Revert of Revert of Implement DisplayList GatherPixelRefs

cc/resources/pixel_ref_map.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_RESOURCES_PIXEL_REF_MAP_H_
 #define CC_RESOURCES_PIXEL_REF_MAP_H_
 
 #include <utility>
 #include <vector>
 
 #include "base/containers/hash_tables.h"
 #include "base/lazy_instance.h"
 #include "base/memory/ref_counted.h"
 #include "cc/base/cc_export.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 
 class SkPixelRef;
 
 namespace cc {
 
 class Picture;
+class DisplayItemList;
 
 typedef std::pair<int, int> PixelRefMapKey;
 typedef std::vector<SkPixelRef*> PixelRefs;
 typedef base::hash_map<PixelRefMapKey, PixelRefs> PixelRefHashmap;
 
 // This class is used and owned by cc Picture class. It is used to gather pixel
 // refs which would happen after record. It takes in |cell_size| to decide how
 // big each grid cell should be.
 class CC_EXPORT PixelRefMap {
  public:
   explicit PixelRefMap(const gfx::Size& cell_size);
   ~PixelRefMap();
   void GatherPixelRefsFromPicture(SkPicture* picture);
 
   bool empty() const { return data_hash_map_.empty(); }
 
   // This iterator imprecisely returns the set of pixel refs that are needed to
   // raster this layer rect from this picture.  Internally, pixel refs are
   // clumped into tile grid buckets, so there may be false positives.
   class CC_EXPORT Iterator {
    public:
     // Default iterator constructor that is used as place holder for invalid
     // Iterator.
     Iterator();
     Iterator(const gfx::Rect& layer_rect, const Picture* picture);
+    Iterator(const gfx::Rect& layer_rect, const DisplayItemList* picture);
     ~Iterator();
 
     SkPixelRef* operator->() const {
       DCHECK_LT(current_index_, current_pixel_refs_->size());
       return (*current_pixel_refs_)[current_index_];
     }
 
     SkPixelRef* operator*() const {
       DCHECK_LT(current_index_, current_pixel_refs_->size());
       return (*current_pixel_refs_)[current_index_];
     }
 
     Iterator& operator++();
     operator bool() const {
       return current_index_ < current_pixel_refs_->size();
     }
 
    private:
+    void PointToFirstPixelRef(const gfx::Rect& query_rect);
+
     static base::LazyInstance<PixelRefs> empty_pixel_refs_;
     const PixelRefMap* target_pixel_ref_map_;
     const PixelRefs* current_pixel_refs_;
     unsigned current_index_;
 
-    gfx::Rect layer_rect_;
+    gfx::Rect map_layer_rect_;
 
     gfx::Point min_point_;
     gfx::Point max_point_;
     int current_x_;
     int current_y_;
   };
 
  private:
   gfx::Point min_pixel_cell_;
   gfx::Point max_pixel_cell_;
   gfx::Size cell_size_;
 
   PixelRefHashmap data_hash_map_;
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PIXEL_REF_MAP_H_