Implement animation UI for opening/closing an app list folder.

ui/app_list/app_list_folder_item.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 UI_APP_LIST_APP_LIST_FOLDER_ITEM_H_
 #define UI_APP_LIST_APP_LIST_FOLDER_ITEM_H_
 
 #include <string>
 #include <vector>
 
 #include "ui/app_list/app_list_export.h"
 #include "ui/app_list/app_list_item.h"
 #include "ui/app_list/app_list_item_list_observer.h"
 #include "ui/app_list/app_list_item_observer.h"
+#include "ui/gfx/geometry/rect.h"
 
 namespace app_list {
 
 class AppListItemList;
 
+typedef std::vector<gfx::Rect> TopIconsBounds;

[xiyuan, 2014/01/16 01:46:48]

nit: TopIconsBounds -> Rects

[jennyz, 2014/01/16 17:49:52]

Done.

+
 // AppListFolderItem implements the model/controller for folders.
 class APP_LIST_EXPORT AppListFolderItem : public AppListItem,
                                           public AppListItemListObserver,
                                           public AppListItemObserver {
  public:
   explicit AppListFolderItem(const std::string& id);
   virtual ~AppListFolderItem();
 
   // Updates the folder's icon.
   void UpdateIcon();
 
+  // Returns the icon of one of the top items with |item_index|.
+  const gfx::ImageSkia& GetTopIcon(size_t item_index);
+
   AppListItemList* item_list() { return item_list_.get(); }
 
   static const char kAppType[];
 
+  // Calculates the top item icons' bounds inside |folder_icon_bounds|.
+  // Returns the bounds of top item icons in sequence of top left, top right,
+  // bottom left, bottom right.
+  static TopIconsBounds GetTopIconsBounds(const gfx::Rect& folder_icon_bounds);
+
  private:
   // AppListItem
   virtual void Activate(int event_flags) OVERRIDE;
   virtual const char* GetAppType() const OVERRIDE;
   virtual ui::MenuModel* GetContextMenuModel() OVERRIDE;
 
   // AppListItemObserver
   virtual void ItemIconChanged() OVERRIDE;
   virtual void ItemTitleChanged() OVERRIDE;
   virtual void ItemHighlightedChanged() OVERRIDE;
@@ skipping 13 matching lines @@
   scoped_ptr<AppListItemList> item_list_;
   // Top items for generating folder icon.
   std::vector<AppListItem*> top_items_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListFolderItem);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APP_LIST_FOLDER_ITEM_H_