Source/WebCore/platform/mac/ScrollingMomentumCalculatorMac.h

/*
 * 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 "ScrollingMomentumCalculator.h"
#include <wtf/RetainPtr.h>

@class _NSScrollingMomentumCalculator;

namespace WebCore {

class ScrollingMomentumCalculatorMac final : public ScrollingMomentumCalculator {
public:
    ScrollingMomentumCalculatorMac(const ScrollExtents&, const FloatPoint& initialOffset, const FloatSize& initialDelta, const FloatSize& initialVelocity);

private:
    FloatPoint scrollOffsetAfterElapsedTime(Seconds) final;
    Seconds animationDuration() final;
    FloatPoint predictedDestinationOffset() final;
    void retargetedScrollOffsetDidChange() final;

    _NSScrollingMomentumCalculator *ensurePlatformMomentumCalculator();
    bool requiresMomentumScrolling();

    RetainPtr<_NSScrollingMomentumCalculator> m_platformMomentumCalculator;
    std::optional<bool> m_requiresMomentumScrolling;
    FloatPoint m_initialDestinationOrigin;
};

} // namespace WebCore