Fix wallpaper fade animation flashing problem.

ash/desktop_background/desktop_background_view.cc

 // 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.
 
 #include "ash/desktop_background/desktop_background_view.h"
 
 #include <limits>
 
 #include "ash/ash_export.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
+#include "ash/wm/root_window_layout_manager.h"
 #include "ash/wm/window_animations.h"
 #include "base/utf_string_conversions.h"
 #include "grit/ui_resources.h"
 #include "ui/aura/root_window.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/canvas.h"
+#include "ui/gfx/compositor/layer.h"
+#include "ui/gfx/compositor/layer_animation_observer.h"
+#include "ui/gfx/compositor/scoped_layer_animation_settings.h"
 #include "ui/gfx/image/image.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 namespace internal {
+namespace {
+
+class ShowWallpaperAnimationObserver : public ui::ImplicitAnimationObserver {
+ public:
+  explicit ShowWallpaperAnimationObserver(views::Widget* desktop_widget) :

[flackr, 2012/04/20 19:04:51]

nit: : goes on next line with desktop_widget_.

[bshe, 2012/04/20 19:13:58]

Done.

+      desktop_widget_(desktop_widget){
+  }

[flackr, 2012/04/20 19:04:51]

nit: newline between functions.

[bshe, 2012/04/20 19:13:58]

Done.

+  virtual ~ShowWallpaperAnimationObserver() {
+  }
+
+ private:
+  // Overridden from ui::ImplicitAnimationObserver:
+  virtual void OnImplicitAnimationsCompleted() OVERRIDE {
+    internal::RootWindowLayoutManager* root_window_layout =
+      Shell::GetInstance()->root_window_layout();
+    root_window_layout->SetBackgroundWidget(desktop_widget_);
+    delete this;
+  }
+
+  views::Widget* desktop_widget_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShowWallpaperAnimationObserver);
+};
+
+} // namespace

[flackr, 2012/04/20 19:04:51]

nit two spaces after }

[bshe, 2012/04/20 19:13:58]

Done.

 
 // For our scaling ratios we need to round positive numbers.
 static int RoundPositive(double x) {
   return static_cast<int>(floor(x + 0.5));
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopBackgroundView, public:
 
 DesktopBackgroundView::DesktopBackgroundView(const SkBitmap& wallpaper,
@@ skipping 56 matching lines @@
 
 bool DesktopBackgroundView::OnMousePressed(const views::MouseEvent& event) {
   return true;
 }
 
 void DesktopBackgroundView::OnMouseReleased(const views::MouseEvent& event) {
   if (event.IsRightMouseButton())
     Shell::GetInstance()->ShowBackgroundMenu(GetWidget(), event.location());
 }
 
-views::Widget* CreateDesktopBackground(const SkBitmap& wallpaper,
-                                       ImageLayout layout) {
+void CreateDesktopBackground(const SkBitmap& wallpaper, ImageLayout layout) {
   views::Widget* desktop_widget = new views::Widget;
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
   DesktopBackgroundView* view = new DesktopBackgroundView(wallpaper, layout);
   params.delegate = view;
   params.parent =
       Shell::GetInstance()->GetContainer(
           ash::internal::kShellWindowId_DesktopBackgroundContainer);
   desktop_widget->Init(params);
   desktop_widget->SetContentsView(view);
   ash::SetWindowVisibilityAnimationType(
       desktop_widget->GetNativeView(),
       ash::WINDOW_VISIBILITY_ANIMATION_TYPE_FADE);
+  ash::SetWindowVisibilityAnimationTransition(
+        desktop_widget->GetNativeView(),
+        ash::ANIMATE_SHOW);

[flackr, 2012/04/20 19:04:51]

nit: only indent 4 spaces.

   desktop_widget->SetBounds(params.parent->bounds());
+  ui::ScopedLayerAnimationSettings settings(desktop_widget->GetNativeView()->
+                                            layer()->GetAnimator());
+  settings.SetPreemptionStrategy(ui::LayerAnimator::ENQUEUE_NEW_ANIMATION);
+  settings.AddObserver(new ShowWallpaperAnimationObserver(desktop_widget));
   desktop_widget->Show();
   desktop_widget->GetNativeView()->SetName("DesktopBackgroundView");
-  return desktop_widget;
 }
 
 }  // namespace internal
 }  // namespace ash