MediaStream Image Capture (3): Adding mojo and browser impl for dummy takePhoto().

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/fileapi/Blob.h"
 #include "core/frame/ImageBitmap.h"
 #include "modules/EventTargetModules.h"
 #include "modules/mediastream/MediaStreamTrack.h"
+#include "platform/mojo/MojoHelper.h"
 #include "public/platform/Platform.h"
+#include "public/platform/ServiceRegistry.h"
 #include "public/platform/WebImageCaptureFrameGrabber.h"
 #include "public/platform/WebMediaStreamTrack.h"
 
 namespace blink {
 
+namespace {
+
+const char kNoServiceError[] = "ImageCapture service unavailable.";
+
+bool trackIsInactive(const MediaStreamTrack& track)
+{
+    // Spec instructs to return an exception if the Track's readyState() is not
+    // "live". Also reject if the track is disabled or muted.
+    return track.readyState() != "live" || !track.enabled() || track.muted();
+}
+
+} // anonymous namespace
+
 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;
     }
 
     return new ImageCapture(context, track);
 }
 
 ImageCapture::~ImageCapture()
 {
     DCHECK(!hasEventListeners());
+    // There should be no more outstanding |m_serviceRequests| at this point
+    // since each of them holds a persistent handle to this object.
+    DCHECK(m_serviceRequests.isEmpty());
 }
 
 const AtomicString& ImageCapture::interfaceName() const
 {
     return EventTargetNames::ImageCapture;
 }
 
 ExecutionContext* ImageCapture::getExecutionContext() const
 {
     return ContextLifecycleObserver::getExecutionContext();
 }
 
 bool ImageCapture::hasPendingActivity() const
 {
     return hasEventListeners();
 }
 
 void ImageCapture::contextDestroyed()
 {
     removeAllEventListeners();
+    m_serviceRequests.clear();

[haraken, 2016/04/29 06:50:20]

I'm just curious but don't you need to reject the promises when the execution
context is gone?

+yhirano

[mcasas, 2016/04/29 21:03:14]

I'm checking other callers like
USB::contextDestroyed() [1]
PaymentRequest::contextDestroyed() [2]
MediaKeys::contextDestroyed() [3]

and none of them do anything special
for the promises around.

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...
[2]
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...
[3]
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

     DCHECK(!hasEventListeners());
 }
 
+ScriptPromise ImageCapture::takePhoto(ScriptState* scriptState, ExceptionState& exceptionState)
+{
+
+    ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
+    ScriptPromise promise = resolver->promise();
+
+    if (trackIsInactive(*m_streamTrack)) {
+        resolver->reject(DOMException::create(InvalidStateError, "The associated Track is in an invalid state."));
+        return promise;
+    }
+
+    if (!m_service) {
+        resolver->reject(DOMException::create(NotFoundError, kNoServiceError));
+        return promise;
+    }
+
+    m_serviceRequests.add(resolver);
+
+    // m_streamTrack->component()->source()->id() is the renderer "name" of the camera;
+    // TODO(mcasas) consider sending the security origin as well:
+    // scriptState->getExecutionContext()->getSecurityOrigin()->toString()
+    m_service->TakePhoto(m_streamTrack->component()->source()->id(), createBaseCallback(bind<String, String>(&ImageCapture::onTakePhoto, this, resolver)));
+    return promise;
+}
+
 ScriptPromise ImageCapture::grabFrame(ScriptState* scriptState, ExceptionState& exceptionState)
 {
     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()) {
+    if (trackIsInactive(*m_streamTrack)) {
         resolver->reject(DOMException::create(InvalidStateError, "The associated Track is in an invalid state."));
         return promise;
     }
 
     // Create |m_frameGrabber| the first time.
-    if (!m_frameGrabber) {
+    if (!m_frameGrabber)
         m_frameGrabber = adoptPtr(Platform::current()->createImageCaptureFrameGrabber());
 
-    }
-
     if (!m_frameGrabber) {
         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);
+    DCHECK(!m_service.is_bound());
+
+    Platform::current()->serviceRegistry()->connectToRemoteService(mojo::GetProxy(&m_service));
+
+    m_service.set_connection_error_handler(createBaseCallback(bind(&ImageCapture::onServiceConnectionError, WeakPersistentThisPointer<ImageCapture>(this))));
+}
+
+void ImageCapture::onTakePhoto(ScriptPromiseResolver* resolver, const String& mimeType, const String& data)
+{
+    if (m_serviceRequests.isEmpty())

[haraken, 2016/04/29 06:50:20]

Nit: A better check might be if(!m_serviceRequests.contains(resolver)).

[mcasas, 2016/04/29 21:03:14]

Done.

+        return;
+
+    WTF::CString string = data.utf8();
+    DCHECK(!string.isNull());
+    resolver->resolve(Blob::create(reinterpret_cast<unsigned char*>(string.mutableData()), string.length(), mimeType));
+    m_serviceRequests.remove(resolver);
+}
+
+void ImageCapture::onServiceConnectionError()
+{
+    m_service.reset();
+    for (ScriptPromiseResolver* resolver : m_serviceRequests)
+        resolver->reject(DOMException::create(NotFoundError, kNoServiceError));
+    m_serviceRequests.clear();
 }
 
 bool ImageCapture::addEventListenerInternal(const AtomicString& eventType, EventListener* listener, const EventListenerOptions& options)
 {
     return EventTarget::addEventListenerInternal(eventType, listener, options);
 }
 
 DEFINE_TRACE(ImageCapture)
 {
     visitor->trace(m_streamTrack);
+    visitor->trace(m_serviceRequests);
     EventTargetWithInlineData::trace(visitor);
     ContextLifecycleObserver::trace(visitor);
 }
 
 } // namespace blink