[metacity] frames: clip drawing to visible region for metacity themes

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 69f79f09293a55764373c25e6d0ff2fa920bd781
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Apr 5 01:41:34 2015 +0300

    frames: clip drawing to visible region for metacity themes

 src/ui/frames.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)
---
diff --git a/src/ui/frames.c b/src/ui/frames.c
index 9dd33ae..7864c4b 100644
--- a/src/ui/frames.c
+++ b/src/ui/frames.c
@@ -2486,7 +2486,21 @@ meta_frames_draw (GtkWidget *widget,
 
   populate_cache (frames, frame);
 
-  region = cairo_region_create_rectangle (&clip);
+  if (meta_prefs_get_theme ())
+    {
+      MetaFrameGeometry fgeom;
+
+      meta_frames_calc_geometry (frames, frame, &fgeom);
+
+      region = get_visible_region (frames, frame, &fgeom, fgeom.width, fgeom.height);
+
+      gdk_cairo_region (cr, region);
+      cairo_clip(cr);
+    }
+  else
+    {
+      region = cairo_region_create_rectangle (&clip);
+    }
 
   pixels = get_cache (frames, frame);