dirdiff 2.1-5 / usr / bin / dirdiff

#!/bin/sh
# Tcl ignores the next line \
exec wish "$0" -- "${1+$@}"

# Copyright (C) 1999-2004 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.

set Script [info script]
set ScriptTail [file tail $Script]
if {[file type $Script] == "link"} {
  set ScriptBin [file join [file dirname $Script] [file readlink $Script]]
} else { 
  set ScriptBin $Script
}
set TclExe [info nameofexecutable]
set compound_ok [expr {$tcl_version >= 8.4}]

set nofilecmp [catch {load libfilecmp.so.0.0}]
set rcsflag {}
set diffbflag {}
set diffBflag {}
set diffiflag {}
set diffwflag {}
set diffdflag {}
set ctxlines 3
set showsame 0
set underlinetabs 0
set redisp_immed 1
set diffnewfirst 0
set nukefiles {*.o *~ *.orig CVS *.a *.link *.old *.save .depend .*.flags SCCS}
set filelistfont {Helvetica -12}
set textfont {Courier -12}
set maxdepth 9999999
set nxdirmode 0
set docvsignore 0

set defaultcvsignore {
    RCS SCCS CVS CVS.adm RCSLOG cvslog.* .svn tags TAGS
    .make.state .nse_depinfo *~ \#* .\#* ,* _$* *$
    *.old *.bak *.BAK *.orig *.rej .del-* *.a *.olb
    *.o *.obj *.so *.exe *.Z *.elc *.ln core
}

if {$tcl_platform(platform) == "windows"} {
   set TclExe [file attributes $TclExe -shortname]
   # I don't like it any better than you do
   set nullfile "C:/temp/nulfile"
   set nf [open "$nullfile" w]
   close $nf
} else {
   set nullfile "/dev/null"
}
set diffprogram {}
set showprogram {}

set numlines 20
set canvy0 0
set canvy 0
set canvx 0

set have_unidiff 1
set caught [catch "exec diff -u $nullfile $nullfile" err]
if {$caught != 0} {
   puts "Unified diff not available.  Will use context diff for patches."
   set have_unidiff 0
}

catch {source ~/.dirdiff}

proc ignorefile pat {
    global nukefiles
    if {$pat == "!"} {
	set nukefiles {}
    } else {
	lappend nukefiles $pat
    }
}

set linespc [font metrics $filelistfont -linespace]
if {$linespc < 15} {set linespc 15}
set blotw [expr $linespc-3]
set bloth [expr $linespc-3]
set blotspc $linespc

proc usage {} {
    puts stderr {Usage: dirdiff [options]... dir1 dir2 ...

Options:
   -a, --all		don't exclude any files
   -o, --only pattern	only process files matching pattern
   -I, --ignore pattern	don't process files matching pattern
   -r, --rcs		ignore differences in RCS strings
   -c, --context num	set number of lines of context to show
   -b, -w, -B, -i, -d	pass these on to diff(1)
   -S			show files that are the same in the file list
   -C			Ignore files listed in .cvsignore files

Note: dirdiff needs to be able to load the libfilecmp.so.0.0 shared library
for the -r or -t flags to work.}
}

proc NewDirDialog {} {
   global d0 d1 d2 d3 d4
   toplevel .newdirDlg
   wm transient .newdirDlg
   wm title .newdirDlg "Directories"
   set waitvar 0

   frame .newdirDlg.top -borderwidth 2 -relief groove
   pack .newdirDlg.top -side top -fill x \
      -ipadx 20 -ipady 20 -padx 5 -pady 5

   button .newdirDlg.top.b0 -text "Browse..." -command { set d0 [tk_chooseDirectory] }
   button .newdirDlg.top.b1 -text "Browse..." -command { set d1 [tk_chooseDirectory] }
   button .newdirDlg.top.b2 -text "Browse..." -command { set d2 [tk_chooseDirectory] }
   button .newdirDlg.top.b3 -text "Browse..." -command { set d3 [tk_chooseDirectory] }
   button .newdirDlg.top.b4 -text "Browse..." -command { set d4 [tk_chooseDirectory] }
   for { set n 0 } { $n < 5 } { incr n } {
      set dn [expr {$n + 1}]
      label .newdirDlg.top.l$n -text "Directory $dn"
      entry .newdirDlg.top.e$n -width 25 -textvariable d$n
      grid .newdirDlg.top.l$n -row $n -column 0 -sticky e
      grid .newdirDlg.top.e$n -row $n -column 1 -sticky sew -pady 4
      grid .newdirDlg.top.b$n -row $n -column 2 -sticky w
   }
   grid columnconfigure .newdirDlg.top 0 -weight 0
   grid columnconfigure .newdirDlg.top 1 -weight 1
   grid columnconfigure .newdirDlg.top 2 -weight 0

   frame .newdirDlg.bot
   button .newdirDlg.bot.ok -text "OK" -width 5 -default active \
      -command {
         set dirs [list $d0 $d1 $d2 $d3 $d4]
         destroy .newdirDlg
         set waitvar 1
      }
   button .newdirDlg.bot.cancel -text "Cancel" -width 5 -default normal \
      -command {
         set dirs {}
         destroy .newdirDlg
         exit 0
      }

   pack .newdirDlg.bot -side bottom -fill x -expand n
   pack .newdirDlg.bot.ok .newdirDlg.bot.cancel \
      -side left -fill none -expand y -pady 4

   tkwait variable waitvar
}

proc addfiles {sd} {
    global dirs stat onlyfiles statinfo fserial nextserial
    global filetype filesize filetime nxdirmode
    global docvsignore cvsignores defaultcvsignore
    if {$nxdirmode == 0} {
	set dcount 0
	foreach d $dirs {
	    if {[catch {file stat $d/$sd stat}] == 0} {
		if {$stat(type) == "directory"} {incr dcount}
	    }
	}
	if {$dcount <= 1} {
	    return {}
	}
    }
    if {$docvsignore} {
	# read the .cvsignore in each directory
	set cvsignores($sd) {}
	foreach d $dirs {
	    catch {
		set ign $defaultcvsignore
		set f [open $d/$sd.cvsignore r]
		while {[gets $f line] >= 0} {
		    foreach i [split $line] {
			if {$i == "!"} {
			    set ign {}
			} else {
			    lappend ign $i
			}
		    }
		}
		close $f
		set cvsignores($sd) [concat $cvsignores($sd) $ign]
	    }
	}
	set cvsignores($sd) [lsort -unique $cvsignores($sd)]
    }
    foreach d $dirs {
	foreach f [lsort [glob -nocomplain $d/$sd* $d/$sd.*]] {
	    set fs $sd[file tail $f]
	    set wantim 0
	    if [notnuked $fs] {
		if {[catch {file lstat $f stat}] == 0} {
		    if {$stat(type) == "file"} {
			if [info exists onlyfiles] {
			    foreach o $onlyfiles {
				if [string match $o $fs] {
				    set wantim 1
				    break
				}
			    }
			} else {
			    set wantim [notcvsignored $fs]
			}
		    } elseif {$stat(type) == "directory"} {
			append fs /
			set wantim 1
		    }
		}
	    }
	    if {$wantim} {
		if {![info exists files($fs)]} {
		    set fserial($fs) [incr nextserial]
		    set files($fs) 1
		}
		set filetype($f) $stat(type)
		set filesize($f) $stat(size)
		set filetime($f) $stat(mtime)
	    }
	}
    }
    return [lsort [array names files]]
}

# Called to re-lstat a given file across all directories
proc updatefileinfo {f} {
    global dirs filetype filesize filetime

    foreach d $dirs {
	set df [joinname $d [string trimright $f /]]
	if {[catch {file lstat $df stat}] == 0} {
	    set filetype($df) $stat(type)
	    set filesize($df) $stat(size)
	    set filetime($df) $stat(mtime)
	} else {
	    catch {unset filetype($df)}
	}
    }
}

# Returns 1 if we are interested in this file, i.e. if it isn't
# matched by something in the exclude list
proc notnuked {f} {
    global nukefiles
    set ft [file tail $f]
    if {$ft == "." || $ft == ".."} {
	return 0
    }
    foreach n $nukefiles {
	if {[string match $n $f] || [string match $n $ft]} {
	    return 0
	}
    }
    return 1
}

proc notcvsignored {f} {
    global docvsignore cvsignores
    set sd [file dirname $f]/
    if {$sd == "./"} {
	set sd ""
    }
    set ft [file tail $f]
    if {$docvsignore && [info exists cvsignores($sd)]} {
	foreach n $cvsignores($sd) {
	    if {[string match $n $ft]} {
		return 0
	    }
	}
    }
    return 1
}

proc joinname {dir f} {
    global filemode
    if {$filemode} {
	return $dir
    }
    return [file join $dir $f]
}

proc fileisa {f t} {
    global filetype
    return [expr {[info exists filetype($f)] && $filetype($f) == $t}]
}

proc diffages {f showsame maxdepth} {
    global dirs nofilecmp rcsflag filesize filetime nxdirmode
    set numgroups 0
    set notexist {}
    set doesexist {}
    foreach d $dirs {
	set sameas($d) {}
	set group($d) 0
	set fname [joinname $d [string trimright $f /]]
	if {!([fileisa $fname "file"]
	      || ($maxdepth <= 0 && [fileisa $fname "directory"]))} {
	    set fd [file dirname $fname]
	    if {$nxdirmode || [file dirname $f] == "." \
		    || [fileisa $fd "directory"]} {
		lappend notexist $d
	    }
	} else {
	    lappend doesexist $d
	    set fsize($d) $filesize($fname)
	    set fmtime($d) $filetime($fname)
	    foreach d2 $dirs {
		if {$d2 == $d} break
		if {$sameas($d2) != "" || $group($d2) == 0} continue
		if {$fsize($d) == $fsize($d2) \
			&& $fmtime($d) == $fmtime($d2)} {
		    set notsame 0
		} elseif {$rcsflag != "" || $fsize($d) == $fsize($d2)} {
		    set fname2 [joinname $d2 [string trimright $f /]]
		    if $nofilecmp {
			set notsame [catch {exec cmp -s $fname $fname2}]
		    } else {
			set same 0
			catch {
			    set same [eval filecmp $rcsflag $fname $fname2]
			}
			set notsame [expr !$same]
		    }
		} else {
		    set notsame 1
		}
		if {$notsame == 0} {
		    set sameas($d) $d2
		    set g $group($d2)
		    set group($d) $g
		    lappend groupelts($g) $d
		    if {$fmtime($d) > $gmtime($g)} {
			set gmtime($g) $fmtime($d)
		    }
		    break
		}
	    }
	    if {$sameas($d) == ""} {
		incr numgroups
		set group($d) $numgroups
		set groupelts($numgroups) $d
		set gmtime($numgroups) $fmtime($d)
	    }
	}
    }
    if {!$showsame && $numgroups == 1 && $notexist == ""} {
	return {}
    }
    set glist {}
    for {set g 1} {$g <= $numgroups} {incr g} {
	lappend glist [list [format "%.8x" $gmtime($g)] $g]
    }
    set grank(0) 0
    set rank 1
    foreach xx [lsort -decreasing $glist] {
	set g [lindex $xx 1]
	set grank($g) $rank
	incr rank
    }
    set res {}
    foreach d $dirs {
	lappend res $grank($group($d))
    }
    return [list $numgroups $res]
}

proc subdirgroups {sd} {
    global dirs
    set nummiss 0
    set groups {}
    foreach d $dirs {
	set fn [joinname $d $sd]
	if {![fileisa $fn "directory"]} {
	    set pd [file dirname $sd]
	    lappend groups 0
	    set fnp [joinname $d $pd]
	    if {$pd == "." || [fileisa $fnp "directory"]} {
		incr nummiss
	    }
	} else {
	    lappend groups 1
	}
    }
    if {$nummiss == 0} {
	return {}
    }
    return [list dir $groups]
}

set stringx 8

proc initcanv {} {
    global canvw canvx canvy canvy0 linespc stringx ruletype
    global dirs arroww blotspc blotw ycoord filelistfont
    $canvw delete all
    $canvw yview moveto 0
    $canvw conf -scrollregion {0 0 0 1}
    catch {unset ycoord}
    catch {unset ruletype}
    set canvy $canvy0
    if {![info exists arroww]} {
	set stringx [expr $blotspc + 8]
	return
    }
    set numdirs [llength $dirs]
    set stringx [expr $numdirs * $blotspc + 8]
    $arroww delete all
    set arrowh [expr ($numdirs+1) * $linespc]
    $arroww conf -height $arrowh
    set y 0
    set yoff [expr $linespc / 2]
    set x [expr $canvx + 3 + ($blotw / 2)]
    set x2 [expr $stringx - 3]
    set horiz [expr $arrowh + 2]
    foreach d $dirs {
	set y2 [expr $y + $yoff]
	set t [$arroww create line $x $horiz $x $y2 $x2 $y2 \
		-width 2 -arrow first]
	$arroww addtag arrows withtag $t
	set t [$arroww create text $stringx $y -text $d -anchor nw \
		   -font $filelistfont]
	$arroww addtag strings withtag $t
	incr y $linespc
	incr x $blotspc
    }
    
    set dx [expr [$arroww cget -width] / 2]
    set dy [expr $horiz - 1]
    $arroww create text $dx $dy -text "Older <- " -anchor se
    $arroww create image $dx $dy -image paper_red -anchor sw
    incr dx $blotspc
    $arroww create image $dx $dy -image paper_orange -anchor sw
    incr dx $blotspc
    $arroww create image $dx $dy -image paper_yellow -anchor sw
    incr dx $blotspc
    $arroww create image $dx $dy -image paper_yellowgreen -anchor sw
    incr dx $blotspc
    $arroww create image $dx $dy -image paper_green -anchor sw
    incr dx $blotspc
    $arroww create text $dx $dy -text " -> Newer" -anchor sw
}

proc addcline {blots str} {
    global canvy canvx linespc stringx blotw bloth blotspc canvw ycoord
    global filelistfont
    set x [expr $canvx+1]
    set y [expr $canvy+1]
    foreach b $blots {
	set t [$canvw create image $x $y -image $b -anchor nw]
	$canvw addtag blots withtag $t
	incr x $blotspc
    }
    set t [$canvw create text $stringx $canvy -anchor nw -text $str \
	      -font $filelistfont]
    $canvw addtag strings withtag $t
    set ycoord($str) $canvy
    incr canvy $linespc
    set vis [lindex [$canvw yview] 1]
    $canvw conf -scrollregion "0 0 0 $canvy"
    if {$vis >= 1.0} {
	$canvw yview moveto 1
    }
}

proc displine {groups name} {
    global agecolors
    set ng [lindex $groups 0]
    set cols $agecolors($ng)
    set blots {}
    foreach g [lindex $groups 1] {
	lappend blots [lindex $cols $g]
    }
    addcline $blots $name
}

proc dispfilelines {groups} {
    global agecolors dirs
    set ng [lindex $groups 0]
    set cols $agecolors($ng)
    set n 0
    foreach g [lindex $groups 1] {
	addcline [lindex $cols $g] [lindex $dirs $n]
	incr n
    }
}

proc ruleoff {stopped} {
    global canvw canvy linespc ruletype
    set y [expr $canvy + $linespc/2]
    set color black
    if {$stopped} {set color red}
    $canvw create line 0 $y [$canvw cget -width] $y -width 2 -fill $color
    incr canvy $linespc
    set vis [lindex [$canvw yview] 1]
    $canvw conf -scrollregion "0 0 0 $canvy"
    if {$vis >= 1.0} {
	$canvw yview moveto 1
    }
    set ruletype $stopped
}

proc updatecline {si di f} {
    global ycoord canvw blotspc bloth blotw groups
    global filemode dirs changed
    if {$filemode} {
	set fs [lindex $dirs $si]
	set fd [lindex $dirs $di]
	if {![info exists ycoord($fs)] || ![info exists ycoord($fd)]} return
	set ys [expr $ycoord($fs) + 2]
	set yd [expr $ycoord($fd) + 2]
	set xs 2
	set xd 2
    } else {
	if {![info exists ycoord($f)]} return
	set ys [expr $ycoord($f) + 2]
	set yd $ys
	set xs [expr $si * $blotspc + 2]
	set xd [expr $di * $blotspc + 2]
    }
    set ts [$canvw find overlapping $xs $ys \
	    [expr $xs+$blotw-2] [expr $ys+$bloth-2]]
    set td [$canvw find overlapping $xd $yd \
	    [expr $xd+$blotw-2] [expr $yd+$bloth-2]]
    if {$ts != "" && $td != ""} {
	$canvw itemconf $td -image [$canvw itemcget $ts -image]
        set changed 1
    }
    set ng [lindex $groups($f) 0]
    set g [lindex $groups($f) 1]
    set groups($f) [list $ng [lreplace $g $di $di [lindex $g $si]]]
}

proc refreshcline {f} {
    global ycoord canvw blotspc bloth blotw groups
    global agecolors changed
    if {![info exists ycoord($f)]} return
    set y [expr $ycoord($f) + 2]
    set ng [lindex $groups($f) 0]
    set cols $agecolors($ng)
    set x 2
    foreach g [lindex $groups($f) 1] {
	set t [$canvw find overlapping $x $y \
		[expr $x+$blotw-2] [expr $y+$bloth-2]]
	if {$t != ""} {
	    $canvw itemconf $t -image [lindex $cols $g]
            set changed 1
	}
	incr x $blotspc
    }
}

proc makepatchmenu {base} {
    global dirs
    menu $base.p -tearoff 0
    set sub1 0
    foreach d1 $dirs {
	set any 0
	incr sub1
	menu $base.p.$sub1 -tearoff 0
	foreach d2 $dirs {
	    if {$d1 == $d2} continue
	    set any 1
	    $base.p.$sub1 add command -label "$d2" \
		    -command [list makepatch $d1 $d2]
	}
	if {$any} {
	    $base.p add cascade -label "$d1 ->" -menu $base.p.$sub1
	}
	incr sub1
    }
    $base add cascade -label "Make patch" -menu $base.p
}

proc maketouchmenu {base} {
    global dirs dirreadonly
    menu $base.t -tearoff 0
    set i 0
    foreach d $dirs {
	if {!$dirreadonly($i)} {
	    $base.t add command -label $d -command [list touchfiles $d]
	}
	incr i
    }
    $base add cascade -label "Touch" -menu $base.t
}

proc readonlychange {i} {
    global dirreadonly
    .bar.file.t entryconf $i \
	-state [expr {$dirreadonly($i)? "disabled": "normal"}]
    selcurfile
}

proc makewins {} {
    global canvw numlines linespc arroww diffbut copybut filelabel nofilecmp
    global filemode dirs dirinterest filelistfont dirreadonly
    global rcsflag diffiflag diffwflag diffbflag diffBflag diffdflag
    global bgcolors

    set i 0
    foreach d $dirs {
	set dirreadonly($i) 0
	incr i
    }

    # Native-style menubar
    menu .bar
    .bar add cascade -label "File" -menu .bar.file

    # File menu
    menu .bar.file
    .bar.file add command -label "Rediff" -command rediff
    if {!$filemode} {
	.bar.file add command -label "Redisplay" -command "redisplay 1"
    }
    set menubg [lindex [.bar.file configure -background] 4]
    set bgcolors(1) [list $menubg $menubg]
    set bgcolors(2) [list $menubg green "#ff8080"]
    set bgcolors(3) [list $menubg green yellow "#ff8080"]
    set bgcolors(4) [list $menubg green yellow orange "#ff8080"]
    set bgcolors(5) [list $menubg green "#e0ff90" yellow orange "#ff8080"]

    makepatchmenu .bar.file
    maketouchmenu .bar.file
    .bar.file add command -label "Exclude selection" -command exclsel
    .bar.file add command -label "Stop" -command "set stopped 1"
    .bar.file add separator
    .bar.file add command -label "Quit" -command "set stopped 1; destroy ."

