Compress the graph horizontally if it gets too wide.

If the graph gets to use more than a certain percentage (default 50%)
of the width of the top-left pane, we now reduce the amount of space
allowed for each graph line.  This means it doesn't look quite as
nice but you can still see the headline for the commit.  (Currently
the only way to customize the percentage is to edit your ~/.gitk
file manually.)

gitk

@@ -480,7 +480,7 @@ proc click {w} {
 
 proc savestuff {w} {
     global canv canv2 canv3 ctext cflist mainfont textfont
-    global stuffsaved findmergefiles gaudydiff
+    global stuffsaved findmergefiles gaudydiff maxgraphpct
 
     if {$stuffsaved} return
     if {![winfo viewable .]} return
@@ -490,6 +490,7 @@ proc savestuff {w} {
 	puts $f [list set textfont $textfont]
 	puts $f [list set findmergefiles $findmergefiles]
 	puts $f [list set gaudydiff $gaudydiff]
+	puts $f [list set maxgraphpct $maxgraphpct]
 	puts $f "set geometry(width) [winfo width .ctop]"
 	puts $f "set geometry(height) [winfo height .ctop]"
 	puts $f "set geometry(canv1) [expr [winfo width $canv]-2]"
@@ -694,7 +695,7 @@ proc bindline {t id} {
 
 proc drawcommitline {level} {
     global parents children nparents nchildren todo
-    global canv canv2 canv3 mainfont namefont canvx0 canvy linespc
+    global canv canv2 canv3 mainfont namefont canvy linespc
     global lineid linehtag linentag linedtag commitinfo
     global colormap numcommits currentparents dupparents
     global oldlevel oldnlines oldtodo
@@ -728,7 +729,7 @@ proc drawcommitline {level} {
 	    }
 	}
     }
-    set x [expr $canvx0 + $level * $linespc]
+    set x [xcoord $level $level $lineno]
     set y1 $canvy
     set canvy [expr $canvy + $linespc]
     allcanvs conf -scrollregion \
@@ -756,7 +757,7 @@ proc drawcommitline {level} {
 	       -fill $ofill -outline black -width 1]
     $canv raise $t
     $canv bind $t <1> {selcanvline {} %x %y}
-    set xt [expr $canvx0 + [llength $todo] * $linespc]
+    set xt [xcoord [llength $todo] $level $lineno]
     if {[llength $currentparents] > 2} {
 	set xt [expr {$xt + ([llength $currentparents] - 2) * $linespc}]
     }
@@ -832,8 +833,8 @@ proc drawtags {id x xt y1} {
 proc updatetodo {level noshortcut} {
     global currentparents ncleft todo
     global mainline oldlevel oldtodo oldnlines
-    global canvx0 canvy linespc mainline
-    global commitinfo
+    global canvy linespc mainline
+    global commitinfo lineno xspc1
 
     set oldlevel $level
     set oldtodo $todo
@@ -842,10 +843,11 @@ proc updatetodo {level noshortcut} {
 	set p [lindex $currentparents 0]
 	if {$ncleft($p) == 1 && [lsearch -exact $todo $p] < 0} {
 	    set ncleft($p) 0
-	    set x [expr $canvx0 + $level * $linespc]
+	    set x [xcoord $level $level $lineno]
 	    set y [expr $canvy - $linespc]
 	    set mainline($p) [list $x $y]
 	    set todo [lreplace $todo $level $level $p]
+	    set xspc1([expr {$lineno + 1}]) $xspc1($lineno)
 	    return 0
 	}
     }
@@ -891,28 +893,54 @@ proc notecrossings {id lo hi corner} {
     }
 }
 
-proc drawslants {} {
-    global canv mainline sidelines canvx0 canvy linespc
-    global oldlevel oldtodo todo currentparents dupparents
-    global lthickness linespc canvy colormap
+proc xcoord {i level ln} {
+    global canvx0 xspc1 xspc2
+
+    set x [expr {$canvx0 + $i * $xspc1($ln)}]
+    if {$i > 0 && $i == $level} {
+	set x [expr {$x + 0.5 * ($xspc2 - $xspc1($ln))}]
+    } elseif {$i > $level} {
+	set x [expr {$x + $xspc2 - $xspc1($ln)}]
+    }
+    return $x
+}
 
