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// Copyright 2014 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.
#include "base/time/time.h"
#include "ui/events/events_base_export.h"
#include "ui/events/gesture_curve.h"
#include "ui/gfx/geometry/vector2d_f.h"
namespace ui {
// Native port of android.widget.Scroller.
// * Change-Id: I4365946f890a76fcfa78ca9d69f2a8e0848095a9
// * Please update the Change-Id as upstream Android changes are pulled.
class EVENTS_BASE_EXPORT Scroller : public GestureCurve {
struct Config {
// Controls fling deceleration. Defaults to 0.015f.
float fling_friction;
// Controls fling accumulation. Defaults to disabled.
bool flywheel_enabled;
explicit Scroller(const Config& config);
~Scroller() override;
// GestureCurve implementation.
bool ComputeScrollOffset(base::TimeTicks time,
gfx::Vector2dF* offset,
gfx::Vector2dF* velocity) override;
// Start scrolling by providing a starting point and the distance to travel.
// The default value of 250 milliseconds will be used for the duration.
void StartScroll(float start_x,
float start_y,
float dx,
float dy,
base::TimeTicks start_time);
// Start scrolling by providing a starting point, the distance to travel,
// and the duration of the scroll.
void StartScroll(float start_x,
float start_y,
float dx,
float dy,
base::TimeTicks start_time,
base::TimeDelta duration);
// Start scrolling based on a fling gesture. The distance travelled will
// depend on the initial velocity of the fling.
void Fling(float start_x,
float start_y,
float velocity_x,
float velocity_y,
float min_x,
float max_x,
float min_y,
float max_y,
base::TimeTicks start_time);
// Extend the scroll animation by |extend|. This allows a running animation
// to scroll further and longer when used with |SetFinalX()| or |SetFinalY()|.
void ExtendDuration(base::TimeDelta extend);
void SetFinalX(float new_x);
void SetFinalY(float new_y);
// Stops the animation. Contrary to |ForceFinished()|, aborting the animation
// causes the scroller to move to the final x and y position.
void AbortAnimation();
// Terminate the scroll without affecting the current x and y positions.
void ForceFinished(bool finished);
// Returns whether the scroller has finished scrolling.
bool IsFinished() const;
// Returns the time elapsed since the beginning of the scrolling.
base::TimeDelta GetTimePassed() const;
// Returns how long the scroll event will take.
base::TimeDelta GetDuration() const;
float GetStartX() const;
float GetStartY() const;
float GetCurrX() const;
float GetCurrY() const;
float GetCurrVelocity() const;
float GetCurrVelocityX() const;
float GetCurrVelocityY() const;
float GetFinalX() const;
float GetFinalY() const;
bool IsScrollingInDirection(float xvel, float yvel) const;
enum Mode {
bool ComputeScrollOffsetInternal(base::TimeTicks time);
void RecomputeDeltas();
double GetSplineDeceleration(float velocity) const;
base::TimeDelta GetSplineFlingDuration(float velocity) const;
double GetSplineFlingDistance(float velocity) const;
Mode mode_;
float start_x_;
float start_y_;
float final_x_;
float final_y_;
float min_x_;
float max_x_;
float min_y_;
float max_y_;
float curr_x_;
float curr_y_;
base::TimeTicks start_time_;
base::TimeTicks curr_time_;
base::TimeDelta duration_;
double duration_seconds_reciprocal_;
float delta_x_;
float delta_x_norm_;
float delta_y_;
float delta_y_norm_;
bool finished_;
bool flywheel_enabled_;
float velocity_;
float curr_velocity_;
float distance_;
float fling_friction_;
float deceleration_;
float tuning_coeff_;
} // namespace ui