text: // 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 <set>
  #include <utility>
  #include <vector>
  
  #include "base/basictypes.h"
  #include "base/containers/hash_tables.h"
  #include "base/memory/scoped_ptr.h"
  #include "cc/base/cc_export.h"
  #include "cc/base/region.h"
  #include "cc/base/tiling_data.h"
  #include "cc/resources/tile.h"
  #include "cc/resources/tile_priority.h"
  #include "ui/gfx/rect.h"
  
  namespace base {
  namespace debug {
  class TracedValue;
  }
  }
  
  namespace cc {
  
  template <typename LayerType>
  class OcclusionTracker;
  class PictureLayerTiling;
  class PicturePileImpl;
  
  class CC_EXPORT PictureLayerTilingClient {
   public:
    // Create a tile at the given content_rect (in the contents scale of the
    // 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 PicturePileImpl* GetPile() = 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 PictureLayerTiling* GetRecycledTwinTiling(
        const PictureLayerTiling* tiling) = 0;
    virtual size_t GetMaxTilesForInterestArea() const = 0;
    virtual float GetSkewportTargetTimeInSeconds() const = 0;
    virtual int GetSkewportExtrapolationLimitInContentPixels() const = 0;
    virtual WhichTree GetTree() const = 0;
  
   protected:
    virtual ~PictureLayerTilingClient() {}
  };
  
  class CC_EXPORT PictureLayerTiling {
   public:
    enum EvictionCategory {
      EVENTUALLY,
      EVENTUALLY_AND_REQUIRED_FOR_ACTIVATION,
      SOON,
      SOON_AND_REQUIRED_FOR_ACTIVATION,
      NOW,
      NOW_AND_REQUIRED_FOR_ACTIVATION
    };
  
    class CC_EXPORT TilingRasterTileIterator {
     public:
      TilingRasterTileIterator();
      TilingRasterTileIterator(PictureLayerTiling* tiling, WhichTree tree);
      ~TilingRasterTileIterator();
  
      operator bool() const { return !!current_tile_; }
      const Tile* operator*() const { return current_tile_; }
      Tile* operator*() { return current_tile_; }
      TilePriority::PriorityBin get_type() const {
        switch (phase_) {
          case VISIBLE_RECT:
            return TilePriority::NOW;
          case SKEWPORT_RECT:
          case SOON_BORDER_RECT:
            return TilePriority::SOON;
          case EVENTUALLY_RECT:
            return TilePriority::EVENTUALLY;
        }
        NOTREACHED();
        return TilePriority::EVENTUALLY;
      }
  
      TilingRasterTileIterator& operator++();
  
     private:
      enum Phase {
        VISIBLE_RECT,
        SKEWPORT_RECT,
        SOON_BORDER_RECT,
        EVENTUALLY_RECT
      };
  
      void AdvancePhase();
      bool TileNeedsRaster(Tile* tile) const {
        RasterMode mode = tile->DetermineRasterModeForTree(tree_);
        return !tile->is_occluded(tree_) && tile->NeedsRasterForMode(mode);
      }
  
      PictureLayerTiling* tiling_;
  
      Phase phase_;
      WhichTree tree_;
  
      Tile* current_tile_;
      TilingData::Iterator visible_iterator_;
      TilingData::SpiralDifferenceIterator spiral_iterator_;
    };
  
    class CC_EXPORT TilingEvictionTileIterator {
     public:
      TilingEvictionTileIterator();
      TilingEvictionTileIterator(PictureLayerTiling* tiling,
                                 TreePriority tree_priority,
                                 EvictionCategory category);
      ~TilingEvictionTileIterator();
  
      operator bool() const;
      const Tile* operator*() const;
      Tile* operator*();
      TilingEvictionTileIterator& operator++();
  
     private:
      const std::vector<Tile*>* eviction_tiles_;
      size_t current_eviction_tiles_index_;
    };
  
    ~PictureLayerTiling();
  
    // Create a tiling with no tiles.  CreateTiles must be called to add some.
    static scoped_ptr<PictureLayerTiling> Create(
        float contents_scale,
        const gfx::Size& layer_bounds,
        PictureLayerTilingClient* client);
    gfx::Size layer_bounds() const { return layer_bounds_; }
    void UpdateTilesToCurrentPile(const Region& layer_invalidation,
                                  const gfx::Size& new_layer_bounds);
    void CreateMissingTilesInLiveTilesRect();
    void RemoveTilesInRegion(const Region& layer_region);
  
    void SetClient(PictureLayerTilingClient* client);
    void set_resolution(TileResolution resolution) { resolution_ = resolution; }
    TileResolution resolution() const { return resolution_; }
  
    gfx::Size tiling_size() const { return tiling_data_.tiling_size(); }
    gfx::Rect live_tiles_rect() const { return live_tiles_rect_; }
    gfx::Size tile_size() const { return tiling_data_.max_texture_size(); }
    float contents_scale() const { return contents_scale_; }
  
    Tile* TileAt(int i, int j) const {
      TileMap::const_iterator iter = tiles_.find(TileMapKey(i, j));
      return (iter == tiles_.end()) ? NULL : iter->second.get();
    }
  
    void CreateAllTilesForTesting() {
      SetLiveTilesRect(gfx::Rect(tiling_data_.tiling_size()));
    }
  
    const TilingData& TilingDataForTesting() const { return tiling_data_; }
  
    std::vector<Tile*> AllTilesForTesting() const {
      std::vector<Tile*> all_tiles;
      for (TileMap::const_iterator it = tiles_.begin();
           it != tiles_.end(); ++it)
        all_tiles.push_back(it->second.get());
      return all_tiles;
    }
  
    std::vector<scoped_refptr<Tile> > AllRefTilesForTesting() const {
      std::vector<scoped_refptr<Tile> > all_tiles;
      for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it)
        all_tiles.push_back(it->second);
      return all_tiles;
    }
  
    const gfx::Rect& GetCurrentVisibleRectForTesting() const {
      return current_visible_rect_;
    }
  
