso-ir-157 l6 ISO_8859-10:1992 csISOLatin6 latin6 }
    { latin-lap lap iso-ir-158 csISO158Lap }
    { JIS_X0212-1990 x0212 iso-ir-159 csISO159JISX02121990 }
    { DS_2089 DS2089 ISO646-DK dk csISO646Danish }
    { us-dk csUSDK }
    { dk-us csDKUS }
    { JIS_X0201 X0201 csHalfWidthKatakana }
    { KSC5636 ISO646-KR csKSC5636 }
    { ISO-10646-UCS-2 csUnicode }
    { ISO-10646-UCS-4 csUCS4 }
    { DEC-MCS dec csDECMCS }
    { hp-roman8 roman8 r8 csHPRoman8 }
    { macintosh mac csMacintosh }
    { IBM037 cp037 ebcdic-cp-us ebcdic-cp-ca ebcdic-cp-wt ebcdic-cp-nl
      csIBM037 }
    { IBM038 EBCDIC-INT cp038 csIBM038 }
    { IBM273 CP273 csIBM273 }
    { IBM274 EBCDIC-BE CP274 csIBM274 }
    { IBM275 EBCDIC-BR cp275 csIBM275 }
    { IBM277 EBCDIC-CP-DK EBCDIC-CP-NO csIBM277 }
    { IBM278 CP278 ebcdic-cp-fi ebcdic-cp-se csIBM278 }
    { IBM280 CP280 ebcdic-cp-it csIBM280 }
    { IBM281 EBCDIC-JP-E cp281 csIBM281 }
    { IBM284 CP284 ebcdic-cp-es csIBM284 }
    { IBM285 CP285 ebcdic-cp-gb csIBM285 }
    { IBM290 cp290 EBCDIC-JP-kana csIBM290 }
    { IBM297 cp297 ebcdic-cp-fr csIBM297 }
    { IBM420 cp420 ebcdic-cp-ar1 csIBM420 }
    { IBM423 cp423 ebcdic-cp-gr csIBM423 }
    { IBM424 cp424 ebcdic-cp-he csIBM424 }
    { IBM437 cp437 437 csPC8CodePage437 }
    { IBM500 CP500 ebcdic-cp-be ebcdic-cp-ch csIBM500 }
    { IBM775 cp775 csPC775Baltic }
    { IBM850 cp850 850 csPC850Multilingual }
    { IBM851 cp851 851 csIBM851 }
    { IBM852 cp852 852 csPCp852 }
    { IBM855 cp855 855 csIBM855 }
    { IBM857 cp857 857 csIBM857 }
    { IBM860 cp860 860 csIBM860 }
    { IBM861 cp861 861 cp-is csIBM861 }
    { IBM862 cp862 862 csPC862LatinHebrew }
    { IBM863 cp863 863 csIBM863 }
    { IBM864 cp864 csIBM864 }
    { IBM865 cp865 865 csIBM865 }
    { IBM866 cp866 866 csIBM866 }
    { IBM868 CP868 cp-ar csIBM868 }
    { IBM869 cp869 869 cp-gr csIBM869 }
    { IBM870 CP870 ebcdic-cp-roece ebcdic-cp-yu csIBM870 }
    { IBM871 CP871 ebcdic-cp-is csIBM871 }
    { IBM880 cp880 EBCDIC-Cyrillic csIBM880 }
    { IBM891 cp891 csIBM891 }
    { IBM903 cp903 csIBM903 }
    { IBM904 cp904 904 csIBBM904 }
    { IBM905 CP905 ebcdic-cp-tr csIBM905 }
    { IBM918 CP918 ebcdic-cp-ar2 csIBM918 }
    { IBM1026 CP1026 csIBM1026 }
    { EBCDIC-AT-DE csIBMEBCDICATDE }
    { EBCDIC-AT-DE-A csEBCDICATDEA }
    { EBCDIC-CA-FR csEBCDICCAFR }
    { EBCDIC-DK-NO csEBCDICDKNO }
    { EBCDIC-DK-NO-A csEBCDICDKNOA }
    { EBCDIC-FI-SE csEBCDICFISE }
    { EBCDIC-FI-SE-A csEBCDICFISEA }
    { EBCDIC-FR csEBCDICFR }
    { EBCDIC-IT csEBCDICIT }
    { EBCDIC-PT csEBCDICPT }
    { EBCDIC-ES csEBCDICES }
    { EBCDIC-ES-A csEBCDICESA }
    { EBCDIC-ES-S csEBCDICESS }
    { EBCDIC-UK csEBCDICUK }
    { EBCDIC-US csEBCDICUS }
