Source/core/animation/AnimationClock.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef AnimationClock_h
#define AnimationClock_h

#include "wtf/CurrentTime.h"
#include "wtf/PassOwnPtr.h"

namespace WebCore {

// FIXME: This value is used to suppress updates when time is required outside of a frame.
// The purpose of allowing the clock to update during such periods is to allow animations
// to have an appropriate start time and for getComputedStyle to attempt to catch-up to a
// compositor animation. However a more accurate system might be to attempt to phase-lock
// with the frame clock.
const double minTimeBeforeUnsynchronizedAnimationClockTick = 0.005;

class AnimationClock {
public:
    static PassOwnPtr<AnimationClock> create(WTF::TimeFunction monotonicallyIncreasingTime = WTF::monotonicallyIncreasingTime)
    {
        return adoptPtr(new AnimationClock(monotonicallyIncreasingTime));
    }

    void updateTime(double time);
    double currentTime();
    void unfreeze() { m_frozen = false; }
    void resetTimeForTesting() { m_time = 0; m_frozen = true; }

private:
    AnimationClock(WTF::TimeFunction monotonicallyIncreasingTime)
        : m_monotonicallyIncreasingTime(monotonicallyIncreasingTime)
        , m_time(0)
        , m_frozen(false)
    {
    }
    WTF::TimeFunction m_monotonicallyIncreasingTime;
    double m_time;
    bool m_frozen;
};

} // namespace WebCore

#endif // AnimationClock_h