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_threadsafe.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. This class is explicitly synchronized and is 19 // safe to use and update from any thread. Observers of the manager will be 20 // notified on the thread they have registered from, and should be removed from 21 // the same thread. 22 class COMPOSITOR_EXPORT CompositorVSyncManager 23 : public base::RefCountedThreadSafe<CompositorVSyncManager> { 24 public: 25 class Observer { 26 public: 27 virtual void OnUpdateVSyncParameters(base::TimeTicks timebase, 28 base::TimeDelta interval) = 0; 29 }; 30 31 CompositorVSyncManager(); 32 33 // The "authoritative" vsync interval, if provided, will override |interval| 34 // as reported by UpdateVSyncParameters() whenever it is called. This is 35 // typically the value reported by a more reliable source, e.g. the platform 36 // display configuration. In the particular case of ChromeOS -- this is the 37 // value queried through XRandR, which is more reliable than the value 38 // queried through the 3D context. 39 void SetAuthoritativeVSyncInterval(base::TimeDelta interval); 40 41 // The vsync parameters consist of |timebase|, which is the platform timestamp 42 // of the last vsync, and |interval|, which is the interval between vsyncs. 43 // |interval| may be overriden by SetAuthoritativeVSyncInterval() above. 44 void UpdateVSyncParameters(base::TimeTicks timebase, 45 base::TimeDelta interval); 46 47 void AddObserver(Observer* observer); 48 void RemoveObserver(Observer* observer); 49 50 private: 51 friend class base::RefCountedThreadSafe<CompositorVSyncManager>; 52 53 ~CompositorVSyncManager(); 54 55 void NotifyObservers(base::TimeTicks timebase, base::TimeDelta interval); 56 57 // List of observers. 58 scoped_refptr<ObserverListThreadSafe<Observer> > observer_list_; 59 60 // Protects the cached vsync parameters below. 61 base::Lock vsync_parameters_lock_; 62 base::TimeTicks last_timebase_; 63 base::TimeDelta last_interval_; 64 base::TimeDelta authoritative_vsync_interval_; 65 66 DISALLOW_COPY_AND_ASSIGN(CompositorVSyncManager); 67 }; 68 69 } // namespace ui 70 71 #endif // UI_COMPOSITOR_COMPOSITOR_VSYNC_MANAGER_H_ 72