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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef mozilla_layout_ScrollAnimationMSDPhysics_h_
#define mozilla_layout_ScrollAnimationMSDPhysics_h_
#include "ScrollAnimationPhysics.h"
#include "mozilla/layers/AxisPhysicsMSDModel.h"
namespace mozilla {
// This class implements a cubic MSD timing function and automatically
// adapts the animation duration based on the scrolling rate.
class ScrollAnimationMSDPhysics final : public ScrollAnimationPhysics {
typedef mozilla::layers::AxisPhysicsMSDModel AxisPhysicsMSDModel;
explicit ScrollAnimationMSDPhysics(const nsPoint& aStartPos);
void Update(const TimeStamp& aTime, const nsPoint& aDestination,
const nsSize& aCurrentVelocity) override;
void ApplyContentShift(const CSSPoint& aShiftDelta) override;
// Get the velocity at a point in time in nscoords/sec.
nsSize VelocityAt(const TimeStamp& aTime) override;
// Returns the expected scroll position at a given point in time, in app
// units, relative to the scroll frame.
nsPoint PositionAt(const TimeStamp& aTime) override;
bool IsFinished(const TimeStamp& aTime) override {
return mModelX.IsFinished(1) && mModelY.IsFinished(1);
// A wrapper around AxisPhysicsMSDModel which takes additional steps to avoid
// oscillating motion.
class NonOscillatingAxisPhysicsMSDModel : public AxisPhysicsMSDModel {
NonOscillatingAxisPhysicsMSDModel(double aInitialPosition,
double aInitialDestination,
double aInitialVelocity,
double aSpringConstant,
double aDampingRatio);
double ComputeSpringConstant(const TimeStamp& aTime);
void SimulateUntil(const TimeStamp& aTime);
TimeStamp mPreviousEventTime;
TimeDuration mPreviousDelta;
TimeStamp mStartTime;
nsPoint mStartPos;
nsPoint mDestination;
TimeStamp mLastSimulatedTime;
NonOscillatingAxisPhysicsMSDModel mModelX;
NonOscillatingAxisPhysicsMSDModel mModelY;
bool mIsFirstIteration;
} // namespace mozilla
#endif // mozilla_layout_ScrollAnimationMSDPhysics_h_