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      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_TREES_DAMAGE_TRACKER_H_
      6 #define CC_TREES_DAMAGE_TRACKER_H_
      7 
      8 #include <vector>
      9 #include "base/memory/scoped_ptr.h"
     10 #include "cc/base/cc_export.h"
     11 #include "cc/layers/layer_lists.h"
     12 #include "ui/gfx/rect.h"
     13 
     14 class SkImageFilter;
     15 
     16 namespace gfx {
     17 class Rect;
     18 }
     19 
     20 namespace cc {
     21 
     22 class FilterOperations;
     23 class LayerImpl;
     24 class RenderSurfaceImpl;
     25 
     26 // Computes the region where pixels have actually changed on a
     27 // RenderSurfaceImpl. This region is used to scissor what is actually drawn to
     28 // the screen to save GPU computation and bandwidth.
     29 class CC_EXPORT DamageTracker {
     30  public:
     31   static scoped_ptr<DamageTracker> Create();
     32   ~DamageTracker();
     33 
     34   void DidDrawDamagedArea() { current_damage_rect_ = gfx::Rect(); }
     35   void AddDamageNextUpdate(const gfx::Rect& dmg) {
     36     current_damage_rect_.Union(dmg);
     37   }
     38   void UpdateDamageTrackingState(
     39       const LayerImplList& layer_list,
     40       int target_surface_layer_id,
     41       bool target_surface_property_changed_only_from_descendant,
     42       const gfx::Rect& target_surface_content_rect,
     43       LayerImpl* target_surface_mask_layer,
     44       const FilterOperations& filters);
     45 
     46   gfx::Rect current_damage_rect() { return current_damage_rect_; }
     47 
     48  private:
     49   DamageTracker();
     50 
     51   gfx::Rect TrackDamageFromActiveLayers(const LayerImplList& layer_list,
     52                                         int target_surface_layer_id);
     53   gfx::Rect TrackDamageFromSurfaceMask(LayerImpl* target_surface_mask_layer);
     54   gfx::Rect TrackDamageFromLeftoverRects();
     55 
     56   void PrepareRectHistoryForUpdate();
     57 
     58   // These helper functions are used only in TrackDamageFromActiveLayers().
     59   void ExtendDamageForLayer(LayerImpl* layer, gfx::Rect* target_damage_rect);
     60   void ExtendDamageForRenderSurface(LayerImpl* layer,
     61                                     gfx::Rect* target_damage_rect);
     62 
     63   struct RectMapData {
     64     RectMapData() : layer_id_(0), mailboxId_(0) {}
     65     explicit RectMapData(int layer_id) : layer_id_(layer_id), mailboxId_(0) {}
     66     void Update(const gfx::Rect& rect, unsigned int mailboxId) {
     67       mailboxId_ = mailboxId;
     68       rect_ = rect;
     69     }
     70 
     71     bool operator < (const RectMapData& other) const {
     72       return layer_id_ < other.layer_id_;
     73     }
     74 
     75     int layer_id_;
     76     unsigned int mailboxId_;
     77     gfx::Rect rect_;
     78   };
     79   typedef std::vector<RectMapData> SortedRectMap;
     80 
     81   RectMapData& RectDataForLayer(int layer_id, bool* layer_is_new);
     82 
     83   SortedRectMap rect_history_;
     84 
     85   unsigned int mailboxId_;
     86   gfx::Rect current_damage_rect_;
     87 
     88   DISALLOW_COPY_AND_ASSIGN(DamageTracker);
     89 };
     90 
     91 }  // namespace cc
     92 
     93 #endif  // CC_TREES_DAMAGE_TRACKER_H_
     94