cc: Simplify picture layer tiling update tile priorities.

cc/resources/picture_layer_tiling.h

 // Copyright 2012 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_PICTURE_LAYER_TILING_H_
 #define CC_RESOURCES_PICTURE_LAYER_TILING_H_
 
 #include <utility>
 #include <vector>
 
@@ skipping 17 matching lines @@
   // tiling) This might return null if the client cannot create such a tile.
   virtual scoped_refptr<Tile> CreateTile(
     PictureLayerTiling* tiling,
     const gfx::Rect& content_rect) = 0;
   virtual void UpdatePile(Tile* tile) = 0;
   virtual gfx::Size CalculateTileSize(
     const gfx::Size& content_bounds) const = 0;
   virtual const Region* GetInvalidation() = 0;
   virtual const PictureLayerTiling* GetTwinTiling(
       const PictureLayerTiling* tiling) const = 0;
+  virtual size_t GetMaxTilesForInterestArea() const = 0;
+  virtual float GetSkewportTargetTimeInSeconds() const = 0;
 
  protected:
   virtual ~PictureLayerTilingClient() {}
 };
 
 class CC_EXPORT PictureLayerTiling {
  public:
   ~PictureLayerTiling();
 
   // Create a tiling with no tiles.  CreateTiles must be called to add some.
@@ skipping 78 matching lines @@
     int right_;
     int bottom_;
 
     friend class PictureLayerTiling;
   };
 
   Region OpaqueRegionInContentRect(const gfx::Rect& content_rect) const;
 
   void Reset();
 
-  void UpdateTilePriorities(
-      WhichTree tree,
-      const gfx::Size& device_viewport,
-      const gfx::Rect& viewport_in_layer_space,
-      const gfx::Rect& visible_layer_rect,
-      const gfx::Size& last_layer_bounds,
-      const gfx::Size& current_layer_bounds,
-      float last_layer_contents_scale,
-      float current_layer_contents_scale,
-      const gfx::Transform& last_screen_transform,
-      const gfx::Transform& current_screen_transform,
-      double current_frame_time_in_seconds,
-      size_t max_tiles_for_interest_area);
+  void UpdateTilePriorities(WhichTree tree,
+                            const gfx::Rect& visible_layer_rect,
+                            float layer_contents_scale,
+                            double current_frame_time_in_seconds);
 
   // Copies the src_tree priority into the dst_tree priority for all tiles.
   // The src_tree priority is reset to the lowest priority possible.  This
   // also updates the pile on each tile to be the current client's pile.
   void DidBecomeActive();
 
   // Resets the active priority for all tiles in a tiling, when an active
   // tiling is becoming recycled. This may include some tiles which are
   // not in the the pending tiling (due to invalidations). This must
   // be called before DidBecomeActive, as it resets the active priority
@@ skipping 32 matching lines @@
  protected:
   typedef std::pair<int, int> TileMapKey;
   typedef base::hash_map<TileMapKey, scoped_refptr<Tile> > TileMap;
 
   PictureLayerTiling(float contents_scale,
                      const gfx::Size& layer_bounds,
                      PictureLayerTilingClient* client);
   void SetLiveTilesRect(const gfx::Rect& live_tiles_rect);
   void CreateTile(int i, int j, const PictureLayerTiling* twin_tiling);
 
+  // Computes a skewport. The calculation extrapolates the last visible
+  // rect and the current visible rect to expand the skewport to where it
+  // would be in |skewport_target_time| seconds. Note that the skewport
+  // is guaranteed to contain the current visible rect.
+  gfx::Rect ComputeSkewport(double current_frame_time_in_seconds,
+                            const gfx::Rect& visible_rect_in_content_space)
+      const;
+
   // Given properties.
   float contents_scale_;
   gfx::Size layer_bounds_;
   TileResolution resolution_;
   PictureLayerTilingClient* client_;
 
   // Internal data.
   TilingData tiling_data_;
   TileMap tiles_;  // It is not legal to have a NULL tile in the tiles_ map.
   gfx::Rect live_tiles_rect_;
 
   // State saved for computing velocities based upon finite differences.
   double last_impl_frame_time_in_seconds_;
+  gfx::RectF last_visible_rect_in_content_space_;
 
   friend class CoverageIterator;
 
  private:
   DISALLOW_ASSIGN(PictureLayerTiling);
 
   RectExpansionCache expansion_cache_;
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_LAYER_TILING_H_