cc/tiles/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_TILES_PICTURE_LAYER_TILING_H_
#define CC_TILES_PICTURE_LAYER_TILING_H_

#include <stddef.h>
#include <stdint.h>

#include <map>
#include <memory>
#include <unordered_map>
#include <utility>
#include <vector>

#include "base/macros.h"
#include "cc/base/region.h"
#include "cc/base/tiling_data.h"
#include "cc/cc_export.h"
#include "cc/tiles/tile.h"
#include "cc/tiles/tile_priority.h"
#include "cc/trees/occlusion.h"
#include "ui/gfx/geometry/axis_transform2d.h"
#include "ui/gfx/geometry/rect.h"

namespace base {
namespace trace_event {
class TracedValue;
}
}

namespace cc {

class RasterSource;
class PictureLayerTiling;
class PrioritizedTile;

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 std::unique_ptr<Tile> CreateTile(const Tile::CreateInfo& info) = 0;
  virtual gfx::Size CalculateTileSize(
    const gfx::Size& content_bounds) const = 0;
  // This invalidation region defines the area (if any, it can by null) that
  // tiles can not be shared between pending and active trees.
  virtual const Region* GetPendingInvalidation() = 0;
  virtual const PictureLayerTiling* GetPendingOrActiveTwinTiling(
      const PictureLayerTiling* tiling) const = 0;
  virtual bool HasValidTilePriorities() const = 0;
  virtual bool RequiresHighResToDraw() const = 0;

 protected:
  virtual ~PictureLayerTilingClient() {}
};

struct TileMapKey {
  TileMapKey(int x, int y) : index_x(x), index_y(y) {}
  explicit TileMapKey(const std::pair<int, int>& index)
      : index_x(index.first), index_y(index.second) {}

  bool operator==(const TileMapKey& other) const {
    return index_x == other.index_x && index_y == other.index_y;
  }
  bool operator<(const TileMapKey& other) const {
    return std::tie(index_x, index_y) < std::tie(other.index_x, other.index_y);
  }

  int index_x;
  int index_y;
};

struct TileMapKeyHash {
  size_t operator()(const TileMapKey& key) const {
    uint16_t value1 = static_cast<uint16_t>(key.index_x);
    uint16_t value2 = static_cast<uint16_t>(key.index_y);
    uint32_t value1_32 = value1;
    return (value1_32 << 16) | value2;
  }
};

class CC_EXPORT PictureLayerTiling {
 public:
  static const int kBorderTexels = 1;

  // Note on raster_transform: In general raster_transform could be arbitrary,
  // the only restriction is that the layer bounds after transform should
  // be positive (because the tiling logic doesn't support negative space).
  // Also the implementation checks the transformed bounds leaves less than
  // 1px margin on top left edges, because there is few reason to do so.
  PictureLayerTiling(WhichTree tree,
                     const gfx::AxisTransform2d& raster_transform,
                     scoped_refptr<RasterSource> raster_source,
                     PictureLayerTilingClient* client,
                     float min_preraster_distance,
                     float max_preraster_distance);
  ~PictureLayerTiling();

  PictureLayerTilingClient* client() const { return client_; }

  void SetRasterSourceAndResize(scoped_refptr<RasterSource> raster_source);
  void Invalidate(const Region& layer_invalidation);
  void CreateMissingTilesInLiveTilesRect();
  void TakeTilesAndPropertiesFrom(PictureLayerTiling* pending_twin,
                                  const Region& layer_invalidation);

  bool IsTileRequiredForActivation(const Tile* tile) const;
  bool IsTileRequiredForDraw(const Tile* tile) const;

  // Returns true if the tile should be processed for decoding images skipped
  // during rasterization.
  bool ShouldDecodeCheckeredImagesForTile(const Tile* tile) const;

  void set_resolution(TileResolution resolution) {
    resolution_ = resolution;
    may_contain_low_resolution_tiles_ |= resolution == LOW_RESOLUTION;
  }
  TileResolution resolution() const { return resolution_; }
  bool may_contain_low_resolution_tiles() const {
    return may_contain_low_resolution_tiles_;
  }
  void reset_may_contain_low_resolution_tiles() {
    may_contain_low_resolution_tiles_ = false;
  }
  void set_can_require_tiles_for_activation(bool can_require_tiles) {
    can_require_tiles_for_activation_ = can_require_tiles;
  }
  bool can_require_tiles_for_activation() const {
    return can_require_tiles_for_activation_;
  }

  const scoped_refptr<RasterSource>& raster_source() const {
    return raster_source_;
  }
  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(); }
  // PictureLayerTilingSet uses the scale component of the raster transform
  // as the key for indexing and sorting. In theory we can have multiple
  // tilings with the same scale but different translation, but currently
  // we only allow tilings with unique scale for the sake of simplicity.
  float contents_scale_key() const { return raster_transform_.scale(); }
  const gfx::AxisTransform2d& raster_transform() const {
    return raster_transform_;
  }
  const TilingData* tiling_data() const { return &tiling_data_; }

