ui/compositor/compositor_vsync_manager.h

   1 // Copyright 2014 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_COMPOSITOR_COMPOSITOR_VSYNC_MANAGER_H_
   6 #define UI_COMPOSITOR_COMPOSITOR_VSYNC_MANAGER_H_
   7
   8 #include "base/memory/ref_counted.h"
   9 #include "base/observer_list.h"
  10 #include "base/synchronization/lock.h"
  11 #include "base/time/time.h"
  12 #include "ui/compositor/compositor_export.h"
  13
  14 namespace ui {
  15
  16 // This class manages vsync parameters for a compositor. It merges updates of
  17 // the parameters from different sources and sends the merged updates to
  18 // observers which register to it.
  19 class COMPOSITOR_EXPORT CompositorVSyncManager
  20     : public base::RefCounted<CompositorVSyncManager> {
  21  public:
  22   class Observer {
  23    public:
  24     virtual void OnUpdateVSyncParameters(base::TimeTicks timebase,
  25                                          base::TimeDelta interval) = 0;
  26   };
  27
  28   CompositorVSyncManager();
  29
  30   // The "authoritative" vsync interval, if provided, will override |interval|
  31   // as reported by UpdateVSyncParameters() whenever it is called.  This is
  32   // typically the value reported by a more reliable source, e.g. the platform
  33   // display configuration.  In the particular case of ChromeOS -- this is the
  34   // value queried through XRandR, which is more reliable than the value
  35   // queried through the 3D context.
  36   void SetAuthoritativeVSyncInterval(base::TimeDelta interval);
  37
  38   // The vsync parameters consist of |timebase|, which is the platform timestamp
  39   // of the last vsync, and |interval|, which is the interval between vsyncs.
  40   // |interval| may be overriden by SetAuthoritativeVSyncInterval() above.
  41   void UpdateVSyncParameters(base::TimeTicks timebase,
  42                              base::TimeDelta interval);
  43
  44   void AddObserver(Observer* observer);
  45   void RemoveObserver(Observer* observer);
  46
  47  private:
  48   friend class base::RefCounted<CompositorVSyncManager>;
  49
  50   ~CompositorVSyncManager();
  51
  52   void NotifyObservers(base::TimeTicks timebase, base::TimeDelta interval);
  53
  54   ObserverList<Observer> observer_list_;
  55
  56   base::TimeTicks last_timebase_;
  57   base::TimeDelta last_interval_;
  58   base::TimeDelta authoritative_vsync_interval_;
  59
  60   DISALLOW_COPY_AND_ASSIGN(CompositorVSyncManager);
  61 };
  62
  63 }  // namespace ui
  64
  65 #endif  // UI_COMPOSITOR_COMPOSITOR_VSYNC_MANAGER_H_