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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef ASH_SHELF_BACKGROUND_ANIMATOR_H_
      6 #define ASH_SHELF_BACKGROUND_ANIMATOR_H_
      7 
      8 #include "ash/ash_export.h"
      9 #include "base/basictypes.h"
     10 #include "ui/base/animation/animation_delegate.h"
     11 #include "ui/base/animation/slide_animation.h"
     12 
     13 namespace ash {
     14 namespace internal {
     15 
     16 // Delegate is notified any time the background changes.
     17 class ASH_EXPORT BackgroundAnimatorDelegate {
     18  public:
     19   virtual void UpdateBackground(int alpha) = 0;
     20 
     21  protected:
     22   virtual ~BackgroundAnimatorDelegate() {}
     23 };
     24 
     25 // BackgroundAnimator is used by the shelf to animate the background (alpha).
     26 class ASH_EXPORT BackgroundAnimator : public ui::AnimationDelegate {
     27  public:
     28   // How the background can be changed.
     29   enum ChangeType {
     30     CHANGE_ANIMATE,
     31     CHANGE_IMMEDIATE
     32   };
     33 
     34   BackgroundAnimator(BackgroundAnimatorDelegate* delegate,
     35                      int min_alpha,
     36                      int max_alpha);
     37   virtual ~BackgroundAnimator();
     38 
     39   // Sets the transition time in ms.
     40   void SetDuration(int time_in_ms);
     41 
     42   // Sets whether a background is rendered. Initial value is false. If |type|
     43   // is |CHANGE_IMMEDIATE| and an animation is not in progress this notifies
     44   // the delegate immediately (synchronously from this method).
     45   void SetPaintsBackground(bool value, ChangeType type);
     46   bool paints_background() const { return paints_background_; }
     47 
     48   // Current alpha.
     49   int alpha() const { return alpha_; }
     50 
     51   // ui::AnimationDelegate overrides:
     52   virtual void AnimationProgressed(const ui::Animation* animation) OVERRIDE;
     53 
     54  private:
     55   BackgroundAnimatorDelegate* delegate_;
     56 
     57   const int min_alpha_;
     58   const int max_alpha_;
     59 
     60   ui::SlideAnimation animation_;
     61 
     62   // Whether the background is painted.
     63   bool paints_background_;
     64 
     65   // Current alpha value of the background.
     66   int alpha_;
     67 
     68   DISALLOW_COPY_AND_ASSIGN(BackgroundAnimator);
     69 };
     70 
     71 }  // namespace internal
     72 }  // namespace ash
     73 
     74 #endif  // ASH_SHELF_BACKGROUND_ANIMATOR_H_
     75