Fix white flash when user sings out and wallpaper animation regression

ash/desktop_background/desktop_background_controller.h

 // Copyright (c) 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 ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_CONTROLLER_H_
 #define ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "ash/desktop_background/desktop_background_resources.h"
 #include "ash/wm/window_animations.h"
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_observer.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/image/image_skia.h"
 
 namespace aura {
 class RootWindow;
 }
 
 namespace ash {
 
+namespace internal {
+class DesktopBackgroundWidgetController;
+}
+
 class UserWallpaperDelegate {
  public:
   virtual ~UserWallpaperDelegate() {}
 
   // Returns type of window animation that should be used when showin wallpaper.
   virtual ash::WindowVisibilityAnimationType GetAnimationType() = 0;
 
   // Initialize wallpaper.
   virtual void InitializeWallpaper() = 0;
 
@@ skipping 51 matching lines @@
   void SetDefaultWallpaper(int index, bool force_reload);
 
   // Sets the user selected custom wallpaper. Called when user selected a file
   // from file system or changed the layout of wallpaper.
   void SetCustomWallpaper(const gfx::ImageSkia& wallpaper,
                           WallpaperLayout layout);
 
   // Cancels the current wallpaper loading operation.
   void CancelPendingWallpaperOperation();
 
+  // Sets the current used component for |root_window|.
+  void SetComponentForRootWindow(aura::RootWindow* root_window);
+
   // Sets the desktop background to solid color mode and creates a solid
   // |color| layout.
   void SetDesktopBackgroundSolidColorMode(SkColor color);
 
   // Creates an empty wallpaper. Some tests require a wallpaper widget is ready
   // when running. However, the wallpaper widgets are now created asynchronously
   // . If loading a real wallpaper, there are cases that these tests crash
   // because the required widget is not ready. This function synchronously
   // creates an empty widget for those tests to prevent crashes. An example test
   // is SystemGestureEventFilterTest.ThreeFingerSwipe.
@@ skipping 45 matching lines @@
   // Returns the appropriate wallpaper resolution for all root windows.
   WallpaperResolution GetAppropriateResolution();
 
   // Can change at runtime.
   bool locked_;
 
   BackgroundMode desktop_background_mode_;
 
   SkColor background_color_;
 
+  typedef std::map<aura::RootWindow*,
+      internal::DesktopBackgroundWidgetController*> RootWindowComponentMap;
+  RootWindowComponentMap root_window_component_map_;

[sky, 2012/08/10 19:20:37]

You never clean this state as roots are removed. I think it would be better to
store this state as a property on the rootwindow.

[bshe, 2012/08/10 19:51:41]

This map is a place to store the component for root window. When animation
finished, the component is stored as a property (kWindowDesktopComponent) on the
root window. The reason I have to wait for the animation finish is because if we
set that property immediately, the old component is removed right away. And a
white screen will be displayed. The new wallpaper/component will fade in from
that white screen. So to avoid the white screen issue, I need to set the
property after animation finished. Given that we already have a property to save
the data, I just want to confirm with you that it is OK to create another
property (something like kWindowDesktopComponentTemp?) on root window to save
the component temporarily (before animation finished). I am not familiar with
root window property, so I am not sure if it is cheap enough. Thanks for
suggestion.

On 2012/08/10 19:20:37, sky wrote:

+
   // The current wallpaper.
   scoped_ptr<WallpaperData> current_wallpaper_;
 
   scoped_refptr<WallpaperOperation> wallpaper_op_;
 
   base::WeakPtrFactory<DesktopBackgroundController> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopBackgroundController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_CONTROLLER_H_