gitk: New infrastructure for working out branches & previous/next tags

[git.git] / gitk

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

# Copyright (C) 2005-2006 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]
    }
}

proc start_rev_list {view} {
    global startmsecs nextupdate
    global commfd leftover tclencoding datemode
    global viewargs viewfiles commitidx

    set startmsecs [clock clicks -milliseconds]
    set nextupdate [expr {$startmsecs + 100}]
    set commitidx($view) 0
    set args $viewargs($view)
    if {$viewfiles($view) ne {}} {
        set args [concat $args "--" $viewfiles($view)]
    }
    set order "--topo-order"
    if {$datemode} {
        set order "--date-order"
    }
    if {[catch {
        set fd [open [concat | git rev-list --header $order \
                          --parents --boundary --default HEAD $args] r]
    } err]} {
        puts stderr "Error executing git rev-list: $err"
        exit 1
    }
    set commfd($view) $fd
    set leftover($view) {}
    fconfigure $fd -blocking 0 -translation lf
    if {$tclencoding != {}} {
        fconfigure $fd -encoding $tclencoding
    }
    fileevent $fd readable [list getcommitlines $fd $view]
    nowbusy $view
}

proc stop_rev_list {} {
    global commfd curview

    if {![info exists commfd($curview)]} return
    set fd $commfd($curview)
    catch {
        set pid [pid $fd]
        exec kill $pid
    }
    catch {close $fd}
    unset commfd($curview)
}

proc getcommits {} {
    global phase canv mainfont curview

    set phase getcommits
    initlayout
    start_rev_list $curview
    show_status "Reading commits..."
}

proc getcommitlines {fd view}  {
    global commitlisted nextupdate
    global leftover commfd
    global displayorder commitidx commitrow commitdata
    global parentlist childlist children curview hlview
    global vparentlist vchildlist vdisporder vcmitlisted

    set stuff [read $fd 500000]
    if {$stuff == {}} {
        if {![eof $fd]} return
        global viewname
        unset commfd($view)
        notbusy $view
        # 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 rev-list."
                if {$viewname($view) eq "Command line"} {
                    append err \
                        "  (Note: arguments to gitk are passed to git rev-list\
                         to allow selection of commits to be displayed.)"
                }
            } else {
                set err "Error reading commits$fv: $err"
            }
            error_popup $err
        }
        if {$view == $curview} {
            after idle finishcommits
        }
        return
    }
    set start 0
    set gotsome 0
    while 1 {
        set i [string first "\0" $stuff $start]
        if {$i < 0} {
            append leftover($view) [string range $stuff $start end]
            break
        }
        if {$start == 0} {
            set cmit $leftover($view)
            append cmit [string range $stuff 0 [expr {$i - 1}]]
            set leftover($view) {}
        } 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} {
            set ids [string range $cmit 0 [expr {$j - 1}]]
            if {[string range $ids 0 0] == "-"} {
                set listed 0
                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 $shortcmit 0 80]..."
            }
            error_popup "Can't parse git rev-list output: {$shortcmit}"
            exit 1
        }
        set id [lindex $ids 0]
        if {$listed} {
            set olds [lrange $ids 1 end]
            set i 0
            foreach p $olds {
                if {$i == 0 || [lsearch -exact $olds $p] >= $i} {
                    lappend children($view,$p) $id
                }
                incr i
            }
        } else {
            set olds {}
        }
        if {![info exists children($view,$id)]} {
            set children($view,$id) {}
        }
        set commitdata($id) [string range $cmit [expr {$j + 1}] end]
        set commitrow($view,$id) $commitidx($view)
        incr commitidx($view)
        if {$view == $curview} {
            lappend parentlist $olds
            lappend childlist $children($view,$id)
            lappend displayorder $id
            lappend commitlisted $listed
        } else {
            lappend vparentlist($view) $olds
            lappend vchildlist($view) $children($view,$id)
            lappend vdisporder($view) $id
            lappend vcmitlisted($view) $listed
        }
        set gotsome 1
    }
    if {$gotsome} {
        if {$view == $curview} {
            while {[layoutmore $nextupdate]} doupdate
        } elseif {[info exists hlview] && $view == $hlview} {
            vhighlightmore
        }
    }
    if {[clock clicks -milliseconds] >= $nextupdate} {
        doupdate
    }
}

proc doupdate {} {
    global commfd nextupdate numcommits

    foreach v [array names commfd] {
        fileevent $commfd($v) readable {}
    }
    update
    set nextupdate [expr {[clock clicks -milliseconds] + 100}]
    foreach v [array names commfd] {
        set fd $commfd($v)
        fileevent $fd readable [list getcommitlines $fd $v]
    }
}

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

proc updatecommits {} {
    global viewdata curview phase displayorder
    global children commitrow selectedline thickerline

    if {$phase ne {}} {
        stop_rev_list
        set phase {}
    }
    set n $curview
    foreach id $displayorder {
        catch {unset children($n,$id)}
        catch {unset commitrow($n,$id)}
    }
    set curview -1
    catch {unset selectedline}
    catch {unset thickerline}
    catch {unset viewdata($n)}
    readrefs
    changedrefs
    regetallcommits
    showview $n
}

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 line of the comment as the headline
    set i [string first "\n" $comment]
    if {$i >= 0} {
        set headline [string trim [string range $comment 0 $i]]
    } else {
        set headline $comment
    }
    if {!$listed} {
        # git rev-list 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) {"No commit information available"}
        }
    }
    return 1
}

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

    foreach v {tagids idtags headids idheads otherrefids idotherrefs} {
        catch {unset $v}
    }
    set refd [open [list | git show-ref] r]
    while {0 <= [set n [gets $refd line]]} {
        if {![regexp {^([0-9a-f]{40}) refs/([^^]*)$} $line \
            match id path]} {
            continue
        }
        if {[regexp {^remotes/.*/HEAD$} $path match]} {
            continue
        }
        if {![regexp {^(tags|heads)/(.*)$} $path match type name]} {
            set type others
            set name $path
        }
        if {[regexp {^remotes/} $path match]} {
            set type heads
        }
        if {$type == "tags"} {
            set tagids($name) $id
            lappend idtags($id) $name
            set obj {}
            set type {}
            set tag {}
            catch {
                set commit [exec git rev-parse "$id^0"]
                if {$commit != $id} {
                    set tagids($name) $commit
                    lappend idtags($commit) $name
                }
            }           
            catch {
                set tagcontents($name) [exec git cat-file tag $id]
            }
        } elseif { $type == "heads" } {
            set headids($name) $id
            lappend idheads($id) $name
        } else {
            set otherrefids($name) $id
            lappend idotherrefs($id) $name
        }
    }
    close $refd
    set mainhead {}
    catch {
        set thehead [exec git symbolic-ref HEAD]
        if {[string match "refs/heads/*" $thehead]} {
            set mainhead [string range $thehead 11 end]
        }
    }
}

# 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 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 OK -command "set confirm_ok 1; destroy $w"
    pack $w.ok -side left -fill x
    button $w.cancel -text 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 makewindow {} {
    global canv canv2 canv3 linespc charspc ctext cflist
    global textfont mainfont uifont tabstop
    global findtype findtypemenu findloc findstring fstring geometry
    global entries sha1entry sha1string sha1but
    global maincursor textcursor curtextcursor
    global rowctxmenu mergemax wrapcomment
    global highlight_files gdttype
    global searchstring sstring
    global bgcolor fgcolor bglist fglist diffcolors selectbgcolor
    global headctxmenu

    menu .bar
    .bar add cascade -label "File" -menu .bar.file
    .bar configure -font $uifont
    menu .bar.file
    .bar.file add command -label "Update" -command updatecommits
    .bar.file add command -label "Reread references" -command rereadrefs
    .bar.file add command -label "Quit" -command doquit
    .bar.file configure -font $uifont
    menu .bar.edit
    .bar add cascade -label "Edit" -menu .bar.edit
    .bar.edit add command -label "Preferences" -command doprefs
    .bar.edit configure -font $uifont

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

    menu .bar.help
    .bar add cascade -label "Help" -menu .bar.help
    .bar.help add command -label "About gitk" -command about
    .bar.help add command -label "Key bindings" -command keys
    .bar.help configure -font $uifont
    . 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 "SHA1 ID: " -state disabled -relief flat \
        -command gotocommit -width 8 -font $uifont
    $sha1but conf -disabledforeground [$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

    button .tf.bar.findbut -text "Find" -command dofind -font $uifont
    pack .tf.bar.findbut -side left
    set findstring {}
    set fstring .tf.bar.findstring
    lappend entries $fstring
    entry $fstring -width 30 -font $textfont -textvariable findstring
    trace add variable findstring write find_change
    pack $fstring -side left -expand 1 -fill x -in .tf.bar
    set findtype Exact
    set findtypemenu [tk_optionMenu .tf.bar.findtype \
                      findtype Exact IgnCase Regexp]
    trace add variable findtype write find_change
    .tf.bar.findtype configure -font $uifont
    .tf.bar.findtype.menu configure -font $uifont
    set findloc "All fields"
    tk_optionMenu .tf.bar.findloc findloc "All fields" Headline \
        Comments Author Committer
    trace add variable findloc write find_change
    .tf.bar.findloc configure -font $uifont
    .tf.bar.findloc.menu configure -font $uifont
    pack .tf.bar.findloc -side right
    pack .tf.bar.findtype -side right

    # build up the bottom bar of upper window
    label .tf.lbar.flabel -text "Highlight:  Commits " \
    -font $uifont
    pack .tf.lbar.flabel -side left -fill y
    set gdttype "touching paths:"
    set gm [tk_optionMenu .tf.lbar.gdttype gdttype "touching paths:" \
        "adding/removing string:"]
    trace add variable gdttype write hfiles_change
    $gm conf -font $uifont
    .tf.lbar.gdttype conf -font $uifont
    pack .tf.lbar.gdttype -side left -fill y
    entry .tf.lbar.fent -width 25 -font $textfont \
        -textvariable highlight_files
    trace add variable highlight_files write hfiles_change
    lappend entries .tf.lbar.fent
    pack .tf.lbar.fent -side left -fill x -expand 1
    label .tf.lbar.vlabel -text " OR in view" -font $uifont
    pack .tf.lbar.vlabel -side left -fill y
    global viewhlmenu selectedhlview
    set viewhlmenu [tk_optionMenu .tf.lbar.vhl selectedhlview None]
    $viewhlmenu entryconf None -command delvhighlight
    $viewhlmenu conf -font $uifont
    .tf.lbar.vhl conf -font $uifont
    pack .tf.lbar.vhl -side left -fill y
    label .tf.lbar.rlabel -text " OR " -font $uifont
    pack .tf.lbar.rlabel -side left -fill y
    global highlight_related
    set m [tk_optionMenu .tf.lbar.relm highlight_related None \
        "Descendent" "Not descendent" "Ancestor" "Not ancestor"]
    $m conf -font $uifont
    .tf.lbar.relm conf -font $uifont
    trace add variable highlight_related write vrel_change
    pack .tf.lbar.relm -side left -fill y

    # 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

    button .bleft.top.search -text "Search" -command dosearch \
        -font $uifont
    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 "Diff" \
        -command changediffdisp -variable diffelide -value {0 0}
    radiobutton .bleft.mid.old -text "Old version" \
        -command changediffdisp -variable diffelide -value {0 1}
    radiobutton .bleft.mid.new -text "New version" \
        -command changediffdisp -variable diffelide -value {1 0}
    pack .bleft.mid.diff .bleft.mid.old .bleft.mid.new -side left
    set ctext .bleft.ctext
    text $ctext -background $bgcolor -foreground $fgcolor \
        -tabs "[expr {$tabstop * $charspc}]" \
        -state disabled -font $textfont \
        -yscrollcommand scrolltext -wrap none
    scrollbar .bleft.sb -command "$ctext yview"
    pack .bleft.top -side top -fill x
    pack .bleft.mid -side top -fill x
    pack .bleft.sb -side right -fill y
    pack $ctext -side left -fill both -expand 1
    lappend bglist $ctext
    lappend fglist $ctext

