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