Implementation of 'AudioContext.getOutputTimestamp' method

third_party/WebKit/Source/modules/webaudio/AudioContext.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/webaudio/AudioContext.h"
 
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/ExceptionCode.h"
+#include "core/frame/LocalDOMWindow.h"
+#include "core/timing/DOMWindowPerformance.h"
+#include "core/timing/Performance.h"
 #include "modules/webaudio/AudioBufferCallback.h"
+#include "modules/webaudio/AudioTimestamp.h"
 #include "platform/Histogram.h"
 #include "platform/audio/AudioUtilities.h"
 
 #if DEBUG_AUDIONODE_REFERENCES
 #include <stdio.h>
 #endif
 
 namespace blink {
 
 // Don't allow more than this number of simultaneous AudioContexts
@@ skipping 50 matching lines @@
         ("WebAudio.AudioContext.HardwareSampleRate"));
     maxChannelCountHistogram.sample(audioContext->destination()->maxChannelCount());
     sampleRateHistogram.sample(audioContext->sampleRate());
 
     return audioContext;
 }
 
 AudioContext::AudioContext(Document& document)
     : AbstractAudioContext(&document)
     , m_contextId(s_contextId++)
+    , m_outputTimestampFramesOrigin(0)
 {
 }
 
 AudioContext::~AudioContext()
 {
 #if DEBUG_AUDIONODE_REFERENCES
     fprintf(stderr, "%p: AudioContext::~AudioContext(): %u\n", this, m_contextId);
 #endif
 }
 
@@ skipping 38 matching lines @@
                 InvalidAccessError,
                 "cannot resume a closed AudioContext"));
     }
 
     recordUserGestureState();
 
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     // Restart the destination node to pull on the audio graph.
-    if (destination())
+    if (destination()) {
+        m_outputTimestampFramesOrigin = currentSampleFrame();
         startRendering();
+    }
 
     // Save the resolver which will get resolved when the destination node starts pulling on the
     // graph again.
     {
         AutoLocker locker(this);
         m_resumeResolvers.append(resolver);
     }
 
     return promise;
 }
 
+static double toPerformanceTime(ExecutionContext* context, double seconds)
+{
+    if (!context)
+        return 0.0;
+
+    LocalDOMWindow* window = context->executingWindow();
+    if (!window)
+        return 0.0;
+
+    Performance* performance = DOMWindowPerformance::performance(*window);
+    if (!performance)
+        return 0.0;
+
+    return performance->monotonicTimeToDOMHighResTimeStamp(seconds);
+}
+
+void AudioContext::getOutputTimestamp(AudioTimestamp& result)
+{
+    DCHECK(isMainThread());
+    if (!destination()) {
+        result.setContextTime(0.0);
+        result.setPerformanceTime(0.0);
+        return;
+    }
+
+    WebAudioTimestamp timestamp = outputTimestamp();
+    double sampleRate = destination()->audioDestinationHandler().sampleRate();
+    double contextTime = (m_outputTimestampFramesOrigin + timestamp.frames) / sampleRate;
+    double performanceTime = timestamp.seconds ? toPerformanceTime(getExecutionContext(), timestamp.seconds) : 0.0;
+
+    result.setContextTime(contextTime);
+    result.setPerformanceTime(performanceTime);
+}
+
 ScriptPromise AudioContext::closeContext(ScriptState* scriptState)
 {
     if (isContextClosed()) {
         // We've already closed the context previously, but it hasn't yet been resolved, so just
         // create a new promise and reject it.
         return ScriptPromise::rejectWithDOMException(
             scriptState,
             DOMException::create(InvalidStateError,
                 "Cannot close a context that is being closed or has already been closed."));
     }
@@ skipping 37 matching lines @@
     ASSERT(destination());
 
     if (contextState() == Running) {
         destination()->audioDestinationHandler().stopRendering();
         setContextState(Suspended);
         deferredTaskHandler().clearHandlersToBeDeleted();
     }
 }
 
 } // namespace blink