    # Diff menu
    set diffbut .bar.diff
    menu $diffbut
    .bar add cascade -label "Diff" -menu $diffbut
    $diffbut add command -label "All" -command difffiles

    # Copy menu
    set copybut .bar.copy
    menu $copybut
    .bar add cascade -label "Copy/Del" -menu $copybut

    # Options menu
    menu .bar.options
    .bar add cascade -label "Options" -menu .bar.options

    .bar.options add radiobutton -label "Literal comparison" \
	    -variable rcsflag -value " " \
	    -state [expr {$nofilecmp? "disabled": "normal"}]
    .bar.options add radiobutton -label "Ignore differences in RCS strings" \
	    -variable rcsflag -value "-rcs" \
	    -state [expr {$nofilecmp? "disabled": "normal"}]
    .bar.options add checkbutton -label "Show files that are identical" \
	    -variable showsame

    .bar.options add checkbutton -label "Redisplay immediately" \
	    -variable redisp_immed
    .bar.options add checkbutton -label "Show files that aren't in some dirs" \
	    -variable nxdirmode
    .bar.options add checkbutton -label "Ignore files in .cvsignore" \
	    -variable docvsignore
    .bar.options add command -label "Excluded files..." -command exclfilelist
    .bar.options add command -label "Diff options..." -command diffoptions
    .bar.options add command -label "External viewers..." -command extprograms
    .bar.options add command -label "Save options" -command saveoptions

    .bar.options add separator
    set i 0
    foreach d $dirs {
	set dirinterest($i) 1
	.bar.options add checkbutton -label "Show $d" \
		-variable dirinterest($i) -command redisplay
	incr i
    }

    .bar.options add separator
    set i 0
    foreach d $dirs {
	.bar.options add checkbutton -label "Read-only $d" \
		-variable dirreadonly($i) -command [list readonlychange $i]
	incr i
    }

    # Help menu
    menu .bar.help
    .bar add cascade -label "Help" -menu .bar.help
    .bar.help add command -label "About dirdiff" -command about
    .bar.help add command -label "About diff" -command about_diff
    .bar.help add command -label "Show help text" -command helptext

    . configure -menu .bar

    # make the filename display bar
    if {!$filemode} {
	frame .file -relief sunk -bd 1
	set filelabel .file.name
	#label $filelabel -relief flat -padx 7 -text "File: "
	label $filelabel -relief flat -padx 7 -image paper
        set fileentry .file.ent
        entry $fileentry -relief sunk -bd 1 -textvariable selfile \
               -font $filelistfont
	pack $filelabel -side left
	pack $fileentry -side left -fill x -expand yes
	pack .file -side top -fill x
    }

    # make the frame containing the 2 canvases (one for the top section
    # containing the directory names, one for the files) and the scrollbar
    # in file mode the top section is omitted
    frame .cf
    if {$filemode} {
	set numlines [llength $dirs]
    }
    canvas .cf.c -height [expr $numlines * $linespc] \
	    -yscrollincr $linespc -yscrollcommand ".csb set" \
            -bg white -relief sunk -bd 1
    set canvw .cf.c
    if {!$filemode} {
	canvas .cf.d -height [expr 3 * $linespc] \
               -relief flat -bd 1 -highlightthickness 0
	set arroww .cf.d
	pack .cf.d -side top -fill x
    }
    pack .cf.c -side bottom -fill both -expand 1
    scrollbar .csb -command "$canvw yview" -highlightthickness 0
    pack .csb -side right -fill y
    pack .cf -side left -fill both -expand 1

    if {!$filemode} {
	bind $fileentry <Return> "search_canvas"
    }
    # set up event bindings on the main canvas
    bind $canvw <1> {selcanvline %x %y 0}
    bind $canvw <Shift-1> {selcanvline %x %y 1}
    bind $canvw <B1-Motion> {selcanvline %x %y 2}
    bind $canvw <Control-1> {selcanvline %x %y 3}
    # This caused selcurfile to always be done twice
    #bind $canvw <ButtonRelease-1> {selcurfile}
    bind $canvw <ButtonRelease-4> "$canvw yview scroll -5 u"
    bind $canvw <ButtonRelease-5> "$canvw yview scroll 5 u"
    bind $canvw <2> "$canvw scan mark 0 %y"
    bind $canvw <B2-Motion> "$canvw scan dragto 0 %y"
    bind $canvw <Double-Button-1> "set doubleclick 1; showsomediff 0"
    bind $canvw <Key-Return> "showsomediff 0"
    $canvw conf -scrollregion {0 0 0 1}
    if {!$filemode} {
	bind . N "diffnextfile 1"
	bind . P "diffnextfile -1"
    }
    bind . C copydifffile
    bind . <Key-Return> "showsomediff 0"
    bind . <Key-Prior> "$canvw yview scroll -1 p"
    bind . <Key-Next> "$canvw yview scroll 1 p"
    bind . <Key-Delete> "$canvw yview scroll -1 p"
    bind . <Key-BackSpace> "$canvw yview scroll -1 p"
    bind . <Key-space> "$canvw yview scroll 1 p"
    bind . <Key-Up> "$canvw yview scroll -1 u"
    bind . <Key-Down> "$canvw yview scroll 1 u"
    bind . Q "set stopped 1; destroy ."
    # Need a way to unselect all
    bind . <Escape> resetsel

}

proc about {} {
    set w .about
    if {[winfo exists $w]} {
	raise $w
	return
    }
    toplevel $w
    wm title $w "About dirdiff"
    message $w.m -text {
Dirdiff version 2.1

Copyright © 1999-2005 Paul Mackerras

Use and redistribute under the terms of the GNU General Public License

(CVS $Revision: 1.70 $)} \
	    -justify center -aspect 400
    pack $w.m -side top -fill x -padx 20 -pady 20
    button $w.ok -text Close -command "destroy $w"
    pack $w.ok -side bottom
}

proc about_diff {} {
    set w .about_diff
    if {[winfo exists $w]} {
	raise $w
	return
    }
    toplevel $w
    wm title $w "About diff"
    set retval [catch "exec diff -v" err]
    message $w.m -text $err -justify center -aspect 600
    pack $w.m -side top -fill x -padx 20 -pady 20
    if {$retval == 0} {
       text $w.t -bg white -yscrollcommand "$w.sb set" -wrap word
       scrollbar $w.sb -command "$w.t yview"
       pack $w.sb -side right -fill y
       pack $w.t -side left -fill both -expand 1
       set fdh [open "|diff --help" r]
       while { [eof $fdh] == 0 } {
          $w.t insert end "[gets $fdh]\n"
       }
       pack $w.t -side top -fill both -expand yes
    }
    button $w.ok -text Close -command "destroy $w"
    pack $w.ok -side bottom
}

proc helptext {} {
    set w .help
    if {[winfo exists $w]} {
	raise $w
	return
    }
    toplevel $w
    wm title $w "Dirdiff help"
    text $w.t -font {Times -14} -yscrollcommand "$w.sb set" -wrap word
    scrollbar $w.sb -command "$w.t yview"
    pack $w.sb -side right -fill y
    pack $w.t -side left -fill both -expand 1
    bind $w <Key-Prior> "$w.t yview scroll -1 p"
    bind $w <Key-BackSpace> "$w.t yview scroll -1 p"
    bind $w <Key-Delete> "$w.t yview scroll -1 p"
    bind $w b "$w.t yview scroll -1 p"
    bind $w B "$w.t yview scroll -1 p"
    bind $w <Key-Up> "$w.t yview scroll -1 u"
    bind $w <Key-Down> "$w.t yview scroll 1 u"
    bind $w d "$w.t yview scroll \[expr \"int(\[$w.t cget -height\]/2)\"\] u"
    bind $w D "$w.t yview scroll \[expr \"int(\[$w.t cget -height\]/2)\"\] u"
    bind $w u "$w.t yview scroll \[expr \"int(-\[$w.t cget -height\]/2)\"\] u"
    bind $w U "$w.t yview scroll \[expr \"int(-\[$w.t cget -height\]/2)\"\] u"
    bind $w q "destroy $w"
    bind $w Q "destroy $w"
    $w.t insert end {Dirdiff instructions.

Dirdiff compares all the files in up to five directories.  There is one \
column in the main window for each directory.

Each file is shown with a coloured square indicating its status.  Files \
are like leaves on a deciduous tree: the newest ones are green, and then \
they turn yellow, orange, and red as they get older.

Double-click a file to show differences between two versions.  By default, \
the first and last versions are compared, but this can be changed by the \
'Diff' menu in the main window.  

You can select several files to copy or to make a patch by shift-clicking.

You can search for a file by typing part of its name in the entry and \
pressing the <Return> key.

In the diff window, check the boxes on the left margin for changes you \
want to preserve, and then choose 'Merge' to move those changes into one \
of the files.  Alternatively, choose 'Copy' in the main window to copy \
across the whole file, replacing any changes.

'Make patch' produces a file describing the changes between the files that \
can be applied by the patch tool.  You can edit the patch before saving, \
and may wish to add explanatory text, instructions, or patch(1) Prereq \
lines at the beginning.  To save the patch, enter a filename in the patch \
window relative to the current directory, and choose 'Save'.  This will \
also close the window.

If you are sending out patches, then the "from" directory should be the \
original version of the source.  Try to make sure that the two files have \
the same number of leading directories.  See the patch(1) man page for \
more information.
    }

    $w.t conf -state disabled
}

proc filediffs {} {
    global groups selitem fserial
    updatefileinfo .
    set groups(.) [set gr [diffages . 1 1]]
    set fserial(.) 1
    dispfilelines $gr
    clearsecsel
    selcurfile
}

proc diffsin {sd maxdepth} {
    global groups stopped showsame alllines nxdirmode
    foreach f [addfiles $sd] {
	if {$stopped} return
	lappend alllines $f
	set d [string trimright $f /]
	if {$d == $f || $maxdepth <= 0} {
	    set groups($f) [set gr [diffages $f $showsame $maxdepth]]
	    if [interesting_line $gr] {
		displine $gr $f
	    }
	} else {
	    set groups($f) [set gr [subdirgroups $d]]
	    if {$nxdirmode == 0 && [interesting_line $gr]} {
		displine $gr $f
	    }
	    diffsin $f [expr $maxdepth-1]
	}
	catch update
    }
}

proc canvdiffs {} {
    global canvw groups stopped filemode alllines
    global filetype filetime filesize maxdepth
    set stopped 0
    set alllines {}
    catch {unset filetype}
    catch {unset filetime}
    catch {unset filesize}
    initcanv
    if {$filemode} {
	filediffs
    } else {
	diffsin {} $maxdepth
	if {[catch update]} return
	ruleoff $stopped
    }
    if {[catch update]} return
    if {[lindex [$canvw yview] 1] >= 1.0} {
	$canvw yview moveto 0
    }
}

proc textitemat {x y} {
    global canvw
    foreach i [$canvw find overlapping $x $y [expr $x+50] $y] {
	if {[$canvw type $i] == "text"} {
	    return $i
	}
    }
    return {}
}

proc itemofname {f} {
    global stringx ycoord linespc
    if {![info exists ycoord($f)]} {
	return {}
    }
    return [textitemat [expr {$stringx+5}] [expr {$ycoord($f) + $linespc/2}]]
}

proc addtobbox {bbox x y} {
    set x0 [lindex $bbox 0]
    set y0 [lindex $bbox 1]
    set x1 [lindex $bbox 2]
    set y1 [lindex $bbox 3]
    if {$x < $x0} {set x0 $x}
    if {$y < $y0} {set y0 $y}
    if {$x > $x1} {set x1 $x}
    if {$x > $y1} {set y1 $y}
    return [list $x0 $y0 $x1 $y1]
}

proc selcanvline {x y tipe} {
    global canvw stringx selitem secsel clickitem groups selfile clickmode
    global filemode doubleclick clicky
    if {$filemode} return
    set x [expr $stringx+5]
    set y [$canvw canvasy $y]
    set it [textitemat $x $y]
    if {$it == {}} return
    if {$tipe == 0} {
	# click, no shift
	clearsecsel
	selectitem $it
	set clickitem $it
	set clicky $y
	set clickmode 1
	selcurfile
	addsecsel $it
	set doubleclick 0
    } elseif {$tipe == 1} {
	# shift-click
	set clickitem $it
	set clicky $y
	if {$it != $selitem} {
	    if {![info exists secsel($it)]} {
		set clickmode 1
		addsecsel $it
	    } else {
		set clickmode 0
		remsecsel $it
	    }
	}
	set doubleclick 0
    } elseif {$tipe == 2 || $tipe == 3} {
	# motion with button 1 down
	if {$tipe == 2 && [info exists doubleclick] && $doubleclick} return
	if {![info exists clickitem]} return
	foreach i [$canvw find overlapping \
		       $x [expr {$y < $clicky? $y: $clicky}] \
		       [expr $x+50] [expr {$y > $clicky? $y: $clicky}]] {
	    if {[$canvw type $i] == "text"} {
		set f [$canvw itemcget $i -text]
		if {$groups($f) == $groups($selfile)} {
		    if {$clickmode && ![info exists secsel($i)]} {
			addsecsel $i
		    } elseif {!$clickmode && [info exists secsel($i)]} {
			remsecsel $i
		    }
		}
	    }
	}
    }
}

proc selectitem {it} {
    global selitem canvw
    set selitem $it
    $canvw select from $it 0
    $canvw select to $it end
}

proc addsecsel {it} {
    global canvw secsel
    set t [eval $canvw create rect [$canvw bbox $it] -outline {{}} \
	    -tags secsel -fill [$canvw cget -selectbackground]]
    $canvw lower $t
    set secsel($it) $t
}

proc remsecsel {it} {
    global canvw secsel
    $canvw delete $secsel($it)
    unset secsel($it)
}

proc clearsecsel {} {
    global canvw secsel
    $canvw delete secsel
    catch {unset secsel}
}

proc selnextline {inc} {
    global canvw selitem linespc stringx canvy filemode
    if {$filemode} {
	if {$inc != 0} {
	    return 0
	}
	selcurfile
	return 1
    }
    if {$selitem == ""} {
	return 0
    }
    set y [expr [lindex [$canvw bbox $selitem] 1] + $linespc * $inc + 5]
    set x [expr $stringx+5]
    set i [textitemat $x $y]
    if {$i == ""} {
	return 0
    }
    clearsecsel
    selectitem $i
    set bbox [$canvw bbox $i]
    set y [expr {([lindex $bbox 1] + [lindex $bbox 3]) / 2.0}]
    if {$canvy > 0} {
	set ytop [expr {($y - $linespc / 2.0) / $canvy}]
	set ybot [expr {($y + $linespc / 2.0) / $canvy}]
	set wnow [$canvw yview]
	if {$ytop < [lindex $wnow 0]} {
	    $canvw yview moveto $ytop
	} elseif {$ybot > [lindex $wnow 1]} {
	    set wh [expr {[lindex $wnow 1] - [lindex $wnow 0]}]
	    $canvw yview moveto [expr {$ybot - $wh}]
	}
    } else {
	$canvw yview moveto 0
    }
    selcurfile
    addsecsel $i
    return 1
}

proc calcgroupelts {f} {
    global groupelts numgroups groups
    set gr $groups($f)
    set numgroups [lindex $gr 0]
    if {$numgroups == "dir"} {
	set numgroups 1
    }
    set gr [lindex $gr 1]
    for {set g 0} {$g <= $numgroups} {incr g} {
	set groupelts($g) {}
    }
    set i 0
    foreach g $gr {
	lappend groupelts($g) $i
	incr i
    }
}

proc selcurfile {} {
    global canvw selitem filelabel selfile groups filemode
    global groupelts diffbut copybut numgroups
    if {!$filemode} {
	if {$selitem == ""} return
	set selfile [$canvw itemcget $selitem -text]
    } else {
	set selfile .
    }
    calcgroupelts $selfile
    set x [string trimright $selfile /]
    if {$x == $selfile} {
	if {[info exists filelabel]} {
	    $filelabel conf -image paper
	}
	confdiffbut 0
	confcopybutfile
    } else {
	if {[info exists filelabel]} {
	    $filelabel conf -image folder
	}
	confdiffbut 1
	confcopybutdir
    }
}

proc mkdiffimage {gn go} {
    global numgroups agecolors
    set cols $agecolors($numgroups)
    set i1 [lindex $cols $go]
    set i2 [lindex $cols $gn]
    set iname "icon-$i1-$i2"
    if {![info exists $iname]} {
	set w1 [image width $i1]
	set w2 [image width $i2]
	set h [image height $i1]
	image create photo $iname -width [expr {$w1+$w2}] -height $h
	$iname copy $i1
	$iname copy $i2 -to $w1 0
    }
    return $iname
}

proc confdiffbut {isdir} {
    global diffbut numgroups dirs selfile groupelts filemode
    global groups agecolors bgcolors compound_ok
    $diffbut delete 0 end
    destroy [winfo children $diffbut]
    set ng [lindex $groups($selfile) 0]

    if {$isdir} {
	# do nothing
    } elseif {$numgroups == 1} {
	set xi [lindex $groupelts(1) 0]
	if {$xi != ""} {
	    set x [lindex $dirs $xi]
	    $diffbut add command -label "Show $x" \
		    -command [list showfile $x $selfile]
	}
    } elseif {$numgroups > 1} {
	if {$numgroups > 2} {
	    set x {}
	    for {set gn 1} {$gn <= $numgroups} {incr gn} {
		set i [lindex $groupelts($gn) 0]
		lappend x [lindex $dirs $i]
	    }
	    $diffbut add command -label "$numgroups-way diff" \
		-command [list diffn $x $selfile]
	}
	for {set gn 1} {$gn < $numgroups} {incr gn} {
	    set yi [lindex $groupelts($gn) 0]
	    if {$yi == ""} continue

