forked from mirrors/gecko-dev
ec6babfeb0
This makes the sample time more "strongly typed" by using a variant-style class instead of a raw TimeStamp. The sample time can come from different sources (vsync, testing, Now()) and it is useful to save that information as we pass around the sample time. It would have been helpful with some of the debugging I did recently, and it also is needed for the next patch. Differential Revision: https://phabricator.services.mozilla.com/D86244
69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_layers_SampleTime_h
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#define mozilla_layers_SampleTime_h
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#include "mozilla/TimeStamp.h"
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namespace mozilla {
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namespace layers {
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/**
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* When compositing frames, there is usually a "sample time" associated
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* with the frame, which may be derived from vsync or controlled by a test.
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* This class encapsulates that and tracks where the sample time comes from,
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* as the desired behaviour may vary based on the time source.
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*/
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class SampleTime {
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public:
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enum TimeType {
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// Uninitialized sample time.
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eNull,
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// Time comes from a vsync tick, possibly adjusted by a vsync interval.
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eVsync,
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// Time comes from a "now" timestamp
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eNow,
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// Time is set by a test
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eTest,
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};
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SampleTime();
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static SampleTime FromVsync(const TimeStamp& aTime);
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static SampleTime FromNow();
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static SampleTime FromTest(const TimeStamp& aTime);
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bool IsNull() const;
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TimeType Type() const;
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const TimeStamp& Time() const;
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// These operators just compare the timestamps
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bool operator==(const SampleTime& aOther) const;
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bool operator!=(const SampleTime& aOther) const;
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bool operator<(const SampleTime& aOther) const;
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bool operator<=(const SampleTime& aOther) const;
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bool operator>(const SampleTime& aOther) const;
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bool operator>=(const SampleTime& aOther) const;
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// These return a new SampleTime with the same type as this one, but the
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// time adjusted by the provided TimeDuration
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SampleTime operator+(const TimeDuration& aDuration) const;
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SampleTime operator-(const TimeDuration& aDuration) const;
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// This just produces the time difference between the two SampleTimes,
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// ignoring the type.
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TimeDuration operator-(const SampleTime& aOther) const;
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private:
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// Private constructor; use one of the static FromXXX methods instead.
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SampleTime(TimeType aType, const TimeStamp& aTime);
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TimeType mType;
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TimeStamp mTime;
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};
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} // namespace layers
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} // namespace mozilla
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#endif // mozilla_layers_SampleTime_h
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