cc/input/single_scrollbar_animation_controller_thinning.h

// Copyright 2013 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_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_
#define CC_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_

#include <memory>

#include "base/macros.h"
#include "base/time/time.h"
#include "cc/cc_export.h"
#include "cc/input/scrollbar.h"
#include "cc/layers/layer_impl.h"
#include "cc/layers/scrollbar_layer_impl_base.h"
#include "ui/gfx/geometry/vector2d_f.h"

namespace cc {

class ScrollbarAnimationControllerClient;

// ScrollbarAnimationControllerThinning for one scrollbar
class CC_EXPORT SingleScrollbarAnimationControllerThinning {
 public:
  static constexpr float kIdleThicknessScale = 0.4f;
  static constexpr float kMouseMoveDistanceToTriggerExpand = 25.f;

  static std::unique_ptr<SingleScrollbarAnimationControllerThinning> Create(
      ElementId scroll_element_id,
      ScrollbarOrientation orientation,
      ScrollbarAnimationControllerClient* client,
      base::TimeDelta thinning_duration);

  ~SingleScrollbarAnimationControllerThinning() {}

  bool mouse_is_over_scrollbar_thumb() const {
    return mouse_is_over_scrollbar_thumb_;
  }
  bool mouse_is_near_scrollbar_thumb() const {
    return mouse_is_near_scrollbar_thumb_;
  }
  bool mouse_is_near_scrollbar_track() const {
    return mouse_is_near_scrollbar_track_;
  }

  bool captured() const { return captured_; }

  bool Animate(base::TimeTicks now);
  void StartAnimation();
  void StopAnimation();

  void UpdateThumbThicknessScale();

  void DidMouseDown();
  void DidMouseUp();
  void DidMouseLeave();
  void DidMouseMove(const gfx::PointF& device_viewport_point);

 private:
  SingleScrollbarAnimationControllerThinning(
      ElementId scroll_element_id,
      ScrollbarOrientation orientation,
      ScrollbarAnimationControllerClient* client,
      base::TimeDelta thinning_duration);

  ScrollbarLayerImplBase* GetScrollbar() const;
  float AnimationProgressAtTime(base::TimeTicks now);
  void RunAnimationFrame(float progress);
  const base::TimeDelta& Duration();

  // Describes whether the current animation should INCREASE (thicken)
  // a bar or DECREASE it (thin).
  enum AnimationChange { NONE, INCREASE, DECREASE };
  float ThumbThicknessScaleAt(float progress);

  float AdjustScale(float new_value,
                    float current_value,
                    AnimationChange animation_change,
                    float min_value,
                    float max_value);
  void ApplyThumbThicknessScale(float thumb_thickness_scale);

  ScrollbarAnimationControllerClient* client_;

  base::TimeTicks last_awaken_time_;
  bool is_animating_;

  ElementId scroll_element_id_;

  ScrollbarOrientation orientation_;
  bool captured_;
  bool mouse_is_over_scrollbar_thumb_;
  bool mouse_is_near_scrollbar_thumb_;
  bool mouse_is_near_scrollbar_track_;
  // Are we narrowing or thickening the bars.
  AnimationChange thickness_change_;

  base::TimeDelta thinning_duration_;

  DISALLOW_COPY_AND_ASSIGN(SingleScrollbarAnimationControllerThinning);
};

}  // namespace cc

#endif  // CC_INPUT_SINGLE_SCROLLBAR_ANIMATION_CONTROLLER_THINNING_H_