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// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_GL_VSYNC_PROVIDER_H_
#define UI_GL_VSYNC_PROVIDER_H_
#include <queue>
#include "base/basictypes.h"
#include "base/callback.h"
#include "base/time.h"
namespace gfx {
class VSyncProvider {
public:
VSyncProvider();
virtual ~VSyncProvider();
typedef base::Callback<void(const base::TimeTicks timebase,
const base::TimeDelta interval)>
UpdateVSyncCallback;
// Get the time of the most recent screen refresh, along with the time
// between consecutive refreshes. The callback is called as soon as
// the data is available: it could be immediately from this method,
// later via a PostTask to the current MessageLoop, or never (if we have
// no data source). We provide the strong guarantee that the callback will
// not be called once the instance of this class is destroyed.
virtual void GetVSyncParameters(const UpdateVSyncCallback& callback) = 0;
private:
DISALLOW_COPY_AND_ASSIGN(VSyncProvider);
};
// Base class for providers based on extensions like GLX_OML_sync_control and
// EGL_CHROMIUM_sync_control.
class SyncControlVSyncProvider : public VSyncProvider {
public:
SyncControlVSyncProvider();
virtual ~SyncControlVSyncProvider();
virtual void GetVSyncParameters(
const UpdateVSyncCallback& callback) OVERRIDE;
protected:
virtual bool GetSyncValues(int64* system_time,
int64* media_stream_counter,
int64* swap_buffer_counter) = 0;
virtual bool GetMscRate(int32* numerator, int32* denominator) = 0;
private:
base::TimeTicks last_timebase_;
uint64 last_media_stream_counter_;
base::TimeDelta last_good_interval_;
// A short history of the last few computed intervals.
// We use this to filter out the noise in the computation resulting
// from configuration change (monitor reconfiguration, moving windows
// between monitors, suspend and resume, etc.).
std::queue<base::TimeDelta> last_computed_intervals_;
DISALLOW_COPY_AND_ASSIGN(SyncControlVSyncProvider);
};
} // namespace gfx
#endif // UI_GL_VSYNC_PROVIDER_H_
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