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/*
* Copyright (C) 2018-2023 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. ``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
* 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 <wtf/TZoneMallocInlines.h>
namespace WebCore {
// This class is used to detect when we are painting frequently so that - even in a painting model
// without display lists - we can build and cache portions of display lists and reuse them only when
// animating. Once we transition fully to display lists, we can probably just pull from the previous
// paint's display list if it is still around and get rid of this code.
class PaintFrequencyTracker {
WTF_MAKE_TZONE_ALLOCATED_INLINE(PaintFrequencyTracker);
public:
PaintFrequencyTracker() = default;
void track(MonotonicTime timestamp)
{
static unsigned paintFrequencyPaintCountThreshold = 20;
static Seconds paintFrequencySecondsIdleThreshold = 5_s;
if (!timestamp)
timestamp = MonotonicTime::now();
// Start by assuming the paint frequency is low
m_paintFrequency = PaintFrequency::Low;
if (timestamp - m_lastPaintTime > paintFrequencySecondsIdleThreshold) {
// It has been 5 seconds since last time we draw this renderer. Reset the state
// of this object as if, we've just started tracking the paint frequency.
m_totalPaints = 0;
} else if (m_totalPaints >= paintFrequencyPaintCountThreshold) {
// Change the paint frequency to be high if this renderer has been painted at least 20 times.
m_paintFrequency = PaintFrequency::High;
}
m_lastPaintTime = timestamp;
++m_totalPaints;
}
bool paintingFrequently() const { return m_paintFrequency == PaintFrequency::High; }
private:
MonotonicTime m_lastPaintTime;
unsigned m_totalPaints { 0 };
enum class PaintFrequency : bool { Low, High };
PaintFrequency m_paintFrequency { PaintFrequency::Low };
};
} // namespace WebCore
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