  Tile* TileAt(int i, int j) const {
    TileMap::const_iterator iter = tiles_.find(TileMapKey(i, j));
    return iter == tiles_.end() ? nullptr : iter->second.get();
  }

  bool has_tiles() const { return !tiles_.empty(); }
  // all_tiles_done() can return false negatives.
  bool all_tiles_done() const { return all_tiles_done_; }
  void set_all_tiles_done(bool all_tiles_done) {
    all_tiles_done_ = all_tiles_done;
  }

  WhichTree tree() const { return tree_; }

  void VerifyNoTileNeedsRaster() const {
#if DCHECK_IS_ON()
    for (const auto& tile_pair : tiles_) {
      DCHECK(!tile_pair.second->draw_info().NeedsRaster() ||
             IsTileOccluded(tile_pair.second.get()));
    }
#endif  // DCHECK_IS_ON()
  }

  // For testing functionality.
  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;
  }

  void UpdateAllRequiredStateForTesting() {
    for (const auto& key_tile_pair : tiles_) {
      Tile* tile = key_tile_pair.second.get();
      UpdateRequiredStatesOnTile(tile);
    }
  }
  std::map<const Tile*, PrioritizedTile>
  UpdateAndGetAllPrioritizedTilesForTesting() const;

  void SetAllTilesOccludedForTesting() {
    gfx::Rect viewport_in_layer_space =
        EnclosingLayerRectFromContentsRect(current_visible_rect_);
    current_occlusion_in_layer_space_ =
        Occlusion(gfx::Transform(),
                  SimpleEnclosedRegion(viewport_in_layer_space),
                  SimpleEnclosedRegion(viewport_in_layer_space));
  }
  const gfx::Rect& GetCurrentVisibleRectForTesting() const {
    return current_visible_rect_;
  }
  void SetTilePriorityRectsForTesting(
      const gfx::Rect& visible_rect_in_content_space,
      const gfx::Rect& skewport,
      const gfx::Rect& soon_border_rect,
      const gfx::Rect& eventually_rect) {
    SetTilePriorityRects(1.f, visible_rect_in_content_space, skewport,
                         soon_border_rect, eventually_rect, Occlusion());
  }

  // 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();
    // This requests an iterator that produces a coverage of the
    // |coverage_rect|, which is specified at |coverage_scale|.
    CoverageIterator(const PictureLayerTiling* tiling,
                     float coverage_scale,
                     const gfx::Rect& coverage_rect);
    ~CoverageIterator();

    // Visible rect (no borders), always in the space of |coverage_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;

    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:
    gfx::Rect ComputeGeometryRect() const;

    const PictureLayerTiling* tiling_ = nullptr;
    gfx::Size coverage_rect_max_bounds_;
    gfx::Rect coverage_rect_;
    gfx::AxisTransform2d coverage_to_content_;

    Tile* current_tile_ = nullptr;
    gfx::Rect current_geometry_rect_;
    int tile_i_ = 0;
    int tile_j_ = 0;
    int left_ = 0;
    int top_ = 0;
    int right_ = -1;
    int bottom_ = -1;

    friend class PictureLayerTiling;
  };

  void Reset();

  void ComputeTilePriorityRects(
      const gfx::Rect& visible_rect_in_layer_space,
      const gfx::Rect& skewport_in_layer_space,
      const gfx::Rect& soon_border_rect_in_layer_space,
      const gfx::Rect& eventually_rect_in_layer_space,
      float ideal_contents_scale,
      const Occlusion& occlusion_in_layer_space);

  void GetAllPrioritizedTilesForTracing(
      std::vector<PrioritizedTile>* prioritized_tiles) const;
  void AsValueInto(base::trace_event::TracedValue* array) const;
  size_t GPUMemoryUsageInBytes() const;

  void UpdateRequiredStatesOnTile(Tile* tile) const;

 protected:
  friend class CoverageIterator;
  friend class PrioritizedTile;
  friend class TilingSetRasterQueueAll;
  friend class TilingSetRasterQueueRequired;
  friend class TilingSetEvictionQueue;