    $ctext tag conf comment -wrap $wrapcomment
    $ctext tag conf filesep -font [concat $textfont bold] -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 [concat $textfont bold]
    $ctext tag conf msep -font [concat $textfont bold]
    $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 "Patch" \
        -command reselectline -variable cmitmode -value "patch"
    .bright.mode.patch configure -font $uifont
    radiobutton .bright.mode.tree -text "Tree" \
        -command reselectline -variable cmitmode -value "tree"
    .bright.mode.tree configure -font $uifont
    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 [concat $mainfont bold]

    .pwbottom add .bright
    .ctop add .pwbottom

    # restore window position if known
    if {[info exists geometry(main)]} {
        wm geometry . "$geometry(main)"
    }

    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}
    bindall <ButtonRelease-4> "allcanvs yview scroll -5 units"
    bindall <ButtonRelease-5> "allcanvs yview scroll 5 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> "next_highlight -1"
    bind . <Shift-Key-Down> "next_highlight 1"
    bindkey <Key-Right> "goforw"
    bindkey <Key-Left> "goback"
    bind . <Key-Prior> "selnextpage -1"
    bind . <Key-Next> "selnextpage 1"
    bind . <Control-Home> "allcanvs yview moveto 0.0"
    bind . <Control-End> "allcanvs yview moveto 1.0"
    bind . <Control-Key-Up> "allcanvs yview scroll -1 units"
    bind . <Control-Key-Down> "allcanvs yview scroll 1 units"
    bind . <Control-Key-Prior> "allcanvs yview scroll -1 pages"
    bind . <Control-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> "$ctext yview scroll 1 pages"
    bindkey p "selnextline -1"
    bindkey n "selnextline 1"
    bindkey z "goback"
    bindkey x "goforw"
    bindkey i "selnextline -1"
    bindkey k "selnextline 1"
    bindkey j "goback"
    bindkey l "goforw"
    bindkey b "$ctext yview scroll -1 pages"
    bindkey d "$ctext yview scroll 18 units"
    bindkey u "$ctext yview scroll -18 units"
    bindkey / {findnext 1}
    bindkey <Key-Return> {findnext 0}
    bindkey ? findprev
    bindkey f nextfile
    bindkey <F5> updatecommits
    bind . <Control-q> doquit
    bind . <Control-f> dofind
    bind . <Control-g> {findnext 0}
    bind . <Control-r> dosearchback
    bind . <Control-s> dosearch
    bind . <Control-equal> {incrfont 1}
    bind . <Control-KP_Add> {incrfont 1}
    bind . <Control-minus> {incrfont -1}
    bind . <Control-KP_Subtract> {incrfont -1}
    wm protocol . WM_DELETE_WINDOW doquit
    bind . <Button-1> "click %W"
    bind $fstring <Key-Return> dofind
    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}

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

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

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

# 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
    drawfrac $f0 $f1
    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 entries
    foreach e $entries {
        if {$w == $e} return
    }
    focus .
}

proc savestuff {w} {
    global canv canv2 canv3 ctext cflist mainfont textfont uifont tabstop
    global stuffsaved findmergefiles maxgraphpct
    global maxwidth showneartags
    global viewname viewfiles viewargs viewperm nextviewnum
    global cmitmode wrapcomment
    global colors bgcolor fgcolor diffcolors selectbgcolor

    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 showneartags $showneartags]
        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 selectbgcolor $selectbgcolor]

        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)]}"
            }
        }
        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 "About gitk"
    message $w.m -text {
Gitk - a commit viewer for git

Copyright © 2005-2006 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
    $w.m configure -font $uifont
    button $w.ok -text Close -command "destroy $w" -default active
    pack $w.ok -side bottom
    $w.ok configure -font $uifont
    bind $w <Visibility> "focus $w.ok"
    bind $w <Key-Escape> "destroy $w"
    bind $w <Key-Return> "destroy $w"
}

proc keys {} {
    global uifont
    set w .keys
    if {[winfo exists $w]} {
        raise $w
        return
    }
    toplevel $w
    wm title $w "Gitk key bindings"
    message $w.m -text {
Gitk key bindings:

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

proc init_flist {first} {
    global cflist cflist_top selectedline 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}]]}
    }
}

# 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 uifont newishighlight
    global newviewargs revtreeargs

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

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

    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)]
    vieweditor $top $curview "Gitk: edit view $viewname($curview)"
}

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

    toplevel $top
    wm title $top $title
    label $top.nl -text "Name" -font $uifont
    entry $top.name -width 20 -textvariable newviewname($n) -font $uifont
    grid $top.nl $top.name -sticky w -pady 5
    checkbutton $top.perm -text "Remember this view" -variable newviewperm($n) \
        -font $uifont
    grid $top.perm - -pady 5 -sticky w
    message $top.al -aspect 1000 -font $uifont \
        -text "Commits to include (arguments to git rev-list):"
    grid $top.al - -sticky w -pady 5
    entry $top.args -width 50 -textvariable newviewargs($n) \
        -background white -font $uifont
    grid $top.args - -sticky ew -padx 5
    message $top.l -aspect 1000 -font $uifont \
        -text "Enter files and directories to include, one per line:"
    grid $top.l - -sticky w
    text $top.t -width 40 -height 10 -background white -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 "OK" -command [list newviewok $top $n] \
        -font $uifont
    button $top.buts.can -text "Cancel" -command [list destroy $top] \
        -font $uifont
    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 viewhlmenu

    if {[catch {
        set newargs [shellsplit $newviewargs($n)]
    } err]} {
        error_popup "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
        addviewmenu $n
        if {!$newishighlight} {
            after idle showview $n
        } else {
            after idle 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)} {
            set viewfiles($n) $files
            set viewargs($n) $newargs
            if {$curview == $n} {
                after idle updatecommits
            }
        }
    }
    catch {destroy $top}
}

proc delview {} {
    global curview viewdata viewperm hlview selectedhlview

    if {$curview == 0} return
    if {[info exists hlview] && $hlview == $curview} {
        set selectedhlview None
        unset hlview
    }
    allviewmenus $curview delete
    set viewdata($curview) {}
    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 flatten {var} {
    global $var

    set ret {}
    foreach i [array names $var] {
        lappend ret $i [set $var\($i\)]
    }
    return $ret
}

proc unflatten {var l} {
    global $var

    catch {unset $var}
    foreach {i v} $l {
        set $var\($i\) $v
    }
}

proc showview {n} {
    global curview viewdata viewfiles
    global displayorder parentlist childlist rowidlist rowoffsets
    global colormap rowtextx commitrow nextcolor canvxmax
    global numcommits rowrangelist commitlisted idrowranges
    global selectedline currentid canv canvy0
    global matchinglines treediffs
    global pending_select phase
    global commitidx rowlaidout rowoptim linesegends
    global commfd nextupdate
    global selectedview
    global vparentlist vchildlist vdisporder vcmitlisted
    global hlview selectedhlview

    if {$n == $curview} return
    set selid {}
    if {[info exists selectedline]} {
        set selid $currentid
        set y [yc $selectedline]
        set ymax [lindex [$canv cget -scrollregion] 3]
        set span [$canv yview]
        set ytop [expr {[lindex $span 0] * $ymax}]
        set ybot [expr {[lindex $span 1] * $ymax}]
        if {$ytop < $y && $y < $ybot} {
            set yscreen [expr {$y - $ytop}]
        } else {
            set yscreen [expr {($ybot - $ytop) / 2}]
        }
    }
    unselectline
    normalline
    stopfindproc
    if {$curview >= 0} {
        set vparentlist($curview) $parentlist
        set vchildlist($curview) $childlist
        set vdisporder($curview) $displayorder
        set vcmitlisted($curview) $commitlisted
        if {$phase ne {}} {
            set viewdata($curview) \
                [list $phase $rowidlist $rowoffsets $rowrangelist \
                     [flatten idrowranges] [flatten idinlist] \
                     $rowlaidout $rowoptim $numcommits $linesegends]
        } elseif {![info exists viewdata($curview)]
                  || [lindex $viewdata($curview) 0] ne {}} {
            set viewdata($curview) \
                [list {} $rowidlist $rowoffsets $rowrangelist]
        }
    }
    catch {unset matchinglines}
    catch {unset treediffs}
    clear_display
    if {[info exists hlview] && $hlview == $n} {
        unset hlview
        set selectedhlview None
    }

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

    if {![info exists viewdata($n)]} {
        set pending_select $selid
        getcommits
        return
    }

    set v $viewdata($n)
    set phase [lindex $v 0]
    set displayorder $vdisporder($n)
    set parentlist $vparentlist($n)
    set childlist $vchildlist($n)
    set commitlisted $vcmitlisted($n)
    set rowidlist [lindex $v 1]
    set rowoffsets [lindex $v 2]
    set rowrangelist [lindex $v 3]
    if {$phase eq {}} {
        set numcommits [llength $displayorder]
        catch {unset idrowranges}
    } else {
        unflatten idrowranges [lindex $v 4]
        unflatten idinlist [lindex $v 5]
        set rowlaidout [lindex $v 6]
        set rowoptim [lindex $v 7]
        set numcommits [lindex $v 8]
        set linesegends [lindex $v 9]
    }

    catch {unset colormap}
    catch {unset rowtextx}
    set nextcolor 0
    set canvxmax [$canv cget -width]
    set curview $n
    set row 0
    setcanvscroll
    set yf 0
    set row 0
    if {$selid ne {} && [info exists commitrow($n,$selid)]} {
        set row $commitrow($n,$selid)
        # try to get the selected row in the same position on the screen
        set ymax [lindex [$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
    selectline $row 0
    if {$phase ne {}} {
        if {$phase eq "getcommits"} {
            show_status "Reading commits..."
        }
        if {[info exists commfd($n)]} {
            layoutmore {}
        } else {
            finishcommits
        }
    } elseif {$numcommits == 0} {
        show_status "No commits selected"
    }
}

# Stuff relating to the highlighting facility

proc ishighlighted {row} {
    global vhighlights fhighlights nhighlights rhighlights

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

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

    lappend boldrows $row
    $canv itemconf $linehtag($row) -font $font
    if {[info exists selectedline] && $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 {[info exists selectedline] && $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 mainfont boldrows

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

proc addvhighlight {n} {
    global hlview curview viewdata vhl_done vhighlights commitidx

    if {[info exists hlview]} {
        delvhighlight
    }
    set hlview $n
    if {$n != $curview && ![info exists viewdata($n)]} {
        set viewdata($n) [list getcommits {{}} {{}} {} {} {} 0 0 0 {}]
        set vparentlist($n) {}
        set vchildlist($n) {}
        set vdisporder($n) {}
        set vcmitlisted($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
    global displayorder vdisporder curview mainfont

    set font [concat $mainfont bold]
    set max $commitidx($hlview)
    if {$hlview == $curview} {
        set disp $displayorder
    } else {
        set disp $vdisporder($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 [lindex $disp $i]
        if {[info exists commitrow($curview,$id)]} {
            set row $commitrow($curview,$id)
            if {$r0 <= $row && $row <= $r1} {
                if {![highlighted $row]} {
                    bolden $row $font
                }
                set vhighlights($row) 1
            }
        }
    }
    set vhl_done $max
}

proc askvhighlight {row id} {
    global hlview vhighlights commitrow iddrawn mainfont

    if {[info exists commitrow($hlview,$id)]} {
        if {[info exists iddrawn($id)] && ![ishighlighted $row]} {
            bolden $row [concat $mainfont bold]
        }
        set vhighlights($row) 1
    } else {
        set vhighlights($row) 0
    }
}

proc hfiles_change {name ix op} {
    global highlight_files filehighlight fhighlights fh_serial
    global mainfont highlight_paths

