MediaStream Image Capture (2): Platform::ImageCaptureFrameGrabber and grabFrame()

third_party/WebKit/Source/modules/imagecapture/ImageCapture.cpp

 // Copyright 2016 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/imagecapture/ImageCapture.h"
 
+#include "bindings/core/v8/CallbackPromiseAdapter.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/ExceptionCode.h"
+#include "core/frame/ImageBitmap.h"
 #include "modules/EventTargetModules.h"
 #include "modules/mediastream/MediaStreamTrack.h"
+#include "platform/graphics/StaticBitmapImage.h"

[emircan, 2016/04/26 19:19:31]

Extra?

[mcasas, 2016/04/27 00:51:29]

Done.

 #include "public/platform/Platform.h"
+#include "public/platform/WebImageCaptureFrameGrabber.h"
+#include "public/platform/WebMediaStreamTrack.h"
 
 namespace blink {
 
 ImageCapture* ImageCapture::create(ExecutionContext* context, MediaStreamTrack* track, ExceptionState& exceptionState)
 {
     if (track->kind() != "video") {
         exceptionState.throwDOMException(NotSupportedError, "Cannot create an ImageCapturer from a non-video Track.");
         return nullptr;
     }
 
@@ skipping 30 matching lines @@
 {
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     // Spec instructs to return an exception if the track's ready state is not "live". Also reject if the track is disabled or muted.
     if (m_streamTrack->readyState() != "live" || !m_streamTrack->enabled() || m_streamTrack->muted()) {
         resolver->reject(DOMException::create(InvalidStateError, "The associated Track is in an invalid state."));
         return promise;
     }
 
-    resolver->reject(DOMException::create(NotSupportedError, "Not implemented yet"));
+    // Create |m_frameGrabber| the first time.
+    if (!m_frameGrabber)
+        m_frameGrabber = adoptPtr(Platform::current()->createImageCaptureFrameGrabber());
+
+    if (!m_frameGrabber) {

[emircan, 2016/04/26 19:19:31]

Can you move this inside the if on l.69? I dont think we need to double check
each time?

[mcasas, 2016/04/27 00:51:29]

This a get-or-create snippet, right? The first 
time around we create |m_frameGrabber|, but
still we need to check that it has been created
properly right? I guess I could move it back 
inside the first if(!) then create, but it'll need
to be there. Alternatives?

+        resolver->reject(DOMException::create(UnknownError, "Couldn't create platform resources"));
+        return promise;
+    }
+
+    // The platform does not know about MediaStreamTrack, so we wrap it up.
+    WebMediaStreamTrack track(m_streamTrack->component());
+    m_frameGrabber->grabFrame(&track, new CallbackPromiseAdapter<ImageBitmap, void>(resolver));
+
     return promise;
 }
 
 ImageCapture::ImageCapture(ExecutionContext* context, MediaStreamTrack* track)
     : ActiveScriptWrappable(this)
     , ContextLifecycleObserver(context)
     , m_streamTrack(track)
 {
     DCHECK(m_streamTrack);
 }
 
 bool ImageCapture::addEventListenerInternal(const AtomicString& eventType, EventListener* listener, const EventListenerOptions& options)
 {
     return EventTarget::addEventListenerInternal(eventType, listener, options);
 }
 
 DEFINE_TRACE(ImageCapture)
 {
     visitor->trace(m_streamTrack);
     EventTargetWithInlineData::trace(visitor);
     ContextLifecycleObserver::trace(visitor);
 }
 
 } // namespace blink