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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_layers_SampleTime_h
#define mozilla_layers_SampleTime_h
#include "mozilla/TimeStamp.h"
namespace mozilla {
namespace layers {
/**
* When compositing frames, there is usually a "sample time" associated
* with the frame, which may be derived from vsync or controlled by a test.
* This class encapsulates that and tracks where the sample time comes from,
* as the desired behaviour may vary based on the time source.
*/
class SampleTime {
public:
enum TimeType {
// Uninitialized sample time.
eNull,
// Time comes from a vsync tick, possibly adjusted by a vsync interval.
eVsync,
// Time comes from a "now" timestamp
eNow,
// Time is set by a test
eTest,
};
SampleTime();
static SampleTime FromVsync(const TimeStamp& aTime);
static SampleTime FromNow();
static SampleTime FromTest(const TimeStamp& aTime);
bool IsNull() const;
TimeType Type() const;
const TimeStamp& Time() const;
// These operators just compare the timestamps
bool operator==(const SampleTime& aOther) const;
bool operator!=(const SampleTime& aOther) const;
bool operator<(const SampleTime& aOther) const;
bool operator<=(const SampleTime& aOther) const;
bool operator>(const SampleTime& aOther) const;
bool operator>=(const SampleTime& aOther) const;
// These return a new SampleTime with the same type as this one, but the
// time adjusted by the provided TimeDuration
SampleTime operator+(const TimeDuration& aDuration) const;
SampleTime operator-(const TimeDuration& aDuration) const;
// This just produces the time difference between the two SampleTimes,
// ignoring the type.
TimeDuration operator-(const SampleTime& aOther) const;
private:
// Private constructor; use one of the static FromXXX methods instead.
SampleTime(TimeType aType, const TimeStamp& aTime);
TimeType mType;
TimeStamp mTime;
};
} // namespace layers
} // namespace mozilla
#endif // mozilla_layers_SampleTime_h
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