    { UNKNOWN-8BIT csUnknown8BiT }
    { MNEMONIC csMnemonic }
    { MNEM csMnem }
    { VISCII csVISCII }
    { VIQR csVIQR }
    { KOI8-R csKOI8R }
    { IBM00858 CCSID00858 CP00858 PC-Multilingual-850+euro }
    { IBM00924 CCSID00924 CP00924 ebcdic-Latin9--euro }
    { IBM01140 CCSID01140 CP01140 ebcdic-us-37+euro }
    { IBM01141 CCSID01141 CP01141 ebcdic-de-273+euro }
    { IBM01142 CCSID01142 CP01142 ebcdic-dk-277+euro ebcdic-no-277+euro }
    { IBM01143 CCSID01143 CP01143 ebcdic-fi-278+euro ebcdic-se-278+euro }
    { IBM01144 CCSID01144 CP01144 ebcdic-it-280+euro }
    { IBM01145 CCSID01145 CP01145 ebcdic-es-284+euro }
    { IBM01146 CCSID01146 CP01146 ebcdic-gb-285+euro }
    { IBM01147 CCSID01147 CP01147 ebcdic-fr-297+euro }
    { IBM01148 CCSID01148 CP01148 ebcdic-international-500+euro }
    { IBM01149 CCSID01149 CP01149 ebcdic-is-871+euro }
    { IBM1047 IBM-1047 }
    { PTCP154 csPTCP154 PT154 CP154 Cyrillic-Asian }
    { Amiga-1251 Ami1251 Amiga1251 Ami-1251 }
    { UNICODE-1-1 csUnicode11 }
    { CESU-8 csCESU-8 }
    { BOCU-1 csBOCU-1 }
    { UNICODE-1-1-UTF-7 csUnicode11UTF7 }
    { ISO-8859-14 iso-ir-199 ISO_8859-14:1998 ISO_8859-14 latin8 iso-celtic
      l8 }
    { ISO-8859-15 ISO_8859-15 Latin-9 }
    { ISO-8859-16 iso-ir-226 ISO_8859-16:2001 ISO_8859-16 latin10 l10 }
    { GBK CP936 MS936 windows-936 }
    { JIS_Encoding csJISEncoding }
    { Shift_JIS MS_Kanji csShiftJIS }
    { Extended_UNIX_Code_Packed_Format_for_Japanese csEUCPkdFmtJapanese
      EUC-JP }
    { Extended_UNIX_Code_Fixed_Width_for_Japanese csEUCFixWidJapanese }
    { ISO-10646-UCS-Basic csUnicodeASCII }
    { ISO-10646-Unicode-Latin1 csUnicodeLatin1 ISO-10646 }
    { ISO-Unicode-IBM-1261 csUnicodeIBM1261 }
    { ISO-Unicode-IBM-1268 csUnicodeIBM1268 }
    { ISO-Unicode-IBM-1276 csUnicodeIBM1276 }
    { ISO-Unicode-IBM-1264 csUnicodeIBM1264 }
    { ISO-Unicode-IBM-1265 csUnicodeIBM1265 }
    { ISO-8859-1-Windows-3.0-Latin-1 csWindows30Latin1 }
    { ISO-8859-1-Windows-3.1-Latin-1 csWindows31Latin1 }
    { ISO-8859-2-Windows-Latin-2 csWindows31Latin2 }
    { ISO-8859-9-Windows-Latin-5 csWindows31Latin5 }
    { Adobe-Standard-Encoding csAdobeStandardEncoding }
    { Ventura-US csVenturaUS }
    { Ventura-International csVenturaInternational }
    { PC8-Danish-Norwegian csPC8DanishNorwegian }
    { PC8-Turkish csPC8Turkish }
    { IBM-Symbols csIBMSymbols }
    { IBM-Thai csIBMThai }
    { HP-Legal csHPLegal }
    { HP-Pi-font csHPPiFont }
    { HP-Math8 csHPMath8 }
    { Adobe-Symbol-Encoding csHPPSMath }
    { HP-DeskTop csHPDesktop }
    { Ventura-Math csVenturaMath }
    { Microsoft-Publishing csMicrosoftPublishing }
    { Windows-31J csWindows31J }
    { GB2312 csGB2312 }
    { Big5 csBig5 }
}

