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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_f.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::RectF(); }
     35   void AddDamageNextUpdate(gfx::RectF dmg) { current_damage_rect_.Union(dmg); }
     36   void UpdateDamageTrackingState(
     37       const LayerImplList& layer_list,
     38       int target_surface_layer_id,
     39       bool target_surface_property_changed_only_from_descendant,
     40       gfx::Rect target_surface_content_rect,
     41       LayerImpl* target_surface_mask_layer,
     42       const FilterOperations& filters);
     43 
     44   gfx::RectF current_damage_rect() { return current_damage_rect_; }
     45 
     46  private:
     47   DamageTracker();
     48 
     49   gfx::RectF TrackDamageFromActiveLayers(
     50       const LayerImplList& layer_list,
     51       int target_surface_layer_id);
     52   gfx::RectF TrackDamageFromSurfaceMask(LayerImpl* target_surface_mask_layer);
     53   gfx::RectF TrackDamageFromLeftoverRects();
     54 
     55   void PrepareRectHistoryForUpdate();
     56 
     57   // These helper functions are used only in TrackDamageFromActiveLayers().
     58   void ExtendDamageForLayer(LayerImpl* layer, gfx::RectF* target_damage_rect);
     59   void ExtendDamageForRenderSurface(LayerImpl* layer,
     60                                     gfx::RectF* target_damage_rect);
     61 
     62   struct RectMapData {
     63     RectMapData() : layer_id_(0), mailboxId_(0) {}
     64     explicit RectMapData(int layer_id) : layer_id_(layer_id), mailboxId_(0) {}
     65     void Update(const gfx::RectF& rect, unsigned int mailboxId) {
     66       mailboxId_ = mailboxId;
     67       rect_ = rect;
     68     }
     69 
     70     bool operator < (const RectMapData& other) const {
     71       return layer_id_ < other.layer_id_;
     72     }
     73 
     74     int layer_id_;
     75     unsigned int mailboxId_;
     76     gfx::RectF rect_;
     77   };
     78   typedef std::vector<RectMapData> SortedRectMap;
     79 
     80   RectMapData& RectDataForLayer(int layer_id, bool* layer_is_new);
     81 
     82   SortedRectMap rect_history_;
     83 
     84   unsigned int mailboxId_;
     85   gfx::RectF current_damage_rect_;
     86 
     87   DISALLOW_COPY_AND_ASSIGN(DamageTracker);
     88 };
     89 
     90 }  // namespace cc
     91 
     92 #endif  // CC_TREES_DAMAGE_TRACKER_H_
     93