cc/trees/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_TREES_DAMAGE_TRACKER_H_
   6 #define CC_TREES_DAMAGE_TRACKER_H_
   7
   8 #include <vector>
   9 #include "base/containers/hash_tables.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "cc/base/cc_export.h"
  12 #include "cc/layers/layer_lists.h"
  13 #include "ui/gfx/rect_f.h"
  14
  15 class SkImageFilter;
  16
  17 namespace gfx {
  18 class Rect;
  19 }
  20
  21 namespace cc {
  22
  23 class FilterOperations;
  24 class LayerImpl;
  25 class RenderSurfaceImpl;
  26
  27 // Computes the region where pixels have actually changed on a
  28 // RenderSurfaceImpl. This region is used to scissor what is actually drawn to
  29 // the screen to save GPU computation and bandwidth.
  30 class CC_EXPORT DamageTracker {
  31  public:
  32   static scoped_ptr<DamageTracker> Create();
  33   ~DamageTracker();
  34
  35   void DidDrawDamagedArea() { current_damage_rect_ = gfx::RectF(); }
  36   void AddDamageNextUpdate(gfx::RectF dmg) { current_damage_rect_.Union(dmg); }
  37   void UpdateDamageTrackingState(
  38       const LayerImplList& layer_list,
  39       int target_surface_layer_id,
  40       bool target_surface_property_changed_only_from_descendant,
  41       gfx::Rect target_surface_content_rect,
  42       LayerImpl* target_surface_mask_layer,
  43       const FilterOperations& filters,
  44       SkImageFilter* filter);
  45
  46   gfx::RectF current_damage_rect() { return current_damage_rect_; }
  47
  48  private:
  49   DamageTracker();
  50
  51   gfx::RectF TrackDamageFromActiveLayers(
  52       const LayerImplList& layer_list,
  53       int target_surface_layer_id);
  54   gfx::RectF TrackDamageFromSurfaceMask(LayerImpl* target_surface_mask_layer);
  55   gfx::RectF TrackDamageFromLeftoverRects();
  56
  57   gfx::RectF RemoveRectFromCurrentFrame(int layer_id, bool* layer_is_new);
  58   void SaveRectForNextFrame(int layer_id, const gfx::RectF& target_space_rect);
  59
  60   // These helper functions are used only in TrackDamageFromActiveLayers().
  61   void ExtendDamageForLayer(LayerImpl* layer, gfx::RectF* target_damage_rect);
  62   void ExtendDamageForRenderSurface(LayerImpl* layer,
  63                                     gfx::RectF* target_damage_rect);
  64
  65   // To correctly track exposed regions, two hashtables of rects are maintained.
  66   // The "current" map is used to compute exposed regions of the current frame,
  67   // while the "next" map is used to collect layer rects that are used in the
  68   // next frame.
  69   typedef base::hash_map<int, gfx::RectF> RectMap;
  70   scoped_ptr<RectMap> current_rect_history_;
  71   scoped_ptr<RectMap> next_rect_history_;
  72
  73   gfx::RectF current_damage_rect_;
  74
  75   DISALLOW_COPY_AND_ASSIGN(DamageTracker);
  76 };
  77
  78 }  // namespace cc
  79
  80 #endif  // CC_TREES_DAMAGE_TRACKER_H_