            set age [lindex [lindex $groups($selfile) 1] $yi]
            set im [lindex $agecolors($ng) $age]
            set cl [lindex $bgcolors($ng) $age]
	    set y [lindex $dirs $yi]
            if {[winfo exists $diffbut.$gn]} {destroy $diffbut.$gn}
            menu $diffbut.$gn -tearoff 0
            set any 0
	    for {set go [expr $gn+1]} {$go <= $numgroups} {incr go} {
		set xi [lindex $groupelts($go) 0]
                set age [lindex [lindex $groups($selfile) 1] $xi]
                set im2 [lindex $agecolors($ng) $age]
                set cl2 [lindex $bgcolors($ng) $age]
		set xi [lindex $groupelts($go) 0]
		if {$xi == ""} continue
		set x [lindex $dirs $xi]
		set cmd [list diff2 $x $y $selfile]
		if {$numgroups <= 3} {
		    if {$compound_ok} {
			$diffbut add command -label "$x vs. $y" \
			    -command $cmd \
			    -image [mkdiffimage $gn $go] \
			    -compound left
		    } else {
			$diffbut add command -label "$x vs. $y" \
			    -command $cmd
		    }
		} else {
		    incr any
		    if {$compound_ok} {
			$diffbut.$gn add command -label "$x" \
			    -image $im2 -compound left \
			    -command $cmd
		    } else {
			$diffbut.$gn add command -label "$x" \
			    -background $cl2 \
			    -command $cmd
		    }
		}
	    }
	    if {$any} {
                if {$compound_ok} {
	            $diffbut add cascade -label "$y vs. ..." \
                       -image $im -compound left \
		       -menu $diffbut.$gn
	        } else {
	            $diffbut add cascade -label "$y vs. ..." \
                       -background $cl \
		       -menu $diffbut.$gn
                }
            }
        }
    }
    if {!$filemode} {
	$diffbut add separator
	$diffbut add command -label "Rediff selected file(s)" \
		-command "redifffiles"
    }
    .bar entryconfigure 2 -state normal
}

proc mkcopyimage {i1 i2} {
    if {$i1 == ""} {
	return $i2
    }
    if {$i2 == ""} {
	return $i1
    }
    set iname "icon-$i1-$i2"
    if {![info exists $iname]} {
	set w1 [image width $i1]
	set w2 [image width $i2]
	set h [image height $i1]
	image create photo $iname -width [expr {$w1+$w2}] -height $h
	$iname copy $i1
	$iname copy $i2 -to $w1 0
    }
    return $iname
}

proc confcopybutfile {} {
    global copybut groupelts numgroups selfile dirs
    global groups agecolors bgcolors compound_ok dirreadonly
    $copybut delete 0 end
    destroy [winfo children $copybut]
    set numdirs [llength $dirs]
    set srcs {}
    set rev {}
    set ng [lindex $groups($selfile) 0]

    for {set gn 1} {$gn <= $numgroups} {incr gn} {
	set srcs [concat $srcs $groupelts($gn)]
	set src [lindex $groupelts($gn) 0]
	if {$src == ""} continue
        set age [lindex [lindex $groups($selfile) 1] $src]
        set im [lindex $agecolors($ng) $age]
        set cl [lindex $bgcolors($ng) $age]

	set x [lindex $dirs $src]
        if {[winfo exists $copybut.new2old$src]} {destroy $copybut.new2old$src}
	menu $copybut.new2old$src -tearoff 0
        set dsts {}
	for {set dst 0} {$dst < $numdirs} {incr dst} {
	    if {!$dirreadonly($dst) && [lsearch $srcs $dst] < 0} {
                lappend dsts $dst
	    }
	}
	set any [llength $dsts]
        if {$any} {
	    foreach dst $dsts {
                set age [lindex [lindex $groups($selfile) 1] $dst]
                set im2 [lindex $agecolors($ng) $age]
                set cl2 [lindex $bgcolors($ng) $age]
                if {$im2 == "ex"} {set im2 ""}
		set y [lindex $dirs $dst]
		set cmd [list copyselfile $src $dst $selfile 0]
		if {$any == 1} {
		    if {$compound_ok} {
			$copybut add command -label "$x -> $y" \
			    -command $cmd -image [mkcopyimage $im $im2] \
			    -compound left
		    } else {
			$copybut add command -label "$x -> $y" \
			    -command $cmd
		    }
		} elseif {$compound_ok} {
		    $copybut.new2old$src add command -label "$y" \
                        -image $im2 -compound left \
			-command $cmd
                } else {
		    $copybut.new2old$src add command -label "$y" \
                        -background $cl2 \
			-command $cmd
                }
	    }
	    if {$any > 1} {
		if {$compound_ok} {
		    $copybut add cascade -label "$x ->" \
			-image $im -compound left \
			-menu $copybut.new2old$src
		} else {
		    $copybut add cascade -label "$x ->" \
			-background $cl \
			-menu $copybut.new2old$src
		}
	    }
        }
    }
    set needsep 1
    for {set gn $numgroups} {$gn >= 1} {incr gn -1} {
	set src [lindex $groupelts($gn) 0]
	if {$src == ""} continue

        set age [lindex [lindex $groups($selfile) 1] $src]
        set im [lindex $agecolors($ng) $age]
        set cl [lindex $bgcolors($ng) $age]
	set x [lindex $dirs $src]
        if {[winfo exists $copybut.old2new$src]} {destroy $copybut.old2new$src}
	menu $copybut.old2new$src -tearoff 0
	set dsts {}
	for {set gd 1} {$gd < $gn} {incr gd} {
	    foreach dst $groupelts($gd) {
		if {!$dirreadonly($dst)} {
		    lappend dsts $dst
		}
	    }
	}
        set any [llength $dsts]
	if {$any} {
	    if $needsep {
		$copybut add separator
		set needsep 0
	    }
	    foreach dst $dsts {
                set age [lindex [lindex $groups($selfile) 1] $dst]
                set im2 [lindex $agecolors($ng) $age]
                set cl2 [lindex $bgcolors($ng) $age]
		set y [lindex $dirs $dst]
		set cmd [list copyselfile $src $dst $selfile 1]
		if {$any == 1} {
		    if {$compound_ok} {
			$copybut add command -label "$x -> $y" \
			    -command $cmd -image [mkcopyimage $im $im2] \
			    -compound left
		    } else {
			$copybut add command -label "$x -> $y" \
			    -command $cmd
		    }
		} elseif {$compound_ok} {
		    $copybut.old2new$src add command -label "$y" \
                        -image $im2 -compound left \
			-command $cmd
                } else {
		    $copybut.old2new$src add command -label "$y" \
                        -background $cl2 \
			-command $cmd
                }
	    }
	}
        if {$any > 1} {
            if {$compound_ok} {
	        $copybut add cascade -label "$x ->" \
                    -image $im -compound left \
                    -menu $copybut.old2new$src
            } else {
	        $copybut add cascade -label "$x ->" \
                    -background $cl \
                    -menu $copybut.old2new$src
            }
        }
    }
    if {$groupelts(0) != {}} {
	set needsep 1
	for {set gn 1} {$gn <= $numgroups} {incr gn} {
	    foreach dst $groupelts($gn) {
		if {$dirreadonly($dst)} continue
		set x [lindex $dirs $dst]
		if $needsep {
		    $copybut add separator
		    set needsep 0
		}
                if {$compound_ok} {
		    $copybut add command -label "Remove from $x" \
                        -image ex -compound left \
			-command [list removeselfile $dst $selfile]
                } else {
		    $copybut add command -label "Remove from $x" \
			-command [list removeselfile $dst $selfile]
                }
	    }
	}
    }
    .bar entryconfigure 3 -state normal
}

proc confcopybutdir {} {
    global copybut groupelts selfile dirs compound_ok dirreadonly
    $copybut delete 0 end
    set srcs $groupelts(1)
    set dsts $groupelts(0)
    if {$srcs != {} && $dsts != {}} {
	foreach s $srcs {
	    set x [lindex $dirs $s]
	    foreach d $dsts {
		if {$dirreadonly($d)} continue
		set y [lindex $dirs $d]
		$copybut add command -label "$x -> $y" \
			-command [list copyselfile $s $d $selfile 0]
	    }
	}
	set needsep 1
	foreach s $srcs {
	    if {$dirreadonly($s)} continue
	    set x [lindex $dirs $s]
	    if {$needsep} {
		$copybut add separator
		set needsep 0
	    }
            if {$compound_ok} {
	        $copybut add command -label "Remove from $x" \
                    -image ex -compound left \
		    -command [list removeselfile $s $selfile]
            } else {
	        $copybut add command -label "Remove from $x" \
		    -command [list removeselfile $s $selfile]
            }
	}
    }
    .bar entryconfigure 3 -state normal
}

proc resetsel {} {
    global selitem selfile filelabel diffbut copybut
    global canvw
    set selitem {}
    set selfile {}
    $canvw select clear
    if {[info exists filelabel]} {
	$filelabel conf -image paper
    }
    .bar entryconfigure 2 -state disabled
    .bar entryconfigure 3 -state disabled
    clearsecsel
}

proc removediffs {} {
    global texttop textw diffing difff
    catch {destroy $texttop}
    catch {unset texttop}
    catch {unset textw}
    catch {close $difff}
    set diffing 0
}

proc showfile {d f} {
    global showprogram incline

    set fn [joinname $d $f]

    # Show the file in an external viewer
    if { [llength $showprogram] > 0} {
       exec $showprogram $fn &
       return
    }
    # Or make our own viewer
    global textw texttop mergebut
    if {!([info exists textw] && [winfo exists $textw])} {
	maketextw
    } else {
	raise $texttop
    }
    wm title $texttop "Contents of $fn"
    $mergebut.m delete 0 end
    $textw conf -state normal -tabs {}
    $textw delete 0.0 end
    set nl {}
    set f [open $fn r]
    set n [gets $f line]
    while {$n >= 0} {
	$textw insert end "$nl$line"
	set nl "\n"
	set n [gets $f line]
    }
    close $f
    $textw conf -state disabled
    bind $textw <1> {}
    bind $textw <Shift-Button-1> {}
    bind $textw <B1-Motion> {}
    bind $textw <ButtonRelease-1> {}
    bind $textw <B1-Leave> {}
    bind $textw <B1-Enter> {}
    bind $textw <2> {}
    bind $textw <B2-Motion> {}
    bind $textw <ButtonRelease-2> {}
    bind $textw <Any-Button-3> {}
    catch {unset incline}
}

proc redifffiles {} {
    global groups showsame selfile rediffed groups filemode
    if {$filemode} {
	resetsel
	canvdiffs
	return
    }
    if {$selfile == {}} return
    set files [secondarysel $selfile]
    foreach f $files {
	updatefileinfo $f
	set d [string trimright $f /]
	if {[lindex $groups($f) 0] != "dir"} {
	    set groups($f) [diffages $f 1 0]
	} else {
	    set groups($f) [subdirgroups $d]
	}
	refreshcline $f
    }
    selcurfile
    set rediffed $selfile
}

proc diff2 {d1 d2 f {orig 1}} {
    global diffprogram nullfile

    global textw groups dirs numgroups bgcolors selfile texttop
    global difff lno diffdirs diffiflag diffwflag diffbflag diffBflag diffdflag
    global ctxlines difffile charwidth mergebut diffcolors
    global diffing filemode rediffed diffnewfirst underlinetabs
    global nextlix diffndirs allf origdiffdirs difftabs
    set diffndirs 2
    set difftabs ""
    set allf {0 1}
    set group [lindex $groups($selfile) 1]
    set i1 [lindex $group [lsearch $dirs $d1]]
    set i2 [lindex $group [lsearch $dirs $d2]]
    if {($i1 > $i2) == $diffnewfirst} {
	set x $d1
	set d1 $d2
	set d2 $x
	set x $i1
	set i1 $i2
	set i2 $x
    }
    set ds [list $d1 $d2]
    if {$diffing} {
	if {$ds == $diffdirs && $f == $difffile} return
	catch {close $difff}
    }
    set diffdirs $ds
    set difffile $f
    if {$orig} {
	set origdiffdirs $ds
    }
    if {[info exists rediffed] && $rediffed == $f} {
	unset rediffed
    }
    set path1 [joinname $d1 $f]
    set path2 [joinname $d2 $f]
    set diffopts "-U $ctxlines $diffiflag $diffwflag $diffbflag $diffBflag $diffdflag"

    if { [llength $diffprogram] > 0} {
       exec $diffprogram $path1 $path2 &
       return
    }
    # If we used an external diff program, its options are used.  If we didn't,
    # we use our diffopts, and we may be in trouble.
    set caught [catch "exec diff $diffopts $nullfile $nullfile" err]
    if {$caught != 0} {
       set msg "diff $diffopts\n$err\n"
       append msg "Suggestion: Use an external diff viewer such as tkdiff or gvimdiff"
       error_popup "$msg"
       return
    }

    # Build a window
    if {![info exists textw] || ![winfo exists $textw]} {
	maketextw
    }
    if {$filemode} {
	wm title $texttop "Differences: $d1 vs $d2"
    } else {
	wm title $texttop "Differences: $f"
    }
    $mergebut.m delete 0 end
    $textw conf -state normal
    $textw delete 0.0 end
    set charwidth [font measure [$textw cget -font] n]
    $textw conf -tabs "[expr 4*$charwidth] left [expr 12*$charwidth] left"
    set x $bgcolors($numgroups)
    $textw tag delete [$textw tag names]
    set diffoldcolor [lindex $x $i1]
    set diffnewcolor [lindex $x $i2]
    $textw tag conf d0 -back $diffoldcolor
    $textw tag conf d1 -back $diffnewcolor
    set diffcolors [list $diffoldcolor $diffnewcolor]
    $textw tag conf sep -back blue -fore white
    $textw tag conf ul -underline $underlinetabs
    $textw tag lower sep
    bind $textw <1> "startbutspan %x %y 0"
    bind $textw <Shift-Button-1> "startbutspan %x %y 1; break"
    bind $textw <B1-Motion> "setbutspan %x %y"
    bind $textw <ButtonRelease-1> "endbutspan"
    bind $textw <B1-Leave> "startbutscroll %W %x %y; break"
    bind $textw <B1-Enter> "endbutscroll %W %x %y; break"
    bind $textw <2> "startdrag $textw %x %y; break"
    bind $textw <B2-Motion> "dragdiff $textw %x %y; break"
    bind $textw <ButtonRelease-2> "finishdrag $textw"
    bind $textw <Any-Button-3> "togglebuts %x %y"

    # Start a diff
    set difff [open "|diff $diffopts $path1 $path2" r]
    set diffing 1
    set lno 1
    set nextlix 1000
    catch {unset oldin}
    catch {unset newin}

    global linelist
    set linelist {{{} {} {}}}

    global fcontents
    update
    catch {
	set f [open $path1 r]
	set fcontents(0) [split [read -nonewline $f] "\n"]
	close $f
    }
    catch {
	set f [open $path2 r]
	set fcontents(1) [split [read -nonewline $f] "\n"]
    }

    global file1lnum file2lnum incline
    set file1lnum 0
    set file2lnum 0
    catch {unset incline}
    fconfigure $difff -blocking 0
    fileevent $difff readable "readdiff $difff"
}

# linelist structure:
# one entry per displayed line, plus a 0'th null entry (not displayed)
# each entry is: linenumbers treenumbers line lix
# linenumbers contains one entry per tree, {} if this line
#  isn't in a tree's version of the file
# treenumbers is a list of the tree numbers where this line appears,
#  or {} for a separator line ($allf for a context line)
# line is the actual text of the line, or for a separator line,
#  a list of the pieces of text to appear across the separator line
# lix is the index of the checkbutton for this line if present
# header lines (---/+++) have linenumbers == {} and treenumbers == {}

proc readdiff {f} {
    global difff lno textw dirreadonly nextlix
    global incline linelist
    global file1lnum file2lnum diffing textfont
    global fcontents allf
    if {$f != $difff} {
	catch {close $f}
	return
    }
    set n [gets $difff line]
    if {$n < 0} {
	if {![eof $difff]} return
	catch {close $difff}
	set diffing 0
	if {$lno > 1} {
	    $textw delete "end - 1c" end
	    set t [$textw tag names "end - 1l"]
	    if {$t != ""} {
		$textw tag add $t "end - 1l" end
	    }
	}
	$textw conf -state disabled
	if {$lno > 3} {
	    confmergebut
	    confmpatchbut
	}
	return
    }
    set x [string index $line 0]
    if {$x == "@" && [regexp { -([0-9,]+) .*\+([0-9,]+) } $line z r1 r2]} {
	set r1 [lindex [split $r1 ,] 0]
	set r2 [lindex [split $r2 ,] 0]
	catch {set file1lnum [expr {$r1+0}]}
	catch {set file2lnum [expr {$r2+0}]}
	lappend linelist [makesepline $lno [list $file1lnum $file2lnum]]
	$textw insert end "\n"
	redisplaylines $textw $lno 1
	incr lno
	return
    }
    set ix 1
    if {($x == "-" || $x == "+") && $lno > 3} {
	set lix $nextlix
	incr nextlix
	set incline($lix) 0
	makecheckbox $textw $lix end
	set ix 2
	set line [string range $line 1 end]
	if {$x == "-"} {
	    lappend linelist [list [list $file1lnum {}] 0 $line $lix]
	} else {
	    lappend linelist [list [list {} $file2lnum] 1 $line $lix]
	}
    } elseif {$x == "-" || $x == "+"} {
	set line [string trimleft $line $x]
	lappend linelist [list {} [expr {$x == "+"}] $line]
    } elseif {$x == " "} {
	set line [string range $line 1 end]
	lappend linelist [list [list $file1lnum $file2lnum] $allf $line]
    }
    set lbeg [$textw index "end - 1c linestart"]
    $textw insert end "\t"
    set r [tabexpand $line $ix]
    $textw insert end [lindex $r 0]
    $textw insert end "\n"
    foreach tgp [lindex $r 1] {
	$textw tag add ul "$lbeg + [lindex $tgp 0]c" "$lbeg + [lindex $tgp 1]c"
    }
    set lend [$textw index "$lbeg + 1l"]
    if {$x == "-"} {
	$textw tag add d0 $lbeg $lend
    } elseif {$x == "+"} {
	$textw tag add d1 $lbeg $lend
    }
    if {$x != "+"} {incr file1lnum}
    if {$x != "-"} {incr file2lnum}
    incr lno
}

proc confmergebut {} {
    global mergebut diffdirs difffile
    global groups dirs diffmtime allf dirreadonly
    set group [lindex $groups($difffile) 1]
    foreach i $allf {
	set g [lindex $group [lsearch $dirs [lindex $diffdirs $i]]]
	set k 0
	foreach gx $group {
	    if {$gx == $g && !$dirreadonly($k)} {
		set f [lindex $dirs $k]
		$mergebut.m add command -label "update $f" \
		    -command [list diffmerge $i $f]
		set path [joinname $f $difffile]
		set diffmtime($path) [file mtime $path]
	    }
	    incr k
	}
    }
}

proc confmpatchbut {} {
    global mpatchbut diffdirs difffile
    global groups dirs allf dirreadonly
    set group [lindex $groups($difffile) 1]
    foreach i $allf {
	set g [lindex $group [lsearch $dirs [lindex $diffdirs $i]]]
	set k 0
	foreach gx $group {
	    if {$gx == $g && !$dirreadonly($k)} {
		set f [lindex $dirs $k]
		$mpatchbut.m add command -label "for $f" \
		    -command [list diffmpatch $i $f]
	    }
	    incr k
	}
    }
}