proc tcl_encoding {enc} {
    global encoding_aliases
    set names [encoding names]
    set lcnames [string tolower $names]
    set enc [string tolower $enc]
    set i [lsearch -exact $lcnames $enc]
    if {$i < 0} {
        # look for "isonnn" instead of "iso-nnn" or "iso_nnn"
        if {[regsub {^iso[-_]} $enc iso encx]} {
            set i [lsearch -exact $lcnames $encx]
        }
    }
    if {$i < 0} {
        foreach l $encoding_aliases {
            set ll [string tolower $l]
            if {[lsearch -exact $ll $enc] < 0} continue
            # look through the aliases for one that tcl knows about
            foreach e $ll {
                set i [lsearch -exact $lcnames $e]
                if {$i < 0} {
                    if {[regsub {^iso[-_]} $e iso ex]} {
                        set i [lsearch -exact $lcnames $ex]
                    }
                }
                if {$i >= 0} break
            }
            break
        }
    }
    if {$i >= 0} {
        return [lindex $names $i]
    }
    return {}
}

# First check that Tcl/Tk is recent enough
if {[catch {package require Tk 8.4} err]} {
    show_error {} . [mc "Sorry, gitk cannot run with this version of Tcl/Tk.\n\
                     Gitk requires at least Tcl/Tk 8.4."]
    exit 1
}

# defaults...
set wrcomcmd "git diff-tree --stdin -p --pretty"

set gitencoding {}
catch {
    set gitencoding [exec git config --get i18n.commitencoding]
}
if {$gitencoding == ""} {
    set gitencoding "utf-8"
}
set tclencoding [tcl_encoding $gitencoding]
if {$tclencoding == {}} {
    puts stderr "Warning: encoding $gitencoding is not supported by Tcl/Tk"
}

set mainfont {Helvetica 9}
set textfont {Courier 9}
set uifont {Helvetica 9 bold}
set tabstop 8
set findmergefiles 0
set maxgraphpct 50
set maxwidth 16
set revlistorder 0
set fastdate 0
set uparrowlen 5
set downarrowlen 5
set mingaplen 100
set cmitmode "patch"
set wrapcomment "none"
set showneartags 1
set maxrefs 20
set maxlinelen 200
set showlocalchanges 1
set limitdiffs 1
set datetimeformat "%Y-%m-%d %H:%M:%S"
set autoselect 1

set extdifftool "meld"

set colors {green red blue magenta darkgrey brown orange}
set bgcolor white
set fgcolor black
set diffcolors {red "#00a000" blue}
set diffcontext 3
set ignorespace 0
set selectbgcolor gray85

set circlecolors {white blue gray blue blue}

## For msgcat loading, first locate the installation location.
if { [info exists ::env(GITK_MSGSDIR)] } {
    ## Msgsdir was manually set in the environment.
    set gitk_msgsdir $::env(GITK_MSGSDIR)
} else {
    ## Let's guess the prefix from argv0.
    set gitk_prefix [file dirname [file dirname [file normalize $argv0]]]
    set gitk_libdir [file join $gitk_prefix share gitk lib]
    set gitk_msgsdir [file join $gitk_libdir msgs]
    unset gitk_prefix
}

## Internationalization (i18n) through msgcat and gettext. See
## http://www.gnu.org/software/gettext/manual/html_node/Tcl.html
package require msgcat
namespace import ::msgcat::mc
## And eventually load the actual message catalog
::msgcat::mcload $gitk_msgsdir

catch {source ~/.gitk}

font create optionfont -family sans-serif -size -12

parsefont mainfont $mainfont
eval font create mainfont [fontflags mainfont]
eval font create mainfontbold [fontflags mainfont 1]

parsefont textfont $textfont
eval font create textfont [fontflags textfont]
eval font create textfontbold [fontflags textfont 1]