    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 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 "touching paths:"} {
        if {[catch {set paths [shellsplit $highlight_files]}]} return
        set highlight_paths [makepatterns $paths]
        highlight_filelist
        set gdtargs [concat -- $paths]
    } else {
        set gdtargs [list "-S$highlight_files"]
    }
    set cmd [concat | git diff-tree -r -s --stdin $gdtargs]
    set filehighlight [open $cmd r+]
    fconfigure $filehighlight -blocking 0
    fileevent $filehighlight readable 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 $id
    set fhighlights($row) -1
    puts $filehighlight $id
}

proc readfhighlight {} {
    global filehighlight fhighlights commitrow curview mainfont iddrawn
    global fhl_list

    while {[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 $j]
            if {[info exists commitrow($curview,$id)]} {
                set fhighlights($commitrow($curview,$id)) 0
            }
        }
        set fhl_list [lrange $fhl_list [expr {$i+1}] end]
        if {$line eq {}} continue
        if {![info exists commitrow($curview,$line)]} continue
        set row $commitrow($curview,$line)
        if {[info exists iddrawn($line)] && ![ishighlighted $row]} {
            bolden $row [concat $mainfont bold]
        }
        set fhighlights($row) 1
    }
    if {[eof $filehighlight]} {
        # strange...
        puts "oops, git diff-tree died"
        catch {close $filehighlight}
        unset filehighlight
    }
    next_hlcont
}

proc find_change {name ix op} {
    global nhighlights mainfont boldnamerows
    global findstring findpattern findtype

    # delete previous highlights, if any
    foreach row $boldnamerows {
        bolden_name $row $mainfont
    }
    set boldnamerows {}
    catch {unset nhighlights}
    unbolden
    if {$findtype ne "Regexp"} {
        set e [string map {"*" "\\*" "?" "\\?" "\[" "\\\[" "\\" "\\\\"} \
                   $findstring]
        set findpattern "*$e*"
    }
    drawvisible
}

proc askfindhighlight {row id} {
    global nhighlights commitinfo iddrawn mainfont
    global findstring findtype findloc findpattern

    if {![info exists commitinfo($id)]} {
        getcommit $id
    }
    set info $commitinfo($id)
    set isbold 0
    set fldtypes {Headline Author Date Committer CDate Comments}
    foreach f $info ty $fldtypes {
        if {$findloc ne "All fields" && $findloc ne $ty} {
            continue
        }
        if {$findtype eq "Regexp"} {
            set doesmatch [regexp $findstring $f]
        } elseif {$findtype eq "IgnCase"} {
            set doesmatch [string match -nocase $findpattern $f]
        } else {
            set doesmatch [string match $findpattern $f]
        }
        if {$doesmatch} {
            if {$ty eq "Author"} {
                set isbold 2
            } else {
                set isbold 1
            }
        }
    }
    if {[info exists iddrawn($id)]} {
        if {$isbold && ![ishighlighted $row]} {
            bolden $row [concat $mainfont bold]
        }
        if {$isbold >= 2} {
            bolden_name $row [concat $mainfont bold]
        }
    }
    set nhighlights($row) $isbold
}

proc vrel_change {name ix op} {
    global highlight_related

    rhighlight_none
    if {$highlight_related ne "None"} {
        after idle 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 rhighlights

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

proc rhighlight_none {} {
    global rhighlights

    catch {unset rhighlights}
    unbolden
}

proc is_descendent {a} {
    global curview children commitrow descendent desc_todo

    set v $curview
    set la $commitrow($v,$a)
    set todo $desc_todo
    set leftover {}
    set done 0
    for {set i 0} {$i < [llength $todo]} {incr i} {
        set do [lindex $todo $i]
        if {$commitrow($v,$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 parentlist commitrow ancestor anc_todo

    set v $curview
    set la $commitrow($v,$a)
    set todo $anc_todo
    set leftover {}
    set done 0
    for {set i 0} {$i < [llength $todo]} {incr i} {
        set do [lindex $todo $i]
        if {![info exists commitrow($v,$do)] || $commitrow($v,$do) > $la} {
            lappend leftover $do
            continue
        }
        foreach np [lindex $parentlist $commitrow($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 mainfont rhighlights
    global selectedline ancestor

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

proc next_hlcont {} {
    global fhl_row fhl_dirn displayorder numcommits
    global vhighlights fhighlights nhighlights rhighlights
    global hlview filehighlight findstring highlight_related

    if {![info exists fhl_dirn] || $fhl_dirn == 0} return
    set row $fhl_row
    while {1} {
        if {$row < 0 || $row >= $numcommits} {
            bell
            set fhl_dirn 0
            return
        }
        set id [lindex $displayorder $row]
        if {[info exists hlview]} {
            if {![info exists vhighlights($row)]} {
                askvhighlight $row $id
            }
            if {$vhighlights($row) > 0} break
        }
        if {$findstring ne {}} {
            if {![info exists nhighlights($row)]} {
                askfindhighlight $row $id
            }
            if {$nhighlights($row) > 0} break
        }
        if {$highlight_related ne "None"} {
            if {![info exists rhighlights($row)]} {
                askrelhighlight $row $id
            }
            if {$rhighlights($row) > 0} break
        }
        if {[info exists filehighlight]} {
            if {![info exists fhighlights($row)]} {
                # ask for a few more while we're at it...
                set r $row
                for {set n 0} {$n < 100} {incr n} {
                    if {![info exists fhighlights($r)]} {
                        askfilehighlight $r [lindex $displayorder $r]
                    }
                    incr r $fhl_dirn
                    if {$r < 0 || $r >= $numcommits} break
                }
                flushhighlights
            }
            if {$fhighlights($row) < 0} {
                set fhl_row $row
                return
            }
            if {$fhighlights($row) > 0} break
        }
        incr row $fhl_dirn
    }
    set fhl_dirn 0
    selectline $row 1
}

proc next_highlight {dirn} {
    global selectedline fhl_row fhl_dirn
    global hlview filehighlight findstring highlight_related

    if {![info exists selectedline]} return
    if {!([info exists hlview] || $findstring ne {} ||
          $highlight_related ne "None" || [info exists filehighlight])} return
    set fhl_row [expr {$selectedline + $dirn}]
    set fhl_dirn $dirn
    next_hlcont
}

proc cancel_next_highlight {} {
    global fhl_dirn

    set fhl_dirn 0
}

# 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 incrange {l x o} {
    set n [llength $l]
    while {$x < $n} {
        set e [lindex $l $x]
        if {$e ne {}} {
            lset l $x [expr {$e + $o}]
        }
        incr x
    }
    return $l
}

proc ntimes {n o} {
    set ret {}
    for {} {$n > 0} {incr n -1} {
        lappend ret $o
    }
    return $ret
}

proc usedinrange {id l1 l2} {
    global children commitrow childlist curview

    if {[info exists commitrow($curview,$id)]} {
        set r $commitrow($curview,$id)
        if {$l1 <= $r && $r <= $l2} {
            return [expr {$r - $l1 + 1}]
        }
        set kids [lindex $childlist $r]
    } else {
        set kids $children($curview,$id)
    }
    foreach c $kids {
        set r $commitrow($curview,$c)
        if {$l1 <= $r && $r <= $l2} {
            return [expr {$r - $l1 + 1}]
        }
    }
    return 0
}

proc sanity {row {full 0}} {
    global rowidlist rowoffsets

    set col -1
    set ids [lindex $rowidlist $row]
    foreach id $ids {
        incr col
        if {$id eq {}} continue
        if {$col < [llength $ids] - 1 &&
            [lsearch -exact -start [expr {$col+1}] $ids $id] >= 0} {
            puts "oops: [shortids $id] repeated in row $row col $col: {[shortids [lindex $rowidlist $row]]}"
        }
        set o [lindex $rowoffsets $row $col]
        set y $row
        set x $col
        while {$o ne {}} {
            incr y -1
            incr x $o
            if {[lindex $rowidlist $y $x] != $id} {
                puts "oops: rowoffsets wrong at row [expr {$y+1}] col [expr {$x-$o}]"
                puts "  id=[shortids $id] check started at row $row"
                for {set i $row} {$i >= $y} {incr i -1} {
                    puts "  row $i ids={[shortids [lindex $rowidlist $i]]} offs={[lindex $rowoffsets $i]}"
                }
                break
            }
            if {!$full} break
            set o [lindex $rowoffsets $y $x]
        }
    }
}

proc makeuparrow {oid x y z} {
    global rowidlist rowoffsets uparrowlen idrowranges

    for {set i 1} {$i < $uparrowlen && $y > 1} {incr i} {
        incr y -1
        incr x $z
        set off0 [lindex $rowoffsets $y]
        for {set x0 $x} {1} {incr x0} {
            if {$x0 >= [llength $off0]} {
                set x0 [llength [lindex $rowoffsets [expr {$y-1}]]]
                break
            }
            set z [lindex $off0 $x0]
            if {$z ne {}} {
                incr x0 $z
                break
            }
        }
        set z [expr {$x0 - $x}]
        lset rowidlist $y [linsert [lindex $rowidlist $y] $x $oid]
        lset rowoffsets $y [linsert [lindex $rowoffsets $y] $x $z]
    }
    set tmp [lreplace [lindex $rowoffsets $y] $x $x {}]
    lset rowoffsets $y [incrange $tmp [expr {$x+1}] -1]
    lappend idrowranges($oid) $y
}

proc initlayout {} {
    global rowidlist rowoffsets displayorder commitlisted
    global rowlaidout rowoptim
    global idinlist rowchk rowrangelist idrowranges
    global numcommits canvxmax canv
    global nextcolor
    global parentlist childlist children
    global colormap rowtextx
    global linesegends

    set numcommits 0
    set displayorder {}
    set commitlisted {}
    set parentlist {}
    set childlist {}
    set rowrangelist {}
    set nextcolor 0
    set rowidlist {{}}
    set rowoffsets {{}}
    catch {unset idinlist}
    catch {unset rowchk}
    set rowlaidout 0
    set rowoptim 0
    set canvxmax [$canv cget -width]
    catch {unset colormap}
    catch {unset rowtextx}
    catch {unset idrowranges}
    set linesegends {}
}