  // PENDING VISIBLE RECT refers to the visible rect that will become current
  // upon activation (ie, the pending tree's visible rect). Tiles in this
  // region that are not part of the current visible rect are all handled
  // here. Note that when processing a pending tree, this rect is the same as
  // the visible rect so no tiles are processed in this case.
  enum PriorityRectType {
    VISIBLE_RECT,
    PENDING_VISIBLE_RECT,
    SKEWPORT_RECT,
    SOON_BORDER_RECT,
    EVENTUALLY_RECT
  };

  using TileMap =
      std::unordered_map<TileMapKey, std::unique_ptr<Tile>, TileMapKeyHash>;

  void SetLiveTilesRect(const gfx::Rect& live_tiles_rect);
  void VerifyLiveTilesRect() const;
  Tile* CreateTile(const Tile::CreateInfo& info);
  // Removes the tile at i, j and returns it. Returns nullptr if the tile did
  // not exist.
  std::unique_ptr<Tile> TakeTileAt(int i, int j);
  bool TilingMatchesTileIndices(const PictureLayerTiling* twin) const;

  // Save the required data for computing tile priorities later.
  void SetTilePriorityRects(float content_to_screen_scale,
                            const gfx::Rect& visible_rect_in_content_space,
                            const gfx::Rect& skewport,
                            const gfx::Rect& soon_border_rect,
                            const gfx::Rect& eventually_rect,
                            const Occlusion& occlusion_in_layer_space);

  bool IsTileOccludedOnCurrentTree(const Tile* tile) const;
  Tile::CreateInfo CreateInfoForTile(int i, int j) const;
  bool ShouldCreateTileAt(const Tile::CreateInfo& info) const;
  bool IsTileOccluded(const Tile* tile) const;
  PrioritizedTile MakePrioritizedTile(
      Tile* tile,
      PriorityRectType priority_rect_type) const;
  TilePriority ComputePriorityForTile(
      const Tile* tile,
      PriorityRectType priority_rect_type) const;
  PriorityRectType ComputePriorityRectTypeForTile(const Tile* tile) const;
  bool has_visible_rect_tiles() const { return has_visible_rect_tiles_; }
  bool has_skewport_rect_tiles() const { return has_skewport_rect_tiles_; }
  bool has_soon_border_rect_tiles() const {
    return has_soon_border_rect_tiles_;
  }
  bool has_eventually_rect_tiles() const { return has_eventually_rect_tiles_; }

  const gfx::Rect& current_visible_rect() const {
    return current_visible_rect_;
  }
  gfx::Rect pending_visible_rect() const {
    const PictureLayerTiling* pending_tiling =
        tree_ == ACTIVE_TREE ? client_->GetPendingOrActiveTwinTiling(this)
                             : this;
    if (pending_tiling)
      return pending_tiling->current_visible_rect();
    return gfx::Rect();
  }
  const gfx::Rect& current_skewport_rect() const {
    return current_skewport_rect_;
  }
  const gfx::Rect& current_soon_border_rect() const {
    return current_soon_border_rect_;
  }
  const gfx::Rect& current_eventually_rect() const {
    return current_eventually_rect_;
  }
  void RemoveTilesInRegion(const Region& layer_region, bool recreate_tiles);

  gfx::Rect EnclosingContentsRectFromLayerRect(
      const gfx::Rect& layer_rect) const;
  gfx::Rect EnclosingLayerRectFromContentsRect(
      const gfx::Rect& contents_rect) const;

  // Given properties.
  const gfx::AxisTransform2d raster_transform_;
  PictureLayerTilingClient* const client_;
  const WhichTree tree_;
  scoped_refptr<RasterSource> raster_source_;
  const float min_preraster_distance_;
  const float max_preraster_distance_;
  TileResolution resolution_ = NON_IDEAL_RESOLUTION;
  bool may_contain_low_resolution_tiles_ = false;

  // Internal data.
  TilingData tiling_data_ = TilingData(gfx::Size(), gfx::Size(), kBorderTexels);
  TileMap tiles_;  // It is not legal to have a NULL tile in the tiles_ map.
  gfx::Rect live_tiles_rect_;

  bool can_require_tiles_for_activation_ = false;

  // 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_;
  // Other properties used for tile iteration and prioritization.
  float current_content_to_screen_scale_ = 0.f;
  Occlusion current_occlusion_in_layer_space_;
  float max_skewport_extent_in_screen_space_ = 0.f;

  bool has_visible_rect_tiles_ = false;
  bool has_skewport_rect_tiles_ = false;
  bool has_soon_border_rect_tiles_ = false;
  bool has_eventually_rect_tiles_ = false;
  bool all_tiles_done_ = true;

 private:
  DISALLOW_COPY_AND_ASSIGN(PictureLayerTiling);
};

}  // namespace cc

#endif  // CC_TILES_PICTURE_LAYER_TILING_H_