proc makesepline {lno lnums} {
    global linelist fcontents diffndirs
    set plinfo [lindex $linelist [expr $lno-1]]
    set lns [lindex $plinfo 0]
    set gapmin [llength $fcontents(0)]
    set gapmax 0
    for {set i 0} {$i < $diffndirs} {incr i} {
	set fl($i) [lindex $lnums $i]
	set pfl [lindex $lns $i]
	if {$pfl == {}} {set pfl 0}
	set gap [expr $fl($i) - $pfl - 1]
	if {$gap < $gapmin} {set gapmin $gap}
	if {$gap > $gapmax} {set gapmax $gap}
	set flen [llength $fcontents($i)]
	if {$flen == 0} {
	    set pct($i) "--"
	} else {
	    set pct($i) [expr {int($fl($i) * 100.0 / $flen)}]
	}
    }
    set nls $gapmin
    if {$nls != $gapmax} {
	append nls "-$gapmax lines"
    } elseif {$nls == 1} {
	append nls " line"
    } else {
	append nls " lines"
    }
    set pad [expr {$diffndirs > 4? "  ": "    "}]
    set line [list "$pad\(gap: $nls)$pad"]
    for {set i 0} {$i < $diffndirs} {incr i} {
	lappend line "$pad$fl($i) ($pct($i)%)$pad"
    }
    return [list $lnums {} $line]
}

proc makecheckbox {w lix pos} {
    checkbutton $w.inc$lix -variable incline($lix) \
	-font {Courier -10} -cursor top_left_arrow \
	-highlightthickness 0 -padx 2 -pady 0
    $w window create $pos -window $w.inc$lix -stretch true
    bind $w.inc$lix <1> "wstartbutspan %W %x %y; break"
    bind $w.inc$lix <B1-Motion> "wsetbutspan %W %x %y; break"
    bind $w.inc$lix <ButtonRelease-1> "endbutspan; break"
    bind $w.inc$lix <Shift-Button-1> "wtogglebuts %W %x %y; break"
    bind $w.inc$lix <Any-Button-3> "wtogglebuts %W %x %y"
}

proc tabexpand {line ix} {
    set col 0
    set txt {}
    set tgs {}
    set trailb [string length [string trimright $line]]
    while {[set tpos [string first "\t" $line]] >= 0} {
	if {$tpos > 0} {
	    append txt [string range $line 0 [expr $tpos-1]]
	    if {$trailb < $tpos} {
		lappend tgs [list [expr $ix+$trailb] [expr $ix+$tpos]]
		set trailb 0
	    } else {
		set trailb [expr $trailb-$tpos]
	    }
	    incr ix $tpos
	    incr col $tpos
	}
	set nsp [expr {8 - ($col & 7)}]
	append txt [string range "         " 1 $nsp]
	lappend tgs [list $ix [expr $ix+$nsp]]
	set line [string range $line [expr $tpos+1] end]
	incr ix $nsp
	incr col $nsp
	if {$trailb > 0} {incr trailb -1}
    }
    append txt $line
    set tpos [string length $line]
    if {$trailb < $tpos} {
	lappend tgs [list [expr $ix+$trailb] [expr $ix+$tpos]]
    }
    return [list $txt $tgs]
}

proc startbutspan {x y doall} {
    global butspanstart textw linelist butspanline
    set l [lindex [split [$textw index @$x,$y] .] 0]
    set lix [lindex [lindex $linelist $l] 3]
    if {$lix != {}} {
	set butspanstart $lix
	set butspanline $l
	$textw.inc$lix toggle
	if {$doall} {
	    togglegroup $l
	}
    }
}

proc setbutspan {x y} {
    global incline butspanstart textw linelist butspanline
    global textscrollx textscrolly
    if {![info exists butspanstart]} return
    set lend [lindex [split [$textw index @$x,$y] .] 0]
    set ln $butspanline
    set textscrollx $x
    set textscrolly $y
    set butspanline $lend
    if {$ln == $lend} return
    set inc [expr {$ln < $lend? 1: -1}]
    set m $butspanstart
    while 1 {
	incr ln $inc
	set l [lindex [lindex $linelist $ln] 3]
	if {[info exists incline($l)] && [info exists incline($m)]} {
	    set incline($l) $incline($m)
	}
	if {$ln == $lend} break
    }
}

proc endbutspan {} {
    global butspanstart
    catch {unset butspanstart}
}

proc wstartbutspan {w x y} {
    incr x [winfo x $w]
    incr y [winfo y $w]
    startbutspan $x $y 0
}

proc wsetbutspan {w x y} {
    incr x [winfo x $w]
    incr y [winfo y $w]
    setbutspan $x $y
}

proc dobutscroll {} {
    global textscrollid textscrollx textscrolly textw
    if {![winfo exists $textw]} return
    if {$textscrolly < 0} {
	$textw yview scroll -2 units
    } elseif {$textscrolly >= [winfo height $textw]} {
	$textw yview scroll 2 units
    }
    setbutspan $textscrollx $textscrolly
    set textscrollid [after 100 dobutscroll]
}

proc startbutscroll {w x y} {
    global textscrollx textscrolly
    set textscrollx $x
    set textscrolly $y
    dobutscroll
}

proc endbutscroll {w x y} {
    global textscrollid
    catch {after cancel $textscrollid; unset textscrollid}
}

proc redisplaylines {w l nl} {
    global linelist diffndirs difftabs
    for {set i 0} {$i < $nl} {incr i} {
	set lend [$w index "$l.0 + 1l"]
	for {set j 0} {$j < $diffndirs} {incr j} {
	    $w tag remove d$j $l.0 $lend
	}
	$w tag remove sep $l.0 $lend
	$w delete $l.0 "$l.0 lineend"
	set linfo [lindex $linelist $l]
	set ty [lindex $linfo 1]
	set line [lindex $linfo 2]
	if {$ty == {}} {
	    $w insert $l.0 "\t$difftabs[lindex $line 0]" sep
	    for {set j 0} {$j < $diffndirs} {incr j} {
		$w insert "$l.0 lineend" [lindex $line [expr $j+1]] d$j
	    }
	    $w insert "$l.0 lineend" "   " sep
	    $w tag add sep "$l.0 lineend" "$l.0 + 1l"
	} else {
	    set nm [llength $ty]
	    set main [lindex $ty [expr $nm-1]]
	    set ix 0
	    set lix [lindex $linfo 3]
	    if {$lix != {}} {
		catch {destroy $w.inc$lix}
		makecheckbox $w $lix $l.0
		incr ix
	    }

	    $w insert $l.$ix "\t$difftabs"
	    incr ix [expr $diffndirs-1]
	    if {$nm < $diffndirs} {
		set sub [lindex $ty 0]
		if {$nm <= 2} {
		    $w tag add d$sub $l.0 $l.$ix
		} else {
		    set pix 0
		    set nix [expr {$ix - $diffndirs + 3}]
		    for {set j 0} {$j < $diffndirs-2} {incr j} {
			set x [lindex $ty $j]
			$w tag add d$x $l.$pix $l.$nix
			set pix $nix
			incr nix
		    }
		}
	    }

	    set x [tabexpand $line $ix]
	    $w insert $l.$ix [lindex $x 0]
	    foreach tgp [lindex $x 1] {
		$w tag add ul $l.[lindex $tgp 0] $l.[lindex $tgp 1]
	    }
	    if {$nm < $diffndirs} {
		set lend [$w index "$l.0 + 1l"]
		$w tag add d$main $l.$ix $lend
	    }
	}
	incr l
    }
}

proc exchangelines {w start na nb} {
    global linelist
    set last [expr $start+$na+$nb-1]
    set eltsa [lrange $linelist $start [expr $start+$na-1]]
    set eltsb [lrange $linelist [expr $start+$na] $last]
    set linelist [eval lreplace \$linelist $start $last $eltsb $eltsa]
    $w conf -state normal
    redisplaylines $w $start [expr $na+$nb]
    $w conf -state disabled
}

proc addtoall {l x} {
    set ret {}
    foreach i $l {
	lappend ret [expr {$i + $x}]
    }
    return $ret
}

proc subfromall {l x} {
    set ret {}
    foreach i $l {
	lappend ret [expr {$i - $x}]
    }
    return $ret
}

proc setunion {a b} {
    return [lsort -unique [concat $a $b]]
}

proc setintersects {a b} {
    return [expr {[llength [setunion $a $b]] < [llength $a] + [llength $b]}]
}

# called on button 2 down in the diff window
# start dragging a diff hunk or separator line
proc startdrag {w x y} {
    global dragline draglineorig draguplines dragdownlines allf
    global dragsep dragseporig linelist dragsplit dragsplitorig
    global diffndirs
    set pos [$w index @$x,$y]
    set l [lindex [split $pos .] 0]
    $w tag remove sel 0.0 end
    set linfo [lindex $linelist $l]
    set ltype [lindex $linfo 1]
    if {$ltype == {}} {
	# dragging a separator line
	set dragsep $l
	set dragseporig $l
	catch {unset dragline}
	catch {unset dragsplit}
	# check for a separator bar covering a single line of context
	dragsepstart $w
	$w tag add sel $l.0 "$l.0 + 1l"
    } elseif {$ltype == $allf} {
	# dragging a context line
	set dragsplit $l
	set dragsplitorig $l
	catch {unset dragline}
	catch {unset dragsep}
	$w tag add sel $l.0 "$l.0 + 1l"
    } else {
	# dragging a diff line
	set dragline $l
	set draglineorig $l
	catch {unset dragsep}
	catch {unset dragsplit}
	$w tag add sel $l.0 "$l.0 + 1l"
    }
}

# called on movement with button 2 down in the diff window
proc dragdiff {w x y} {
    global dragline draglineorig linelist dragsep dragsplit
    global diffndirs allf dragnlines
    if {[info exists dragsep]} {
	dragsepbar $w $x $y
	return
    } elseif {[info exists dragsplit]} {
	dragdiffsplit $w $x $y
	return
    }
    if {![info exists dragline]} return
    set pos [$w index @$x,$y]
    set l [lindex [split $pos .] 0]
    if {$l == $dragline} return
    $w tag remove sel 0.0 end
    set id [lindex $linelist $dragline]
    # t = set of trees this line is in
    set t [lindex $id 1]
    set dist [expr $l - $dragline]
    while {$dist != 0} {
	if {$dragline < $draglineorig \
		|| ($dragline == $draglineorig && $l < $dragline)} {
	    # moving line $dragline and lines above it of same type
	    if {$dist < 0} {
		# dragging upwards
		set i [expr $dragline - 1]
		while 1 {
		    set pt [lindex [lindex $linelist $i] 1]
		    if {$pt == {} || $pt == $allf \
			    || ![setintersects $pt $t]} break
		    set t [setunion $t $pt]
		    incr i -1
		}
		set nlines [expr $dragline - $i]
		set j $i
		while {$i > $j + $dist} {
		    set pt [lindex [lindex $linelist $i] 1]
		    if {$pt == {} || $pt == $allf \
			    || [setintersects $pt $t]} break
		    incr i -1
		}
		set nabove [expr $j - $i]
		if {$nabove > 0} {
		    exchangelines $w [expr $i+1] $nabove $nlines
		    incr dist $nabove
		    for {set k 0} {$k < $nabove} {incr k} {
			set dragnlines($dragline) $nlines
			incr dragline -1
		    }
		} else {
		    set dist 0
		}
	    } else {
		# dragging back downwards
		incr dragline
		incr dist -1
		set nlines $dragnlines($dragline)
		exchangelines $w [expr {$dragline - $nlines}] $nlines 1
	    }
	} else {
	    # moving line $dragline and lines below it of same type
	    if {$dist > 0} {
		# dragging downwards
		set i [expr $dragline + 1]
		while 1 {
		    set pt [lindex [lindex $linelist $i] 1]
		    if {$pt == {} || $pt == $allf \
			    || ![setintersects $pt $t]} break
		    set t [setunion $t $pt]
		    incr i
		}
		set nlines [expr $i - $dragline]
		set j $i
		while {$i < $j + $dist} {
		    set pt [lindex [lindex $linelist $i] 1]
		    if {$pt == {} || $pt == $allf \
			    || [setintersects $pt $t]} break
		    incr i
		}
		set nbelow [expr $i - $j]
		if {$nbelow > 0} {
		    exchangelines $w $dragline $nlines $nbelow
		    incr dist -$nbelow
		    for {set k 0} {$k < $nbelow} {incr k} {
			set dragnlines($dragline) $nlines
			incr dragline
		    }
		} else {
		    set dist 0
		}
	    } else {
		# dragging back upwards
		incr dragline -1
		incr dist
		set nlines $dragnlines($dragline)
		exchangelines $w $dragline 1 $nlines
	    }
	}
    }
    $w tag add sel $dragline.0 "$dragline.0 + 1l"
}

# starting to drag a separator bar (button 2 down)
proc dragsepstart {w} {
    global dragsep linelist fcontents dragsepnowhere allf diffndirs
    set plinfob [lindex $linelist [expr $dragsep-1]]
    set f1lb [lindex [lindex $plinfob 0] 0]
    set plinfo [lindex $linelist $dragsep]
    set plns [lindex $plinfo 0]
    set f1l [lindex $plns 0]
    set dragsepnowhere [expr {$f1l <= $f1lb + 2}]
    if {$f1l == $f1lb + 2} {
	# turn the separator into a line of context
	set line [lindex $fcontents(0) [expr {$f1l - 2}]]
	set linelist [lreplace $linelist $dragsep $dragsep \
			  [list [subfromall $plns 1] $allf $line]]
	$w conf -state normal
	redisplaylines $w $dragsep 1
	$w conf -state disabled
    }
}

proc dragsepbar {w x y} {
    global dragsep dragseporig linelist fcontents dragsepnowhere allf
    set l [lindex [split [$w index @$x,$y] .] 0]
    if {$l == $dragsep || $dragsepnowhere} return
    $w tag remove sel 0.0 end
    set dist [expr $l - $dragsep]
    while {$dist != 0} {
	set plinfob [lindex $linelist [expr $dragsep-1]]
	set f1lb [lindex [lindex $plinfob 0] 0]
	set plinfo [lindex $linelist $dragsep]
	set plns [lindex $plinfo 0]
	set f1l [lindex $plns 0]
	set ty [lindex $plinfo 1]
	if {$dragsep < $dragseporig \
		|| ($dragsep == $dragseporig && $l < $dragsep)} {
	    # the separator bar is above its original location (or will be)
	    set inc [expr {$dist < 0? 1: -1}]
	    set lnums [subfromall $plns $inc]
	    if {$ty != {}} {
		if {$dist < 0} break
		set lnums [addtoall $lnums 1]
	    }
	    set f1l [lindex $lnums 0]
	    $w conf -state normal
	    if {$dist < 0} {
		# dragging further upwards
		set line [lindex $fcontents(0) [expr $f1l-1]]
		if {$f1lb + 2 == $f1l} {
		    # turn the separator into an ordinary line
		    set lns [subfromall $lnums 1]
		    set f1ls [lindex $lns 0]
		    set lsep [lindex $fcontents(0) [expr $f1ls-1]]
		    set linelist [lreplace $linelist $dragsep $dragsep \
				      [list $lns $allf $lsep] \
				      [list $lnums $allf $line]]
		} else {
		    set sline [makesepline $dragsep $lnums]
		    set linelist [lreplace $linelist $dragsep $dragsep \
				    $sline [list $lnums $allf $line]]
		}
		$w insert "$dragsep.0 + 1l" "\n"
		redisplaylines $w $dragsep 2
		$w yview scroll 1 units
	    } else {
		# moving back down towards original location
		set sline [makesepline $dragsep $lnums]
		set linelist [lreplace $linelist $dragsep [expr $dragsep+1] \
				  $sline]
		$w delete "$dragsep.0 + 1l" "$dragsep.0 + 2l"
		redisplaylines $w $dragsep 1
		$w yview scroll -1 units
	    }
	    $w conf -state disabled
	    incr dragseporig $inc
	    incr dist $inc
	} else {
	    # the separator bar is below its original location (or will be)
	    if {$dist > 0} {
		# dragging further downwards
		if {$ty != {}} break
		set plnsb [lindex $plinfob 0]
		set lnumsb [addtoall $plnsb 1]
		set f1lb [lindex $lnumsb 0]
		set line [lindex $fcontents(0) [expr $f1lb-1]]
		set linelist [linsert $linelist $dragsep \
				  [list $lnumsb $allf $line]]
		$w conf -state normal
		$w insert $dragsep.0 "\n"
		redisplaylines $w $dragsep 1
		incr dragsep
		incr dist -1
		if {$f1l == $f1lb + 2} {
		    # replace separator bar by normal line
		    set lnums [subfromall $plns 1]
		    set f1l [lindex $lnums 0]
		    set line [lindex $fcontents(0) [expr $f1l-1]]
		    set linelist [lreplace $linelist $dragsep $dragsep \
				      [list $lnums $allf $line]]
		} else {
		    set sline [makesepline $dragsep $plns]
		    set linelist [lreplace $linelist $dragsep $dragsep $sline]
		}
		redisplaylines $w $dragsep 1
		$w conf -state disabled
	    } else {
		# moving back up towards original location
		incr dragsep -1
		set linelist [lreplace $linelist $dragsep $dragsep]
		$w conf -state normal
		$w delete $dragsep.0 "$dragsep.0 + 1l"
		# reconstruct the separator line
		if {$ty != {}} {
		    set plns [addtoall $plns 1]
		}
		set sline [makesepline $dragsep $plns]
		set linelist [lreplace $linelist $dragsep $dragsep $sline]
		redisplaylines $w $dragsep 1
		$w conf -state disabled
		incr dist
	    }
	}
    }
    $w tag add sel $dragsep.0 "$dragsep.0 + 1l"
}

