GTK: Step 1 of tab strip refresh.

chrome/browser/ui/gtk/cairo_cached_surface.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/gtk/cairo_cached_surface.h"
 
 #include <gtk/gtk.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 
 CairoCachedSurface::CairoCachedSurface() : pixbuf_(NULL), surface_(NULL) {
 }
 
 CairoCachedSurface::~CairoCachedSurface() {
-  if (surface_)
+  Reset();
+}
+
+void CairoCachedSurface::Reset() {
+  if (surface_) {
     cairo_surface_destroy(surface_);
+    surface_ = NULL;
+  }
 
-  if (pixbuf_)
+  if (pixbuf_) {
     g_object_unref(pixbuf_);
+    pixbuf_ = NULL;
+  }
 }
 
 int CairoCachedSurface::Width() const {
   return pixbuf_ ? gdk_pixbuf_get_width(pixbuf_) : -1;
 }
 
 int CairoCachedSurface::Height() const {
   return pixbuf_ ? gdk_pixbuf_get_height(pixbuf_) : -1;
 }
 
 void CairoCachedSurface::UsePixbuf(GdkPixbuf* pixbuf) {
   if (surface_) {
     cairo_surface_destroy(surface_);
     surface_ = NULL;
   }
 
   if (pixbuf)
     g_object_ref(pixbuf);
 
   if (pixbuf_)
     g_object_unref(pixbuf_);
 
   pixbuf_ = pixbuf;
 }
 
 void CairoCachedSurface::SetSource(cairo_t* cr, int x, int y) {
   DCHECK(pixbuf_);
   DCHECK(cr);
 
+  EnsureSurfaceValid(cr);
+  cairo_set_source_surface(cr, surface_, x, y);
+}
+
+void CairoCachedSurface::MaskSource(cairo_t* cr, int x, int y) {
+  DCHECK(pixbuf_);
+  DCHECK(cr);
+
+  EnsureSurfaceValid(cr);
+  cairo_mask_surface(cr, surface_, x, y);
+}
+
+void CairoCachedSurface::EnsureSurfaceValid(cairo_t* cr) {
   if (!surface_) {
     // First time here since last UsePixbuf call. Generate the surface.
     cairo_surface_t* target = cairo_get_target(cr);
     surface_ = cairo_surface_create_similar(
         target,
         CAIRO_CONTENT_COLOR_ALPHA,
         gdk_pixbuf_get_width(pixbuf_),
         gdk_pixbuf_get_height(pixbuf_));
 
     DCHECK(surface_);
 #if !defined(NDEBUG)
     int surface_type = cairo_surface_get_type(surface_);
     DCHECK(surface_type == CAIRO_SURFACE_TYPE_XLIB ||
            surface_type == CAIRO_SURFACE_TYPE_XCB ||
            surface_type == CAIRO_SURFACE_TYPE_IMAGE);
 #endif
 
     cairo_t* copy_cr = cairo_create(surface_);
     gdk_cairo_set_source_pixbuf(copy_cr, pixbuf_, 0, 0);
     cairo_paint(copy_cr);
     cairo_destroy(copy_cr);
   }
-
-  cairo_set_source_surface(cr, surface_, x, y);
 }