Image Capture: MediaStreamTrack::getCapabilities()

third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  * Copyright (C) 2011 Ericsson AB. All rights reserved.
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  * modification, are permitted provided that the following conditions
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  * 1.  Redistributions of source code must retain the above copyright
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  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 #include "modules/mediastream/MediaStreamTrack.h"
 
+#include <memory>
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/events/Event.h"
 #include "core/frame/Deprecation.h"
+#include "modules/imagecapture/ImageCapture.h"
 #include "modules/mediastream/MediaConstraintsImpl.h"
 #include "modules/mediastream/MediaStream.h"
+#include "modules/mediastream/MediaTrackCapabilities.h"
 #include "modules/mediastream/MediaTrackSettings.h"
 #include "modules/mediastream/UserMediaController.h"
 #include "platform/mediastream/MediaStreamCenter.h"
 #include "platform/mediastream/MediaStreamComponent.h"
 #include "public/platform/WebMediaStreamTrack.h"
 #include "wtf/Assertions.h"
-#include <memory>
 
 namespace blink {
 
 namespace {
 static const char kContentHintStringNone[] = "";
 static const char kContentHintStringAudioSpeech[] = "speech";
 static const char kContentHintStringAudioMusic[] = "music";
 static const char kContentHintStringVideoMotion[] = "motion";
 static const char kContentHintStringVideoDetail[] = "detail";
 }  // namespace
 
 MediaStreamTrack* MediaStreamTrack::create(ExecutionContext* context,
                                            MediaStreamComponent* component) {
   return new MediaStreamTrack(context, component);
 }
 
 MediaStreamTrack::MediaStreamTrack(ExecutionContext* context,
                                    MediaStreamComponent* component)
     : ContextLifecycleObserver(context),
       m_readyState(MediaStreamSource::ReadyStateLive),
       m_isIteratingRegisteredMediaStreams(false),
       m_stopped(false),
       m_component(component),
       // The source's constraints aren't yet initialized at creation time.
       m_constraints() {
   m_component->source()->addObserver(this);
+
+  DCHECK(!m_imageCapture);

[Reilly Grant (use Gerrit), 2017/03/14 21:38:57]

It seems odd to do this check in a constructor.

[mcasas, 2017/03/14 22:28:02]

Done.

+  if (m_component->source() &&
+      m_component->source()->type() == MediaStreamSource::TypeVideo) {
+    NonThrowableExceptionState exceptionState;

[haraken, 2017/03/14 19:56:37]

How is it guaranteed that the following create doesn't throw any exception?

[mcasas, 2017/03/14 22:28:02]

The only reason ImageCapture::create() throws is if the
track passed (|this|) is not of video type, which in this case
is guaranteed, hence no need to throw.  I'll add a comment.

+    m_imageCapture = ImageCapture::create(context, this, exceptionState);
+  }
 }
 
 MediaStreamTrack::~MediaStreamTrack() {}
 
 String MediaStreamTrack::kind() const {
   DEFINE_STATIC_LOCAL(String, audioKind, ("audio"));
   DEFINE_STATIC_LOCAL(String, videoKind, ("video"));
 
   switch (m_component->source()->type()) {
     case MediaStreamSource::TypeAudio:
@@ skipping 126 matching lines @@
 }
 
 void MediaStreamTrack::getConstraints(MediaTrackConstraints& constraints) {
   MediaConstraintsImpl::convertConstraints(m_constraints, constraints);
 }
 
 void MediaStreamTrack::setConstraints(const WebMediaConstraints& constraints) {
   m_constraints = constraints;
 }
 
+void MediaStreamTrack::getCapabilities(MediaTrackCapabilities& capabilities) {
+  if (m_imageCapture)
+    capabilities = m_imageCapture->getMediaTrackCapabilities();
+}
+
 void MediaStreamTrack::getSettings(MediaTrackSettings& settings) {
   WebMediaStreamTrack::Settings platformSettings;
   m_component->getSettings(platformSettings);
   if (platformSettings.hasFrameRate()) {
     settings.setFrameRate(platformSettings.frameRate);
   }
   if (platformSettings.hasWidth()) {
     settings.setWidth(platformSettings.width);
   }
   if (platformSettings.hasHeight()) {
@@ skipping 112 matching lines @@
   return EventTargetNames::MediaStreamTrack;
 }
 
 ExecutionContext* MediaStreamTrack::getExecutionContext() const {
   return ContextLifecycleObserver::getExecutionContext();
 }
 
 DEFINE_TRACE(MediaStreamTrack) {
   visitor->trace(m_registeredMediaStreams);
   visitor->trace(m_component);
+  visitor->trace(m_imageCapture);
   EventTargetWithInlineData::trace(visitor);
   ContextLifecycleObserver::trace(visitor);
 }
 
 }  // namespace blink