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

    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]
}

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 {tmax} {
    global rowlaidout rowoptim commitidx numcommits optim_delay
    global uparrowlen curview

    while {1} {
        if {$rowoptim - $optim_delay > $numcommits} {
            showstuff [expr {$rowoptim - $optim_delay}]
        } elseif {$rowlaidout - $uparrowlen - 1 > $rowoptim} {
            set nr [expr {$rowlaidout - $uparrowlen - 1 - $rowoptim}]
            if {$nr > 100} {
                set nr 100
            }
            optimize_rows $rowoptim 0 [expr {$rowoptim + $nr}]
            incr rowoptim $nr
        } elseif {$commitidx($curview) > $rowlaidout} {
            set nr [expr {$commitidx($curview) - $rowlaidout}]
            # may need to increase this threshold if uparrowlen or
            # mingaplen are increased...
            if {$nr > 150} {
                set nr 150
            }
            set row $rowlaidout
            set rowlaidout [layoutrows $row [expr {$row + $nr}] 0]
            if {$rowlaidout == $row} {
                return 0
            }
        } else {
            return 0
        }
        if {$tmax ne {} && [clock clicks -milliseconds] >= $tmax} {
            return 1
        }
    }
}

proc showstuff {canshow} {
    global numcommits commitrow pending_select selectedline
    global linesegends idrowranges idrangedrawn curview

    if {$numcommits == 0} {
        global phase
        set phase "incrdraw"
        allcanvs delete all
    }
    set row $numcommits
    set numcommits $canshow
    setcanvscroll
    set rows [visiblerows]
    set r0 [lindex $rows 0]
    set r1 [lindex $rows 1]
    set selrow -1
    for {set r $row} {$r < $canshow} {incr r} {
        foreach id [lindex $linesegends [expr {$r+1}]] {
            set i -1
            foreach {s e} [rowranges $id] {
                incr i
                if {$e ne {} && $e < $numcommits && $s <= $r1 && $e >= $r0
                    && ![info exists idrangedrawn($id,$i)]} {
                    drawlineseg $id $i
                    set idrangedrawn($id,$i) 1
                }
            }
        }
    }
    if {$canshow > $r1} {
        set canshow $r1
    }
    while {$row < $canshow} {
        drawcmitrow $row
        incr row
    }
    if {[info exists pending_select] &&
        [info exists commitrow($curview,$pending_select)] &&
        $commitrow($curview,$pending_select) < $numcommits} {
        selectline $commitrow($curview,$pending_select) 1
    }
    if {![info exists selectedline] && ![info exists pending_select]} {
        selectline 0 1
    }
}

proc layoutrows {row endrow last} {
    global rowidlist rowoffsets displayorder
    global uparrowlen downarrowlen maxwidth mingaplen
    global childlist parentlist
    global idrowranges linesegends
    global commitidx curview
    global idinlist rowchk rowrangelist

    set idlist [lindex $rowidlist $row]
    set offs [lindex $rowoffsets $row]
    while {$row < $endrow} {
        set id [lindex $displayorder $row]
        set oldolds {}
        set newolds {}
        foreach p [lindex $parentlist $row] {
            if {![info exists idinlist($p)]} {
                lappend newolds $p
            } elseif {!$idinlist($p)} {
                lappend oldolds $p
            }
        }
        set lse {}
        set nev [expr {[llength $idlist] + [llength $newolds]
                       + [llength $oldolds] - $maxwidth + 1}]
        if {$nev > 0} {
            if {!$last &&
                $row + $uparrowlen + $mingaplen >= $commitidx($curview)} break
            for {set x [llength $idlist]} {[incr x -1] >= 0} {} {
                set i [lindex $idlist $x]
                if {![info exists rowchk($i)] || $row >= $rowchk($i)} {
                    set r [usedinrange $i [expr {$row - $downarrowlen}] \
                               [expr {$row + $uparrowlen + $mingaplen}]]
                    if {$r == 0} {
                        set idlist [lreplace $idlist $x $x]
                        set offs [lreplace $offs $x $x]
                        set offs [incrange $offs $x 1]
                        set idinlist($i) 0
                        set rm1 [expr {$row - 1}]
                        lappend lse $i
                        lappend idrowranges($i) $rm1
                        if {[incr nev -1] <= 0} break
                        continue
                    }
                    set rowchk($id) [expr {$row + $r}]
                }
            }
            lset rowidlist $row $idlist
            lset rowoffsets $row $offs
        }
        lappend linesegends $lse
        set col [lsearch -exact $idlist $id]
        if {$col < 0} {
            set col [llength $idlist]
            lappend idlist $id
            lset rowidlist $row $idlist
            set z {}
            if {[lindex $childlist $row] ne {}} {
                set z [expr {[llength [lindex $rowidlist [expr {$row-1}]]] - $col}]
                unset idinlist($id)
            }
            lappend offs $z
            lset rowoffsets $row $offs
            if {$z ne {}} {
                makeuparrow $id $col $row $z
            }
        } else {
            unset idinlist($id)
        }
        set ranges {}
        if {[info exists idrowranges($id)]} {
            set ranges $idrowranges($id)
            lappend ranges $row
            unset idrowranges($id)
        }
        lappend rowrangelist $ranges
        incr row
        set offs [ntimes [llength $idlist] 0]
        set l [llength $newolds]
        set idlist [eval lreplace \$idlist $col $col $newolds]
        set o 0
        if {$l != 1} {
            set offs [lrange $offs 0 [expr {$col - 1}]]
            foreach x $newolds {
                lappend offs {}
                incr o -1
            }
            incr o
            set tmp [expr {[llength $idlist] - [llength $offs]}]
            if {$tmp > 0} {
                set offs [concat $offs [ntimes $tmp $o]]
            }
        } else {
            lset offs $col {}
        }
        foreach i $newolds {
            set idinlist($i) 1
            set idrowranges($i) $row
        }
        incr col $l
        foreach oid $oldolds {
            set idinlist($oid) 1
            set idlist [linsert $idlist $col $oid]
            set offs [linsert $offs $col $o]
            makeuparrow $oid $col $row $o
            incr col
        }
        lappend rowidlist $idlist
        lappend rowoffsets $offs
    }
    return $row
}

proc addextraid {id row} {
    global displayorder commitrow commitinfo
    global commitidx commitlisted
    global parentlist childlist children curview

    incr commitidx($curview)
    lappend displayorder $id
    lappend commitlisted 0
    lappend parentlist {}
    set commitrow($curview,$id) $row
    readcommit $id
    if {![info exists commitinfo($id)]} {
        set commitinfo($id) {"No commit information available"}
    }
    if {![info exists children($curview,$id)]} {
        set children($curview,$id) {}
    }
    lappend childlist $children($curview,$id)
}

proc layouttail {} {
    global rowidlist rowoffsets idinlist commitidx curview
    global idrowranges rowrangelist

    set row $commitidx($curview)
    set idlist [lindex $rowidlist $row]
    while {$idlist ne {}} {
        set col [expr {[llength $idlist] - 1}]
        set id [lindex $idlist $col]
        addextraid $id $row
        unset idinlist($id)
        lappend idrowranges($id) $row
        lappend rowrangelist $idrowranges($id)
        unset idrowranges($id)
        incr row
        set offs [ntimes $col 0]
        set idlist [lreplace $idlist $col $col]
        lappend rowidlist $idlist
        lappend rowoffsets $offs
    }

    foreach id [array names idinlist] {
        addextraid $id $row
        lset rowidlist $row [list $id]
        lset rowoffsets $row 0
        makeuparrow $id 0 $row 0
        lappend idrowranges($id) $row
        lappend rowrangelist $idrowranges($id)
        unset idrowranges($id)
        incr row
        lappend rowidlist {}
        lappend rowoffsets {}
    }
}

proc insert_pad {row col npad} {
    global rowidlist rowoffsets

    set pad [ntimes $npad {}]
    lset rowidlist $row [eval linsert [list [lindex $rowidlist $row]] $col $pad]
    set tmp [eval linsert [list [lindex $rowoffsets $row]] $col $pad]
    lset rowoffsets $row [incrange $tmp [expr {$col + $npad}] [expr {-$npad}]]
}

proc optimize_rows {row col endrow} {
    global rowidlist rowoffsets idrowranges displayorder

    for {} {$row < $endrow} {incr row} {
        set idlist [lindex $rowidlist $row]
        set offs [lindex $rowoffsets $row]
        set haspad 0
        for {} {$col < [llength $offs]} {incr col} {
            if {[lindex $idlist $col] eq {}} {
                set haspad 1
                continue
            }
            set z [lindex $offs $col]
            if {$z eq {}} continue
            set isarrow 0
            set x0 [expr {$col + $z}]
            set y0 [expr {$row - 1}]
            set z0 [lindex $rowoffsets $y0 $x0]
            if {$z0 eq {}} {
                set id [lindex $idlist $col]
                set ranges [rowranges $id]
                if {$ranges ne {} && $y0 > [lindex $ranges 0]} {
                    set isarrow 1
                }
            }
            if {$z < -1 || ($z < 0 && $isarrow)} {
                set npad [expr {-1 - $z + $isarrow}]
                set offs [incrange $offs $col $npad]
                insert_pad $y0 $x0 $npad
                if {$y0 > 0} {
                    optimize_rows $y0 $x0 $row
                }
                set z [lindex $offs $col]
                set x0 [expr {$col + $z}]
                set z0 [lindex $rowoffsets $y0 $x0]
            } elseif {$z > 1 || ($z > 0 && $isarrow)} {
                set npad [expr {$z - 1 + $isarrow}]
                set y1 [expr {$row + 1}]
                set offs2 [lindex $rowoffsets $y1]
                set x1 -1
                foreach z $offs2 {
                    incr x1
                    if {$z eq {} || $x1 + $z < $col} continue
                    if {$x1 + $z > $col} {
                        incr npad
                    }
                    lset rowoffsets $y1 [incrange $offs2 $x1 $npad]
                    break
                }
                set pad [ntimes $npad {}]
                set idlist [eval linsert \$idlist $col $pad]
                set tmp [eval linsert \$offs $col $pad]
                incr col $npad
                set offs [incrange $tmp $col [expr {-$npad}]]
                set z [lindex $offs $col]
                set haspad 1
            }
            if {$z0 eq {} && !$isarrow} {
                # this line links to its first child on row $row-2
                set rm2 [expr {$row - 2}]
                set id [lindex $displayorder $rm2]
                set xc [lsearch -exact [lindex $rowidlist $rm2] $id]
                if {$xc >= 0} {
                    set z0 [expr {$xc - $x0}]
                }
            }
            if {$z0 ne {} && $z < 0 && $z0 > 0} {
                insert_pad $y0 $x0 1
                set offs [incrange $offs $col 1]
                optimize_rows $y0 [expr {$x0 + 1}] $row
            }
        }
        if {!$haspad} {
            set o {}
            for {set col [llength $idlist]} {[incr col -1] >= 0} {} {
                set o [lindex $offs $col]
                if {$o eq {}} {
                    # check if this is the link to the first child
                    set id [lindex $idlist $col]
                    set ranges [rowranges $id]
                    if {$ranges ne {} && $row == [lindex $ranges 0]} {
                        # it is, work out offset to child
                        set y0 [expr {$row - 1}]
                        set id [lindex $displayorder $y0]
                        set x0 [lsearch -exact [lindex $rowidlist $y0] $id]
                        if {$x0 >= 0} {
                            set o [expr {$x0 - $col}]
                        }
                    }
                }
                if {$o eq {} || $o <= 0} break
            }
            if {$o ne {} && [incr col] < [llength $idlist]} {
                set y1 [expr {$row + 1}]
                set offs2 [lindex $rowoffsets $y1]
                set x1 -1
                foreach z $offs2 {
                    incr x1
                    if {$z eq {} || $x1 + $z < $col} continue
                    lset rowoffsets $y1 [incrange $offs2 $x1 1]
                    break
                }
                set idlist [linsert $idlist $col {}]
                set tmp [linsert $offs $col {}]
                incr col
                set offs [incrange $tmp $col -1]
            }
        }
        lset rowidlist $row $idlist
        lset rowoffsets $row $offs
        set col 0
    }
}

