[mutter] theme: Allow using custom colors from the GTK+ theme

[Florian MÃllner <fmuellner src gnome org>]

commit 54b2fab849dee46c55314edaaae048886a5d335c
Author: Florian MÃllner <fmuellner gnome org>
Date:   Wed May 4 16:13:55 2011 +0200

    theme: Allow using custom colors from the GTK+ theme
    
    Add an additional color type to pick up colors defined with
    @define-color in the GTK+ theme's CSS:
    
      gtk:custom(name,fallback)
    
    (where "name" refers to the name defined in GTK+'s CSS, and fallback
    refers to an alternative color spec which is used when the color
    referenced by "name" is not found)
    
    The main intent of the change is to allow designers to improve
    Adwaita's dark theme variant without having to compromise on colors
    which work in the light variant as well.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=648709

 doc/theme-format.txt   |   12 ++++++
 src/ui/theme-parser.c  |    2 +-
 src/ui/theme-private.h |    5 +++
 src/ui/theme.c         |   92 +++++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 109 insertions(+), 2 deletions(-)
---
diff --git a/doc/theme-format.txt b/doc/theme-format.txt
index 52e4099..2a58e35 100644
--- a/doc/theme-format.txt
+++ b/doc/theme-format.txt
@@ -22,6 +22,18 @@ This document has separate sections for each format version. You may
 want to read the document in reverse order, since the base features
 are discussed under version 1.
 
+New Features in Theme Format Version 3.4
+========================================
+
+An additional color type is added to pick up custom colors defined
+in the GTK+ theme's CSS:
+
+  gtk:custom(name,fallback)
+
+where <name> refers to a custom color defined with @define-color in
+the GTK+ theme, and <fallback> provides an alternative color definition
+in case the color referenced by <name> is not found.
+
 New Features in Theme Format Version 3.3
 ========================================
 
diff --git a/src/ui/theme-parser.c b/src/ui/theme-parser.c
index 36056ac..9063541 100644
--- a/src/ui/theme-parser.c
+++ b/src/ui/theme-parser.c
@@ -38,7 +38,7 @@
  * look out for.
  */
 #define THEME_MAJOR_VERSION 3
-#define THEME_MINOR_VERSION 3
+#define THEME_MINOR_VERSION 4
 #define THEME_VERSION (1000 * THEME_MAJOR_VERSION + THEME_MINOR_VERSION)
 
 #define METACITY_THEME_FILENAME_FORMAT "metacity-theme-%d.xml"
diff --git a/src/ui/theme-private.h b/src/ui/theme-private.h
index 015a889..73f6fcd 100644
--- a/src/ui/theme-private.h
+++ b/src/ui/theme-private.h
@@ -281,6 +281,7 @@ typedef enum
 {
   META_COLOR_SPEC_BASIC,
   META_COLOR_SPEC_GTK,
+  META_COLOR_SPEC_GTK_CUSTOM,
   META_COLOR_SPEC_BLEND,
   META_COLOR_SPEC_SHADE
 } MetaColorSpecType;
@@ -311,6 +312,10 @@ struct _MetaColorSpec
       GtkStateFlags state;
     } gtk;
     struct {
+      char *color_name;
+      MetaColorSpec *fallback;
+    } gtkcustom;
+    struct {
       MetaColorSpec *foreground;
       MetaColorSpec *background;
       double alpha;
diff --git a/src/ui/theme.c b/src/ui/theme.c
index 1088998..7dedc6b 100644
--- a/src/ui/theme.c
+++ b/src/ui/theme.c
@@ -1118,6 +1118,10 @@ meta_color_spec_new (MetaColorSpecType type)
       size += sizeof (dummy.data.gtk);
       break;
 
+    case META_COLOR_SPEC_GTK_CUSTOM:
+      size += sizeof (dummy.data.gtkcustom);
+      break;
+
     case META_COLOR_SPEC_BLEND:
       size += sizeof (dummy.data.blend);
       break;
@@ -1149,6 +1153,14 @@ meta_color_spec_free (MetaColorSpec *spec)
       DEBUG_FILL_STRUCT (&spec->data.gtk);
       break;
 