# dragging a context line - splits it into -/+ versions
proc dragdiffsplit {w x y} {
    global dragsplit dragsplitorig linelist fcontents diffndirs
    global nextlix incline allf
    set pos [$w index @$x,$y]
    set l [lindex [split $pos .] 0]
    if {$l == $dragsplit} return
    $w tag remove sel 0.0 end
    set dist [expr $l - $dragsplit]
    $w conf -state normal
    while {$dist != 0} {
	if {$dragsplit < $dragsplitorig \
		|| ($dragsplit == $dragsplitorig && $l < $dragsplit)} {
	    # moving line $dragsplit up
	    if {$dist < 0} {
		# split line dragsplit
		set linfo [lindex $linelist $dragsplit]
		if {[lindex $linfo 1] != $allf} break
		set lns [lindex $linfo 0]
		set newlns {}
		for {set i 0} {$i < $diffndirs} {incr i} {
		    lappend newlns {}
		}

		set f1l [lindex $lns 0]
		set line1 [lindex $fcontents(0) [expr $f1l-1]]
		set lix1 $nextlix
		set incline($lix1) 0
		set lnsx [lreplace $newlns 0 0 $f1l]
		set linelist [lreplace $linelist $dragsplit $dragsplit \
				  [list $lnsx 0 $line1 $lix1]]
		redisplaylines $w $dragsplit 1

		set l [expr $dragsplitorig + 1]
		set deltal [expr {$l - $dragsplit}]

		for {set i 1} {$i < $diffndirs} {incr i} {
		    set fl [lindex $lns $i]
		    set line [lindex $fcontents($i) [expr $fl-1]]
		    set lix [incr nextlix]
		    set incline($lix) 0
		    set lnsx [lreplace $newlns $i $i $fl]
		    set linelist [linsert $linelist $l \
				      [list $lnsx $i $line $lix]]
		    $w insert $l.0 "\n"
		    redisplaylines $w $l 1
		    incr l $deltal
		}

		incr nextlix
		incr dragsplit -1
		incr dist
	    } else {
		# reduce split by one line
		incr dragsplit
		set l [expr $dragsplitorig + 1]
		set deltal [expr {$l - $dragsplit}]
		set kl $dragsplit
		set lnums {}
		for {set k 0} {$k < $diffndirs} {incr k} {
		    set fl [lindex [lindex [lindex $linelist $kl] 0] $k]
		    lappend lnums $fl
		    incr kl $deltal
		}

		set f1l [lindex $lnums 0]
		set line1 [lindex $fcontents(0) [expr $f1l-1]]
		set linelist [lreplace $linelist $dragsplit $dragsplit \
				  [list $lnums $allf $line1]]
		redisplaylines $w $dragsplit 1

		incr deltal -1
		for {set k 1} {$k < $diffndirs} {incr k} {
		    set linelist [lreplace $linelist $l $l]
		    $w delete $l.0 "$l.0 + 1l"
		    incr l $deltal
		}

		incr dist -1
	    }
	} else {
	    # moving line $dragsplit down
	    if {$dist > 0} {
		# split another line
		set deltal [expr {$dragsplit - $dragsplitorig}]
		set l [expr $dragsplit + ($diffndirs - 1) * $deltal]
		set linfo [lindex $linelist $l]
		if {[lindex $linfo 1] != $allf} break
		set lns [lindex $linfo 0]
		set nullns {}
		for {set i 0} {$i < $diffndirs} {incr i} {
		    lappend nullns {}
		}

		set l $dragsplit
		for {set i 0} {$i < $diffndirs} {incr i} {
		    set fl [lindex $lns $i]
		    set line [lindex $fcontents($i) [expr $fl-1]]
		    set lix $nextlix
		    incr nextlix
		    set incline($lix) 0
		    set lnums [lreplace $nullns $i $i $fl]
		    if {$i < $diffndirs - 1} {
			set linelist [linsert $linelist $l \
					  [list $lnums $i $line $lix]]
			$w insert $l.0 "\n"
			redisplaylines $w $l 1
			incr l
		    } else {
			set linelist [lreplace $linelist $l $l \
				  [list $lnums $i $line $lix]]
			redisplaylines $w $l 1
		    }
		    incr l $deltal
		}

		incr dragsplit
		incr dist -1
	    } else {
		# reduce split by one line
		incr dragsplit -1
		incr dist
		set deltal [expr {$dragsplit - $dragsplitorig}]
		set l $dragsplit
		set lnums {}
		for {set i 0} {$i < $diffndirs} {incr i} {
		    lappend lnums [lindex [lindex [lindex $linelist $l] 0] $i]
		    if {$i < $diffndirs - 1} {
			set linelist [lreplace $linelist $l $l]
			$w delete $l.0 "$l.0 + 1l"
		    } else {
			set f1l [lindex $lnums 0]
			set line1 [lindex $fcontents(0) [expr $f1l-1]]
			set linelist [lreplace $linelist $l $l \
					  [list $lnums $allf $line1]]
			redisplaylines $w $l 1
		    }
		    incr l $deltal
		}
	    }
	    break
	}
    }
    $w conf -state disabled
}

# button 2 up
proc finishdrag {w} {
    global dragline dragsep dragsplit
    if {[info exists dragline]} {
	$w tag remove sel 0.0 end
	unset dragline
    }
    if {[info exists dragsep]} {
	$w tag remove sel 0.0 end
	unset dragsep
    }
    if {[info exists dragsplit]} {
	$w tag remove sel 0.0 end
	unset dragsplit
    }
}

proc togglegroup {l} {
    global incline textw linelist
    set linfo [lindex $linelist $l]
    set lix [lindex $linfo 3]
    if {$lix == {}} return
    if $incline($lix) {
	set state select
    } else {
	set state deselect
    }
    set l0 $l
    while 1 {
	incr l0 -1
	set linfo [lindex $linelist $l0]
	set lix [lindex $linfo 3]
	if {$lix == {}} break
	$textw.inc$lix $state
    }
    set l1 $l
    while 1 {
	incr l1
	set linfo [lindex $linelist $l1]
	set lix [lindex $linfo 3]
	if {$lix == {}} break
	$textw.inc$lix $state
    }
}

proc togglebuts {x y} {
    global textw linelist
    set l [lindex [split [$textw index @$x,$y] .] 0]
    set lix [lindex [lindex $linelist $l] 3]
    if {$lix != {}} {
	$textw.inc$lix toggle
	togglegroup $l
    }
}

proc wtogglebuts {w x y} {
    incr x [winfo x $w]
    incr y [winfo y $w]
    togglebuts $x $y
}

proc invertbuttons {} {
    global incline textw
    foreach l [array names incline] {
	set incline($l) [expr {1 - $incline($l)}]
    }
}

proc changeunderlinetabs {} {
    global textw underlinetabs
    $textw tag conf ul -underline $underlinetabs
}

proc diffn {dirlist f {orig 1}} {
    global diffing diffdirs difffile difffds diffrel allf
    global difflnos diffndirs diffstate difflnum nextdiffhdr diffhdr
    global diffiflag diffwflag diffbflag diffdflag incline
    global diffblocked fcontents ldisp havediffs nextlix origdiffdirs

    if {$orig} {
	set origdiffdirs $dirlist
    }
    # reverse the list so we have oldest first
    set x {}
    for {set i [llength $dirlist]} {[incr i -1] >= 0} {} {
	lappend x [lindex $dirlist $i]
    }
    set dirlist $x
    if {$diffing} {
	if {$dirlist == $diffdirs && $f == $difffile} return
	foreach i [array names difffds] {
	    catch {close $difffds($i)}
	}
    }
    set diffdirs $dirlist
    set difffile $f
    set diffndirs [llength $dirlist]
    set nextdiffhdr 0
    catch {unset diffhdr}
    set havediffs 0
    set nextlix 1000
    catch {unset incline}

    set diffopts "-u $diffiflag $diffwflag $diffbflag $diffdflag"
    set d [lindex $dirlist 0]
    set p [joinname $d $f]
    set diffrel(0) 0
    set allf 0
    for {set j 1} {$j < $diffndirs} {incr j} {
	set e [lindex $dirlist $j]
	set q [joinname $e $f]
	set difflnos($j) {0 0}
	set diffstate($j) 0
	set difflnum($j) 0
	set diffblocked($j) 0
	set diffrel($j) 0
	set fd [open "|diff $diffopts $p $q" r]
	set difffds($j) $fd
	fconfigure $fd -blocking 0
	fileevent $fd readable "readndiff $fd $j"
	lappend allf $j
    }
    for {set i 0} {$i < $diffndirs} {incr i} {
	set ldisp($i) 0
    }

    # Build a window
    global textw filemode mergebut mpatchbut bgcolors numgroups
    global groups dirs difftabs linelist texttop underlinetabs
    global diffcolors
    if {![info exists textw] || ![winfo exists $textw]} {
	maketextw
    }
    if {$filemode} {
	wm title $texttop "Differences: all files"
    } else {
	wm title $texttop "Differences: $f"
    }
    $mergebut.m delete 0 end
    $mpatchbut.m delete 0 end
    $textw conf -state normal
    $textw delete 0.0 end
    set charwidth [font measure [$textw cget -font] n]
    set tlist "[expr 4*$charwidth] left"
    set difftabs ""
    set j 4
    for {set i 2} {$i < $diffndirs} {incr i} {
	incr j 2
	if {$diffndirs < 4} {
	    incr j
	}
	append tlist " [expr $j*$charwidth] left"
	append difftabs "\t"
    }
    incr j 8
    append tlist " [expr $j*$charwidth] left"
    $textw conf -tabs $tlist
    set x $bgcolors($numgroups)
    $textw tag delete [$textw tag names]
    set group [lindex $groups($f) 1]
    set diffcolors {}
    for {set i 0} {$i < $diffndirs} {incr i} {
	set d [lindex $diffdirs $i]
	set j [lindex $group [lsearch $dirs $d]]
	set c [lindex $x $j]
	$textw tag conf d$i -back $c
	lappend diffcolors $c
    }
    $textw tag conf sep -back blue -fore white
    $textw tag conf ul -underline $underlinetabs
    $textw tag lower sep
    bind $textw <1> "startbutspan %x %y 0; break"
    bind $textw <Shift-Button-1> "startbutspan %x %y 1; break"
    bind $textw <B1-Motion> "setbutspan %x %y; break"
    bind $textw <ButtonRelease-1> "endbutspan; break"
    bind $textw <B1-Leave> "startbutscroll %W %x %y; break"
    bind $textw <B1-Enter> "endbutscroll %W %x %y; break"
    bind $textw <2> "startdrag $textw %x %y; break"
    bind $textw <B2-Motion> "dragdiff $textw %x %y; break"
    bind $textw <ButtonRelease-2> "finishdrag $textw"
    bind $textw <Any-Button-3> "togglebuts %x %y"
    set linelist {{{} {} {}}}

    # read in the files
    set i 0
    foreach d $dirlist {
	set p [joinname $d $f]
	set fcontents($i) {}
	if {[catch {
	    set fd [open $p r]
	    set fcontents($i) [split [read -nonewline $fd] "\n"]
	    close $fd
	} err]} {
	    puts "error reading $p: $err"
	}
	incr i
    }
}

proc readndiff {fd ix} {
    global difflnos diffeof difflnum diffhdr
    global nextdiffhdr diffstate diffhunk
    global parthunklen parthunkstart diffblocked

    set n [gets $fd line]
    set l [incr difflnum($ix)]
    if {$n < 0} {
	if {![eof $fd]} return
	#puts "eof for $ix"
	addhunk $ix 2
	close $fd
	return
    }
    set x [string index $line 0]
    if {$l <= 2} {
	# expect --- or +++ line or "Binary files ..."
	if {$ix == 1 && $x == "-"} {
	    set diffhdr(0) [string range $line 4 end]
	}
	if {$x == "+"} {
	    set diffhdr($ix) [string range $line 4 end]
	}
	while {[info exists diffhdr($nextdiffhdr)]} {
	    emithdr $nextdiffhdr $diffhdr($nextdiffhdr)
	    incr nextdiffhdr
	}
	return
    }
    if {$x == "-" || $x == "+"} {
	set addit [expr {$x == "+"}]
	set line [string range $line 1 end]
	if {$diffstate($ix) == 0} {
	    # start of a new hunk of diff
	    set parthunklen($ix,0) 0
	    set parthunklen($ix,1) 0
	    set parthunkstart($ix) $difflnos($ix)
	    if {[info exists diffhunk($ix)]} {
		# block this diff for now
		fileevent $fd readable {}
		set diffblocked($ix) 1
		#puts "blocking $ix"
	    }
	    set diffstate($ix) 1
	}
	set fl [lindex $difflnos($ix) $addit]
	incr parthunklen($ix,$addit)
	set difflnos($ix) [lreplace $difflnos($ix) $addit $addit [incr fl]]
    } else {
	if {$diffstate($ix) == 1} {
	    # end of a new hunk of diff
	    addhunk $ix 0
	}
	set f0l [lindex $difflnos($ix) 0]
	set f1l [lindex $difflnos($ix) 1]
	if {$x == "@" && [regexp { -([0-9,]+) .*\+([0-9,]+) } $line z r1 r2]} {
	    set r1 [lindex [split $r1 ,] 0]
	    set r2 [lindex [split $r2 ,] 0]
	    catch {set f0l [expr {$r1+0}]}
	    catch {set f1l [expr {$r2+0}]}
	} else {
	    incr f0l
	    incr f1l
	}
	set difflnos($ix) [list $f0l $f1l]
    }
}

proc addhunk {ix newstate} {
    global diffstate parthunklen parthunkstart diffhunk
    #puts "addhunk $ix newstate=$newstate diffstate($ix)=$diffstate($ix)"
    if {$diffstate($ix) == 1} {
	#puts "   start=$parthunkstart($ix) len= $parthunklen($ix,0) $parthunklen($ix,1)"
	if {[info exists diffhunk($ix)]} {
	    puts "oops, overwriting hunk for $ix"
	}
	set diffhunk($ix) [list $parthunkstart($ix) \
			       $parthunklen($ix,0) $parthunklen($ix,1)]
    }
    set diffstate($ix) $newstate
    processhunks
}

proc consumehunk {ix} {
    global diffhunk diffblocked difffds
    #puts "consumehunk $ix"
    unset diffhunk($ix)
    if {$diffblocked($ix)} {
	set fd $difffds($ix)
	fileevent $fd readable "readndiff $fd $ix"
	set diffblocked($ix) 0
    }
}

proc diffstart {lno} {
    global hunkstart hunkend diffndirs diffrel
    #puts -nonewline "diffstart $lno:"
    for {set j 0} {$j < $diffndirs} {incr j} {
	set hunkstart($j) [expr $lno + $diffrel($j)]
	set hunkend($j) $hunkstart($j)
	#puts -nonewline " $hunkstart($j)"
    }
    #puts ""
}

proc adddiffhunk {ix} {
    global hunkend diffndirs diffhunk
    #puts "adddiffhunk $ix: $diffhunk($ix)"
    set stl [lindex $diffhunk($ix) 0]
    set lst [lindex $stl 0]
    set rst [lindex $stl 1]
    set llen [lindex $diffhunk($ix) 1]
    set rlen [lindex $diffhunk($ix) 2]
    set lend [expr $lst + $llen]
    set rend [expr $rst + $rlen]
    set x [expr $lend - $hunkend(0)]
    if {$x < 0} {
	set rend [expr $rend - $x]
    } elseif {$x > 0} {
	for {set i 0} {$i < $diffndirs} {incr i} {
	    incr hunkend($i) $x
	}
    }
    set hunkend($ix) $rend
}

proc addoverlaps {} {
    global diffhunk hunkend diffndirs diffstate
    set overlap 0
    for {set j 1} {$j < $diffndirs} {incr j} {
	if {![info exists diffhunk($j)]} continue
	set lnos [lindex $diffhunk($j) 0]
	if {[lindex $lnos 0] <= $hunkend(0) || \
		[lindex $lnos 1] <= $hunkend($j)} {
	    set overlap 1
	    adddiffhunk $j
	    consumehunk $j
	}
    }
    return $overlap
}

proc processhunks {} {
    global diffhunk diffstate diffndirs diffrel
    global havediffs hunkstart hunkend

    while 1 {
	if {$havediffs} {
	    addoverlaps
	}

	# check that we have a hunk or EOF for each pair
	set alleof 1
	for {set j 1} {$j < $diffndirs} {incr j} {
	    if {$diffstate($j) != 2} {
		set alleof 0
		if {![info exists diffhunk($j)]} return
	    }
	}
	#if {$alleof} {puts "processhunks: eof on all"}

	if {$havediffs} {
	    putdiffhunks
	    #puts -nonewline "diffrel:"
	    for {set j 1} {$j < $diffndirs} {incr j} {
		set diffrel($j) [expr $hunkend($j) - $hunkend(0)]
		#puts -nonewline " $diffrel($j)"
	    }
	    #puts ""
	    set havediffs 0
	    unset hunkstart
	    unset hunkend
	}

	# find which hunk is the earliest
	set first {}
	for {set j 1} {$j < $diffndirs} {incr j} {
	    if {[info exists diffhunk($j)]} {
		set st0 [lindex [lindex $diffhunk($j) 0] 0]
		if {$first == {} || $st0 < $earliest} {
		    set first $j
		    set earliest $st0
		}
	    }
	}
	if {$first == {}} {
	    # have reached EOF on all diffs
	    ndiffdone
	    return
	}

	set havediffs 1
	diffstart $earliest
	adddiffhunk $first
	consumehunk $first
    }
}

proc existingmatch {matches f fl} {
    global diffndirs
    foreach m $matches {
	if {$f == [lindex $m 0]} {
	    set nl [lindex $m 2]
	    set lnos [lindex $m 1]
	    set o [expr [lindex $fl 0] - [lindex $lnos 0]]
	    if {$o < 0 || $o >= $nl} {
		return 0
	    }
	    for {set i 0} {$i < [llength $f]} {incr i} {
		if {[lindex $fl $i] != [lindex $lnos $i] + $o} {
		    return 0
		}
	    }
	    return 1
	}
    }
    return 0
}

# f is a list of file indices, fl is a corresponding list of line numbers
# relative to the start of this section
proc matchlength {f fl} {
    global difflines
    set l0 [lindex $fl 0]
    set f0 [lindex $f 0]
    set f0len [llength $difflines($f0)]
    set nf [llength $f]
    set len 1
    while {[incr l0] < $f0len} {
	set line [lindex $difflines($f0) $l0]
	for {set i 1} {$i < $nf} {incr i} {
	    set fi [lindex $f $i]
	    set li [expr [lindex $fl $i] + $len]
	    if {$li >= [llength $difflines($fi)] || \
		    [lindex $difflines($fi) $li] != $line} {
		return $len
	    }
	}
	incr len
    }
    return $len
}

