[gtk] cssrgbavalue: Add an opaque white singleton

[Timm Bäder <baedert src gnome org>]

commit 19f69f6ac8ca5b8b9550fc695094c17e0a30d662
Author: Timm Bäder <mail baedert org>
Date:   Fri Aug 23 08:13:20 2019 +0200

    cssrgbavalue: Add an opaque white singleton
    
    Used a few hundred times in the widget-factory.

 gtk/gtkcssrgbavalue.c | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/gtk/gtkcssrgbavalue.c b/gtk/gtkcssrgbavalue.c
index f840160bde..ab3d180648 100644
--- a/gtk/gtkcssrgbavalue.c
+++ b/gtk/gtkcssrgbavalue.c
@@ -109,6 +109,7 @@ static const GtkCssValueClass GTK_CSS_VALUE_RGBA = {
 
 static GtkCssValue transparent_black_singleton = (GtkCssValue) { &GTK_CSS_VALUE_RGBA, 1, { 0, 0, 0, 0 }};
 static GtkCssValue transparent_white_singleton = (GtkCssValue) { &GTK_CSS_VALUE_RGBA, 1, { 1, 1, 1, 0 }};
+static GtkCssValue opaque_white_singleton      = (GtkCssValue) { &GTK_CSS_VALUE_RGBA, 1, { 1, 1, 1, 1 }};
 
 GtkCssValue *
 _gtk_css_rgba_value_new_from_rgba (const GdkRGBA *rgba)
@@ -129,6 +130,13 @@ _gtk_css_rgba_value_new_from_rgba (const GdkRGBA *rgba)
           rgba->blue == 0)
         return _gtk_css_value_ref (&transparent_black_singleton);
     }
+  else if (gdk_rgba_is_opaque (rgba))
+    {
+      if (rgba->red == 1 &&
+          rgba->green == 1 &&
+          rgba->blue == 1)
+        return _gtk_css_value_ref (&opaque_white_singleton);
+    }
 
   value = _gtk_css_value_new (GtkCssValue, &GTK_CSS_VALUE_RGBA);
   value->rgba = *rgba;