Upload GdkPixbufs into cairo surfaces so they (hopefully) live on X

chrome/browser/gtk/cairo_cached_surface.cc

+// Copyright (c) 2009 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/gtk/cairo_cached_surface.h"
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+CairoCachedSurface::CairoCachedSurface() : pixbuf_(NULL), surface_(NULL) {
+}
+
+CairoCachedSurface::~CairoCachedSurface() {
+  if (surface_)
+    cairo_surface_destroy(surface_);
+
+  if (pixbuf_)
+    g_object_unref(pixbuf_);
+}
+
+bool CairoCachedSurface::valid() const {
+  return pixbuf_;
+}
+
+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);
+
+  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_);
+    DCHECK(cairo_surface_get_type(surface_) == CAIRO_SURFACE_TYPE_XLIB ||
+           cairo_surface_get_type(surface_) == CAIRO_SURFACE_TYPE_XCB);
+
+    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);
+}