+proc drawslants {level} {
+    global canv mainline sidelines canvx0 canvy xspc1 xspc2 lthickness
+    global oldlevel oldtodo todo currentparents dupparents
+    global lthickness linespc canvy colormap lineno geometry
+    global maxgraphpct
+
+    # decide on the line spacing for the next line
+    set lj [expr {$lineno + 1}]
+    set maxw [expr {$maxgraphpct * $geometry(canv1) / 100}]
+    set n [llength $todo]
+    if {$n <= 1 || $canvx0 + $n * $xspc2 <= $maxw} {
+	set xspc1($lj) $xspc2
+    } else {
+	set xspc1($lj) [expr {($maxw - $canvx0 - $xspc2) / ($n - 1)}]
+	if {$xspc1($lj) < $lthickness} {
+	    set xspc1($lj) $lthickness
+	}
+    }
+
     set y1 [expr $canvy - $linespc]
     set y2 $canvy
     set i -1
     foreach id $oldtodo {
 	incr i
 	if {$id == {}} continue
-	set xi [expr {$canvx0 + $i * $linespc}]
+	set xi [xcoord $i $oldlevel $lineno]
 	if {$i == $oldlevel} {
 	    foreach p $currentparents {
 		set j [lsearch -exact $todo $p]
 		set coords [list $xi $y1]
-		set xj [expr {$canvx0 + $j * $linespc}]
-		if {$j < $i - 1} {
-		    lappend coords [expr $xj + $linespc] $y1
+		set xj [xcoord $j $level $lj]
+		if {$xj < $xi - $linespc} {
+		    lappend coords [expr {$xj + $linespc}] $y1
 		    notecrossings $p $j $i [expr {$j + 1}]
-		} elseif {$j > $i + 1} {
-		    lappend coords [expr $xj - $linespc] $y1
+		} elseif {$xj > $xi + $linespc} {
+		    lappend coords [expr {$xj - $linespc}] $y1
 		    notecrossings $p $i $j [expr {$j - 1}]
 		}
 		if {[lsearch -exact $dupparents $p] >= 0} {
@@ -924,28 +952,48 @@ proc drawslants {} {
 		    }
 		} else {
 		    # normal case, no parent duplicated
+		    set yb $y2
+		    set dx [expr {abs($xi - $xj)}]
+		    if {0 && $dx < $linespc} {
+			set yb [expr {$y1 + $dx}]
+		    }
 		    if {![info exists mainline($p)]} {
-			if {$i != $j} {
-			    lappend coords $xj $y2
+			if {$xi != $xj} {
+			    lappend coords $xj $yb
 			}
 			set mainline($p) $coords
 		    } else {
-			lappend coords $xj $y2
+			lappend coords $xj $yb
+			if {$yb < $y2} {
+			    lappend coords $xj $y2
+			}
 			lappend sidelines($p) [list $coords 1]
 		    }
 		}
 	    }
-	} elseif {[lindex $todo $i] != $id} {
-	    set j [lsearch -exact $todo $id]
-	    set xj [expr {$canvx0 + $j * $linespc}]
-	    lappend mainline($id) $xi $y1 $xj $y2
+	} else {
+	    set j $i
+	    if {[lindex $todo $i] != $id} {
+		set j [lsearch -exact $todo $id]
+	    }
+	    if {$j != $i || $xspc1($lineno) != $xspc1($lj)
+		|| ($oldlevel <= $i && $i <= $level)
+		|| ($level <= $i && $i <= $oldlevel)} {
+		set xj [xcoord $j $level $lj]
+		set dx [expr {abs($xi - $xj)}]
+		set yb $y2
+		if {0 && $dx < $linespc} {
+		    set yb [expr {$y1 + $dx}]
+		}
+		lappend mainline($id) $xi $y1 $xj $yb
+	    }
 	}
     }
 }
 
 proc decidenext {{noread 0}} {
     global parents children nchildren ncleft todo
-    global canv canv2 canv3 mainfont namefont canvx0 canvy linespc
+    global canv canv2 canv3 mainfont namefont canvy linespc
     global datemode cdate
     global commitinfo
     global currentparents oldlevel oldnlines oldtodo
@@ -1036,7 +1084,7 @@ proc drawcommit {id} {
 	    return
 	}
 	while 1 {
-	    drawslants
+	    drawslants $level
 	    drawcommitline $level
 	    if {[updatetodo $level $datemode]} {
 		set level [decidenext 1]
@@ -1065,8 +1113,8 @@ proc finishcommits {} {
 	    -font $mainfont -tags textitems
 	set phase {}
     } else {
-	drawslants
 	set level [decidenext]
+	drawslants $level
 	drawrest $level [llength $startcommits]
     }
     . config -cursor $maincursor
@@ -1114,7 +1162,7 @@ proc drawrest {level startix} {
 	    if {$hard} {
 		set level [decidenext]
 		if {$level < 0} break
-		drawslants
+		drawslants $level
 	    }
 	    if {[clock clicks -milliseconds] >= $nextupdate} {
 		update
@@ -2451,10 +2499,14 @@ proc listboxsel {} {
 
 proc setcoords {} {
     global linespc charspc canvx0 canvy0 mainfont
+    global xspc1 xspc2
+
     set linespc [font metrics $mainfont -linespace]
     set charspc [font measure $mainfont "m"]
     set canvy0 [expr 3 + 0.5 * $linespc]
     set canvx0 [expr 3 + 0.5 * $linespc]
+    set xspc1(0) $linespc
+    set xspc2 $linespc
 }
 
 proc redisplay {} {
@@ -2941,6 +2993,7 @@ set mainfont {Helvetica 9}
 set textfont {Courier 9}
 set findmergefiles 0
 set gaudydiff 0
+set maxgraphpct 50
 
 set colors {green red blue magenta darkgrey brown orange}