ui/gl/vsync_provider.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef UI_GL_VSYNC_PROVIDER_H_
   6 #define UI_GL_VSYNC_PROVIDER_H_
   7
   8 #include <queue>
   9
  10 #include "base/basictypes.h"
  11 #include "base/callback.h"
  12 #include "base/time.h"
  13
  14 namespace gfx {
  15
  16 class VSyncProvider {
  17  public:
  18   VSyncProvider();
  19   virtual ~VSyncProvider();
  20
  21   typedef base::Callback<void(const base::TimeTicks timebase,
  22                               const base::TimeDelta interval)>
  23       UpdateVSyncCallback;
  24
  25   // Get the time of the most recent screen refresh, along with the time
  26   // between consecutive refreshes. The callback is called as soon as
  27   // the data is available: it could be immediately from this method,
  28   // later via a PostTask to the current MessageLoop, or never (if we have
  29   // no data source). We provide the strong guarantee that the callback will
  30   // not be called once the instance of this class is destroyed.
  31   virtual void GetVSyncParameters(const UpdateVSyncCallback& callback) = 0;
  32
  33  private:
  34   DISALLOW_COPY_AND_ASSIGN(VSyncProvider);
  35 };
  36
  37 // Base class for providers based on extensions like GLX_OML_sync_control and
  38 // EGL_CHROMIUM_sync_control.
  39 class SyncControlVSyncProvider : public VSyncProvider {
  40  public:
  41   SyncControlVSyncProvider();
  42   virtual ~SyncControlVSyncProvider();
  43
  44   virtual void GetVSyncParameters(
  45       const UpdateVSyncCallback& callback) OVERRIDE;
  46
  47  protected:
  48   virtual bool GetSyncValues(int64* system_time,
  49                              int64* media_stream_counter,
  50                              int64* swap_buffer_counter) = 0;
  51
  52   virtual bool GetMscRate(int32* numerator, int32* denominator) = 0;
  53
  54  private:
  55   base::TimeTicks last_timebase_;
  56   uint64 last_media_stream_counter_;
  57   base::TimeDelta last_good_interval_;
  58
  59   // A short history of the last few computed intervals.
  60   // We use this to filter out the noise in the computation resulting
  61   // from configuration change (monitor reconfiguration, moving windows
  62   // between monitors, suspend and resume, etc.).
  63   std::queue<base::TimeDelta> last_computed_intervals_;
  64
  65   DISALLOW_COPY_AND_ASSIGN(SyncControlVSyncProvider);
  66 };
  67
  68 }  // namespace gfx
  69
  70 #endif  // UI_GL_VSYNC_PROVIDER_H_