widget/VsyncDispatcher.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   4  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef mozilla_widget_VsyncDispatcher_h
   7 #define mozilla_widget_VsyncDispatcher_h
   8
   9 #include "mozilla/Mutex.h"
  10 #include "mozilla/TimeStamp.h"
  11 #include "nsISupportsImpl.h"
  12 #include "nsTArray.h"
  13 #include "nsRefPtr.h"
  14
  15 namespace mozilla {
  16
  17 class VsyncObserver
  18 {
  19   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(VsyncObserver)
  20
  21 public:
  22   // The method called when a vsync occurs. Return true if some work was done.
  23   // In general, this vsync notification will occur on the hardware vsync
  24   // thread from VsyncSource. But it might also be called on PVsync ipc thread
  25   // if this notification is cross process. Thus all observer should check the
  26   // thread model before handling the real task.
  27   virtual bool NotifyVsync(TimeStamp aVsyncTimestamp) = 0;
  28
  29 protected:
  30   VsyncObserver() {}
  31   virtual ~VsyncObserver() {}
  32 }; // VsyncObserver
  33
  34 // Used to dispatch vsync events in the parent process to compositors
  35 class CompositorVsyncDispatcher MOZ_FINAL
  36 {
  37   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorVsyncDispatcher)
  38
  39 public:
  40   CompositorVsyncDispatcher();
  41
  42   // Called on the vsync thread when a hardware vsync occurs
  43   // The aVsyncTimestamp can mean different things depending on the platform:
  44   // b2g - The vsync timestamp of the previous frame that was just displayed
  45   // OSX - The vsync timestamp of the upcoming frame
  46   // TODO: Windows / Linux. DOCUMENT THIS WHEN IMPLEMENTING ON THOSE PLATFORMS
  47   // Android: TODO
  48   void NotifyVsync(TimeStamp aVsyncTimestamp);
  49
  50   // Compositor vsync observers must be added/removed on the compositor thread
  51   void SetCompositorVsyncObserver(VsyncObserver* aVsyncObserver);
  52   void Shutdown();
  53
  54 private:
  55   virtual ~CompositorVsyncDispatcher();
  56   void ObserveVsync(bool aEnable);
  57
  58   Mutex mCompositorObserverLock;
  59   nsRefPtr<VsyncObserver> mCompositorVsyncObserver;
  60   bool mDidShutdown;
  61 };
  62
  63 // Dispatch vsync event to ipc actor parent and chrome RefreshTimer.
  64 class RefreshTimerVsyncDispatcher MOZ_FINAL
  65 {
  66   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RefreshTimerVsyncDispatcher)
  67
  68 public:
  69   RefreshTimerVsyncDispatcher();
  70
  71   // Please check CompositorVsyncDispatcher::NotifyVsync().
  72   void NotifyVsync(TimeStamp aVsyncTimestamp);
  73
  74   // Set chrome process's RefreshTimer to this dispatcher.
  75   // This function can be called from any thread.
  76   void SetParentRefreshTimer(VsyncObserver* aVsyncObserver);
  77
  78   // Add or remove the content process' RefreshTimer to this dispatcher. This
  79   // will be a no-op for AddChildRefreshTimer() if the observer is already
  80   // registered.
  81   // These functions can be called from any thread.
  82   void AddChildRefreshTimer(VsyncObserver* aVsyncObserver);
  83   void RemoveChildRefreshTimer(VsyncObserver* aVsyncObserver);
  84
  85 private:
  86   virtual ~RefreshTimerVsyncDispatcher();
  87   void UpdateVsyncStatus();
  88   bool NeedsVsync();
  89
  90   Mutex mRefreshTimersLock;
  91   nsRefPtr<VsyncObserver> mParentRefreshTimer;
  92   nsTArray<nsRefPtr<VsyncObserver>> mChildRefreshTimers;
  93 };
  94
  95 } // namespace mozilla
  96
  97 #endif // mozilla_widget_VsyncDispatcher_h