cc/damage_tracker.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 CC_DAMAGE_TRACKER_H_
   6 #define CC_DAMAGE_TRACKER_H_
   7
   8 #include "base/hash_tables.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "cc/cc_export.h"
  11 #include "ui/gfx/rect_f.h"
  12 #include <vector>
  13
  14 class SkImageFilter;
  15
  16 namespace gfx {
  17 class Rect;
  18 }
  19
  20 namespace WebKit {
  21 class WebFilterOperations;
  22 }
  23
  24 namespace cc {
  25
  26 class LayerImpl;
  27 class RenderSurfaceImpl;
  28
  29 // Computes the region where pixels have actually changed on a RenderSurfaceImpl. This region is used
  30 // to scissor what is actually drawn to the screen to save GPU computation and bandwidth.
  31 class CC_EXPORT DamageTracker {
  32 public:
  33     static scoped_ptr<DamageTracker> create();
  34     ~DamageTracker();
  35
  36     void didDrawDamagedArea() { m_currentDamageRect = gfx::RectF(); }
  37     void forceFullDamageNextUpdate() { m_forceFullDamageNextUpdate = true; }
  38     void updateDamageTrackingState(const std::vector<LayerImpl*>& layerList, int targetSurfaceLayerID, bool targetSurfacePropertyChangedOnlyFromDescendant, const gfx::Rect& targetSurfaceContentRect, LayerImpl* targetSurfaceMaskLayer, const WebKit::WebFilterOperations&, SkImageFilter* filter);
  39
  40     const gfx::RectF& currentDamageRect() { return m_currentDamageRect; }
  41
  42 private:
  43     DamageTracker();
  44
  45     gfx::RectF trackDamageFromActiveLayers(const std::vector<LayerImpl*>& layerList, int targetSurfaceLayerID);
  46     gfx::RectF trackDamageFromSurfaceMask(LayerImpl* targetSurfaceMaskLayer);
  47     gfx::RectF trackDamageFromLeftoverRects();
  48
  49     gfx::RectF removeRectFromCurrentFrame(int layerID, bool& layerIsNew);
  50     void saveRectForNextFrame(int layerID, const gfx::RectF& targetSpaceRect);
  51
  52     // These helper functions are used only in trackDamageFromActiveLayers().
  53     void extendDamageForLayer(LayerImpl*, gfx::RectF& targetDamageRect);
  54     void extendDamageForRenderSurface(LayerImpl*, gfx::RectF& targetDamageRect);
  55
  56     // To correctly track exposed regions, two hashtables of rects are maintained.
  57     // The "current" map is used to compute exposed regions of the current frame, while
  58     // the "next" map is used to collect layer rects that are used in the next frame.
  59     typedef base::hash_map<int, gfx::RectF> RectMap;
  60     scoped_ptr<RectMap> m_currentRectHistory;
  61     scoped_ptr<RectMap> m_nextRectHistory;
  62
  63     gfx::RectF m_currentDamageRect;
  64     bool m_forceFullDamageNextUpdate;
  65
  66     DISALLOW_COPY_AND_ASSIGN(DamageTracker);
  67 };
  68
  69 } // namespace cc
  70
  71 #endif  // CC_DAMAGE_TRACKER_H_