# m is a match expressed as a list {files lines length}
# existing is a list of matches in that format
proc expandmatchback {m existing} {
    global difflines
    set fi [lindex $m 0]
    set fl [lindex $m 1]
    set len [lindex $m 2]
    set f0 [lindex $fi 0]
    set l0 [lindex $fl 0]
    set nf [llength $fi]
    for {set j 0} {$j < $nf} {incr j} {
	set f [lindex $fi $j]
	set l [lindex $fl $j]
	set lno($f) $l
	set minlno($f) 0
    }
    foreach e $existing {
	set k 0
	foreach ef [lindex $e 0] {
	    if {[info exists lno($ef)]} {
		set el [lindex [lindex $e 1] $k]
		if {$el < $lno($ef)} {
		    incr el [lindex $e 2]
		    if {$el > $minlno($ef)} {
			set minlno($ef) $el
		    }
		}
	    }
	    incr k
	}
    }
    set nl [expr $l0 - $minlno($f0)]
    for {set x 1} {$x <= $nl} {incr x} {
	set line [lindex $difflines($f0) [expr $l0 - $x]]
	for {set j 1} {$j < $nf} {incr j} {
	    set f [lindex $fi $j]
	    set l [expr [lindex $fl $j] - $x]
	    if {$l < $minlno($f)} break
	    if {[lindex $difflines($f) $l] != $line} break
	}
	if {$j < $nf} break
    }
    if {$x == 1} {
	return $m
    }
    set newfl {}
    incr x -1
    foreach l $fl {
	lappend newfl [expr $l - $x]
    }
    return [list $fi $newfl [expr $len + $x]]
}

proc removematches {matches f l nl} {
    set new {}
    set el [expr $l + $nl]
    foreach m $matches {
	set i [lsearch [lindex $m 0] $f]
	if {$i < 0} {
	    lappend new $m
	} else {
	    set lm [lindex [lindex $m 1] $i]
	    set elm [expr [lindex $m 2] + $lm]
	    if {$el <= $lm || $elm <= $l} {
		lappend new $m
	    } else {
		if {$lm < $l} {
		    lappend new [lreplace $m 2 2 [expr $l - $lm]]
		}
		if {$elm > $el} {
		    set inc [expr $el - $lm]
		    set lnos {}
		    foreach x [lindex $m 1] {
			lappend lnos [expr $x + $inc]
		    }
		    lappend new [lreplace $m 1 2 $lnos [expr $elm - $el]]
		}
	    }
	}
    }
    return $new
}

proc removeinversions {matches bm} {
    set bf [lindex $bm 0]
    set bl [lindex $bm 1]
    set new {}
    foreach m $matches {
	set isbefore 0
	set isafter 0
	set i 0
	set mf [lindex $m 0]
	set ml [lindex $m 1]
	foreach f $mf {
	    set j [lsearch -exact $bf $f]
	    if {$j >= 0} {
		if {[lindex $ml $i] < [lindex $bl $j]} {
		    set isbefore 1
		} else {
		    set isafter 1
		}
	    }
	    incr i
	}
	if {!($isbefore && $isafter)} {
	    lappend new $m
	}
    }
    return $new
}

proc overlapsbest {bestmatches mf ml mlen} {
    foreach bm $bestmatches {
	set bf [lindex $bm 0]
	set bl [lindex $bm 1]
	set blen [lindex $bm 2]
	set isbefore 0
	set isafter 0
	set i 0
	foreach f $mf {
	    set j [lsearch -exact $bf $f]
	    if {$j >= 0} {
		set li [lindex $ml $i]
		set lj [lindex $bl $j]
		if {$li < $lj} {
		    if {$isafter || $li + $mlen > $lj} {
			return 1
		    }
		    set isbefore 1
		} else {
		    if {$isbefore || $lj + $blen > $li} {
			return 1
		    }
		    set isafter 1
		}
	    }
	    incr i
	}
    }
    return 0
}

proc findbestmatch {matches} {
    set best 0
    set bestnf 0
    set bm {}
    foreach m $matches {
	set nf [llength [lindex $m 0]]
	set good [lindex $m 2]
	if {$nf > $bestnf || ($nf == $bestnf && $good > $best)} {
	    set best $good
	    set bestnf $nf
	    set bm $m
	}
    }
    return $bm
}

proc findmatches {} {
    global hunkstart hunkend diffndirs
    global difflines fcontents lineinst diffwflag diffbflag
    set matches {}
    catch {unset lineinst}
    for {set i 0} {$i < $diffndirs} {incr i} {
	set difflines($i) {}
	for {set j $hunkstart($i)} {$j < $hunkend($i)} {incr j} {
	    set line [lindex $fcontents($i) [expr $j-1]]
	    if {$diffwflag != ""} {
		regsub -all {[ 	]+} $line {} line
	    } elseif {$diffbflag != ""} {
		regsub -all {[ 	]+} $line { } line
		regsub { $} $line {} line
	    }
	    lappend difflines($i) $line
	}
    }
    for {set i 0} {$i < $diffndirs} {incr i} {
	set l 0
	foreach line $difflines($i) {
	    lappend lineinst($line) [list $i $l]
	    if {![regexp {^[[:space:]]*$} $line]} {
		foreach inst $lineinst($line) {
		    set f [lindex $inst 0]
		    if {$f == $i || [lsearch -exact $f $i] >= 0} continue
		    set fl [lindex $inst 1]
		    lappend f $i
		    lappend fl $l
		    if {![existingmatch $matches $f $fl]} {
			lappend matches [list $f $fl [matchlength $f $fl]]
		    }
		    lappend lineinst($line) [list $f $fl]
		}
	    }
	    incr l
	}
    }
    set bestmatches {}
    while {$matches != {}} {
	set bm [findbestmatch $matches]
	set bm [expandmatchback $bm $bestmatches]
	lappend bestmatches $bm
	set i 0
	set nl [lindex $bm 2]
	foreach f [lindex $bm 0] {
	    set lno [lindex [lindex $bm 1] $i]
	    set matches [removematches $matches $f $lno $nl]
	    incr i
	}
	set matches [removeinversions $matches $bm]
    }

    # now add in the blank-line matches that we ignored before
    set matches {}
    for {set i 0} {$i < $diffndirs} {incr i} {
	set l 0
	foreach line $difflines($i) {
	    if {[regexp {^[[:space:]]*$} $line]} {
		foreach inst $lineinst($line) {
		    set f [lindex $inst 0]
		    if {$f >= $i || [lsearch -exact $f $i] >= 0} continue
		    set fl [lindex $inst 1]
		    lappend f $i
		    lappend fl $l
		    if {![existingmatch $matches $f $fl]} {
			set mlen [matchlength $f $fl]
			if {![overlapsbest $bestmatches $f $fl $mlen]} {
			    lappend matches [list $f $fl $mlen]
			}
		    }
		    lappend lineinst($line) [list $f $fl]
		}
	    }
	    incr l
	}
    }
    while {$matches != {}} {
	set bm [findbestmatch $matches]
	lappend bestmatches $bm
	set i 0
	set nl [lindex $bm 2]
	foreach f [lindex $bm 0] {
	    set lno [lindex [lindex $bm 1] $i]
	    set matches [removematches $matches $f $lno $nl]
	    incr i
	}
	set matches [removeinversions $matches $bm]
    }
	
    #puts "best matches: $bestmatches"
    return $bestmatches
}

proc filematches {matches i nlines} {
    global hunkstart hunkend diffndirs
    set res {}
    foreach m $matches {
	set k [lsearch -exact [lindex $m 0] $i]
	if {$k >= 0} {
	    set l [lindex [lindex $m 1] $k]
	    set e [expr $l + [lindex $m 2]]
	    lappend res [list $l $e $m]
	}
    }
    set full {}
    set ld 0
    foreach m [lsort -integer -index 0 $res] {
	set l [lindex $m 0]
	if {$ld < $l} {
	    lappend full [list $ld $l [list $i $ld [expr $l - $ld]]]
	}
	if {[lindex [lindex [lindex $m 2] 0] 0] == $i} {
	    lappend full $m
	}
	set ld [lindex $m 1]
    }
    if {$ld < $nlines} {
	lappend full [list $ld $nlines [list $i $ld [expr $nlines - $ld]]]
    }
    #puts "filematches $i -> {$full}"
    return $full
}

proc putdiffhunks {} {
    global hunkstart hunkend diffndirs
    global matchlist fcontents
    #puts -nonewline "putdiffhunks"
    #for {set i 0} {$i < $diffndirs} {incr i} {
	#puts -nonewline " $i: ($hunkstart($i),$hunkend($i))"
    #}
    #puts ""
    set matches [findmatches]
    #puts "matches: $matches"
    set totsegs 0
    for {set i 0} {$i < $diffndirs} {incr i} {
	set nlines($i) [expr $hunkend($i) - $hunkstart($i)]
	set displ($i) [filematches $matches $i $nlines($i)]
	set nsegs($i) [llength $displ($i)]
	set ix($i) 0
	if {$nsegs($i) > 0} {
	    set curseg($i) [lindex $displ($i) 0]
	    incr totsegs $nsegs($i)
	}
	set nextline($i) 0
    }
    set displist {}
    while {$totsegs > 0} {
	for {set i 0} {$i < $diffndirs} {incr i} {
	    if {$nsegs($i) == 0} continue
	    set m [lindex $curseg($i) 2]
	    set blocked 0
	    set k 0
	    set lnos [lindex $m 1]
	    foreach f [lindex $m 0] {
		set l [lindex $lnos $k]
		if {$l > $nextline($f)} {
		    set blocked 1
		    break
		}
		if {$l < $nextline($f)} {
		    puts "oops, misordered span for $i {$curseg($i)}"
		    #puts -nonewline "nextline: "
		    #for {set z 0} {$z < $diffndirs} {incr z} {
			#puts -nonewline " $nextline($z)"
		    #}
		    #puts -nonewline "\nix: "
		    #for {set z 0} {$z < $diffndirs} {incr z} {
			#puts -nonewline " $ix($z)"
		    #}
		    #puts -nonewline "\nnsegs: "
		    #for {set z 0} {$z < $diffndirs} {incr z} {
			#puts -nonewline " $nsegs($z)"
		    #}
		    #puts ""
		    #for {set z 0} {$z < $diffndirs} {incr z} {
			#puts "displ($z): {$displ($z)}"
		    #}
		    #puts "displist:"
		    #foreach z $displist {
			#puts "  $z"
		    #}
		    #puts ""
		}
		incr k
	    }
	    if {!$blocked} {
		lappend displist $curseg($i)
		set nl [lindex $m 2]
		foreach f [lindex $m 0] {
		    incr nextline($f) $nl
		}
		incr ix($i)
		incr nsegs($i) -1
		if {$nsegs($i) > 0} {
		    set curseg($i) [lindex $displ($i) $ix($i)]
		} else {
		    unset curseg($i)
		}
		break
	    }
	}
	incr totsegs -1
    }
    #puts "displist:"
    #foreach d $displist {
	#puts $d
    #}
    emitstart
    foreach d $displist {
	set l [lindex $d 0]
	set e [lindex $d 1]
	set m [lindex $d 2]
	set fs [lindex $m 0]
	set i [lindex $fs 0]
	set fl [expr $hunkstart($i) + $l - 1]
	for {} {$l < $e} {incr l} {
	    emitdiff $fs [lindex $fcontents($i) $fl]
	    incr fl
	}
    }
}

proc emithdr {i line} {
    global textw difftabs linelist
    $textw insert end "\t$difftabs$line\n" d$i
    lappend linelist [list {} {} $line]
}

proc emitctxline {} {
    global textw linelist ldisp fcontents difftabs diffndirs
    set lnums {}
    set memb {}
    set line [lindex $fcontents(0) [expr $ldisp(0)-1]]
    for {set i 0} {$i < $diffndirs} {incr i} {
	lappend lnums $ldisp($i)
	incr ldisp($i)
	lappend memb $i
    }
    lappend linelist [list $lnums $memb $line]
    set ix [expr $diffndirs-1]
    set r [tabexpand $line $ix]
    set l [lindex [split [$textw index "end - 1c"] .] 0]
    $textw insert end "\t$difftabs[lindex $r 0]\n"
    foreach tgp [lindex $r 1] {
	$textw tag add ul $l.[lindex $tgp 0] $l.[lindex $tgp 1]
    }
}

proc emitstart {} {
    global diffndirs ctxlines ldisp textw difftabs linelist
    global prevhunkend fcontents hunkstart
    set nctx $ctxlines
    set needsep 1
    if {[info exists prevhunkend]} {
	if {$hunkstart(0) - $prevhunkend <= 2 * $ctxlines + 1} {
	    set nctx [expr $hunkstart(0) - $prevhunkend]
	    set needsep 0
	} else {
	    for {set l 0} {$l < $ctxlines} {incr l} {
		emitctxline
	    }
	}
    }
    if {$nctx >= $hunkstart(0)} {
	set nctx [expr $hunkstart(0) - 1]
    }
    if {$needsep} {
	set lnums {}
	for {set i 0} {$i < $diffndirs} {incr i} {
	    set ldisp($i) [expr $hunkstart($i) - $nctx]
	    lappend lnums $ldisp($i)
	}
	set l [llength $linelist]
	lappend linelist [makesepline $l $lnums]
	$textw insert end "\n"
	redisplaylines $textw $l 1
    }
    for {set l 0} {$l < $nctx} {incr l} {
	emitctxline
    }
}

proc emitdiff {set line} {
    global diffndirs ldisp textw difftabs linelist
    global prevhunkend fcontents nextlix incline
    #puts -nonewline "emitdiff set={$set} ldisp ="
    #for {set i 0} {$i < $diffndirs} {incr i} {puts -nonewline " $ldisp($i)"}
    #puts " line={$line}"
    set nm [llength $set]
    if {$nm == $diffndirs} {
	emitctxline
	return
    }
    if {$nm == 0 || $nm > $diffndirs} {
	#puts "oops, $nm members in emitdiff?"
	return
    }
    for {set i 0} {$i < $diffndirs} {incr i} {
	set isin($i) 0
    }
    foreach i $set {
	set isin($i) 1
    }
    set lnums {}
    for {set i 0} {$i < $diffndirs} {incr i} {
	if {$isin($i)} {
	    lappend lnums $ldisp($i)
	    incr ldisp($i)
	} else {
	    lappend lnums {}
	}
    }
    set lix $nextlix
    incr nextlix
    set incline($lix) 0
    set l [llength $linelist]
    lappend linelist [list $lnums $set $line $lix]
    $textw insert end "\n"
    redisplaylines $textw $l 1
    set prevhunkend $ldisp(0)
}

proc ndiffdone {} {
    global textw prevhunkend fcontents ctxlines
    global diffing ldisp diffndirs
    #puts -nonewline "ldisp ="
    #for {set i 0} {$i < $diffndirs} {incr i} {puts -nonewline " $ldisp($i)"}
    #puts ""
    if {[info exists prevhunkend]} {
	set l0 [llength $fcontents(0)]
	#puts "ndiffdone, prevhunkend=$prevhunkend l0=$l0 ctxlines=$ctxlines"
	set nctx $ctxlines
	if {$prevhunkend - 1 + $nctx > $l0} {
	    set nctx [expr $l0 - $prevhunkend + 1]
	}
	for {set l 0} {$l < $nctx} {incr l} {
	    emitctxline
	}
	unset prevhunkend
    } else {
	#puts "ndiffdone, prevhunkend not set"
    }
    set diffing 0
    $textw delete "end - 1c" end
    $textw conf -state disabled

    # configure the merge button
    confmergebut
    confmpatchbut
}

proc diffmerge {ix dir} {
    global diffdirs difffile diffmtime fserial linelist
    global dirs diffcolors textfont incline diffndirs
    global fcontents allf
    set infile [joinname $dir $difffile]
    if {$diffmtime($infile) != [file mtime $infile]} {
	error_popup "File $infile has changed since the diff was performed."
	return
    }

    set di [lsearch -exact $dirs $dir]
    set fi $fserial($difffile)
    set w ".merge:$di:$fi"
    catch {destroy $w}
    toplevel $w
    wm title $w "Dirdiff: merged $infile"
    frame $w.bar -relief raised -border 2
    pack $w.bar -side top -fill x
    menubutton $w.bar.file -text File -menu $w.bar.file.m -padx 10 -pady 1
    menu $w.bar.file.m -tearoff 0
    $w.bar.file.m add command -label Save -command "savemerge $w"
    $w.bar.file.m add command -label Close -command "destroy $w"
    pack $w.bar.file -side left
    menubutton $w.bar.edit -text Edit -menu $w.bar.edit.m -padx 10 -pady 1
    menu $w.bar.edit.m -tearoff 0
    $w.bar.edit.m add command -label Cut -command "tk_textCut $w.t"
    $w.bar.edit.m add command -label Copy -command "tk_textCopy $w.t"
    $w.bar.edit.m add command -label Paste -command "tk_textPaste $w.t"
    $w.bar.edit.m add command -label Find \
	    -command [list difffind :merge:$di:$fi $w.t]
    pack $w.bar.edit -side left
    frame $w.f -relief sunk -border 2
    entry $w.f.filename
    $w.f.filename insert 0 $infile
    pack $w.f.filename -side left -fill x -expand 1
    pack $w.f -side top -fill x
    text $w.t -yscrollcommand "$w.sb set" -font $textfont
    scrollbar $w.sb -command "$w.t yview"
    pack $w.sb -side right -fill y
    pack $w.t -side left -fill both -expand 1
    bind $w <Key-Prior> "$w.t yview scroll -1 p"
    bind $w <Key-Next> "$w.t yview scroll 1 p"
    for {set x 0} {$x < $diffndirs} {incr x} {
	$w.t tag conf d$x -back [lindex $diffcolors $x]
    }

    set inf $fcontents($ix)
    set l 1
    foreach m $linelist {
	set lns [lindex $m 0]
	set ty [lindex $m 1]
	if {$lns == {} || $ty == {}} continue
	set tl [lindex $lns $ix]
	if {$tl != {}} {
	    for {} {$l < $tl} {incr l} {
		set line [lindex $inf [expr $l-1]]
		$w.t insert end "$line\n"
	    }
	}
	if {$ty == $allf} {
	    set line [lindex $inf [expr $l-1]]
	    $w.t insert end "$line\n"
	    incr l
	} elseif {[llength $ty] < $diffndirs} {
	    set isme [expr {$ty == $ix || [lsearch -exact $ty $ix] >= 0}]
	    set lix [lindex $m 3]
	    set inc $incline($lix)
	    if {!$inc} {
		if {$isme} {
		    set line [lindex $inf [expr $l-1]]
		    $w.t insert end "$line\n" d$ix
		    incr l
		}
	    } else {
		if {!$isme} {
		    # insert this line
		    set line [lindex $m 2]
		    set last [lindex $ty end]
		    $w.t insert end "$line\n" d$last
		} else {
		    # delete this line
		    incr l
		}
	    }
	}
    }
    for {set nl [llength $inf]} {$l <= $nl} {incr l} {
	set line [lindex $inf [expr $l-1]]
	$w.t insert end "$line\n"
    }
    # delete last newline
    catch {$w.t delete "end - 1c" end}
}

proc savemerge {w} {
    set infile [$w.f.filename get]
    if {$infile == {}} {return}
    set tmpfile "$infile.tmp"
    set tf [open $tmpfile w]
    puts -nonewline $tf [$w.t get 0.0 end]
    close $tf
    scmedit $infile
    catch {file attr $tmpfile -perm [file attr $infile -perm]}
    file rename -force $infile $infile.orig
    file rename $tmpfile $infile
    destroy $w
    redifffiles
}

# Make a patch that would make the same changes to a destination
# file that doing a merge would have made.
proc diffmpatch {ix dir} {
    global difffile diffmtime linelist
    global dirs textfont incline diffndirs filemode
    global fcontents allf mpatchserial

    if {![info exists mpatchserial]} {
	set mpatchserial 0
    }
    set fi [incr mpatchserial]
    set w ".mpatch:$fi"
    toplevel $w
    set fname [joinname $dir $difffile]
    set ftail [file tail $fname]
    wm title $w "Dirdiff: patch for $ftail"
    frame $w.bar -relief raised -border 2
    pack $w.bar -side top -fill x
    menubutton $w.bar.file -text File -menu $w.bar.file.m -padx 10 -pady 1
    menu $w.bar.file.m -tearoff 0
    $w.bar.file.m add command -label Save -command "savemerge $w"
    $w.bar.file.m add command -label Close -command "destroy $w"
    pack $w.bar.file -side left
    menubutton $w.bar.edit -text Edit -menu $w.bar.edit.m -padx 10 -pady 1
    menu $w.bar.edit.m -tearoff 0
    $w.bar.edit.m add command -label Cut -command "tk_textCut $w.t"
    $w.bar.edit.m add command -label Copy -command "tk_textCopy $w.t"
    $w.bar.edit.m add command -label Paste -command "tk_textPaste $w.t"
    $w.bar.edit.m add command -label Find \
	    -command [list difffind :mpatch:$fi $w.t]
    pack $w.bar.edit -side left
    frame $w.f -relief sunk -border 2
    entry $w.f.filename
    $w.f.filename insert 0 "$ftail.patch"
    pack $w.f.filename -side left -fill x -expand 1
    pack $w.f -side top -fill x
    text $w.t -yscrollcommand "$w.sb set" -font $textfont
    scrollbar $w.sb -command "$w.t yview"
    pack $w.sb -side right -fill y
    pack $w.t -side left -fill both -expand 1
    bind $w <Key-Prior> "$w.t yview scroll -1 p"
    bind $w <Key-Next> "$w.t yview scroll 1 p"

    set inf $fcontents($ix)
    set l 1
    set delta 0
    set pluslines {}
    set ctxstart {}
    set filelen [llength $fcontents($ix)]

    foreach m $linelist {
	set lns [lindex $m 0]
	set ty [lindex $m 1]
	set lix [lindex $m 3]
	if {$lns == {}} continue
	set lineno [lindex $lns $ix]
	if {$lineno != {}} {
	    set l $lineno
	}
	if {$ty == {} || $ty == $allf || $lix == {} \
		|| ($lineno != {} && !$incline($lix))} {
	    # output accumulated '+' lines
	    if {$pluslines != {}} {
		$w.t insert end $pluslines
		set pluslines {}
	    }
	    if {$ty != {} && $lineno != {}} {
		incr l
	    }
	    continue
	}
	if {!$incline($lix)} continue

