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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/gfx/animation/animation_delegate.h"
     11 #include "ui/gfx/animation/slide_animation.h"
     12 
     13 namespace ash {
     14 
     15 // How the background can be changed.
     16 enum BackgroundAnimatorChangeType {
     17   BACKGROUND_CHANGE_ANIMATE,
     18   BACKGROUND_CHANGE_IMMEDIATE
     19 };
     20 
     21 // Delegate is notified any time the background changes.
     22 class ASH_EXPORT BackgroundAnimatorDelegate {
     23  public:
     24   virtual void UpdateBackground(int alpha) = 0;
     25 
     26  protected:
     27   virtual ~BackgroundAnimatorDelegate() {}
     28 };
     29 
     30 // BackgroundAnimator is used by the shelf to animate the background (alpha).
     31 class ASH_EXPORT BackgroundAnimator : public gfx::AnimationDelegate {
     32  public:
     33   BackgroundAnimator(BackgroundAnimatorDelegate* delegate,
     34                      int min_alpha,
     35                      int max_alpha);
     36   virtual ~BackgroundAnimator();
     37 
     38   // Sets the transition time in ms.
     39   void SetDuration(int time_in_ms);
     40 
     41   // Sets whether a background is rendered. Initial value is false. If |type|
     42   // is |CHANGE_IMMEDIATE| and an animation is not in progress this notifies
     43   // the delegate immediately (synchronously from this method).
     44   void SetPaintsBackground(bool value, BackgroundAnimatorChangeType type);
     45   bool paints_background() const { return paints_background_; }
     46 
     47   // Current alpha.
     48   int alpha() const { return alpha_; }
     49 
     50   // gfx::AnimationDelegate overrides:
     51   virtual void AnimationProgressed(const gfx::Animation* animation) OVERRIDE;
     52 
     53  private:
     54   BackgroundAnimatorDelegate* delegate_;
     55 
     56   const int min_alpha_;
     57   const int max_alpha_;
     58 
     59   gfx::SlideAnimation animation_;
     60 
     61   // Whether the background is painted.
     62   bool paints_background_;
     63 
     64   // Current alpha value of the background.
     65   int alpha_;
     66 
     67   DISALLOW_COPY_AND_ASSIGN(BackgroundAnimator);
     68 };
     69 
     70 }  // namespace ash
     71 
     72 #endif  // ASH_SHELF_BACKGROUND_ANIMATOR_H_
     73