1 files changed, 62 insertions, 0 deletions
diff --git a/cc/CCDamageTracker.h b/cc/CCDamageTracker.h
new file mode 100644
index 0000000..eb2a644
--- /dev/null
+++ b/cc/CCDamageTracker.h
@@ -0,0 +1,62 @@
+// Copyright 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.
+
+#ifndef CCDamageTracker_h
+#define CCDamageTracker_h
+
+#include "FloatRect.h"
+#include <wtf/HashMap.h>
+#include <wtf/PassOwnPtr.h>
+#include <wtf/Vector.h>
+
+namespace WebKit {
+class WebFilterOperations;
+}
+
+namespace WebCore {
+
+class CCLayerImpl;
+class CCRenderSurface;
+
+// Computes the region where pixels have actually changed on a RenderSurface. This region is used
+// to scissor what is actually drawn to the screen to save GPU computation and bandwidth.
+class CCDamageTracker {
+public:
+    static PassOwnPtr<CCDamageTracker> create();
+    ~CCDamageTracker();
+
+    void didDrawDamagedArea() { m_currentDamageRect = FloatRect(); }
+    void forceFullDamageNextUpdate() { m_forceFullDamageNextUpdate = true; }
+    void updateDamageTrackingState(const Vector<CCLayerImpl*>& layerList, int targetSurfaceLayerID, bool targetSurfacePropertyChangedOnlyFromDescendant, const IntRect& targetSurfaceContentRect, CCLayerImpl* targetSurfaceMaskLayer, const WebKit::WebFilterOperations&);
+
+    const FloatRect& currentDamageRect() { return m_currentDamageRect; }
+
+private:
+    CCDamageTracker();
+
+    FloatRect trackDamageFromActiveLayers(const Vector<CCLayerImpl*>& layerList, int targetSurfaceLayerID);
+    FloatRect trackDamageFromSurfaceMask(CCLayerImpl* targetSurfaceMaskLayer);
+    FloatRect trackDamageFromLeftoverRects();
+
+    FloatRect removeRectFromCurrentFrame(int layerID, bool& layerIsNew);
+    void saveRectForNextFrame(int layerID, const FloatRect& targetSpaceRect);
+
+    // These helper functions are used only in trackDamageFromActiveLayers().
+    void extendDamageForLayer(CCLayerImpl*, FloatRect& targetDamageRect);
+    void extendDamageForRenderSurface(CCLayerImpl*, FloatRect& targetDamageRect);
+
+    // To correctly track exposed regions, two hashtables of rects are maintained.
+    // The "current" map is used to compute exposed regions of the current frame, while
+    // the "next" map is used to collect layer rects that are used in the next frame.
+    typedef HashMap<int, FloatRect> RectMap;
+    OwnPtr<RectMap> m_currentRectHistory;
+    OwnPtr<RectMap> m_nextRectHistory;
+
+    FloatRect m_currentDamageRect;
+    bool m_forceFullDamageNextUpdate;
+};
+
+} // namespace WebCore
+
+#endif // CCDamageTracker_h