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/*
* Copyright (C) 2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "PlatformWheelEvent.h"
#include "ScrollExtents.h"
#include "ScrollTypes.h"
#include <wtf/Seconds.h>
#include <wtf/TZoneMalloc.h>
namespace WebCore {
class FloatPoint;
class FloatSize;
class ScrollingMomentumCalculator {
WTF_MAKE_TZONE_ALLOCATED(ScrollingMomentumCalculator);
public:
WEBCORE_EXPORT static void setPlatformMomentumScrollingPredictionEnabled(bool);
static std::unique_ptr<ScrollingMomentumCalculator> create(const ScrollExtents&, const FloatPoint& initialOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity);
ScrollingMomentumCalculator(const ScrollExtents&, const FloatPoint& initialOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity);
virtual ~ScrollingMomentumCalculator() = default;
virtual FloatPoint scrollOffsetAfterElapsedTime(Seconds) = 0;
virtual Seconds animationDuration() = 0;
FloatPoint destinationScrollOffset() const { return m_retargetedScrollOffset.value_or(m_initialDestinationOffset); }
void setRetargetedScrollOffset(const FloatPoint&);
protected:
virtual FloatPoint predictedDestinationOffset();
virtual void destinationScrollOffsetDidChange() { }
FloatSize m_initialDelta;
FloatSize m_initialVelocity;
FloatPoint m_initialScrollOffset;
FloatPoint m_initialDestinationOffset;
ScrollExtents m_scrollExtents;
private:
std::optional<FloatPoint> m_retargetedScrollOffset;
};
class BasicScrollingMomentumCalculator final : public ScrollingMomentumCalculator {
public:
BasicScrollingMomentumCalculator(const ScrollExtents&, const FloatPoint& initialOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity);
private:
FloatPoint scrollOffsetAfterElapsedTime(Seconds) final;
Seconds animationDuration() final;
void initializeInterpolationCoefficientsIfNecessary();
void initializeSnapProgressCurve();
float animationProgressAfterElapsedTime(Seconds) const;
FloatPoint linearlyInterpolatedOffsetAtProgress(float progress);
FloatPoint cubicallyInterpolatedOffsetAtProgress(float progress) const;
float m_snapAnimationCurveMagnitude { 0 };
float m_snapAnimationDecayFactor { 0 };
std::array<FloatSize, 4> m_snapAnimationCurveCoefficients = { };
bool m_forceLinearAnimationCurve { false };
bool m_momentumCalculatorRequiresInitialization { true };
};
} // namespace WebCore
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