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 phase idrowranges commitrow rowlaidout rowrangelist curview

    set ranges {}
    if {$phase eq {} ||
        ([info exists commitrow($curview,$id)]
         && $commitrow($curview,$id) < $rowlaidout)} {
        set ranges [lindex $rowrangelist $commitrow($curview,$id)]
    } elseif {[info exists idrowranges($id)]} {
        set ranges $idrowranges($id)
    }
    return $ranges
}

proc drawlineseg {id i} {
    global rowoffsets rowidlist
    global displayorder
    global canv colormap linespc
    global numcommits commitrow curview

    set ranges [rowranges $id]
    set downarrow 1
    if {[info exists commitrow($curview,$id)]
        && $commitrow($curview,$id) < $numcommits} {
        set downarrow [expr {$i < [llength $ranges] / 2 - 1}]
    } else {
        set downarrow 1
    }
    set startrow [lindex $ranges [expr {2 * $i}]]
    set row [lindex $ranges [expr {2 * $i + 1}]]
    if {$startrow == $row} return
    assigncolor $id
    set coords {}
    set col [lsearch -exact [lindex $rowidlist $row] $id]
    if {$col < 0} {
        puts "oops: drawline: id $id not on row $row"
        return
    }
    set lasto {}
    set ns 0
    while {1} {
        set o [lindex $rowoffsets $row $col]
        if {$o eq {}} break
        if {$o ne $lasto} {
            # changing direction
            set x [xc $row $col]
            set y [yc $row]
            lappend coords $x $y
            set lasto $o
        }
        incr col $o
        incr row -1
    }
    set x [xc $row $col]
    set y [yc $row]
    lappend coords $x $y
    if {$i == 0} {
        # draw the link to the first child as part of this line
        incr row -1
        set child [lindex $displayorder $row]
        set ccol [lsearch -exact [lindex $rowidlist $row] $child]
        if {$ccol >= 0} {
            set x [xc $row $ccol]
            set y [yc $row]
            if {$ccol < $col - 1} {
                lappend coords [xc $row [expr {$col - 1}]] [yc $row]
            } elseif {$ccol > $col + 1} {
                lappend coords [xc $row [expr {$col + 1}]] [yc $row]
            }
            lappend coords $x $y
        }
    }
    if {[llength $coords] < 4} return
    if {$downarrow} {
        # This line has an arrow at the lower end: check if the arrow is
        # on a diagonal segment, and if so, work around the Tk 8.4
        # refusal to draw arrows on diagonal lines.
        set x0 [lindex $coords 0]
        set x1 [lindex $coords 2]
        if {$x0 != $x1} {
            set y0 [lindex $coords 1]
            set y1 [lindex $coords 3]
            if {$y0 - $y1 <= 2 * $linespc && $x1 == [lindex $coords 4]} {
                # we have a nearby vertical segment, just trim off the diag bit
                set coords [lrange $coords 2 end]
            } else {
                set slope [expr {($x0 - $x1) / ($y0 - $y1)}]
                set xi [expr {$x0 - $slope * $linespc / 2}]
                set yi [expr {$y0 - $linespc / 2}]
                set coords [lreplace $coords 0 1 $xi $y0 $xi $yi]
            }
        }
    }
    set arrow [expr {2 * ($i > 0) + $downarrow}]
    set arrow [lindex {none first last both} $arrow]
    set t [$canv create line $coords -width [linewidth $id] \
               -fill $colormap($id) -tags lines.$id -arrow $arrow]
    $canv lower $t
    bindline $t $id
}

proc drawparentlinks {id row col olds} {
    global rowidlist canv colormap

    set row2 [expr {$row + 1}]
    set x [xc $row $col]
    set y [yc $row]
    set y2 [yc $row2]
    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 ranges [rowranges $p]
        if {$ranges ne {} && $row2 == [lindex $ranges 0]
            && $row2 < [lindex $ranges 1]} {
            # drawlineseg will do this one for us
            continue
        }
        assigncolor $p
        # should handle duplicated parents here...
        set coords [list $x $y]
        if {$i < $col - 1} {
            lappend coords [xc $row [expr {$i + 1}]] $y
        } elseif {$i > $col + 1} {
            lappend coords [xc $row [expr {$i - 1}]] $y
        }
        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
    }
    return $rmx
}

proc drawlines {id} {
    global colormap canv
    global idrangedrawn
    global children iddrawn commitrow rowidlist curview

    $canv delete lines.$id
    set nr [expr {[llength [rowranges $id]] / 2}]
    for {set i 0} {$i < $nr} {incr i} {
        if {[info exists idrangedrawn($id,$i)]} {
            drawlineseg $id $i
        }
    }
    foreach child $children($curview,$id) {
        if {[info exists iddrawn($child)]} {
            set row $commitrow($curview,$child)
            set col [lsearch -exact [lindex $rowidlist $row] $child]
            if {$col >= 0} {
                drawparentlinks $child $row $col [list $id]
            }
        }
    }
}

proc drawcmittext {id row col rmx} {
    global linespc canv canv2 canv3 canvy0 fgcolor
    global commitlisted commitinfo rowidlist
    global rowtextx idpos idtags idheads idotherrefs
    global linehtag linentag linedtag
    global mainfont canvxmax boldrows boldnamerows fgcolor

    set ofill [expr {[lindex $commitlisted $row]? "blue": "white"}]
    set x [xc $row $col]
    set y [yc $row]
    set orad [expr {$linespc / 3}]
    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]
    $canv raise $t
    $canv bind $t <1> {selcanvline {} %x %y}
    set xt [xc $row [llength [lindex $rowidlist $row]]]
    if {$xt < $rmx} {
        set xt $rmx
    }
    set rowtextx($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 $row]
    if {$isbold > 0} {
        lappend boldrows $row
        lappend font bold
        if {$isbold > 1} {
            lappend boldnamerows $row
            lappend nfont bold
        }
    }
    set linehtag($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 $mainfont -tags text]
    set xr [expr {$xt + [font measure $mainfont $headline]}]
    if {$xr > $canvxmax} {
        set canvxmax $xr
        setcanvscroll
    }
}

proc drawcmitrow {row} {
    global displayorder rowidlist
    global idrangedrawn iddrawn
    global commitinfo parentlist numcommits
    global filehighlight fhighlights findstring nhighlights
    global hlview vhighlights
    global highlight_related rhighlights

    if {$row >= $numcommits} return
    foreach id [lindex $rowidlist $row] {
        if {$id eq {}} continue
        set i -1
        foreach {s e} [rowranges $id] {
            incr i
            if {$row < $s} continue
            if {$e eq {}} break
            if {$row <= $e} {
                if {$e < $numcommits && ![info exists idrangedrawn($id,$i)]} {
                    drawlineseg $id $i
                    set idrangedrawn($id,$i) 1
                }
                break
            }
        }
    }

    set id [lindex $displayorder $row]
    if {[info exists hlview] && ![info exists vhighlights($row)]} {
        askvhighlight $row $id
    }
    if {[info exists filehighlight] && ![info exists fhighlights($row)]} {
        askfilehighlight $row $id
    }
    if {$findstring ne {} && ![info exists nhighlights($row)]} {
        askfindhighlight $row $id
    }
    if {$highlight_related ne "None" && ![info exists rhighlights($row)]} {
        askrelhighlight $row $id
    }
    if {[info exists iddrawn($id)]} return
    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
    set olds [lindex $parentlist $row]
    if {$olds ne {}} {
        set rmx [drawparentlinks $id $row $col $olds]
    } else {
        set rmx 0
    }
    drawcmittext $id $row $col $rmx
    set iddrawn($id) 1
}

proc drawfrac {f0 f1} {
    global numcommits canv
    global linespc

    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax == 0} return
    set y0 [expr {int($f0 * $ymax)}]
    set row [expr {int(($y0 - 3) / $linespc) - 1}]
    if {$row < 0} {
        set row 0
    }
    set y1 [expr {int($f1 * $ymax)}]
    set endrow [expr {int(($y1 - 3) / $linespc) + 1}]
    if {$endrow >= $numcommits} {
        set endrow [expr {$numcommits - 1}]
    }
    for {} {$row <= $endrow} {incr row} {
        drawcmitrow $row
    }
}

proc drawvisible {} {
    global canv
    eval drawfrac [$canv yview]
}

proc clear_display {} {
    global iddrawn idrangedrawn
    global vhighlights fhighlights nhighlights rhighlights

    allcanvs delete all
    catch {unset iddrawn}
    catch {unset idrangedrawn}
    catch {unset vhighlights}
    catch {unset fhighlights}
    catch {unset nhighlights}
    catch {unset rhighlights}
}

proc findcrossings {id} {
    global rowidlist parentlist numcommits rowoffsets displayorder

    set cross {}
    set ccross {}
    foreach {s e} [rowranges $id] {
        if {$e >= $numcommits} {
            set e [expr {$numcommits - 1}]
        }
        if {$e <= $s} continue
        set x [lsearch -exact [lindex $rowidlist $e] $id]
        if {$x < 0} {
            puts "findcrossings: oops, no [shortids $id] in row $e"
            continue
        }
        for {set row $e} {[incr row -1] >= $s} {} {
            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
                    }
                }
            }
            set inc [lindex $rowoffsets $row $x]
            if {$inc eq {}} break
            incr x $inc
        }
    }
    return [concat $ccross {{}} $cross]
}

proc assigncolor {id} {
    global colormap colors nextcolor
    global commitrow parentlist 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 [lindex $parentlist $commitrow($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 [lindex $parentlist $commitrow($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 mainfont commitrow 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 [concat $mainfont bold] $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 $tag 1]
            set rowtextx($commitrow($curview,$id)) [expr {$xr + $linespc}]
        } else {
            # draw a head or other ref
            if {[incr nheads -1] >= 0} {
                set col green
                if {$tag eq $mainhead} {
                    lappend font bold
                }
            } else {
                set col "#ddddff"
            }
            set xl [expr {$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 mainfont fgcolor

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

proc finishcommits {} {
    global commitidx phase curview
    global pending_select

    if {$commitidx($curview) > 0} {
        drawrest
    } else {
        show_status "No commits selected"
    }
    set phase {}
    catch {unset pending_select}
}

# Insert a new commit as the child of the commit on row $row.
# The new commit will be displayed on row $row and the commits
# on that row and below will move down one row.
proc insertrow {row newcmit} {
    global displayorder parentlist childlist commitlisted
    global commitrow curview rowidlist rowoffsets numcommits
    global rowrangelist idrowranges rowlaidout rowoptim numcommits
    global linesegends selectedline

    if {$row >= $numcommits} {
        puts "oops, inserting new row $row but only have $numcommits rows"
        return
    }
    set p [lindex $displayorder $row]
    set displayorder [linsert $displayorder $row $newcmit]
    set parentlist [linsert $parentlist $row $p]
    set kids [lindex $childlist $row]
    lappend kids $newcmit
    lset childlist $row $kids
    set childlist [linsert $childlist $row {}]
    set commitlisted [linsert $commitlisted $row 1]
    set l [llength $displayorder]
    for {set r $row} {$r < $l} {incr r} {
        set id [lindex $displayorder $r]
        set commitrow($curview,$id) $r
    }

    set idlist [lindex $rowidlist $row]
    set offs [lindex $rowoffsets $row]
    set newoffs {}
    foreach x $idlist {
        if {$x eq {} || ($x eq $p && [llength $kids] == 1)} {
            lappend newoffs {}
        } else {
            lappend newoffs 0
        }
    }
    if {[llength $kids] == 1} {
        set col [lsearch -exact $idlist $p]
        lset idlist $col $newcmit
    } else {
        set col [llength $idlist]
        lappend idlist $newcmit
        lappend offs {}
        lset rowoffsets $row $offs
    }
    set rowidlist [linsert $rowidlist $row $idlist]
    set rowoffsets [linsert $rowoffsets [expr {$row+1}] $newoffs]

    set rowrangelist [linsert $rowrangelist $row {}]
    set l [llength $rowrangelist]
    for {set r 0} {$r < $l} {incr r} {
        set ranges [lindex $rowrangelist $r]
        if {$ranges ne {} && [lindex $ranges end] >= $row} {
            set newranges {}
            foreach x $ranges {
                if {$x >= $row} {
                    lappend newranges [expr {$x + 1}]
                } else {
                    lappend newranges $x
                }
            }
            lset rowrangelist $r $newranges
        }
    }
    if {[llength $kids] > 1} {
        set rp1 [expr {$row + 1}]
        set ranges [lindex $rowrangelist $rp1]
        if {$ranges eq {}} {
            set ranges [list $row $rp1]
        } elseif {[lindex $ranges end-1] == $rp1} {
            lset ranges end-1 $row
        }
        lset rowrangelist $rp1 $ranges
    }
    foreach id [array names idrowranges] {
        set ranges $idrowranges($id)
        if {$ranges ne {} && [lindex $ranges end] >= $row} {
            set newranges {}
            foreach x $ranges {
                if {$x >= $row} {
                    lappend newranges [expr {$x + 1}]
                } else {
                    lappend newranges $x
                }
            }
            set idrowranges($id) $newranges
        }
    }

    set linesegends [linsert $linesegends $row {}]

    incr rowlaidout
    incr rowoptim
    incr numcommits

    if {[info exists selectedline] && $selectedline >= $row} {
        incr selectedline
    }
    redisplay
}

