ash/shelf/shelf_item_delegate_manager.h

// Copyright 2013 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 ASH_SHELF_SHELF_ITEM_DELEGATE_MANAGER_H_
#define ASH_SHELF_SHELF_ITEM_DELEGATE_MANAGER_H_

#include <map>

#include "ash/ash_export.h"
#include "ash/shelf/shelf_item_types.h"
#include "ash/shelf/shelf_model_observer.h"
#include "base/compiler_specific.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"

namespace ash {
class ShelfItemDelegate;
class ShelfModel;

namespace test {
class ShelfItemDelegateManagerTestAPI;
}

// This class is added as a temporary fix for M39 to fix crbug.com/329597.
// TODO(skuhne): Find the real reason for this problem and remove this fix.
class ASH_EXPORT ShelfItemDelegateManagerObserver {
 public:
  ShelfItemDelegateManagerObserver() {}
  virtual ~ShelfItemDelegateManagerObserver() {}

  // Gets called when a ShelfItemDelegate gets changed. Note that
  // |item_delegate| can be NULL.
  virtual void OnSetShelfItemDelegate(ShelfID id,
                                      ShelfItemDelegate* item_delegate) = 0;
};

// ShelfItemDelegateManager manages the set of ShelfItemDelegates for the
// launcher. ShelfItemDelegateManager does not create ShelfItemDelegates,
// rather it is expected that someone else invokes SetShelfItemDelegate
// appropriately. On the other hand, ShelfItemDelegateManager destroys
// ShelfItemDelegates when the corresponding item from the model is removed.
class ASH_EXPORT ShelfItemDelegateManager : public ShelfModelObserver {
 public:
  explicit ShelfItemDelegateManager(ShelfModel* model);
  ~ShelfItemDelegateManager() override;

  void AddObserver(ShelfItemDelegateManagerObserver* observer);
  void RemoveObserver(ShelfItemDelegateManagerObserver* observer);

  // Set |item_delegate| for |id| and take an ownership.
  void SetShelfItemDelegate(ShelfID id,
                            scoped_ptr<ShelfItemDelegate> item_delegate);

  // Returns ShelfItemDelegate for |item_type|. Always returns non-NULL.
  ShelfItemDelegate* GetShelfItemDelegate(ShelfID id);

  // ShelfModelObserver overrides:
  void ShelfItemAdded(int model_index) override;
  void ShelfItemRemoved(int index, ShelfID id) override;
  void ShelfItemMoved(int start_index, int targetindex) override;
  void ShelfItemChanged(int index, const ShelfItem& old_item) override;
  void ShelfStatusChanged() override;

 private:
  friend class test::ShelfItemDelegateManagerTestAPI;

  typedef std::map<ShelfID, ShelfItemDelegate*> ShelfIDToItemDelegateMap;

  // Remove and destroy ShelfItemDelegate for |id|.
  void RemoveShelfItemDelegate(ShelfID id);

  // Owned by Shell.
  ShelfModel* model_;

  ShelfIDToItemDelegateMap id_to_item_delegate_map_;

  ObserverList<ShelfItemDelegateManagerObserver> observers_;

  DISALLOW_COPY_AND_ASSIGN(ShelfItemDelegateManager);
};

}  // namespace ash

#endif  // ASH_SHELF_SHELF_ITEM_DELEGATE_MANAGER_H_