[gtk] rendericon: Ignore transparent icons

[Timm Bäder <baedert src gnome org>]

commit d1ea591f18f71e059a76af8d659540c10293270a
Author: Timm Bäder <mail baedert org>
Date:   Sun Feb 10 10:27:27 2019 +0100

    rendericon: Ignore transparent icons
    
    If the recoloring would end up multiplying the alpha component with 0
    anyway, just skip drawing anything altogether.
    
    This increases the icon count in the switch demo of the fishbowl from
    ~260 to ~280 on my system.

 gtk/gtkrendericon.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/gtk/gtkrendericon.c b/gtk/gtkrendericon.c
index 2d2dfa05f5..a4d867001f 100644
--- a/gtk/gtkrendericon.c
+++ b/gtk/gtkrendericon.c
@@ -133,6 +133,9 @@ gtk_css_style_snapshot_icon_paintable (GtkCssStyle  *style,
 
       gtk_icon_theme_lookup_symbolic_colors (style, &fg, &sc, &wc, &ec);
 
+      if (fg.alpha == 0.0f)
+        goto transparent;
+
       graphene_matrix_init_from_float (&color_matrix, (float[16]) {
                                          sc.red - fg.red, sc.green - fg.green, sc.blue - fg.blue, 0,
                                          wc.red - fg.red, wc.green - fg.green, wc.blue - fg.blue, 0,
@@ -171,5 +174,6 @@ gtk_css_style_snapshot_icon_paintable (GtkCssStyle  *style,
   if (has_shadow)
     gtk_snapshot_pop (snapshot);
 
+transparent:
   gtk_css_filter_value_pop_snapshot (filter_value, snapshot);
 }