[gtk+/wip/ebassi/gsk-renderer: 121/135] Don't create render nodes for empty backgrounds

[Emmanuele Bassi <ebassi src gnome org>]

commit a21409c61b6f7237834d42d4d190a0c507a158ef
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Aug 12 18:23:25 2016 -0400

    Don't create render nodes for empty backgrounds

 gtk/gtkrenderbackground.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkrenderbackground.c b/gtk/gtkrenderbackground.c
index b877245..1189e4c 100644
--- a/gtk/gtkrenderbackground.c
+++ b/gtk/gtkrenderbackground.c
@@ -442,6 +442,20 @@ gtk_css_style_add_background_render_nodes (GtkCssStyle      *style,
 {
   GskRenderNode *bg_node;
   cairo_t *cr;
+  GtkCssValue *background_image;
+  GtkCssValue *box_shadow;
+  const GdkRGBA *bg_color;
+
+  background_image = gtk_css_style_get_value (style, GTK_CSS_PROPERTY_BACKGROUND_IMAGE);
+  bg_color = _gtk_css_rgba_value_get_rgba (gtk_css_style_get_value (style, 
GTK_CSS_PROPERTY_BACKGROUND_COLOR));
+  box_shadow = gtk_css_style_get_value (style, GTK_CSS_PROPERTY_BOX_SHADOW);
+
+  /* This is the common default case of no background */
+  if (gtk_rgba_is_clear (bg_color) &&
+      _gtk_css_array_value_get_n_values (background_image) == 1 &&
+      _gtk_css_image_value_get_image (_gtk_css_array_value_get_nth (background_image, 0)) == NULL &&
+      _gtk_css_shadows_value_is_none (box_shadow))
+    return;
 
   bg_node = gsk_renderer_create_render_node (renderer);
   gsk_render_node_set_name (bg_node, name);