tenfourfox/gfx/thebes/SoftwareVsyncSource.cpp

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2017-04-19 07:56:45 +00:00
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* 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/.
*/
#include "SoftwareVsyncSource.h"
#include "base/task.h"
#include "gfxPlatform.h"
#include "nsThreadUtils.h"
SoftwareVsyncSource::SoftwareVsyncSource()
{
MOZ_ASSERT(NS_IsMainThread());
mGlobalDisplay = new SoftwareDisplay();
}
SoftwareVsyncSource::~SoftwareVsyncSource()
{
MOZ_ASSERT(NS_IsMainThread());
mGlobalDisplay->Shutdown();
mGlobalDisplay = nullptr;
}
SoftwareDisplay::SoftwareDisplay()
: mCurrentVsyncTask(nullptr)
, mVsyncEnabled(false)
{
// Mimic 60 fps
MOZ_ASSERT(NS_IsMainThread());
const double rate = 1000.0 / (double) gfxPlatform::GetSoftwareVsyncRate();
mVsyncRate = mozilla::TimeDuration::FromMilliseconds(rate);
mVsyncThread = new base::Thread("SoftwareVsyncThread");
MOZ_RELEASE_ASSERT(mVsyncThread->Start(), "Could not start software vsync thread");
}
SoftwareDisplay::~SoftwareDisplay() {}
void
SoftwareDisplay::EnableVsync()
{
MOZ_ASSERT(mVsyncThread->IsRunning());
if (NS_IsMainThread()) {
if (mVsyncEnabled) {
return;
}
mVsyncEnabled = true;
mVsyncThread->message_loop()->PostTask(FROM_HERE,
NewRunnableMethod(this, &SoftwareDisplay::EnableVsync));
return;
}
MOZ_ASSERT(IsInSoftwareVsyncThread());
NotifyVsync(mozilla::TimeStamp::Now());
}
void
SoftwareDisplay::DisableVsync()
{
MOZ_ASSERT(mVsyncThread->IsRunning());
if (NS_IsMainThread()) {
if (!mVsyncEnabled) {
return;
}
mVsyncEnabled = false;
mVsyncThread->message_loop()->PostTask(FROM_HERE,
NewRunnableMethod(this, &SoftwareDisplay::DisableVsync));
return;
}
MOZ_ASSERT(IsInSoftwareVsyncThread());
if (mCurrentVsyncTask) {
mCurrentVsyncTask->Cancel();
mCurrentVsyncTask = nullptr;
}
}
bool
SoftwareDisplay::IsVsyncEnabled()
{
MOZ_ASSERT(NS_IsMainThread());
return mVsyncEnabled;
}
bool
SoftwareDisplay::IsInSoftwareVsyncThread()
{
return mVsyncThread->thread_id() == PlatformThread::CurrentId();
}
void
SoftwareDisplay::NotifyVsync(mozilla::TimeStamp aVsyncTimestamp)
{
MOZ_ASSERT(IsInSoftwareVsyncThread());
mozilla::TimeStamp displayVsyncTime = aVsyncTimestamp;
mozilla::TimeStamp now = mozilla::TimeStamp::Now();
// Posted tasks can only have integer millisecond delays
// whereas TimeDurations can have floating point delays.
// Thus the vsync timestamp can be in the future, which large parts
// of the system can't handle, including animations. Force the timestamp to be now.
if (aVsyncTimestamp > now) {
displayVsyncTime = now;
}
Display::NotifyVsync(displayVsyncTime);
// Prevent skew by still scheduling based on the original
// vsync timestamp
ScheduleNextVsync(aVsyncTimestamp);
}
mozilla::TimeDuration
SoftwareDisplay::GetVsyncRate()
{
return mVsyncRate;
}
void
SoftwareDisplay::ScheduleNextVsync(mozilla::TimeStamp aVsyncTimestamp)
{
MOZ_ASSERT(IsInSoftwareVsyncThread());
mozilla::TimeStamp nextVsync = aVsyncTimestamp + mVsyncRate;
mozilla::TimeDuration delay = nextVsync - mozilla::TimeStamp::Now();
if (delay.ToMilliseconds() < 0) {
delay = mozilla::TimeDuration::FromMilliseconds(0);
nextVsync = mozilla::TimeStamp::Now();
}
mCurrentVsyncTask = NewRunnableMethod(this,
&SoftwareDisplay::NotifyVsync,
nextVsync);
mVsyncThread->message_loop()->PostDelayedTask(FROM_HERE,
mCurrentVsyncTask,
delay.ToMilliseconds());
}
void
SoftwareDisplay::Shutdown()
{
MOZ_ASSERT(NS_IsMainThread());
DisableVsync();
mVsyncThread->Stop();
delete mVsyncThread;
}