parsefont uifont $uifont
eval font create uifont [fontflags uifont]

setoptions

# check that we can find a .git directory somewhere...
if {[catch {set gitdir [gitdir]}]} {
    show_error {} . [mc "Cannot find a git repository here."]
    exit 1
}
if {![file isdirectory $gitdir]} {
    show_error {} . [mc "Cannot find the git directory \"%s\"." $gitdir]
    exit 1
}

set revtreeargs {}
set cmdline_files {}
set i 0
set revtreeargscmd {}
foreach arg $argv {
    switch -glob -- $arg {
        "" { }
        "--" {
            set cmdline_files [lrange $argv [expr {$i + 1}] end]
            break
        }
        "--argscmd=*" {
            set revtreeargscmd [string range $arg 10 end]
        }
        default {
            lappend revtreeargs $arg
        }
    }
    incr i
}

if {$i >= [llength $argv] && $revtreeargs ne {}} {
    # no -- on command line, but some arguments (other than --argscmd)
    if {[catch {
        set f [eval exec git rev-parse --no-revs --no-flags $revtreeargs]
        set cmdline_files [split $f "\n"]
        set n [llength $cmdline_files]
        set revtreeargs [lrange $revtreeargs 0 end-$n]
        # Unfortunately git rev-parse doesn't produce an error when
        # something is both a revision and a filename.  To be consistent
        # with git log and git rev-list, check revtreeargs for filenames.
        foreach arg $revtreeargs {
            if {[file exists $arg]} {
                show_error {} . [mc "Ambiguous argument '%s': both revision\
                                 and filename" $arg]
                exit 1
            }
        }
    } err]} {
        # unfortunately we get both stdout and stderr in $err,
        # so look for "fatal:".
        set i [string first "fatal:" $err]
        if {$i > 0} {
            set err [string range $err [expr {$i + 6}] end]
        }
        show_error {} . "[mc "Bad arguments to gitk:"]\n$err"
        exit 1
    }
}

set nullid "0000000000000000000000000000000000000000"
set nullid2 "0000000000000000000000000000000000000001"
set nullfile "/dev/null"

set have_tk85 [expr {[package vcompare $tk_version "8.5"] >= 0}]

set runq {}
set history {}
set historyindex 0
set fh_serial 0
set nhl_names {}
set highlight_paths {}
set findpattern {}
set searchdirn -forwards
set boldrows {}
set boldnamerows {}
set diffelide {0 0}
set markingmatches 0
set linkentercount 0
set need_redisplay 0
set nrows_drawn 0
set firsttabstop 0

set nextviewnum 1
set curview 0
set selectedview 0
set selectedhlview [mc "None"]
set highlight_related [mc "None"]
set highlight_files {}
set viewfiles(0) {}
set viewperm(0) 0
set viewargs(0) {}
set viewargscmd(0) {}

set selectedline {}
set numcommits 0
set loginstance 0
set cmdlineok 0
set stopped 0
set stuffsaved 0
set patchnum 0
set lserial 0
set isworktree [expr {[exec git rev-parse --is-inside-work-tree] == "true"}]
setcoords
makewindow
# wait for the window to become visible
tkwait visibility .
wm title . "[file tail $argv0]: [file tail [pwd]]"
readrefs

if {$cmdline_files ne {} || $revtreeargs ne {} || $revtreeargscmd ne {}} {
    # create a view for the files/dirs specified on the command line
    set curview 1
    set selectedview 1
    set nextviewnum 2
    set viewname(1) [mc "Command line"]
    set viewfiles(1) $cmdline_files
    set viewargs(1) $revtreeargs
    set viewargscmd(1) $revtreeargscmd
    set viewperm(1) 0
    set vdatemode(1) 0
    addviewmenu 1
    .bar.view entryconf [mc "Edit view..."] -state normal
    .bar.view entryconf [mc "Delete view"] -state normal
}

if {[info exists permviews]} {
    foreach v $permviews {
        set n $nextviewnum
        incr nextviewnum
        set viewname($n) [lindex $v 0]
        set viewfiles($n) [lindex $v 1]
        set viewargs($n) [lindex $v 2]
        set viewargscmd($n) [lindex $v 3]
        set viewperm($n) 1
        addviewmenu $n
    }
}
getcommits {}