cc/tile_manager.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_TILE_MANAGER_H_
#define CC_TILE_MANAGER_H_

#include <vector>

#include "base/memory/scoped_ptr.h"
#include "base/values.h"
#include "cc/resource_pool.h"
#include "cc/tile_priority.h"

namespace base {
class SequencedWorkerPool;
}

namespace cc {

class Tile;
class TileVersion;
class ResourceProvider;

class CC_EXPORT TileManagerClient {
 public:
  virtual void ScheduleManageTiles() = 0;
  virtual void ScheduleRedraw() = 0;

 protected:
  virtual ~TileManagerClient() {}
};

// Tile manager classifying tiles into a few basic
// bins:
enum TileManagerBin {
  NOW_BIN = 0, // Needed ASAP.
  SOON_BIN = 1, // Impl-side version of prepainting.
  EVENTUALLY_BIN = 2, // Nice to have, if we've got memory and time.
  NEVER_BIN = 3, // Dont bother.
  NUM_BINS = 4
};

// This is state that is specific to a tile that is
// managed by the TileManager.
class CC_EXPORT ManagedTileState {
 public:
  ManagedTileState();
  ~ManagedTileState();

  // Persisted state: valid all the time.
  bool can_use_gpu_memory;
  bool can_be_freed;
  ResourceProvider::ResourceId resource_id;
  bool resource_id_is_being_initialized;

  // Ephemeral state, valid only during Manage.
  TileManagerBin bin;
  TileResolution resolution;
  float time_to_needed_in_seconds;
};

// This class manages tiles, deciding which should get rasterized and which
// should no longer have any memory assigned to them. Tile objects are "owned"
// by layers; they automatically register with the manager when they are
// created, and unregister from the manager when they are deleted.
class CC_EXPORT TileManager {
 public:
  TileManager(TileManagerClient* client, ResourceProvider *resource_provider);
  virtual ~TileManager();

  const GlobalStateThatImpactsTilePriority& GlobalState() const { return global_state_; }
  void SetGlobalState(const GlobalStateThatImpactsTilePriority& state);

  void ManageTiles();

 protected:
  // Methods called by Tile
  friend class Tile;
  void RegisterTile(Tile*);
  void UnregisterTile(Tile*);
  void WillModifyTilePriority(Tile*, WhichTree, const TilePriority& new_priority);

 private:
  void AssignGpuMemoryToTiles();
  void FreeResourcesForTile(Tile*);
  void ScheduleManageTiles();
  void DispatchMoreRasterTasks();
  void DispatchOneRasterTask(scoped_refptr<Tile>);
  void OnRasterTaskCompleted(
      scoped_refptr<Tile>,
      ResourceProvider::ResourceId,
      scoped_refptr<PicturePileImpl>);
  void DidFinishTileInitialization(Tile*, ResourceProvider::ResourceId);

  TileManagerClient* client_;
  scoped_ptr<ResourcePool> resource_pool_;
  bool manage_tiles_pending_;
  int pending_raster_tasks_;
  scoped_refptr<base::SequencedWorkerPool> worker_pool_;

  GlobalStateThatImpactsTilePriority global_state_;

  typedef std::vector<Tile*> TileVector;
  TileVector tiles_;
  TileVector tiles_that_need_to_be_rasterized_;
};

}  // namespace cc

#endif  // CC_TILE_MANAGER_H_