From da4d86da97a316413cf25bef99332525dbfb4d59 Mon Sep 17 00:00:00 2001
From: Stefan Haller <stefan@haller-berlin.de>
Date: Fri, 18 Dec 2020 10:43:14 +0100
Subject: [PATCH] git-gui: use gray background for inactive text widgets

This makes it easier to see at a glance which of the four main views has the
keyboard focus.

Signed-off-by: Stefan Haller <stefan@haller-berlin.de>
Signed-off-by: Pratyush Yadav <me@yadavpratyush.com>
---
 git-gui.sh     | 18 ++++++++++++------
 lib/themed.tcl | 35 +++++++++++++++++++++++++----------
 2 files changed, 37 insertions(+), 16 deletions(-)

diff --git a/git-gui.sh b/git-gui.sh
index cc6c2aa2c3..201524c34e 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -720,9 +720,6 @@ proc rmsel_tag {text} {
 		-background [$text cget -background] \
 		-foreground [$text cget -foreground] \
 		-borderwidth 0
-	$text tag conf in_sel\
-		-background $color::select_bg \
-		-foreground $color::select_fg
 	bind $text <Motion> break
 	return $text
 }
@@ -3328,11 +3325,20 @@ if {!$use_ttk} {
 	.vpane.files paneconfigure .vpane.files.index -sticky news
 }
 
+proc set_selection_colors {w has_focus} {
+	foreach tag [list in_diff in_sel] {
+		$w tag conf $tag \
+			-background [expr {$has_focus ? $color::select_bg : $color::inactive_select_bg}] \
+			-foreground [expr {$has_focus ? $color::select_fg : $color::inactive_select_fg}]
+	}
+}
+
 foreach i [list $ui_index $ui_workdir] {
 	rmsel_tag $i
-	$i tag conf in_diff \
-		-background $color::select_bg \
-		-foreground $color::select_fg
+
+	set_selection_colors $i 0
+	bind $i <FocusIn>	{ set_selection_colors %W 1 }
+	bind $i <FocusOut>	{ set_selection_colors %W 0 }
 }
 unset i
 
diff --git a/lib/themed.tcl b/lib/themed.tcl
index 244c061391..f43d84e54f 100644
--- a/lib/themed.tcl
+++ b/lib/themed.tcl
@@ -6,19 +6,25 @@ namespace eval color {
 	# Variable colors
 	# Preffered way to set widget colors is using add_option.
 	# In some cases, like with tags in_diff/in_sel, we use these colors.
-	variable select_bg		lightgray
-	variable select_fg		black
+	variable select_bg				lightgray
+	variable select_fg				black
+	variable inactive_select_bg		lightgray
+	variable inactive_select_fg		black
 
 	proc sync_with_theme {} {
-		set base_bg		[ttk::style lookup . -background]
-		set base_fg		[ttk::style lookup . -foreground]
-		set text_bg		[ttk::style lookup Treeview -background]
-		set text_fg		[ttk::style lookup Treeview -foreground]
-		set select_bg	[ttk::style lookup Default -selectbackground]
-		set select_fg	[ttk::style lookup Default -selectforeground]
+		set base_bg				[ttk::style lookup . -background]
+		set base_fg				[ttk::style lookup . -foreground]
+		set text_bg				[ttk::style lookup Treeview -background]
+		set text_fg				[ttk::style lookup Treeview -foreground]
+		set select_bg			[ttk::style lookup Default -selectbackground]
+		set select_fg			[ttk::style lookup Default -selectforeground]
+		set inactive_select_bg	[convert_rgb_to_gray $select_bg]
+		set inactive_select_fg	$select_fg
 
 		set color::select_bg $select_bg
 		set color::select_fg $select_fg
+		set color::inactive_select_bg $inactive_select_bg
+		set color::inactive_select_fg $inactive_select_fg
 
 		proc add_option {key val} {
 			option add $key $val widgetDefault
@@ -36,11 +42,20 @@ namespace eval color {
 		add_option *Text.Foreground $text_fg
 		add_option *Text.selectBackground $select_bg
 		add_option *Text.selectForeground $select_fg
-		add_option *Text.inactiveSelectBackground $select_bg
-		add_option *Text.inactiveSelectForeground $select_fg
+		add_option *Text.inactiveSelectBackground $inactive_select_bg
+		add_option *Text.inactiveSelectForeground $inactive_select_fg
 	}
 }
 
+proc convert_rgb_to_gray {rgb} {
+	# Simply take the average of red, green and blue. This wouldn't be good
+	# enough for, say, converting a photo to grayscale, but for this simple
+	# purpose of approximating the brightness of a color it's good enough.
+	lassign [winfo rgb . $rgb] r g b
+	set gray [expr {($r / 256 + $g / 256 + $b / 256) / 3}]
+	return [format "#%2.2X%2.2X%2.2X" $gray $gray $gray]
+}
+
 proc ttk_get_current_theme {} {
 	# Handle either current Tk or older versions of 8.5
 	if {[catch {set theme [ttk::style theme use]}]} {