ui/views/animation/scroll_animator.h

   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:
  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   ~ScrollAnimator() override;
  33
  34   // Use this if you would prefer different acceleration than the default.
  35   void set_acceleration(float acceleration) { acceleration_ = acceleration; }
  36
  37   void Start(float velocity_x, float velocity_y);
  38   void Stop();
  39
  40   bool is_scrolling() const { return !!animation_.get(); }
  41
  42  private:
  43   // Implementation of gfx::AnimationDelegate.
  44   void AnimationEnded(const gfx::Animation* animation) override;
  45   void AnimationProgressed(const gfx::Animation* animation) override;
  46   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_