	# see if we need to start a new hunk
	if {$ctxstart == {} || $l > $ctxstart + 6} {
	    if {$ctxstart == {}} {
		# insert diff header
		set difftimefmt "%Y-%m-%d %H:%M:%S"
		$w.t insert end "--- $fname.orig\t"
		$w.t insert end [clock format $diffmtime($fname) \
				     -format $difftimefmt]
		$w.t insert end "\n+++ $fname\t"
		$w.t insert end [clock format [clock seconds] \
				     -format $difftimefmt]
		$w.t insert end "\n"
	    } else {
		finishhunk $w $ix $ctxstart $nctx $ndel $nadd
	    }
	    set nctx 0
	    set ndel 0
	    set nadd 0
	    set ctxstart [expr $l - 3]
	    if {$ctxstart < 1} {set ctxstart 1}
	    $w.t insert end "@@ -$ctxstart, "
	    $w.t mark set nminus "end - 2c"
	    $w.t insert end "+[expr $ctxstart + $delta], "
	    $w.t mark set nplus "end - 2c"
	    $w.t insert end "\n"
	}
	while {$ctxstart < $l} {
	    set line [lindex $fcontents($ix) [expr $ctxstart - 1]]
	    $w.t insert end " $line\n"
	    incr nctx
	    incr ctxstart
	}

	if {$lineno != {}} {
	    # delete this line
	    set line [lindex $inf [expr $lineno-1]]
	    $w.t insert end "-$line\n"
	    incr delta -1
	    incr l
	    incr ndel
	} else {
	    # insert this line
	    set line [lindex $m 2]
	    append pluslines "+$line\n"
	    incr delta
	    incr nadd
	}
	set ctxstart $l
    }

    if {$pluslines != {}} {
	$w.t insert end $pluslines
    }
    if {$ctxstart != {}} {
	finishhunk $w $ix $ctxstart $nctx $ndel $nadd
    }
    # delete last newline
    catch {$w.t delete "end - 1c" end}
}

proc finishhunk {w ix ctxstart nctx nneg npos} {
    global fcontents

    set filelen [llength $fcontents($ix)]
    for {set i $ctxstart} {$i < $ctxstart + 3} {incr i} {
	if {$i > $filelen} break
	set line [lindex $fcontents($ix) [expr $i - 1]]
	$w.t insert end " $line\n"
	incr nctx
    }
    $w.t insert nminus [expr $nctx + $nneg]
    $w.t insert nplus [expr $nctx + $npos]
}

proc nextdiff {} {
    global textw linelist
    set l [lindex [split [$textw index @0,0] .] 0]
    set nl [llength $linelist]
    while {[incr l] < $nl} {
	if {[lindex [lindex $linelist $l] 1] == {}} {
	    $textw yview $l.0
	    break
	}
    }
}

proc prevdiff {} {
    global textw linelist
    set l [lindex [split [$textw index @0,0] .] 0]
    while {[incr l -1] > 0} {
	if {[lindex [lindex $linelist $l] 1] == {}} {
	    $textw yview $l.0
	    break
	}
    }
}

proc diffnextfile {inc} {
    global diffdirs selfile numgroups groups dirs textw
    global ycoord canvw origdiffdirs
    if {!([info exists textw] && [winfo exists $textw])} return
    if {![selnextline $inc] || $numgroups <= 1 \
	    || ![info exists origdiffdirs]} {
	return
    }
    set seengrps {}
    set group [lindex $groups($selfile) 1]
    set ds {}
    foreach d $origdiffdirs {
	set i [lindex $group [lsearch $dirs $d]]
	if {$i != 0 && [lsearch -exact $seengrps $i] < 0} {
	    lappend ds $d
	    lappend seengrps $i
	}
    }
    if {[llength $ds] == 2} {
	diff2 [lindex $ds 0] [lindex $ds 1] $selfile 0
    } elseif {[llength $ds] > 2} {
	diffn $ds $selfile 0
    }
}

proc showsomediff {inc} {
    global diffdirs difffile selfile numgroups groups dirs textw
    global ycoord canvw groupelts dirinterest
    if {![selnextline $inc]} return
    if {[lindex $groups($selfile) 0] == "dir"} return

    if {$numgroups <= 1} {
	set xi [lindex $groupelts(1) 0]
	if {$xi != ""} {
	    showfile [lindex $dirs $xi] $selfile
	}
	return
    }

    set dirlist {}
    for {set gn 1} {$gn <= $numgroups} {incr gn} {
	foreach i $groupelts($gn) {
	    if {$dirinterest($i)} {
		lappend dirlist [lindex $dirs $i]
		break
	    }
	}
    }
    if {[llength $dirlist] == 2} {
	diff2 [lindex $dirlist 0] [lindex $dirlist 1] $selfile
    } elseif {[llength $dirlist] > 2} {
	diffn $dirlist $selfile
    }
}

proc copydifffile {} {
    global diffdirs selfile groups dirs changed
    if {![info exists diffdirs] || [llength $diffdirs] != 2} return
    set d1 [lindex $diffdirs 0]
    set d2 [lindex $diffdirs 1]
    if {[lindex $groups($selfile) 0] == "dir"} return
    set group [lindex $groups($selfile) 1]
    set n1 [lsearch $dirs $d1]
    set n2 [lsearch $dirs $d2]
    set i1 [lindex $group $n1]
    set i2 [lindex $group $n2]
    if {$i1 == 0 || $i2 == 0 || $i1 == $i2} return
    set changed 0
    copyfile $n2 $n1 $selfile 0
    if {$changed} redisplay
}

proc maketextw {} {
    global textw texttop mergebut mpatchbut filemode textfont dirs
    toplevel .diffs
    wm title .diffs "Differences"
    frame .diffs.bar -relief sunken -border 2
    pack .diffs.bar -side top -fill x
    button .diffs.bar.rediff -text Rediff -command "diffnextfile 0"
    pack .diffs.bar.rediff -side left
    button .diffs.bar.options -text Options -command diffoptions
    pack .diffs.bar.options -side left
    button .diffs.bar.find -text Find -command "difffind :diffs .diffs.t"
    pack .diffs.bar.find -side left
    menubutton .diffs.bar.merge -text Merge -menu .diffs.bar.merge.m -padx 10
    menu .diffs.bar.merge.m -tearoff 0
    pack .diffs.bar.merge -side left
    menubutton .diffs.bar.mpatch -text Patch -menu .diffs.bar.mpatch.m -padx 10
    menu .diffs.bar.mpatch.m -tearoff 0
    pack .diffs.bar.mpatch -side left
    if {!$filemode} {
	button .diffs.bar.next -text "Next file" -command "diffnextfile 1"
	pack .diffs.bar.next -side left
	button .diffs.bar.prev -text "Previous file" -command "diffnextfile -1"
	pack .diffs.bar.prev -side left
    }
    button .diffs.bar.invert -text "Invert" -command "invertbuttons"
    pack .diffs.bar.invert -side left
    set texttop .diffs
    set textw .diffs.t
    set mergebut .diffs.bar.merge
    set mpatchbut .diffs.bar.mpatch
    set wid [expr 82 + 2 * [llength $dirs]]
    text $textw -width $wid -height 32 -yscrollcommand ".diffs.sb set" \
	-font $textfont
    scrollbar .diffs.sb -command "$textw yview"
    pack .diffs.sb -side right -fill y
    pack $textw -side left -fill both -expand 1
    bind .diffs <Key-Prior> "$textw yview scroll -1 p"
    bind .diffs b "$textw yview scroll -1 p"
    bind .diffs B "$textw yview scroll -1 p"
    bind .diffs <Key-BackSpace> "$textw yview scroll -1 p"
    bind .diffs <Key-Delete> "$textw yview scroll -1 p"
    bind .diffs <Key-Next> "$textw yview scroll 1 p"
    bind .diffs <Key-space> "$textw yview scroll 1 p"
    bind .diffs <Key-Up> "$textw yview scroll -1 u"
    bind .diffs <Key-Down> "$textw yview scroll 1 u"
    bind .diffs d "$textw yview scroll \[expr \"int(\[$textw cget -height\]/2)\"\] u"
    bind .diffs D "$textw yview scroll \[expr \"int(\[$textw cget -height\]/2)\"\] u"
    bind .diffs u "$textw yview scroll \[expr \"int(-\[$textw cget -height\]/2)\"\] u"
    bind .diffs U "$textw yview scroll \[expr \"int(-\[$textw cget -height\]/2)\"\] u"
    bind .diffs n nextdiff
    bind .diffs p prevdiff
    if {!$filemode} {
	bind .diffs N "diffnextfile 1"
	bind .diffs P "diffnextfile -1"
    }
    bind .diffs q removediffs
    bind .diffs Q "set stopped 1; destroy ."
    bind .diffs <Key-Home> "$textw yview 1.0"
    bind .diffs g "$textw yview 1.0"
    bind .diffs <Key-End> "$textw yview -pickplace \[$textw index end\]"
    bind .diffs G "$textw yview -pickplace \[$textw index end\]"
    bind .diffs C copydifffile
}

proc diffoptions {} {
    global optionw
    if {[info exists optionw] && [winfo exists $optionw]} {
	raise $optionw
	return
    }
    set optionw .options
    toplevel $optionw
    wm title .options "Dirdiff options"
    checkbutton $optionw.diffiflag -text "Ignore case" \
	    -offvalue "" -onvalue "-i" -anchor w
    pack $optionw.diffiflag -side top -fill x
    checkbutton $optionw.diffwflag -text "Ignore all white space" \
	    -offvalue "" -onvalue "-w" -anchor w
    pack $optionw.diffwflag -side top -fill x
    checkbutton $optionw.diffbflag -text "Ignore amount of white space" \
	    -offvalue "" -onvalue "-b" -anchor w
    pack $optionw.diffbflag -side top -fill x
    checkbutton $optionw.diffBflag -text "Ignore blank lines" \
	    -offvalue "" -onvalue "-B" -anchor w
    pack $optionw.diffBflag -side top -fill x
    checkbutton $optionw.diffdflag -text "Minimize diffs" \
	    -offvalue "" -onvalue "-d" -anchor w
    pack $optionw.diffdflag -side top -fill x
    checkbutton $optionw.ultabs -text "Underline tabs" -anchor w \
	    -variable underlinetabs -command changeunderlinetabs
    pack $optionw.ultabs -side top -fill x
    checkbutton $optionw.newfirst -text "Newer file first" -anchor w \
	    -variable diffnewfirst
    pack $optionw.newfirst -side top -fill x
    frame $optionw.ctx
    pack $optionw.ctx -side top
    label $optionw.ctx.l -text "Lines of context: "
    pack $optionw.ctx.l -side left
    entry $optionw.ctx.v -width 5 -textvariable ctxlines
    pack $optionw.ctx.v -side left
    button $optionw.save -text "Save options" -command saveoptions
    pack $optionw.save -side top -fill x
    frame $optionw.space -height 6
    pack $optionw.space -side top -fill x
    button $optionw.dismiss -text "Dismiss" -command "destroy $optionw"
    pack $optionw.dismiss -side bottom -fill x
    bind $optionw <Return> "destroy $optionw"
}

proc saveoptions {} {
    global rcsflag diffiflag diffwflag diffbflag diffBflag diffdflag
    global ctxlines showsame underlinetabs nukefiles redisp_immed
    global diffprogram showprogram
    global diffnewfirst textfont filelistfont nxdirmode
    global docvsignore
    set f [open "~/.dirdiff" w]
    puts $f [list set diffprogram $diffprogram]
    puts $f [list set showprogram $showprogram]
    puts $f [list set rcsflag $rcsflag]
    puts $f [list set diffiflag $diffiflag]
    puts $f [list set diffwflag $diffwflag]
    puts $f [list set diffbflag $diffbflag]
    puts $f [list set diffBflag $diffBflag]
    puts $f [list set diffdflag $diffdflag]
    puts $f [list set ctxlines $ctxlines]
    puts $f [list set showsame $showsame]
    puts $f [list set underlinetabs $underlinetabs]
    puts $f [list set redisp_immed $redisp_immed]
    puts $f [list set diffnewfirst $diffnewfirst]
    puts $f [list set nukefiles $nukefiles]
    puts $f [list set filelistfont $filelistfont]
    puts $f [list set textfont $textfont]
    puts $f [list set nxdirmode $nxdirmode]
    puts $f [list set docvsignore $docvsignore]
    close $f
}

proc difffind {tag txt} {
    global dfindw$tag igncase$tag diffiflag regexp$tag backwards$tag
    if {[info exists dfindw$tag] && [winfo exists [set dfindw$tag]]} {
	raise [set dfindw$tag]
	return
    }
    set w .find$tag
    set dfindw$tag $w
    toplevel $w
    wm title $w "Dirdiff: Find"
    frame $w.f
    pack $w.f -side top -fill x -expand 1
    button $w.f.b -text "Find:" -command [list dofind $tag $txt $w]
    bind $w <Return> [list dofind $tag $txt $w]
    pack $w.f.b -side left
    entry $w.f.e
    pack $w.f.e -side right
    if {![info exists igncase$tag]} {
	set igncase$tag [expr {$diffiflag != {}}]
    }
    checkbutton $w.case -variable igncase$tag -text "Ignore case" -anchor w
    pack $w.case -side top -fill x
    checkbutton $w.regexp -variable regexp$tag -text "Regular expression" \
	    -anchor w
    pack $w.regexp -side top -fill x
    checkbutton $w.backwards -variable backwards$tag \
	    -text "Search backwards" -anchor w
    pack $w.backwards -side top -fill x
    button $w.close -text "Close" -command "destroy $w"
    pack $w.close -side top -fill x
}

proc dofind {tag txt w} {
    global dfindw$tag igncase$tag regexp$tag backwards$tag
    if {![winfo exists $txt]} return
    set w [set dfindw$tag]
    set str [$w.f.e get]
    if {$str == {}} return
    set back [set backwards$tag]
    # By default, start the search from the insertion point.
    # If there is a selection, start from the end of the selection for
    # a forwards search, or from the beginning for a backwards search.
    set start [$txt index insert]
    if {[$txt tag ranges sel] != {}} {
	if {$back} {
	    set start [$txt index sel.first]
	} else {
	    set start [$txt index sel.last]
	}
    }
    set opts {}
    if {$back} {
	lappend opts "-backwards"
    }
    if {[set regexp$tag]} {
	lappend opts "-regexp"
    }
    if {[set igncase$tag]} {
	lappend opts "-nocase"
    }
    set pos [eval $txt search $opts -count count -- [list $str] $start]
    if {$pos == {}} {
	bell
	return
    }
    set epos "$pos + $count c"
    $txt mark set insert $epos
    $txt tag remove sel 0.0 end
    $txt tag add sel $pos $epos
    $txt see $epos
    $txt see $pos
}

proc makepatch {d1 d2} {
    global patchnum selfile patchfiles patch_outfile
    global showprogram

    set files [secondarysel $selfile]
    if {$files == {}} {
	error_popup "No files selected!"
	return
    }
    if {![info exists patchnum]} {
	set patchnum 0
    }
    set patchfiles($patchnum) $files

    # Put the diff in a temporary file for external viewer
    if { [llength $showprogram] > 0} {
       set patch_outfile "patch${patchnum}.diff"
       set w [open $patch_outfile w]
    # Or build our own viewer
    } else {
       set w ".patch:$patchnum"
       catch {destroy $w}
       toplevel $w
       wm title $w "Patch: $d1 to $d2"
       frame $w.bar -relief raised -border 2
       pack $w.bar -side top -fill x
       menubutton $w.bar.file -text File -menu $w.bar.file.m -padx 10 -pady 1
       menu $w.bar.file.m -tearoff 0
       $w.bar.file.m add command -label Save -command "savepatch $w"
       $w.bar.file.m add command -label Close -command "destroy $w"
       pack $w.bar.file -side left
       menubutton $w.bar.edit -text Edit -menu $w.bar.edit.m -padx 10 -pady 1
       menu $w.bar.edit.m -tearoff 0
       $w.bar.edit.m add command -label Cut -command "tk_textCut $w.t"
       $w.bar.edit.m add command -label Copy -command "tk_textCopy $w.t"
       $w.bar.edit.m add command -label Paste -command "tk_textPaste $w.t"
       $w.bar.edit.m add command -label Find \
	    -command [list difffind :patch:$patchnum $w.t]
       pack $w.bar.edit -side left
       frame $w.f -relief sunk -border 2
       label $w.f.l -text "Filename: "
       entry $w.f.filename
       $w.f.filename insert 0 "patch$patchnum"
       pack $w.f.l -side left
       pack $w.f.filename -side left -fill x -expand 1
       pack $w.f -side top -fill x
       text $w.t -yscrollcommand "$w.sb set"
       scrollbar $w.sb -command "$w.t yview"
       pack $w.sb -side right -fill y
       pack $w.t -side left -fill both -expand 1
       bind $w <Key-Prior> "$w.t yview scroll -1 p"
       bind $w <Key-Next> "$w.t yview scroll 1 p"
    }

    patchnext $patchnum $w $d1 $d2 0
    incr patchnum
}

# Output lines to either our external patchfile or the internal vieiwer
proc lineout {w line} {
    if {[string match ".*" $w]} {
        $w.t insert end "$line\n"
    } else {
        puts $w "$line"
    }
}

proc patchnext {pnum w d1 d2 i} {
    global patchfiles have_unidiff showprogram patch_outfile nullfile

    set contextopt [expr {$have_unidiff ? "-u" : "-c"}]
    update
    for {} {[set f [lindex $patchfiles($pnum) $i]] != {}} {incr i} {
	set p1 [joinname $d1 $f]
	set p2 [joinname $d2 $f]
	if {[file exists $p1] && [file exists $p2]} {
	    set fh [open [list |diff $contextopt $p1 $p2] r]
	} elseif {[file exists $p1] && ! [file exists $p2]} {
	    set fh [open [list |diff $contextopt $p1 $nullfile] r]
	} elseif {! [file exists $p1] && [file exists $p2]} {
	    set fh [open [list |diff $contextopt $nullfile $p2] r]
	} else {
            continue
	}
	fconfigure $fh -blocking 0
	fileevent $fh readable [list readpatch $fh $pnum $w $d1 $d2 $i $f]
	return
    }
    if {[string match ".*" $w]} {
       $w.t delete "end - 1c" end
    } else {
        close $w
        exec $showprogram $patch_outfile &
        # Should we remove the tempfile here?  We don't have it if we used 
        # the internal viewer
    }
    unset patchfiles($pnum)
}

proc diffl_out {w d1 d2 f} {
    global have_unidiff
    set contextopt [expr {$have_unidiff ? "-urN" : "-cr"}]
    lineout $w "diff $contextopt [joinname $d1 $f] [joinname $d2 $f]"
}

proc readpatch {difff pnum w d1 d2 i f} {
    global have_unidiff showprogram
    set n [gets $difff line]
    if {$n < 0} {
	if {![eof $difff]} return
	catch {close $difff}
	patchnext $pnum $w $d1 $d2 [expr $i+1]
	return
    }
    if {[string match "Binary*" $line]} return
    if {$have_unidiff} {
       if {[string match "---*" $line]} {
           diffl_out $w $d1 $d2 $f
        }
    } else {
       if {[string match "\*\*\* ${d1}*" $line]} {
           diffl_out $w $d1 $d2 $f
        }
    }
    lineout $w $line
}

proc savepatch {w} {
    set outfile [$w.f.filename get]
    if {$outfile == {}} {return}
    set outf [open $outfile w]
    puts -nonewline $outf [$w.t get 0.0 end]
    close $outf
    destroy $w
}