    // Iterate over all tiles to fill content_rect.  Even if tiles are invalid
    // (i.e. no valid resource) this tiling should still iterate over them.
    // The union of all geometry_rect calls for each element iterated over should
    // exactly equal content_rect and no two geometry_rects should intersect.
    class CC_EXPORT CoverageIterator {
     public:
      CoverageIterator();
      CoverageIterator(const PictureLayerTiling* tiling,
          float dest_scale,
          const gfx::Rect& rect);
      ~CoverageIterator();
  
      // Visible rect (no borders), always in the space of content_rect,
      // regardless of the contents scale of the tiling.
      gfx::Rect geometry_rect() const;
      // Texture rect (in texels) for geometry_rect
      gfx::RectF texture_rect() const;
      gfx::Size texture_size() const;
  
      // Full rect (including borders) of the current tile, always in the space
      // of content_rect, regardless of the contents scale of the tiling.
      gfx::Rect full_tile_geometry_rect() const;
  
      Tile* operator->() const { return current_tile_; }
      Tile* operator*() const { return current_tile_; }
  
      CoverageIterator& operator++();
      operator bool() const { return tile_j_ <= bottom_; }
  
      int i() const { return tile_i_; }
      int j() const { return tile_j_; }
  
     private:
      const PictureLayerTiling* tiling_;
      gfx::Rect dest_rect_;
      float dest_to_content_scale_;
  
      Tile* current_tile_;
      gfx::Rect current_geometry_rect_;
      int tile_i_;
      int tile_j_;
      int left_;
      int top_;
      int right_;
      int bottom_;
  
      friend class PictureLayerTiling;
    };
  
    void Reset();
  
    void UpdateTilePriorities(
        WhichTree tree,
        const gfx::Rect& visible_layer_rect,
        float ideal_contents_scale,
        double current_frame_time_in_seconds,
        const OcclusionTracker<LayerImpl>* occlusion_tracker,
        const LayerImpl* render_target,
        const gfx::Transform& draw_transform);
  
    // 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
    // while DidBecomeActive promotes pending priority on a similar set of tiles.
    void DidBecomeRecycled();
  
    bool NeedsUpdateForFrameAtTime(double frame_time_in_seconds) {
      return frame_time_in_seconds != last_impl_frame_time_in_seconds_;
    }
  
    void GetAllTilesForTracing(std::set<const Tile*>* tiles) const;
    void AsValueInto(base::debug::TracedValue* array) const;
    size_t GPUMemoryUsageInBytes() const;
  
    struct RectExpansionCache {
      RectExpansionCache();
  
      gfx::Rect previous_start;
      gfx::Rect previous_bounds;
      gfx::Rect previous_result;
      int64 previous_target;
    };
  
    static
    gfx::Rect ExpandRectEquallyToAreaBoundedBy(
        const gfx::Rect& starting_rect,
        int64 target_area,
        const gfx::Rect& bounding_rect,
        RectExpansionCache* cache);
  
    bool has_ever_been_updated() const {
      return last_impl_frame_time_in_seconds_ != 0.0;
    }
  
   protected:
    friend class CoverageIterator;
    friend class TilingRasterTileIterator;
    friend class TilingEvictionTileIterator;
  
    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 VerifyLiveTilesRect();
    Tile* CreateTile(int i, int j, const PictureLayerTiling* twin_tiling);
    // Returns true if the Tile existed and was removed from the tiling.
    bool RemoveTileAt(int i, int j, PictureLayerTiling* recycled_twin);
  
    // 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;
  
    void UpdateEvictionCacheIfNeeded(TreePriority tree_priority);
    const std::vector<Tile*>* GetEvictionTiles(TreePriority tree_priority,
                                               EvictionCategory category);
  
    void Invalidate(const Region& layer_region);
  
    void DoInvalidate(const Region& layer_region,
                      bool recreate_invalidated_tiles);
  
    // 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::Rect last_visible_rect_in_content_space_;
  
    // Iteration rects in content space
    gfx::Rect current_visible_rect_;
    gfx::Rect current_skewport_rect_;
    gfx::Rect current_soon_border_rect_;
    gfx::Rect current_eventually_rect_;
  
    bool has_visible_rect_tiles_;
    bool has_skewport_rect_tiles_;
    bool has_soon_border_rect_tiles_;
    bool has_eventually_rect_tiles_;
  
    // TODO(reveman): Remove this in favour of an array of eviction_tiles_ when we
    // change all enums to have a consistent way of getting the count/last
    // element.
    std::vector<Tile*> eviction_tiles_now_;
    std::vector<Tile*> eviction_tiles_now_and_required_for_activation_;
    std::vector<Tile*> eviction_tiles_soon_;
    std::vector<Tile*> eviction_tiles_soon_and_required_for_activation_;
    std::vector<Tile*> eviction_tiles_eventually_;
    std::vector<Tile*> eviction_tiles_eventually_and_required_for_activation_;
  
    bool eviction_tiles_cache_valid_;
    TreePriority eviction_cache_tree_priority_;
  
   private:
    DISALLOW_ASSIGN(PictureLayerTiling);
  
    RectExpansionCache expansion_cache_;
  };
  
  }  // namespace cc
  
  #endif  // CC_RESOURCES_PICTURE_LAYER_TILING_H_
  