Implementation of 'AudioContext.getOutputTimestamp' method

third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.h

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 186 matching lines @@
     // nodes reference all nodes they're connected to.  All nodes are ultimately
     // connected to the AudioDestinationNode.  When the context release a source
     // node, it will be deactivated from the rendering graph along with all
     // other nodes it is uniquely connected to.
     void notifySourceNodeStartedProcessing(AudioNode*);
     // When a source node has no more processing to do (has finished playing),
     // this method tells the context to release the corresponding node.
     void notifySourceNodeFinishedProcessing(AudioHandler*);
 
     // Called at the start of each render quantum.
-    void handlePreRenderTasks();
+    void handlePreRenderTasks(const WebAudioTimestamp&);
 
     // Called at the end of each render quantum.
     void handlePostRenderTasks();
 
     // Called periodically at the end of each render quantum to release finished
     // source nodes.
     void releaseFinishedSourceNodes();
 
     // Keeps track of the number of connections made.
     void incrementConnectionCount()
@@ skipping 42 matching lines @@
 
     // Get the PeriodicWave for the specified oscillator type.  The table is initialized internally
     // if necessary.
     PeriodicWave* periodicWave(int type);
 
     // Check whether the AudioContext requires a user gesture and whether the
     // current stack is processing user gesture and record these information in
     // a histogram.
     void recordUserGestureState();
 
+    // Gets the audio timestamp of the currently audiable signal.
+    virtual void getOutputTimestamp(AudioTimestamp&) {}
+
 protected:
     explicit AbstractAudioContext(Document*);
     AbstractAudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
 
     void initialize();
     void uninitialize();
 
     void setContextState(AudioContextState);
 
     virtual void didClose() {}
 
     // Tries to handle AudioBufferSourceNodes that were started but became disconnected or was never
     // connected. Because these never get pulled anymore, they will stay around forever. So if we
     // can, try to stop them so they can be collected.
     void handleStoppableSourceNodes();
 
     Member<AudioDestinationNode> m_destinationNode;
 
     // FIXME(dominicc): Move m_resumeResolvers to AudioContext, because only
     // it creates these Promises.
     // Vector of promises created by resume(). It takes time to handle them, so we collect all of
     // the promises here until they can be resolved or rejected.
     HeapVector<Member<ScriptPromiseResolver>> m_resumeResolvers;
 
     void setClosedContextSampleRate(float newSampleRate) { m_closedContextSampleRate = newSampleRate; }
     float closedContextSampleRate() const { return m_closedContextSampleRate; }
 
     void rejectPendingDecodeAudioDataResolvers();
 
+    WebAudioTimestamp outputTimestamp();
+
 private:
     bool m_isCleared;
     void clear();
 
     // When the context goes away, there might still be some sources which
     // haven't finished playing.  Make sure to release them here.
     void releaseActiveSourceNodes();
 
     void removeFinishedSourceNodes();
 
@@ skipping 59 matching lines @@
     // they can be shared with all OscillatorNodes in the context.  To conserve memory, these are
     // lazily initiialized on first use.
     Member<PeriodicWave> m_periodicWaveSine;
     Member<PeriodicWave> m_periodicWaveSquare;
     Member<PeriodicWave> m_periodicWaveSawtooth;
     Member<PeriodicWave> m_periodicWaveTriangle;
 
     // This is considering 32 is large enough for multiple channels audio.
     // It is somewhat arbitrary and could be increased if necessary.
     enum { MaxNumberOfChannels = 32 };
+
+    // Output audio stream timestamp.
+    WebAudioTimestamp m_outputTimestamp;
 };
 
 } // namespace blink
 
 #endif // AbstractAudioContext_h