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

ui/app_list/views/apps_container_view.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_VIEWS_APPS_CONTAINER_VIEW_H_
 #define UI_APP_LIST_VIEWS_APPS_CONTAINER_VIEW_H_
 
+#include "ui/app_list/app_list_folder_item.h"
 #include "ui/views/view.h"
 
 namespace content {
 class WebContents;
 }
 
 namespace app_list {
 
 class AppsGridView;
 class AppListFolderItem;
 class AppListFolderView;
 class AppListMainView;
 class AppListModel;
 class ContentsView;
 class PaginationModel;
 
+class TopIconAnimationObserver {
+ public:
+  // Called when top icon animation completes.
+  virtual void OnTopIconAnimationsComplete(views::View* icon_view) {}
+
+ protected:
+  TopIconAnimationObserver() {}
+  virtual ~TopIconAnimationObserver() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TopIconAnimationObserver);
+};
+
 // AppsContainerView contains a root level AppsGridView to render the root level
 // app items, and a AppListFolderView to render the app items inside the
 // active folder. Only one if them is visible to user at any time.
-class AppsContainerView : public views::View {
+class AppsContainerView : public views::View,
+                          public TopIconAnimationObserver {
  public:
   AppsContainerView(AppListMainView* app_list_main_view,
                     PaginationModel* pagination_model,
                     AppListModel* model,
                     content::WebContents* start_page_contents);
   virtual ~AppsContainerView();
 
   // Shows the active folder content specified by |folder_item|.
   void ShowActiveFolder(AppListFolderItem* folder_item);
 
-  // Shows the apps list from root.
-  void ShowApps();
+  // Shows the root level apps list. This is called when UI navigate back from
+  // a folder view with |folder_item|.
+  void ShowApps(AppListFolderItem* folder_item);
 
   // Overridden from views::View:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
   virtual void Layout() OVERRIDE;
   virtual bool OnKeyPressed(const ui::KeyEvent& event) OVERRIDE;
 
+  // Overridden from TopIconAnimationObserver.
+  virtual void OnTopIconAnimationsComplete(views::View* icon_view) OVERRIDE;
+
   AppsGridView* apps_grid_view() { return apps_grid_view_; }
 
  private:
   enum ShowState {
     SHOW_APPS,
     SHOW_ACTIVE_FOLDER,
   };
 
   void SetShowState(ShowState show_state);
 
+  // Calculates the top item icon bounds in the active folder icon. The bounds
+  // is relative to AppsContainerView.
+  // Returns the bounds of top items' icon in sequence of top left, top right,
+  // bottom left, bottom right.
+  Rects GetTopItemIconBoundsInActiveFolder();
+
+  // Creates the transitional views for animating the top items in the folder
+  // when opening or closing a folder.
+  void CreateViewsForFolderTopItemsAnimation(
+      AppListFolderItem* active_folder, bool open_folder);
+
   AppListModel* model_;
   AppsGridView* apps_grid_view_;  // Owned by views hierarchy.
   AppListFolderView* app_list_folder_view_;  // Owned by views hierarchy.
   ShowState show_state_;
 
+  // The transitional views for animating the top items in folder
+  // when opening or closing a folder.
+  std::vector<views::View*> top_icon_views_;
+
   DISALLOW_COPY_AND_ASSIGN(AppsContainerView);
 };
 
 }  // namespace app_list
 
 
 #endif  // UI_APP_LIST_VIEWS_APPS_CONTAINER_VIEW_H_