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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 UI_VIEWS_ANIMATION_SCROLL_ANIMATOR_H_
6 #define UI_VIEWS_ANIMATION_SCROLL_ANIMATOR_H_
7 
8 #include "base/basictypes.h"
9 #include "base/memory/scoped_ptr.h"
10 #include "ui/gfx/animation/animation_delegate.h"
11 #include "ui/views/views_export.h"
12 
13 namespace gfx {
14 class SlideAnimation;
15 }
16 
17 namespace views {
18 
19 class VIEWS_EXPORT ScrollDelegate {
20  public:
21   // Returns true if the content was actually scrolled, false otherwise.
22   virtual bool OnScroll(float dx, float dy) = 0;
23 
24  protected:
~ScrollDelegate()25   ~ScrollDelegate() {}
26 };
27 
28 class VIEWS_EXPORT ScrollAnimator : public gfx::AnimationDelegate {
29  public:
30   // The ScrollAnimator does not own the delegate. Uses default acceleration.
31   explicit ScrollAnimator(ScrollDelegate* delegate);
32   virtual ~ScrollAnimator();
33 
34   // Use this if you would prefer different acceleration than the default.
set_acceleration(float acceleration)35   void set_acceleration(float acceleration) { acceleration_ = acceleration; }
36 
37   void Start(float velocity_x, float velocity_y);
38   void Stop();
39 
is_scrolling()40   bool is_scrolling() const { return !!animation_.get(); }
41 
42  private:
43   // Implementation of gfx::AnimationDelegate.
44   virtual void AnimationEnded(const gfx::Animation* animation) OVERRIDE;
45   virtual void AnimationProgressed(const gfx::Animation* animation) OVERRIDE;
46   virtual void AnimationCanceled(const gfx::Animation* animation) OVERRIDE;
47 
48   ScrollDelegate* delegate_;
49 
50   float velocity_x_;
51   float velocity_y_;
52   float last_t_;
53   float duration_;
54   float acceleration_;
55 
56   scoped_ptr<gfx::SlideAnimation> animation_;
57 
58   DISALLOW_COPY_AND_ASSIGN(ScrollAnimator);
59 };
60 
61 }  // namespace views
62 
63 #endif  // UI_VIEWS_ANIMATION_SCROLL_ANIMATOR_H_
64