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// Copyright 2017 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"
namespace remoting {
// A class for tracking the positions of an object moving through a viscous
// liquid.
class FlingTracker {
// time_constant: The larger the number the longer it takes to fling and the
// further the object can move.
explicit FlingTracker(float time_constant);
// Sets the position of the object and start fling. This will reset the
// existing fling.
// |velocity_x| and |velocity_y| need to be in pixel per second.
void StartFling(float velocity_x, float velocity_y);
void StopFling();
bool IsFlingInProgress() const;
// time_elapsed: The time elapsed since the animation has started.
// Moves forward the object to catch up with |time_elapsed|. The change in
// positions will be written to |dx| and |dy|.
// Returns true if the fling is still in progress at |time_elapsed|, false
// otherwise, in which case |dx| and |dy| will not be touched.
bool TrackMovement(base::TimeDelta time_elapsed, float* dx, float* dy);
float time_constant_;
float initial_speed_rate_ = 0.f;
float fling_duration_ = 0.f;
float velocity_ratio_x_ = 0.f;
float velocity_ratio_y_ = 0.f;
float previous_position_x_ = 0.f;
float previous_position_y_ = 0.f;
// FlingTracker is neither copyable nor movable.
FlingTracker(const FlingTracker&) = delete;
FlingTracker& operator=(const FlingTracker&) = delete;
} // namespace remoting