# invoked from the File->Touch menu item
proc touchfiles {d} {
    global selfile
    set files [secondarysel $selfile]
    if {$files == {}} {
	error_popup "No files selected!"
	return
    }
    set now [clock seconds]
    set bad {}
    foreach f $files {
	set df [file join $d $f]
	if {[catch {file mtime $df $now} err]} {
	    append bad "$df: $err\n"
	}
    }
    if {$bad != {}} {
	error_popup "Errors occurred:\n$bad"
    }
    redifffiles
}

proc exclfilelist {} {
    global exclw nukefiles
    if {[info exists exclw] && [winfo exists $exclw]} {
	raise $exclw
	return
    }
    toplevel .excl
    wm title .excl "Dirdiff: excluded files"
    set exclw .excl
    frame $exclw.b
    listbox $exclw.l -height 10 -width 40 -yscrollcommand "$exclw.sb set" \
	    -selectmode single
    scrollbar $exclw.sb -command "$exclw.l yview"
    entry $exclw.e
    pack $exclw.b -side bottom -fill x
    pack $exclw.e -side bottom -fill x
    pack $exclw.sb -side right -fill y
    pack $exclw.l -side left -fill both -expand 1
    button $exclw.b.add -text "Add" -padx 20 -command addexcl
    button $exclw.b.rem -text "Remove" -command remexcl
    button $exclw.b.close -text "Close" -command closeexcl
    pack $exclw.b.add -side left -fill x
    pack $exclw.b.rem -side left -fill x
    pack $exclw.b.close -side right -fill x
    bind $exclw.e <Return> "addexcl"
    foreach i $nukefiles {
	$exclw.l insert end $i
    }
}

proc addexcl {} {
    global exclw nukefiles
    if {[info exists exclw] && [winfo exists $exclw]} {
	set e [$exclw.e get]
	if {$e != {}} {
	    $exclw.l insert end $e
	    lappend nukefiles $e
	    $exclw.l see end
	}
    }
}

proc remexcl {} {
    global exclw nukefiles
    if {[info exists exclw] && [winfo exists $exclw]} {
	set s [$exclw.l curselection]
	if {$s != {}} {
	    $exclw.l delete $s
	    set nukefiles [lreplace $nukefiles $s $s]
	}
    }
}

proc exclsel {} {
    global selfile nukefiles exclw
    set files [secondarysel $selfile]
    foreach f $files {
	set df [string trimright $f /]
	if {$df != {}} {
	    lappend nukefiles $df
	    if {[info exists exclw] && [winfo exists $exclw]} {
		$exclw.l insert end $df
	    }
	}
    }
    redisplay
}

proc extprograms {} {
   global showprogram diffprogram
   toplevel .ext
   frame .ext.top
   label .ext.top.diffl -text "Diff Viewing/Merging"
   entry .ext.top.diffe -textvariable diffprogram
   label .ext.top.showl -text "File Viewing"
   entry .ext.top.showe -textvariable showprogram
   grid .ext.top.diffl -row 0 -column 0 -sticky e
   grid .ext.top.diffe -row 0 -column 1 -sticky nsew -pady 4
   grid .ext.top.showl -row 1 -column 0 -sticky e
   grid .ext.top.showe -row 1 -column 1 -sticky nsew -pady 4
   grid columnconfigure .ext.top 0 -weight 0
   grid columnconfigure .ext.top 1 -weight 1
   pack .ext.top -fill x -expand yes
   frame .ext.bot
   button .ext.bot.ok -text "OK" \
     -command {
        destroy .ext
     }
  pack .ext.bot .ext.bot.ok -fill x -expand yes
}

proc closeexcl {} {
    global exclw
    catch {destroy $exclw}
    catch {unset exclw}
}

proc secondarysel {fname} {
    global secsel canvw
    set files {}
    foreach it [array names secsel] {
	lappend files [$canvw itemcget $it -text]
    }
    if {$files == {}} {
	if {$fname == {}} {
	    return {}
	}
	set files [list $fname]
    }
    return [lsort $files]
}

proc copyselfile {src dst fname confirm} {
    global dirs changed
    set files [secondarysel $fname]
    set n [llength $files]
    set changed 0
    if {$n == 1} {
	copyfile $src $dst $fname $confirm
    } else {
	if {$confirm} {
	    set sd [lindex $dirs $src]
	    set dd [lindex $dirs $dst]
	    if {![confirm_popup "Copy $n older files from $sd to $dd?"]} {
		return
	    }
	}
	foreach f $files {
	    copyfile $src $dst $f 0
	}
    }
    if {$changed} redisplay
    after idle selcurfile
}

proc copyfile {src dst fname confirm} {
    global dirs filemode
    set sd [lindex $dirs $src]
    set dd [lindex $dirs $dst]
    set srcf [joinname $sd $fname]
    set dstf [joinname $dd $fname]
    if {$filemode} {
	set msg "$src to $dst"
	set copydst $dstf
    } else {
	set msg "$fname from $sd to $dd"
	set copydst [file dirname $dstf]
    }
    if {$confirm} {
	if {![confirm_popup "Copy older $msg?"]} {
	    return
	}
    }
    set z [string trimright $fname /]
    if {$z != $fname} {
	copydir $src $dst $z
	return
    }
    scmedit $dstf
    if [catch {file copy -force -- $srcf $copydst} err] {
	error_popup "Error copying $msg: $err"
    } else {
	scmnew $dstf
	updatecline $src $dst $fname
    }
}

proc copydir {src dst dname} {
    global dirs groups alllines
    set sn [lindex $dirs $src]
    set dn [lindex $dirs $dst]
    if [catch {exec cp -p -r $sn/$dname [file dirname $dn/$dname]} err] {
	error_popup "Error copying $dname from $sn to $dn: $err"
	return
    }
    foreach f $alllines {
	if [string match $dname* $f] {
	    updatecline $src $dst $f
	}
    }
}

proc scmedit {name} {
}

proc scmnew {name} {
}

proc removeselfile {dst fname} {
    global groupelts dirs changed
    set files [secondarysel $fname]
    if {$files == {}} return
    set nf 0
    set nd 0
    foreach x $files {
	if {[string range $x end end] == "/"} {
	    incr nd
	} else {
	    incr nf
	}
    }
    set dd [lindex $dirs $dst]
    if {$nd + $nf == 1} {
	set x [string trimright [joinname $dd $fname] /]
	if {![confirm_popup "Remove $x?"]} {
	    return
	}
    } else {
	set stuff "Remove "
	if {$nd > 0} {
	    if {$nd == 1} {
		append stuff "1 directory "
	    } else {
		append stuff "$nd directories "
	    }
	    if {$nf > 0} {
		append stuff "and "
	    }
	}
	if {$nf == 1} {
	    append stuff "1 file "
	} elseif {$nf > 1} {
	    append stuff "$nf files "
	}
	append stuff "from $dd?"
	if {![confirm_popup $stuff]} {
	    return
	}
    }
    set changed 0
    foreach f $files {
	set d [string trimright $f /]
	set dstf [joinname $dd $d]
	if {$d == $f} {
	    set bad [catch {file delete $dstf} err]
	} else {
	    set bad [catch {file delete -force $dstf} err]
	}
	if $bad {
	    error_popup "Error deleting $dstf: $err"
	} else {
	    updatecline [lindex $groupelts(0) 0] $dst $f
	}
    }
    if {$changed} redisplay
    after idle selcurfile
}

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 error_popup msg {
    set w .error
    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 "destroy $w"
    pack $w.ok -side bottom -fill x
    bind $w <Visibility> "grab $w; focus $w"
    tkwait window $w
}

proc notalldirs {dirs} {
    set type ""
    foreach d $dirs {
	if {[catch {file lstat $d stat} err]} {
	    puts stderr $err
	    exit 1
	}
	if {$type == ""} {
	    set type $stat(type)
	} elseif {$type != $stat(type)} {
	    puts stderr "Error: $d is a $stat(type) but [lindex $dirs 0] is a $type"
	    exit 1
	}
    }
    return [expr {$type == "file"}]
}

proc go {} {
    global diffing filemode dirs nextserial
    if {[llength $dirs] == 0} {exit 0}
    set diffing 0
    set nextserial 0
    set filemode [notalldirs $dirs]
    icons
    makewins
    initcanv
    resetsel
    removediffs
    update
    canvdiffs
}

proc rediff {} {
    initcanv
    resetsel
    removediffs
    update
    canvdiffs
}

proc repackgroups {gr} {
    if {[lindex $gr 0] == "dir"} {
	return $gr
    }
    set glist [lindex $gr 1]
    set glsort [lsort $glist]
    set ng(0) 0
    set lg 0
    set gc 0
    foreach e $glsort {
	if {$e != $lg} {
	    set lg $e
	    incr gc
	    set ng($e) $gc
	}
    }
    if {$gc == [lindex $gr 0]} {
	return $gr
    }
    set newlist {}
    foreach e $glist {
	lappend newlist $ng($e)
    }
    return [list $gc $newlist]
}

proc interesting_line {gr} {
    global dirinterest dirs showsame
    if {$gr == {}} {
	return 0
    }
    if {$showsame} {
	return 1
    }
    set glist [lindex $gr 1]
    set i 0
    foreach e $glist {
	if $dirinterest($i) {
	    if {[info exists first]} {
		if {$e != $first} {
		    return 1
		}
	    } else {
		set first $e
	    }
	}
	incr i
    }
    return 0
}

proc redisplay {{zapdiffs 0}} {
    global canvw canvy canvy0 alllines groups ruletype linespc stringx
    global ruletype selfile secsel ycoord filemode redisp_immed
    if {$filemode || !($zapdiffs || $redisp_immed)} return
    set y [expr {[lindex [$canvw yview] 0] * $canvy}]
    set i [textitemat [expr {$stringx+5}] [expr {$y + $linespc/2}]]
    set topy 0
    set topline {}
    if {$i != {}} {
	set topline [$canvw itemcget $i -text]
    }
    if {$zapdiffs} {
	removediffs
    } else {
	set filesel $selfile
	set filesecsel [secondarysel $selfile]
    }
    $canvw delete all
    set canvy $canvy0
    $canvw conf -scrollregion "0 0 0 1"
    catch {unset ycoord}
    resetsel
    foreach f $alllines {
	if {$f == $topline} {
	    set topy $canvy
	}
	set gr $groups($f)
	if {$gr != {} && [notnuked [string trimright $f /]]} {
	    set gr [repackgroups $gr]
	    set groups($f) $gr
	    if {[interesting_line $gr]} {
		displine $gr $f
	    }
	}
    }
    if {[info exists ruletype]} {
	ruleoff $ruletype
    }
    if {$canvy > 0} {
	$canvw yview moveto [expr {$topy * 1.0 / $canvy}]
    } else {
	$canvw yview moveto 0
    }
    if {!$zapdiffs} {
	foreach f $filesecsel {
	    set i [itemofname $f]
	    if {$i != {}} {
		addsecsel $i
	    }
	}
	set i [itemofname $filesel]
	if {$i != {}} {
	    selectitem $i
	    addsecsel $i
	}
	selcurfile
    }
}

proc icons {} {
   global agecolors

   image create photo ex \
       -format gif -data {
R0lGODlhEAANAIAAAAAAAP///yH+Dk1hZGUgd2l0aCBHSU1QACH5BAEAAAEA
LAAAAAAQAA0AAAIgjI95ABqcWENSVXMtzE5CR30g5o3PJkYiR05LenauqRQA
Ow==
}
   image create photo folder \
       -format gif -data {
R0lGODlhEAANAMIAAISEhMbGxv/si////wAAAAAAAAAAAAAAACH+Dk1hZGUg
d2l0aCBHSU1QACH5BAEAAAQALAAAAAAQAA0AAAMoSATM+nAFQUUAUYFZ6W3g
II4kyQxd2p1qy7bpC1fyLNQzDusu6P+ABAA7
}
   image create photo paper \
       -format gif -data {
R0lGODlhEAANAKEAAISEhP///8bGxgAAACH+Dk1hZGUgd2l0aCBHSU1QACH5
BAEAAAMALAAAAAAQAA0AAAIp3ICpxhcPAxCgufhAoE1jmXRfVDHeKIloaq6s
cY4l7M4XasdfrvSIUQAAOw==
}
   image create photo paper_green \
       -format gif -data {
R0lGODlhEAANAMIAAP///4SEhP7/vsbGxgDKAP///////////yH5BAEAAAcALAAAAAAQAA0A
AAMoeBfcrnCRSUmwUdZ5Mezb821hBJKecpKBiVLt+KbaG6szvZaf4zOKBAA7
}
   image create photo paper_yellowgreen \
       -format gif -data {
R0lGODlhEAANAMIAAP///4SEhP7/vsbGxgCAAACAQNLmAP///yH5BAEAAAcALAAAAAAQAA0A
AAMoeBfcrnCZSU2wUdZ5Mezb821hBJKecpKBiVLt+KbaG6szvZaf4zOKBAA7
}
   image create photo paper_yellow \
       -format gif -data {
R0lGODlhEAANAMIAAP///4SEhPfhAMbGxv///////////////yH5BAEAAAMALAAAAAAQAA0A
AAMoOBPcrnCJSUWwUdZ5Mezb821hBJKecpKBiVLt+KbaG6szvZaf4zOKBAA7
}
   image create photo paper_orange \
       -format gif -data {
R0lGODlhEAANAMIAAP///4SEhOxzAMbGxv///////////////yH5BAEAAAMALAAAAAAQAA0A
AAMoOBPcrnCJSUWwUdZ5Mezb821hBJKecpKBiVLt+KbaG6szvZaf4zOKBAA7
}
   image create photo paper_red \
       -format gif -data {
R0lGODlhEAANAKEAAISEhOE+IbchAP///yH5BAEAAAMALAAAAAAQAA0AAAIo3ICpxhcPA5DN
xQcEZfPK1HQeFo4QUJqbIY4op66W+bJxPbuhwiNGAQA7
}


   set agecolors(dir) {ex folder}
   set agecolors(0) {ex}
   set agecolors(1) {ex paper}
   set agecolors(2) {ex paper_green paper_red}
   set agecolors(3) {ex paper_green paper_yellow paper_red}
   set agecolors(4) {ex paper_green paper_yellow paper_orange paper_red}
   set agecolors(5) {ex paper_green paper_yellowgreen paper_yellow paper_orange paper_red}
}

proc midy {bbox} {
    return [expr ([lindex $bbox 1] + [lindex $bbox 3]) / 2]
}

proc search_canvas {} {
    global canvw selfile clickitem clickmode clicky
    set search $selfile
    resetsel
    update
    set str_items [$canvw find withtag strings]
    foreach idx $str_items {
	set name [$canvw itemcget $idx -text]
	if {[string match "*$search*" $name]} {
	    set selitem $idx
	    $canvw select from $idx 0
	    $canvw select to $idx end
	    set clickitem $idx
	    set clicky [midy [$canvw bbox $clickitem]]
	    set clickmode 1
	    selcurfile
	    addsecsel $idx
	}
    }
}

if {![info exists dirs]} {
    global onlyfiles ctxlines showsame
    set dirs {}
    set ok 1
    set argc [llength $argv]
    set moreopts 1
    for {set i 0} {$i < $argc} {incr i} {
	set arg [lindex $argv $i]
	if {$moreopts && [string range $arg 0 0] == "-"} {
	    switch -regexp -- $arg {
		"--" {
		    set moreopts 0
		}
		"-a|--all" {
		    set nukefiles {}
		}
		"-o|--only" {
		    incr i
		    if {$i < $argc} {
			lappend onlyfiles [lindex $argv $i]
			set nukefiles {}
		    } else {
			puts stderr "no argument given to $arg option"
			set ok 0
		    }
		}
		"-I|--ignore" {
		    incr i
		    if {$i < $argc} {
			ignorefile [lindex $argv $i]
		    } else {
			puts stderr "no argument given to $arg option"
			set ok 0
		    }
		}
		"-r|--rcs" {
		    if $nofilecmp {
			puts stderr "can't use $arg: libfilecmp.so.0.0 couldn't be loaded"
			set ok 0
		    }
		    set rcsflag "-rcs"
		}
		"-c|--context" {
		    incr i
		    if {$i < $argc} {
			set ctxlines [lindex $argv $i]
		    } else {
			puts stderr "no argument given to $arg option"
			set ok 0
		    }
		}
		"-D|--maxdepth" {
		    incr i
		    if {$i < $argc} {
			set maxdepth [lindex $argv $i]
		    } else {
			puts stderr "no argument given to $arg option"
			set ok 0
		    }
		}
		"-b" { set diffbflag "-b" }
		"-w" { set diffwflag "-w" }
		"-B" { set diffBflag "-B" }
		"-i" { set diffiflag "-i" }
		"-d" { set diffdflag "-d" }
		"-S" { set showsame 1 }
		"-C" { set docvsignore 1 }
		"-h|--help" {
		    usage
		    exit 0
		}
		default {
		    puts stderr "unrecognized option $arg"
		    set ok 0
		}
	    }
	} elseif {$arg != {}} {
	    lappend dirs $arg
	}
    }
    if {$ok && [llength $dirs] == 0} {
        # Ask for directories if they weren't on the command line
        wm withdraw .
        NewDirDialog
        #set dirs [list $d0 $d1 $d2 $d3 $d4]
        # Prune out the empty entries
        set newlist {}
        for {set i 0} {$i < [llength $dirs]} {incr i} {
           if {[lindex $dirs $i] != {} } {
               lappend newlist [lindex $dirs $i]
           }
        }
        set dirs $newlist
        if {[llength $dirs] < 2 } {
            # Can't user error_popup here without de-iconifying . first
            tk_dialog .err "Error" "Need at least 2 directories" error 0 {OK}
	    set ok 0
        }
        wm deiconify .
    }
    if {!$ok} {exit 1}
    set newd {}
    foreach d $dirs {
	set x [glob -nocomplain $d]
	if {$x == {}} {
	    set x $d
	}
	set newd [concat $newd $x]
    }
    if {[llength $newd] > 5} {
	puts stderr "Error: more than 5 directories or files specified"
	exit 1
    }
    set dirs $newd
    set doit 1
}

if [info exists doit] {go}