Add TimedCanvasDrawListener

third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp

Index: third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp
diff --git a/third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp b/third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp
index d199fdfe2c4ac30f4bae66c9cfe3183b7e842770..f6e7a5a117401e9aa1e38c4a6cede078e2e3365d 100644
--- a/third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp
+++ b/third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp
@@ -22,6 +22,16 @@ namespace blink {
 
 MediaStream* HTMLCanvasElementCapture::captureStream(HTMLCanvasElement& element, ExceptionState& exceptionState)
 {
+    return HTMLCanvasElementCapture::captureStream(element, false, 0, exceptionState);
+}
+
+MediaStream* HTMLCanvasElementCapture::captureStream(HTMLCanvasElement& element, double frameRate, ExceptionState& exceptionState)
+{
+    return HTMLCanvasElementCapture::captureStream(element, true, frameRate, exceptionState);
+}
+
+MediaStream* HTMLCanvasElementCapture::captureStream(HTMLCanvasElement& element, bool givenFrameRate, double frameRate, ExceptionState& exceptionState)
+{
     if (!element.originClean()) {
         exceptionState.throwDOMException(SecurityError, "Canvas is not origin-clean.");
         return MediaStream::create(element.executionContext());
@@ -29,7 +39,11 @@ MediaStream* HTMLCanvasElementCapture::captureStream(HTMLCanvasElement& element,
 
     WebMediaStreamTrack track;
     WebSize size(element.width(), element.height());
-    OwnPtr<WebCanvasCaptureHandler> handler = adoptPtr(Platform::current()->createCanvasCaptureHandler(size, kDefaultFrameRate, &track));
+    OwnPtr<WebCanvasCaptureHandler> handler;
+    if (givenFrameRate)
+        handler = adoptPtr(Platform::current()->createCanvasCaptureHandler(size, frameRate, &track));
+    else
+        handler = adoptPtr(Platform::current()->createCanvasCaptureHandler(size, kDefaultFrameRate, &track));
     ASSERT(handler);
     if (!handler) {
         exceptionState.throwDOMException(NotSupportedError, "No CanvasCapture handler can be created.");
@@ -37,7 +51,10 @@ MediaStream* HTMLCanvasElementCapture::captureStream(HTMLCanvasElement& element,
     }
 
     MediaStreamTrackVector tracks;
-    tracks.append(CanvasCaptureMediaStreamTrack::create(track, &element, handler.release()));
+    if (givenFrameRate)
+        tracks.append(CanvasCaptureMediaStreamTrack::create(track, &element, handler.release(), frameRate));
+    else
+        tracks.append(CanvasCaptureMediaStreamTrack::create(track, &element, handler.release()));

[esprehn, 2015/12/19 03:33:04]

I don't understand why we can't use kDefaultFrameRate here?

[emircan, 2015/12/29 22:57:08]

I need a way to distinguish between captureStream(60) and captureStream() calls.
captureStream(60) should lead to TimedCanvasDrawListener and captureStream()
should lead to AutoCanvasDrawListener. kDefaultFrameRate has nothing to do with
blink side classes or CanvasDrawListeners. 

It is just that the Chrome side VideoCapturerSource interface[0] needs to return
some frame_rate information. I decided to have a single
Platform::current()->createCanvasCaptureHandler() signature and define the
kDefaultFrameRate here, see l.46. I can revisit this later as each
captureStream() mode is introduced.

[0]
https://code.google.com/p/chromium/codesearch#chromium/src/media/base/video_c...

     return MediaStream::create(element.executionContext(), tracks);
 }