# 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} {
    global isbusy

    if {[array names isbusy] eq {}} {
        . config -cursor watch
        settextcursor watch
    }
    set isbusy($what) 1
}

proc notbusy {what} {
    global isbusy maincursor textcursor

    catch {unset isbusy($what)}
    if {[array names isbusy] eq {}} {
        . config -cursor $maincursor
        settextcursor $textcursor
    }
}

proc drawrest {} {
    global startmsecs
    global rowlaidout commitidx curview
    global pending_select

    set row $rowlaidout
    layoutrows $rowlaidout $commitidx($curview) 1
    layouttail
    optimize_rows $row 0 $commitidx($curview)
    showstuff $commitidx($curview)
    if {[info exists pending_select]} {
        selectline 0 1
    }

    set drawmsecs [expr {[clock clicks -milliseconds] - $startmsecs}]
    #global numcommits
    #puts "overall $drawmsecs ms for $numcommits commits"
}

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

proc dofind {} {
    global findtype findloc findstring markedmatches commitinfo
    global numcommits displayorder linehtag linentag linedtag
    global mainfont canv canv2 canv3 selectedline
    global matchinglines foundstring foundstrlen matchstring
    global commitdata

    stopfindproc
    unmarkmatches
    cancel_next_highlight
    focus .
    set matchinglines {}
    if {$findtype == "IgnCase"} {
        set foundstring [string tolower $findstring]
    } else {
        set foundstring $findstring
    }
    set foundstrlen [string length $findstring]
    if {$foundstrlen == 0} return
    regsub -all {[*?\[\\]} $foundstring {\\&} matchstring
    set matchstring "*$matchstring*"
    if {![info exists selectedline]} {
        set oldsel -1
    } else {
        set oldsel $selectedline
    }
    set didsel 0
    set fldtypes {Headline Author Date Committer CDate Comments}
    set l -1
    foreach id $displayorder {
        set d $commitdata($id)
        incr l
        if {$findtype == "Regexp"} {
            set doesmatch [regexp $foundstring $d]
        } elseif {$findtype == "IgnCase"} {
            set doesmatch [string match -nocase $matchstring $d]
        } else {
            set doesmatch [string match $matchstring $d]
        }
        if {!$doesmatch} continue
        if {![info exists commitinfo($id)]} {
            getcommit $id
        }
        set info $commitinfo($id)
        set doesmatch 0
        foreach f $info ty $fldtypes {
            if {$findloc != "All fields" && $findloc != $ty} {
                continue
            }
            set matches [findmatches $f]
            if {$matches == {}} continue
            set doesmatch 1
            if {$ty == "Headline"} {
                drawcmitrow $l
                markmatches $canv $l $f $linehtag($l) $matches $mainfont
            } elseif {$ty == "Author"} {
                drawcmitrow $l
                markmatches $canv2 $l $f $linentag($l) $matches $mainfont
            } elseif {$ty == "Date"} {
                drawcmitrow $l
                markmatches $canv3 $l $f $linedtag($l) $matches $mainfont
            }
        }
        if {$doesmatch} {
            lappend matchinglines $l
            if {!$didsel && $l > $oldsel} {
                findselectline $l
                set didsel 1
            }
        }
    }
    if {$matchinglines == {}} {
        bell
    } elseif {!$didsel} {
        findselectline [lindex $matchinglines 0]
    }
}

proc findselectline {l} {
    global findloc commentend ctext
    selectline $l 1
    if {$findloc == "All fields" || $findloc == "Comments"} {
        # highlight the matches in the comments
        set f [$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"
        }
    }
}

proc findnext {restart} {
    global matchinglines selectedline
    if {![info exists matchinglines]} {
        if {$restart} {
            dofind
        }
        return
    }
    if {![info exists selectedline]} return
    foreach l $matchinglines {
        if {$l > $selectedline} {
            findselectline $l
            return
        }
    }
    bell
}

proc findprev {} {
    global matchinglines selectedline
    if {![info exists matchinglines]} {
        dofind
        return
    }
    if {![info exists selectedline]} return
    set prev {}
    foreach l $matchinglines {
        if {$l >= $selectedline} break
        set prev $l
    }
    if {$prev != {}} {
        findselectline $prev
    } else {
        bell
    }
}

proc stopfindproc {{done 0}} {
    global findprocpid findprocfile findids
    global ctext findoldcursor phase maincursor textcursor
    global findinprogress

    catch {unset findids}
    if {[info exists findprocpid]} {
        if {!$done} {
            catch {exec kill $findprocpid}
        }
        catch {close $findprocfile}
        unset findprocpid
    }
    catch {unset findinprogress}
    notbusy find
}

# mark a commit as matching by putting a yellow background
# behind the headline
proc markheadline {l id} {
    global canv mainfont linehtag

    drawcmitrow $l
    set bbox [$canv bbox $linehtag($l)]
    set t [$canv create rect $bbox -outline {} -tags matches -fill yellow]
    $canv lower $t
}

# mark the bits of a headline, author or date that match a find string
proc markmatches {canv l str tag matches font} {
    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 matches -fill yellow]
        $canv lower $t
    }
}

proc unmarkmatches {} {
    global matchinglines findids
    allcanvs delete matches
    catch {unset matchinglines}
    catch {unset findids}
}

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 $canv} {
        if {![info exists rowtextx($l)] || $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 commitrow linknum curview

    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 $e]
        if {![info exists commitrow($curview,$linkid)]} continue
        incr e
        $ctext tag add link "$start + $s c" "$start + $e c"
        $ctext tag add link$linknum "$start + $s c" "$start + $e c"
        $ctext tag bind link$linknum <1> \
            [list selectline $commitrow($curview,$linkid) 1]
        incr linknum
    }
    $ctext tag conf link -foreground blue -underline 1
    $ctext tag bind link <Enter> { %W configure -cursor hand2 }
    $ctext tag bind link <Leave> { %W configure -cursor $curtextcursor }
}

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 commitrow linknum curview $var

    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]
        }
    }
    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] $lk
        if {[info exists commitrow($curview,$id)]} {
            $ctext tag conf $lk -foreground blue
            $ctext tag bind $lk <1> \
                [list selectline $commitrow($curview,$id) 1]
            $ctext tag conf $lk -underline 1
            $ctext tag bind $lk <Enter> { %W configure -cursor hand2 }
            $ctext tag bind $lk <Leave> { %W configure -cursor $curtextcursor }
        }
        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 {![info exists selectedline] || !$showneartags} return
    after cancel dispnexttag
    if {$delay} {
        after 200 dispnexttag
        set tagphase -1
    } else {
        after idle dispnexttag
        set tagphase 0
    }
}

proc dispnexttag {} {
    global selectedline currentid showneartags tagphase ctext

    if {![info exists selectedline] || !$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 selectline {l isnew} {
    global canv canv2 canv3 ctext commitinfo selectedline
    global displayorder linehtag linentag linedtag
    global canvy0 linespc parentlist childlist
    global currentid sha1entry
    global commentend idtags linknum
    global mergemax numcommits pending_select
    global cmitmode showneartags allcommits

    catch {unset pending_select}
    $canv delete hover
    normalline
    cancel_next_highlight
    if {$l < 0 || $l >= $numcommits} return
    set y [expr {$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
    }

    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

    if {$isnew} {
        addtohistory [list selectline $l 0]
    }

    set selectedline $l

    set id [lindex $displayorder $l]
    set currentid $id
    $sha1entry delete 0 end
    $sha1entry insert 0 $id
    $sha1entry selection from 0
    $sha1entry selection to end
    rhighlight_sel $id

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

    set headers {}
    set olds [lindex $parentlist $l]
    if {[llength $olds] > 1} {
        set np 0
        foreach p $olds {
            if {$np >= $mergemax} {
                set tag mmax
            } else {
                set tag m$np
            }
            $ctext insert end "Parent: " $tag
            appendwithlinks [commit_descriptor $p] {}
            incr np
        }
    } else {
        foreach p $olds {
            append headers "Parent: [commit_descriptor $p]"
        }
    }

    foreach c [lindex $childlist $l] {
        append headers "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 "Branch: "
        $ctext mark set branch "end -1c"
        $ctext mark gravity branch left
        $ctext insert end "\nFollows: "
        $ctext mark set follows "end -1c"
        $ctext mark gravity follows left
        $ctext insert end "\nPrecedes: "
        $ctext mark set precedes "end -1c"
        $ctext mark gravity precedes left
        $ctext insert end "\n"
        dispneartags 1
    }
    $ctext insert end "\n"
    appendwithlinks [lindex $info 5] {comment}

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

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

proc selfirstline {} {
    unmarkmatches
    selectline 0 1
}

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

proc selnextline {dir} {
    global selectedline
    if {![info exists selectedline]} 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 * $lpp}] units
    drawvisible
    if {![info exists selectedline]} return
    set l [expr {$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

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

proc reselectline {} {
    global selectedline

    if {[info exists selectedline]} {
        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

    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

    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

    set diffids $id
    catch {unset diffmergeid}
    if {![info exists treefilelist($id)]} {
        if {![info exists treepending]} {
            if {[catch {set gtf [open [concat | git ls-tree -r $id] r]}]} {
                return
            }
            set treepending $id
            set treefilelist($id) {}
            set treeidlist($id) {}
            fconfigure $gtf -blocking 0
            fileevent $gtf readable [list gettreeline $gtf $id]
        }
    } else {
        setfilelist $id
    }
}

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

    while {[gets $gtf line] >= 0} {
        if {[lindex $line 1] ne "blob"} continue
        set sha1 [lindex $line 2]
        set fname [lindex $line 3]
        lappend treefilelist($id) $fname
        lappend treeidlist($id) $sha1
    }
    if {![eof $gtf]} return
    close $gtf
    unset treepending
    if {$cmitmode ne "tree"} {
        if {![info exists diffmergeid]} {
            gettreediffs $diffids
        }
    } elseif {$id ne $diffids} {
        gettree $diffids
    } else {
        setfilelist $id
    }
}

