cc/animation/scrollbar_animation_controller.h

// Copyright 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.

#ifndef CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_H_
#define CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_H_

#include "base/cancelable_callback.h"
#include "base/memory/weak_ptr.h"
#include "base/time/time.h"
#include "cc/base/cc_export.h"
#include "ui/gfx/vector2d_f.h"

namespace cc {

class CC_EXPORT ScrollbarAnimationControllerClient {
 public:
  virtual ~ScrollbarAnimationControllerClient() {}

  virtual void PostDelayedScrollbarFade(const base::Closure& start_fade,
                                        base::TimeDelta delay) = 0;
  virtual void SetNeedsScrollbarAnimationFrame() = 0;
};

// This abstract class represents the compositor-side analogy of
// ScrollbarAnimator.  Individual platforms should subclass it to provide
// specialized implementation.
class CC_EXPORT ScrollbarAnimationController {
 public:
  virtual ~ScrollbarAnimationController();

  void Animate(base::TimeTicks now);

  virtual void DidScrollBegin();
  virtual void DidScrollUpdate();
  virtual void DidScrollEnd();
  virtual void DidMouseMoveOffScrollbar() {}
  virtual void DidMouseMoveNear(float distance) {}

 protected:
  ScrollbarAnimationController(ScrollbarAnimationControllerClient* client,
                               base::TimeDelta delay_before_starting,
                               base::TimeDelta duration);

  virtual void RunAnimationFrame(float progress) = 0;

  void StartAnimation();
  void StopAnimation();

 private:
  // Returns how far through the animation we are as a progress value from
  // 0 to 1.
  float AnimationProgressAtTime(base::TimeTicks now);

  void PostDelayedFade();

  ScrollbarAnimationControllerClient* client_;
  base::TimeTicks last_awaken_time_;
  base::TimeDelta delay_before_starting_;
  base::TimeDelta duration_;
  bool is_animating_;

  bool currently_scrolling_;
  bool scroll_gesture_has_scrolled_;
  base::CancelableClosure delayed_scrollbar_fade_;

  base::WeakPtrFactory<ScrollbarAnimationController> weak_factory_;
};

}  // namespace cc

#endif  // CC_ANIMATION_SCROLLBAR_ANIMATION_CONTROLLER_H_