86 lines
3.8 KiB
C++
86 lines
3.8 KiB
C++
/*
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* Copyright (C) 2019 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include "VelocityData.h"
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#include <wtf/text/TextStream.h>
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namespace WebCore {
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VelocityData HistoricalVelocityData::velocityForNewData(FloatPoint newPosition, double scale, MonotonicTime timestamp)
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{
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auto append = [&](FloatPoint newPosition, double scale, MonotonicTime timestamp)
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{
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m_latestDataIndex = (m_latestDataIndex + 1) % maxHistoryDepth;
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m_positionHistory[m_latestDataIndex] = { timestamp, newPosition, scale };
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m_historySize = std::min(m_historySize + 1, maxHistoryDepth);
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m_lastAppendTimestamp = timestamp;
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};
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// Due to all the source of rect update, the input is very noisy. To smooth the output, we accumulate all changes
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// within 1 frame as a single update. No speed computation is ever done on data within the same frame.
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const Seconds filteringThreshold(1.0 / 60);
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VelocityData velocityData;
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if (m_historySize > 0) {
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unsigned oldestDataIndex;
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unsigned distanceToLastHistoricalData = m_historySize - 1;
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if (distanceToLastHistoricalData <= m_latestDataIndex)
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oldestDataIndex = m_latestDataIndex - distanceToLastHistoricalData;
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else
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oldestDataIndex = m_historySize - (distanceToLastHistoricalData - m_latestDataIndex);
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Seconds timeDelta = timestamp - m_positionHistory[oldestDataIndex].timestamp;
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if (timeDelta > filteringThreshold) {
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Data& oldestData = m_positionHistory[oldestDataIndex];
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velocityData = VelocityData((newPosition.x() - oldestData.position.x()) / timeDelta.seconds(), (newPosition.y() - oldestData.position.y()) / timeDelta.seconds(), (scale - oldestData.scale) / timeDelta.seconds(), timestamp);
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}
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}
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Seconds timeSinceLastAppend = timestamp - m_lastAppendTimestamp;
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if (timeSinceLastAppend > filteringThreshold)
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append(newPosition, scale, timestamp);
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else
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m_positionHistory[m_latestDataIndex] = { timestamp, newPosition, scale };
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return velocityData;
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}
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TextStream& operator<<(TextStream& ts, const VelocityData& velocityData)
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{
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ts.dumpProperty("timestamp", velocityData.lastUpdateTime.secondsSinceEpoch().value());
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if (velocityData.horizontalVelocity)
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ts.dumpProperty("horizontalVelocity", velocityData.horizontalVelocity);
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if (velocityData.verticalVelocity)
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ts.dumpProperty("verticalVelocity", velocityData.verticalVelocity);
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if (velocityData.scaleChangeRate)
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ts.dumpProperty("scaleChangeRate", velocityData.scaleChangeRate);
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return ts;
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}
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} // namespace WebCore
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