gitk: Add a font chooser

This adds buttons to the edit preferences window to allow the user to
choose the main font, the text font (used for the diff display window)
and the UI font.  Pressing those buttons pops up a font chooser window
that lets the user pick the font family, size, weight (bold/normal)
and slant (roman/italic).

Signed-off-by: Paul Mackerras <paulus@samba.org>

gitk

@@ -7875,6 +7875,130 @@ proc doquit {} {
     destroy .
 }
 
+proc mkfontdisp {font top which} {
+    global fontattr fontpref $font
+
+    set fontpref($font) [set $font]
+    button $top.${font}but -text $which -font optionfont \
+	-command [list choosefont $font $which]
+    label $top.$font -relief flat -font $font \
+	-text $fontattr($font,family) -justify left
+    grid x $top.${font}but $top.$font -sticky w
+}
+
+proc choosefont {font which} {
+    global fontparam fontlist fonttop fontattr
+
+    set fontparam(which) $which
+    set fontparam(font) $font
+    set fontparam(family) [font actual $font -family]
+    set fontparam(size) $fontattr($font,size)
+    set fontparam(weight) $fontattr($font,weight)
+    set fontparam(slant) $fontattr($font,slant)
+    set top .gitkfont
+    set fonttop $top
+    if {![winfo exists $top]} {
+	font create sample
+	eval font config sample [font actual $font]
+	toplevel $top
+	wm title $top "Gitk font chooser"
+	label $top.l -textvariable fontparam(which) -font uifont
+	pack $top.l -side top
+	set fontlist [lsort [font families]]
+	frame $top.f
+	listbox $top.f.fam -listvariable fontlist \
+	    -yscrollcommand [list $top.f.sb set]
+	bind $top.f.fam <<ListboxSelect>> selfontfam
+	scrollbar $top.f.sb -command [list $top.f.fam yview]
+	pack $top.f.sb -side right -fill y
+	pack $top.f.fam -side left -fill both -expand 1
+	pack $top.f -side top -fill both -expand 1
+	frame $top.g
+	spinbox $top.g.size -from 4 -to 40 -width 4 \
+	    -textvariable fontparam(size) \
+	    -validatecommand {string is integer -strict %s}
+	checkbutton $top.g.bold -padx 5 \
+	    -font {{Times New Roman} 12 bold} -text "B" -indicatoron 0 \
+	    -variable fontparam(weight) -onvalue bold -offvalue normal
+	checkbutton $top.g.ital -padx 5 \
+	    -font {{Times New Roman} 12 italic} -text "I" -indicatoron 0  \
+	    -variable fontparam(slant) -onvalue italic -offvalue roman
+	pack $top.g.size $top.g.bold $top.g.ital -side left
+	pack $top.g -side top
+	canvas $top.c -width 150 -height 50 -border 2 -relief sunk \
+	    -background white
+	$top.c create text 100 25 -anchor center -text $which -font sample \
+	    -fill black -tags text
+	bind $top.c <Configure> [list centertext $top.c]
+	pack $top.c -side top -fill x
+	frame $top.buts
+	button $top.buts.ok -text "OK" -command fontok -default active \
+	    -font uifont
+	button $top.buts.can -text "Cancel" -command fontcan -default normal \
+	    -font uifont
+	grid $top.buts.ok $top.buts.can
+	grid columnconfigure $top.buts 0 -weight 1 -uniform a
+	grid columnconfigure $top.buts 1 -weight 1 -uniform a
+	pack $top.buts -side bottom -fill x
+	trace add variable fontparam write chg_fontparam
+    } else {
+	raise $top
+	$top.c itemconf text -text $which
+    }
+    set i [lsearch -exact $fontlist $fontparam(family)]
+    if {$i >= 0} {
+	$top.f.fam selection set $i
+	$top.f.fam see $i
+    }
+}
+
+proc centertext {w} {
+    $w coords text [expr {[winfo width $w] / 2}] [expr {[winfo height $w] / 2}]
+}
+
+proc fontok {} {
+    global fontparam fontpref prefstop
+
+    set f $fontparam(font)
+    set fontpref($f) [list $fontparam(family) $fontparam(size)]
+    if {$fontparam(weight) eq "bold"} {
+	lappend fontpref($f) "bold"
+    }
+    if {$fontparam(slant) eq "italic"} {
+	lappend fontpref($f) "italic"
+    }
+    set w $prefstop.$f
+    $w conf -text $fontparam(family) -font $fontpref($f)
+	
+    fontcan
+}
+
+proc fontcan {} {
+    global fonttop fontparam
+
+    if {[info exists fonttop]} {
+	catch {destroy $fonttop}
+	catch {font delete sample}
+	unset fonttop
+	unset fontparam
+    }
+}
+
+proc selfontfam {} {
+    global fonttop fontparam
+
+    set i [$fonttop.f.fam curselection]
+    if {$i ne {}} {
+	set fontparam(family) [$fonttop.f.fam get $i]
+    }
+}
+
+proc chg_fontparam {v sub op} {
+    global fontparam
+
+    font config sample -$sub $fontparam($sub)
+}
+
 proc doprefs {} {
     global maxwidth maxgraphpct diffopts
     global oldprefs prefstop showneartags showlocalchanges
@@ -7958,6 +8082,13 @@ proc doprefs {} {
 	-command [list choosecolor selectbgcolor 0 $top.selbgsep background setselbg]
     grid x $top.selbgbut $top.selbgsep -sticky w
 
+    label $top.cfont -text "Fonts: press to choose"
+    $top.cfont configure -font uifont
+    grid $top.cfont - -sticky w -pady 10
+    mkfontdisp mainfont $top "Main font"
+    mkfontdisp textfont $top "Diff display font"
+    mkfontdisp uifont $top "User interface font"
+
     frame $top.buts
     button $top.buts.ok -text "OK" -command prefsok -default active
     $top.buts.ok configure -font uifont
@@ -8018,14 +8149,37 @@ proc prefscan {} {
     }
     catch {destroy $prefstop}
     unset prefstop
+    fontcan
 }
 
 proc prefsok {} {
     global maxwidth maxgraphpct
     global oldprefs prefstop showneartags showlocalchanges
+    global fontpref mainfont textfont uifont
 
     catch {destroy $prefstop}
     unset prefstop
+    fontcan
+    set fontchanged 0
+    if {$mainfont ne $fontpref(mainfont)} {
+	set mainfont $fontpref(mainfont)
+	parsefont mainfont $mainfont
+	eval font configure mainfont [fontflags mainfont]
+	eval font configure mainfontbold [fontflags mainfont 1]
+	setcoords
+	set fontchanged 1
+    }
+    if {$textfont ne $fontpref(textfont)} {
+	set textfont $fontpref(textfont)
+	parsefont textfont $textfont
+	eval font configure textfont [fontflags textfont]
+	eval font configure textfontbold [fontflags textfont 1]
+    }
+    if {$uifont ne $fontpref(uifont)} {
+	set uifont $fontpref(uifont)
+	parsefont uifont $uifont
+	eval font configure uifont [fontflags uifont]
+    }
     settabs
     if {$showlocalchanges != $oldprefs(showlocalchanges)} {
 	if {$showlocalchanges} {
@@ -8034,7 +8188,7 @@ proc prefsok {} {
 	    dohidelocalchanges
 	}
     }
-    if {$maxwidth != $oldprefs(maxwidth)
+    if {$fontchanged || $maxwidth != $oldprefs(maxwidth)
 	|| $maxgraphpct != $oldprefs(maxgraphpct)} {
 	redisplay
     } elseif {$showneartags != $oldprefs(showneartags)} {