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

    set i [lsearch -exact $treefilelist($diffids) $f]
    if {$i < 0} {
        puts "oops, $f not in list for id $diffids"
        return
    }
    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
    fileevent $bf readable [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
}

proc getblobline {bf id} {
    global diffids cmitmode ctext

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

proc mergediff {id l} {
    global diffmergeid diffopts mdifffd
    global diffids
    global parentlist

    set diffmergeid $id
    set diffids $id
    # this doesn't seem to actually affect anything...
    set env(GIT_DIFF_OPTS) $diffopts
    set cmd [concat | git diff-tree --no-commit-id --cc $id]
    if {[catch {set mdf [open $cmd r]} err]} {
        error_popup "Error getting merge diffs: $err"
        return
    }
    fconfigure $mdf -blocking 0
    set mdifffd($id) $mdf
    set np [llength [lindex $parentlist $l]]
    fileevent $mdf readable [list getmergediffline $mdf $id $np]
    set nextupdate [expr {[clock clicks -milliseconds] + 100}]
}

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

    set n [gets $mdf line]
    if {$n < 0} {
        if {[eof $mdf]} {
            close $mdf
        }
        return
    }
    if {![info exists diffmergeid] || $id != $diffmergeid
        || $mdf != $mdifffd($id)} {
        return
    }
    $ctext conf -state normal
    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 {[clock clicks -milliseconds] >= $nextupdate} {
        incr nextupdate 100
        fileevent $mdf readable {}
        update
        fileevent $mdf readable [list getmergediffline $mdf $id $np]
    }
}

proc startdiff {ids} {
    global treediffs diffids treepending diffmergeid

    set diffids $ids
    catch {unset diffmergeid}
    if {![info exists treediffs($ids)]} {
        if {![info exists treepending]} {
            gettreediffs $ids
        }
    } else {
        addtocflist $ids
    }
}

proc addtocflist {ids} {
    global treediffs cflist
    add_flist $treediffs($ids)
    getblobdiffs $ids
}

proc gettreediffs {ids} {
    global treediff treepending
    set treepending $ids
    set treediff {}
    if {[catch \
         {set gdtf [open [concat | git diff-tree --no-commit-id -r $ids] r]} \
        ]} return
    fconfigure $gdtf -blocking 0
    fileevent $gdtf readable [list gettreediffline $gdtf $ids]
}

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

    set n [gets $gdtf line]
    if {$n < 0} {
        if {![eof $gdtf]} return
        close $gdtf
        set treediffs($ids) $treediff
        unset treepending
        if {$cmitmode eq "tree"} {
            gettree $diffids
        } elseif {$ids != $diffids} {
            if {![info exists diffmergeid]} {
                gettreediffs $diffids
            }
        } else {
            addtocflist $ids
        }
        return
    }
    set file [lindex $line 5]
    lappend treediff $file
}

proc getblobdiffs {ids} {
    global diffopts blobdifffd diffids env curdifftag curtagstart
    global nextupdate diffinhdr treediffs

    set env(GIT_DIFF_OPTS) $diffopts
    set cmd [concat | git diff-tree --no-commit-id -r -p -C $ids]
    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
    set curdifftag Comments
    set curtagstart 0.0
    fileevent $bdf readable [list getblobdiffline $bdf $diffids]
    set nextupdate [expr {[clock clicks -milliseconds] + 100}]
}

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 getblobdiffline {bdf ids} {
    global diffids blobdifffd ctext curdifftag curtagstart
    global diffnexthead diffnextnote difffilestart
    global nextupdate diffinhdr treediffs

    set n [gets $bdf line]
    if {$n < 0} {
        if {[eof $bdf]} {
            close $bdf
            if {$ids == $diffids && $bdf == $blobdifffd($ids)} {
                $ctext tag add $curdifftag $curtagstart end
            }
        }
        return
    }
    if {$ids != $diffids || $bdf != $blobdifffd($ids)} {
        return
    }
    $ctext conf -state normal
    if {[regexp {^diff --git a/(.*) b/(.*)} $line match fname newname]} {
        # start of a new file
        $ctext insert end "\n"
        $ctext tag add $curdifftag $curtagstart end
        set here [$ctext index "end - 1c"]
        set curtagstart $here
        set header $newname
        set i [lsearch -exact $treediffs($ids) $fname]
        if {$i >= 0} {
            setinlist difffilestart $i $here
        }
        if {$newname ne $fname} {
            set i [lsearch -exact $treediffs($ids) $newname]
            if {$i >= 0} {
                setinlist difffilestart $i $here
            }
        }
        set curdifftag "f:$fname"
        $ctext tag delete $curdifftag
        set l [expr {(78 - [string length $header]) / 2}]
        set pad [string range "----------------------------------------" 1 $l]
        $ctext insert end "$pad $header $pad\n" filesep
        set diffinhdr 1
    } elseif {$diffinhdr && [string compare -length 3 $line "---"] == 0} {
        # do nothing
    } elseif {$diffinhdr && [string compare -length 3 $line "+++"] == 0} {
        set diffinhdr 0
    } 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
    } 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"
        } elseif {$diffinhdr || $x == "\\"} {
            # e.g. "\ No newline at end of file"
            $ctext insert end "$line\n" filesep
        } else {
            # Something else we don't recognize
            if {$curdifftag != "Comments"} {
                $ctext insert end "\n"
                $ctext tag add $curdifftag $curtagstart end
                set curtagstart [$ctext index "end - 1c"]
                set curdifftag Comments
            }
            $ctext insert end "$line\n" filesep
        }
    }
    $ctext conf -state disabled
    if {[clock clicks -milliseconds] >= $nextupdate} {
        incr nextupdate 100
        fileevent $bdf readable {}
        update
        fileevent $bdf readable "getblobdiffline $bdf {$ids}"
    }
}

proc changediffdisp {} {
    global ctext diffelide

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

proc prevfile {} {
    global difffilestart ctext
    set prev [lindex $difffilestart 0]
    set here [$ctext index @0,0]
    foreach loc $difffilestart {
        if {[$ctext compare $loc >= $here]} {
            $ctext yview $prev
            return
        }
        set prev $loc
    }
    $ctext yview $prev
}

proc nextfile {} {
    global difffilestart ctext
    set here [$ctext index @0,0]
    foreach loc $difffilestart {
        if {[$ctext compare $loc > $here]} {
            $ctext yview $loc
            return
        }
    }
}

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

    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
}

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

proc setcoords {} {
    global linespc charspc canvx0 canvy0 mainfont
    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 {[info exists selectedline]} {
        selectline $selectedline 0
        allcanvs yview moveto [lindex $span 0]
    }
}

proc incrfont {inc} {
    global mainfont textfont ctext canv phase cflist
    global charspc tabstop
    global stopped entries
    unmarkmatches
    set mainfont [lreplace $mainfont 1 1 [expr {[lindex $mainfont 1] + $inc}]]
    set textfont [lreplace $textfont 1 1 [expr {[lindex $textfont 1] + $inc}]]
    setcoords
    $ctext conf -font $textfont -tabs "[expr {$tabstop * $charspc}]"
    $cflist conf -font $textfont
    $ctext tag conf filesep -font [concat $textfont bold]
    foreach e $entries {
        $e conf -font $mainfont
    }
    if {$phase eq "getcommits"} {
        $canv itemconf textitems -font $mainfont
    }
    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 "Goto: "
    } else {
        $sha1but conf -state disabled -relief flat -text "SHA1 ID: "
    }
}

proc gotocommit {} {
    global sha1string currentid commitrow tagids headids
    global displayorder numcommits curview

    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 {}
            foreach i $displayorder {
                if {[string match $id* $i]} {
                    lappend matches $i
                }
            }
            if {$matches ne {}} {
                if {[llength $matches] > 1} {
                    error_popup "Short SHA1 id $id is ambiguous"
                    return
                }
                set id [lindex $matches 0]
            }
        }
    }
    if {[info exists commitrow($curview,$id)]} {
        selectline $commitrow($curview,$id) 1
        return
    }
    if {[regexp {^[0-9a-fA-F]{4,}$} $sha1string]} {
        set type "SHA1 id"
    } else {
        set type "Tag/Head"
    }
    error_popup "$type $sha1string is not known"
}

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 mainfont

    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
    $ctext tag conf link -foreground blue -underline 1
    $ctext tag bind link <Enter> { %W configure -cursor hand2 }
    $ctext tag bind link <Leave> { %W configure -cursor $curtextcursor }
    $ctext insert end "Parent:\t"
    $ctext insert end $id [list link link0]
    $ctext tag bind link0 <1> [list selbyid $id]
    set info $commitinfo($id)
    $ctext insert end "\n\t[lindex $info 0]\n"
    $ctext insert end "\tAuthor:\t[lindex $info 1]\n"
    set date [formatdate [lindex $info 2]]
    $ctext insert end "\tDate:\t$date\n"
    set kids $children($curview,$id)
    if {$kids ne {}} {
        $ctext insert end "\nChildren:"
        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 $child [list link link$i]
            $ctext tag bind link$i <1> [list selbyid $child]
            $ctext insert end "\n\t[lindex $info 0]"
            $ctext insert end "\n\tAuthor:\t[lindex $info 1]"
            set date [formatdate [lindex $info 2]]
            $ctext insert end "\n\tDate:\t$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 commitrow curview
    if {[info exists commitrow($curview,$id)]} {
        selectline $commitrow($curview,$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 commitrow selectedline rowmenuid curview

    if {![info exists selectedline]
        || $commitrow($curview,$id) eq $selectedline} {
        set state disabled
    } else {
        set state normal
    }
    $rowctxmenu entryconfigure "Diff this*" -state $state
    $rowctxmenu entryconfigure "Diff selected*" -state $state
    $rowctxmenu entryconfigure "Make patch" -state $state
    set rowmenuid $id
    tk_popup $rowctxmenu $x $y
}

proc diffvssel {dirn} {
    global rowmenuid selectedline displayorder

    if {![info exists selectedline]} return
    if {$dirn} {
        set oldid [lindex $displayorder $selectedline]
        set newid $rowmenuid
    } else {
        set oldid $rowmenuid
        set newid [lindex $displayorder $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 "Top"
    $ctext insert end "From "
    $ctext tag conf link -foreground blue -underline 1
    $ctext tag bind link <Enter> { %W configure -cursor hand2 }
    $ctext tag bind link <Leave> { %W configure -cursor $curtextcursor }
    $ctext tag bind link0 <1> [list selbyid $oldid]
    $ctext insert end $oldid [list link link0]
    $ctext insert end "\n     "
    $ctext insert end [lindex $commitinfo($oldid) 0]
    $ctext insert end "\n\nTo   "
    $ctext tag bind link1 <1> [list selbyid $newid]
    $ctext insert end $newid [list link link1]
    $ctext insert end "\n     "
    $ctext insert end [lindex $commitinfo($newid) 0]
    $ctext insert end "\n"
    $ctext conf -state disabled
    $ctext tag delete Comments
    $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 "Generate patch"
    grid $top.title - -pady 10
    label $top.from -text "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 "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 "Reverse" -command mkpatchrev -padx 5
    grid $top.rev x -pady 10
    label $top.flab -text "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 "Generate" -command mkpatchgo
    button $top.buts.can -text "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

    set oldid [$patchtop.fromsha1 get]
    set newid [$patchtop.tosha1 get]
    set fname [$patchtop.fname get]
    if {[catch {exec git diff-tree -p $oldid $newid >$fname &} err]} {
        error_popup "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 "Create tag"
    grid $top.title - -pady 10
    label $top.id -text "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 "Tag name:"
    entry $top.tag -width 60
    grid $top.tlab $top.tag -sticky w
    frame $top.buts
    button $top.buts.gen -text "Create" -command mktaggo
    button $top.buts.can -text "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 {$tag == {}} {
        error_popup "No tag name specified"
        return
    }
    if {[info exists tagids($tag)]} {
        error_popup "Tag \"$tag\" already exists"
        return
    }
    if {[catch {
        set dir [gitdir]
        set fname [file join $dir "refs/tags" $tag]
        set f [open $fname w]
        puts $f $id
        close $f
    } err]} {
        error_popup "Error creating tag: $err"
        return
    }

    set tagids($tag) $id
    lappend idtags($id) $tag
    redrawtags $id
    addedtag $id
}

proc redrawtags {id} {
    global canv linehtag commitrow idpos selectedline curview
    global mainfont canvxmax

    if {![info exists commitrow($curview,$id)]} return
    drawcmitrow $commitrow($curview,$id)
    $canv delete tag.$id
    set xt [eval drawtags $id $idpos($id)]
    $canv coords $linehtag($commitrow($curview,$id)) $xt [lindex $idpos($id) 2]
    set text [$canv itemcget $linehtag($commitrow($curview,$id)) -text]
    set xr [expr {$xt + [font measure $mainfont $text]}]
    if {$xr > $canvxmax} {
        set canvxmax $xr
        setcanvscroll
    }
    if {[info exists selectedline]
        && $selectedline == $commitrow($curview,$id)} {
        selectline $selectedline 0
    }
}