+    case META_COLOR_SPEC_GTK_CUSTOM:
+      if (spec->data.gtkcustom.color_name)
+        g_free (spec->data.gtkcustom.color_name);
+      if (spec->data.gtkcustom.fallback)
+        meta_color_spec_free (spec->data.gtkcustom.fallback);
+      DEBUG_FILL_STRUCT (&spec->data.gtkcustom);
+      break;
+
     case META_COLOR_SPEC_BLEND:
       if (spec->data.blend.foreground)
         meta_color_spec_free (spec->data.blend.foreground);
@@ -1179,7 +1191,68 @@ meta_color_spec_new_from_string (const char *str,
 
   spec = NULL;
   
-  if (str[0] == 'g' && str[1] == 't' && str[2] == 'k' && str[3] == ':')
+  if (str[0] == 'g' && str[1] == 't' && str[2] == 'k' && str[3] == ':' &&
+      str[4] == 'c' && str[5] == 'u' && str[6] == 's' && str[7] == 't' &&
+      str[8] == 'o' && str[9] == 'm')
+    {
+      const char *color_name_start, *fallback_str_start, *end;
+      char *color_name, *fallback_str;
+      MetaColorSpec *fallback = NULL;
+
+      if (str[10] != '(')
+        {
+          g_set_error (err, META_THEME_ERROR,
+                       META_THEME_ERROR_FAILED,
+                       _("GTK custom color specification must have color name and fallback in parentheses, e.g. gtk:custom(foo,bar); could not parse \"%s\""),
+                       str);
+          return NULL;
+        }
+
+      color_name_start = str + 11;
+
+      fallback_str_start = color_name_start;
+      while (*fallback_str_start && *fallback_str_start != ',')
+        {
+          if (!(g_ascii_isalnum (*fallback_str_start)
+                || *fallback_str_start == '-'
+                || *fallback_str_start == '_'))
+            {
+              g_set_error (err, META_THEME_ERROR,
+                           META_THEME_ERROR_FAILED,
+                           _("Invalid character '%c' in color_name parameter of gtk:custom, only A-Za-z0-9-_ are valid"),
+                           *fallback_str_start);
+              return NULL;
+            }
+          fallback_str_start++;
+        }
+      fallback_str_start++;
+
+      end = strrchr (str, ')');
+
+      if (color_name_start == NULL || fallback_str_start == NULL || end == NULL)
+        {
+          g_set_error (err, META_THEME_ERROR,
+                       META_THEME_ERROR_FAILED,
+                       _("Gtk:custom format is \"gtk:custom(color_name,fallback)\", \"%s\" does not fit the format"),
+                       str);
+          return NULL;
+        }
+
+      fallback_str = g_strndup (fallback_str_start, end - fallback_str_start);
+      fallback = meta_color_spec_new_from_string (fallback_str, err);
+      g_free (fallback_str);
+
+      if (fallback == NULL)
+        return NULL;
+
+      color_name = g_strndup (color_name_start,
+                              fallback_str_start - color_name_start - 1);
+
+      spec = meta_color_spec_new (META_COLOR_SPEC_GTK_CUSTOM);
+      spec->data.gtkcustom.color_name = color_name;
+      spec->data.gtkcustom.fallback = fallback;
+    }
+  else if (str[0] == 'g' && str[1] == 't' && str[2] == 'k' && str[3] == ':')
     {
       /* GTK color */
       const char *bracket;
@@ -1479,6 +1552,16 @@ meta_set_color_from_style (GdkRGBA               *color,
     }
 }
 
+static void
+meta_set_custom_color_from_style (GdkRGBA         *color,
+                                  GtkStyleContext *context,
+                                  char            *color_name,
+                                  MetaColorSpec   *fallback)
+{
+  if (!gtk_style_context_lookup_color (context, color_name, color))
+    meta_color_spec_render (fallback, context, color);
+}
+
 void
 meta_color_spec_render (MetaColorSpec   *spec,
                         GtkStyleContext *context,
@@ -1500,6 +1583,13 @@ meta_color_spec_render (MetaColorSpec   *spec,
                                  spec->data.gtk.component);
       break;
 
+    case META_COLOR_SPEC_GTK_CUSTOM:
+      meta_set_custom_color_from_style (color,
+                                        context,
+                                        spec->data.gtkcustom.color_name,
+                                        spec->data.gtkcustom.fallback);
+      break;
+
     case META_COLOR_SPEC_BLEND:
       {
         GdkRGBA bg, fg;