cc/CCDamageTracker.h

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CCDamageTracker_h
   6 #define CCDamageTracker_h
   7
   8 #include "FloatRect.h"
   9 #include <wtf/HashMap.h>
  10 #include <wtf/PassOwnPtr.h>
  11 #include <wtf/Vector.h>
  12
  13 namespace WebKit {
  14 class WebFilterOperations;
  15 }
  16
  17 namespace WebCore {
  18
  19 class CCLayerImpl;
  20 class CCRenderSurface;
  21
  22 // Computes the region where pixels have actually changed on a RenderSurface. This region is used
  23 // to scissor what is actually drawn to the screen to save GPU computation and bandwidth.
  24 class CCDamageTracker {
  25 public:
  26     static PassOwnPtr<CCDamageTracker> create();
  27     ~CCDamageTracker();
  28
  29     void didDrawDamagedArea() { m_currentDamageRect = FloatRect(); }
  30     void forceFullDamageNextUpdate() { m_forceFullDamageNextUpdate = true; }
  31     void updateDamageTrackingState(const Vector<CCLayerImpl*>& layerList, int targetSurfaceLayerID, bool targetSurfacePropertyChangedOnlyFromDescendant, const IntRect& targetSurfaceContentRect, CCLayerImpl* targetSurfaceMaskLayer, const WebKit::WebFilterOperations&);
  32
  33     const FloatRect& currentDamageRect() { return m_currentDamageRect; }
  34
  35 private:
  36     CCDamageTracker();
  37
  38     FloatRect trackDamageFromActiveLayers(const Vector<CCLayerImpl*>& layerList, int targetSurfaceLayerID);
  39     FloatRect trackDamageFromSurfaceMask(CCLayerImpl* targetSurfaceMaskLayer);
  40     FloatRect trackDamageFromLeftoverRects();
  41
  42     FloatRect removeRectFromCurrentFrame(int layerID, bool& layerIsNew);
  43     void saveRectForNextFrame(int layerID, const FloatRect& targetSpaceRect);
  44
  45     // These helper functions are used only in trackDamageFromActiveLayers().
  46     void extendDamageForLayer(CCLayerImpl*, FloatRect& targetDamageRect);
  47     void extendDamageForRenderSurface(CCLayerImpl*, FloatRect& targetDamageRect);
  48
  49     // To correctly track exposed regions, two hashtables of rects are maintained.
  50     // The "current" map is used to compute exposed regions of the current frame, while
  51     // the "next" map is used to collect layer rects that are used in the next frame.
  52     typedef HashMap<int, FloatRect> RectMap;
  53     OwnPtr<RectMap> m_currentRectHistory;
  54     OwnPtr<RectMap> m_nextRectHistory;
  55
  56     FloatRect m_currentDamageRect;
  57     bool m_forceFullDamageNextUpdate;
  58 };
  59
  60 } // namespace WebCore
  61
  62 #endif // CCDamageTracker_h