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 "Write commit to file"
    grid $top.title - -pady 10
    label $top.id -text "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 "Command:"
    entry $top.cmd -width 60 -textvariable wrcomcmd
    grid $top.clab $top.cmd -sticky w -pady 10
    label $top.flab -text "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 "Write" -command wrcomgo
    button $top.buts.can -text "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 "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 "Create new branch"
    grid $top.title - -pady 10
    label $top.id -text "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 "Name:"
    entry $top.name -width 40
    grid $top.nlab $top.name -sticky w
    frame $top.buts
    button $top.buts.go -text "Create" -command [list mkbrgo $top]
    button $top.buts.can -text "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 "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
    }
}

proc cherrypick {} {
    global rowmenuid curview commitrow
    global mainhead

    set oldhead [exec git rev-parse HEAD]
    set dheads [descheads $rowmenuid]
    if {$dheads ne {} && [lsearch -exact $dheads $oldhead] >= 0} {
        set ok [confirm_popup "Commit [string range $rowmenuid 0 7] is already\
                        included in branch $mainhead -- really re-apply it?"]
        if {!$ok} return
    }
    nowbusy cherrypick
    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 "No changes committed"
        return
    }
    addnewchild $newhead $oldhead
    if {[info exists commitrow($curview,$oldhead)]} {
        insertrow $commitrow($curview,$oldhead) $newhead
        if {$mainhead ne {}} {
            movehead $newhead $mainhead
            movedhead $newhead $mainhead
        }
        redrawtags $oldhead
        redrawtags $newhead
    }
    notbusy cherrypick
}

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

    set headmenuid $id
    set headmenuhead $head
    tk_popup $headctxmenu $x $y
}

proc cobranch {} {
    global headmenuid headmenuhead mainhead headids

    # check the tree is clean first??
    set oldmainhead $mainhead
    nowbusy checkout
    update
    if {[catch {
        exec git checkout -q $headmenuhead
    } err]} {
        notbusy checkout
        error_popup $err
    } else {
        notbusy checkout
        set mainhead $headmenuhead
        if {[info exists headids($oldmainhead)]} {
            redrawtags $headids($oldmainhead)
        }
        redrawtags $headmenuid
    }
}

proc rmbranch {} {
    global headmenuid headmenuhead mainhead
    global headids idheads

    set head $headmenuhead
    set id $headmenuid
    if {$head eq $mainhead} {
        error_popup "Cannot delete the currently checked-out branch"
        return
    }
    set dheads [descheads $id]
    if {$dheads eq $headids($head)} {
        # the stuff on this branch isn't on any other branch
        if {![confirm_popup "The commits on branch $head aren't on any other\
                        branch.\nReally delete branch $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
}

# Stuff for finding nearby tags
proc getallcommits {} {
    global allcommits allids nbmp nextarc seeds

    set allids {}
    set nbmp 0
    set nextarc 0
    set allcommits 0
    set seeds {}
    regetallcommits
}

# Called when the graph might have changed
proc regetallcommits {} {
    global allcommits seeds

    set cmd [concat | git rev-list --all --parents]
    foreach id $seeds {
        lappend cmd "^$id"
    }
    set fd [open $cmd r]
    fconfigure $fd -blocking 0
    incr allcommits
    nowbusy allcommits
    restartgetall $fd
}

proc restartgetall {fd} {
    fileevent $fd readable [list getallclines $fd]
}

# 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 allids allparents allchildren idtags nextarc nbmp
    global arcnos arcids arctags arcout arcend arcstart archeads growing
    global seeds allcommits allcstart

    if {![info exists allcstart]} {
        set allcstart [clock clicks -milliseconds]
    }
    set nid 0
    while {[gets $fd line] >= 0} {
        set id [lindex $line 0]
        if {[info exists allparents($id)]} {
            # seen it already
            continue
        }
        lappend allids $id
        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
            }
        }
        incr nbmp
        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 {[incr nid] >= 50} {
            set nid 0
            if {[clock clicks -milliseconds] - $allcstart >= 50} {
                fileevent $fd readable {}
                after idle restartgetall $fd
                unset allcstart
                return
            }
        }
    }
    if {![eof $fd]} return
    close $fd
    if {[incr allcommits -1] == 0} {
        notbusy allcommits
    }
    dispneartags 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 nbmp 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)
    }
    incr nbmp

    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 allids allparents allchildren idtags nextarc nbmp
    global arcnos arcids arctags arcout arcend arcstart archeads growing
    global seeds

    lappend allids $id
    set allparents($id) [list $p]
    set allchildren($id) {}
    set arcnos($id) {}
    lappend seeds $id
    incr nbmp
    lappend allchildren($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]
}

# 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).
        if {$a eq $b} {
            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 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 ret {}
    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 $ret $t
            }
        }
        set id $arcstart($a)
    }
    set origid $id
    set todo [list $id]
    set seen($id) 1
    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 {}} {
                    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
}

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 mainhead

    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 $mainhead
    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) != $v ||
            ($id eq $oldmainhead && $id ne $mainhead) ||
            ($id eq $mainhead && $id ne $oldmainhead)} {
            redrawtags $id
        }
    }
}

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

    if {$isnew} {
        addtohistory [list showtag $tag 0]
    }
    $ctext conf -state normal
    clear_ctext
    set linknum 0
    if {[info exists tagcontents($tag)]} {
        set text $tagcontents($tag)
    } else {
        set text "Tag: $tag\nId:  $tagids($tag)"
    }
    appendwithlinks $text {}
    $ctext conf -state disabled
    init_flist {}
}

proc doquit {} {
    global stopped
    set stopped 100
    savestuff .
    destroy .
}

proc doprefs {} {
    global maxwidth maxgraphpct diffopts
    global oldprefs prefstop showneartags
    global bgcolor fgcolor ctext diffcolors selectbgcolor
    global uifont tabstop

    set top .gitkprefs
    set prefstop $top
    if {[winfo exists $top]} {
        raise $top
        return
    }
    foreach v {maxwidth maxgraphpct diffopts showneartags} {
        set oldprefs($v) [set $v]
    }
    toplevel $top
    wm title $top "Gitk preferences"
    label $top.ldisp -text "Commit list display options"
    $top.ldisp configure -font $uifont
    grid $top.ldisp - -sticky w -pady 10
    label $top.spacer -text " "
    label $top.maxwidthl -text "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 "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

    label $top.ddisp -text "Diff display options"
    $top.ddisp configure -font $uifont
    grid $top.ddisp - -sticky w -pady 10
    label $top.diffoptl -text "Options for diff program" \
        -font optionfont
    entry $top.diffopt -width 20 -textvariable diffopts
    grid x $top.diffoptl $top.diffopt -sticky w
    frame $top.ntag
    label $top.ntag.l -text "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
    label $top.tabstopl -text "tabstop" -font optionfont
    entry $top.tabstop -width 10 -textvariable tabstop
    grid x $top.tabstopl $top.tabstop -sticky w

    label $top.cdisp -text "Colors: press to choose"
    $top.cdisp configure -font $uifont
    grid $top.cdisp - -sticky w -pady 10
    label $top.bg -padx 40 -relief sunk -background $bgcolor
    button $top.bgbut -text "Background" -font optionfont \
        -command [list choosecolor bgcolor 0 $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 "Foreground" -font optionfont \
        -command [list choosecolor fgcolor 0 $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 "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 "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 "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 "Select bg" -font optionfont \
        -command [list choosecolor selectbgcolor 0 $top.bg background setselbg]
    grid x $top.selbgbut $top.selbgsep -sticky w

    frame $top.buts
    button $top.buts.ok -text "OK" -command prefsok -default active
    $top.buts.ok configure -font $uifont
    button $top.buts.can -text "Cancel" -command prefscan -default normal
    $top.buts.can configure -font $uifont
    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 choosecolor {v vi w x cmd} {
    global $v

    set c [tk_chooseColor -initialcolor [lindex [set $v] $vi] \
               -title "Gitk: choose color for $x"]
    if {$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 maxwidth maxgraphpct diffopts
    global oldprefs prefstop showneartags

    foreach v {maxwidth maxgraphpct diffopts showneartags} {
        set $v $oldprefs($v)
    }
    catch {destroy $prefstop}
    unset prefstop
}

proc prefsok {} {
    global maxwidth maxgraphpct
    global oldprefs prefstop showneartags
    global charspc ctext tabstop

    catch {destroy $prefstop}
    unset prefstop
    $ctext configure -tabs "[expr {$tabstop * $charspc}]"
    if {$maxwidth != $oldprefs(maxwidth)
        || $maxgraphpct != $oldprefs(maxgraphpct)} {
        redisplay
    } elseif {$showneartags != $oldprefs(showneartags)} {
        reselectline
    }
}

proc formatdate {d} {
    return [clock format $d -format "%Y-%m-%d %H:%M:%S"]
}

# 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 {}
}

# defaults...
set datemode 0
set diffopts "-U 5 -p"
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 7
set downarrowlen 7
set mingaplen 30
set cmitmode "patch"
set wrapcomment "none"
set showneartags 1

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

catch {source ~/.gitk}

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

set revtreeargs {}
foreach arg $argv {
    switch -regexp -- $arg {
        "^$" { }
        "^-d" { set datemode 1 }
        default {
            lappend revtreeargs $arg
        }
    }
}

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

set cmdline_files {}
set i [lsearch -exact $revtreeargs "--"]
if {$i >= 0} {
    set cmdline_files [lrange $revtreeargs [expr {$i + 1}] end]
    set revtreeargs [lrange $revtreeargs 0 [expr {$i - 1}]]
} elseif {$revtreeargs ne {}} {
    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]
    } 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 {} . "Bad arguments to gitk:\n$err"
        exit 1
    }
}

set history {}
set historyindex 0
set fh_serial 0
set nhl_names {}
set highlight_paths {}
set searchdirn -forwards
set boldrows {}
set boldnamerows {}
set diffelide {0 0}

set optim_delay 16

set nextviewnum 1
set curview 0
set selectedview 0
set selectedhlview None
set viewfiles(0) {}
set viewperm(0) 0
set viewargs(0) {}

set cmdlineok 0
set stopped 0
set stuffsaved 0
set patchnum 0
setcoords
makewindow
wm title . "[file tail $argv0]: [file tail [pwd]]"
readrefs

if {$cmdline_files ne {} || $revtreeargs 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) "Command line"
    set viewfiles(1) $cmdline_files
    set viewargs(1) $revtreeargs
    set viewperm(1) 0
    addviewmenu 1
    .bar.view entryconf Edit* -state normal
    .bar.view entryconf Delete* -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 $v 2]
        set viewperm($n) 1
        addviewmenu $n
    }
}
getcommits