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/*
* Copyright (C) 2014-2015 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.
*/
#include "config.h"
#include "ScrollSnapAnimatorState.h"
#include <wtf/MathExtras.h>
#include <wtf/text/TextStream.h>
namespace WebCore {
void ScrollSnapAnimatorState::transitionToSnapAnimationState(const FloatSize& contentSize, const FloatSize& viewportSize, float pageScale, const FloatPoint& initialOffset)
{
setupAnimationForState(ScrollSnapState::Snapping, contentSize, viewportSize, pageScale, initialOffset, { }, { });
}
void ScrollSnapAnimatorState::transitionToGlideAnimationState(const FloatSize& contentSize, const FloatSize& viewportSize, float pageScale, const FloatPoint& initialOffset, const FloatSize& initialVelocity, const FloatSize& initialDelta)
{
setupAnimationForState(ScrollSnapState::Gliding, contentSize, viewportSize, pageScale, initialOffset, initialVelocity, initialDelta);
}
void ScrollSnapAnimatorState::setupAnimationForState(ScrollSnapState state, const FloatSize& contentSize, const FloatSize& viewportSize, float pageScale, const FloatPoint& initialOffset, const FloatSize& initialVelocity, const FloatSize& initialDelta)
{
ASSERT(state == ScrollSnapState::Snapping || state == ScrollSnapState::Gliding);
if (m_currentState == state)
return;
m_momentumCalculator = ScrollingMomentumCalculator::create(viewportSize, contentSize, initialOffset, initialDelta, initialVelocity);
FloatPoint predictedScrollTarget { m_momentumCalculator->predictedDestinationOffset() };
float targetOffsetX, targetOffsetY;
std::tie(targetOffsetX, m_activeSnapIndexX) = targetOffsetForStartOffset(ScrollEventAxis::Horizontal, viewportSize, contentSize.width() - viewportSize.width(), initialOffset.x(), predictedScrollTarget, pageScale, initialDelta.width());
std::tie(targetOffsetY, m_activeSnapIndexY) = targetOffsetForStartOffset(ScrollEventAxis::Vertical, viewportSize, contentSize.height() - viewportSize.height(), initialOffset.y(), predictedScrollTarget, pageScale, initialDelta.height());
m_momentumCalculator->setRetargetedScrollOffset({ targetOffsetX, targetOffsetY });
m_startTime = MonotonicTime::now();
m_currentState = state;
}
void ScrollSnapAnimatorState::transitionToUserInteractionState()
{
teardownAnimationForState(ScrollSnapState::UserInteraction);
}
void ScrollSnapAnimatorState::transitionToDestinationReachedState()
{
teardownAnimationForState(ScrollSnapState::DestinationReached);
}
void ScrollSnapAnimatorState::teardownAnimationForState(ScrollSnapState state)
{
ASSERT(state == ScrollSnapState::UserInteraction || state == ScrollSnapState::DestinationReached);
if (m_currentState == state)
return;
m_momentumCalculator = nullptr;
m_startTime = MonotonicTime();
m_currentState = state;
}
FloatPoint ScrollSnapAnimatorState::currentAnimatedScrollOffset(MonotonicTime currentTime, bool& isAnimationComplete) const
{
if (!m_momentumCalculator) {
isAnimationComplete = true;
return { };
}
Seconds elapsedTime = currentTime - m_startTime;
isAnimationComplete = elapsedTime >= m_momentumCalculator->animationDuration();
return m_momentumCalculator->scrollOffsetAfterElapsedTime(elapsedTime);
}
std::pair<float, std::optional<unsigned>> ScrollSnapAnimatorState::targetOffsetForStartOffset(ScrollEventAxis axis, const FloatSize& viewportSize, float maxScrollOffset, float startOffset, FloatPoint predictedOffset, float pageScale, float initialDelta) const
{
const auto& snapOffsets = m_snapOffsetsInfo.offsetsForAxis(axis);
if (snapOffsets.isEmpty())
return std::make_pair(clampTo<float>(axis == ScrollEventAxis::Horizontal ? predictedOffset.x() : predictedOffset.y(), 0, maxScrollOffset), std::nullopt);
LayoutPoint predictedLayoutOffset(predictedOffset.x() / pageScale, predictedOffset.y() / pageScale);
auto [targetOffset, snapIndex] = m_snapOffsetsInfo.closestSnapOffset(axis, LayoutSize { viewportSize }, predictedLayoutOffset, initialDelta, LayoutUnit(startOffset / pageScale));
return std::make_pair(pageScale * clampTo<float>(float { targetOffset }, 0, maxScrollOffset), snapIndex);
}
TextStream& operator<<(TextStream& ts, const ScrollSnapAnimatorState& state)
{
ts << "ScrollSnapAnimatorState";
ts.dumpProperty("snap offsets x", state.snapOffsetsForAxis(ScrollEventAxis::Horizontal));
ts.dumpProperty("snap offsets y", state.snapOffsetsForAxis(ScrollEventAxis::Vertical));
ts.dumpProperty("active snap index x", state.activeSnapIndexForAxis(ScrollEventAxis::Horizontal));
ts.dumpProperty("active snap index y", state.activeSnapIndexForAxis(ScrollEventAxis::Vertical));
return ts;
}
} // namespace WebCore
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