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

third_party/WebKit/Source/core/frame/ImageBitmap.cpp

 // Copyright 2013 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 "core/frame/ImageBitmap.h"
 
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/ImageData.h"
+#include "platform/graphics/skia/SkiaUtils.h"
 #include "platform/image-decoders/ImageDecoder.h"
 #include "third_party/skia/include/core/SkSurface.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 static const char* imageOrientationFlipY = "flipY";
 static const char* imageBitmapOptionNone = "none";
 
 // The following two functions are helpers used in cropImage
@@ skipping 375 matching lines @@
 }
 
 void ImageBitmap::close()
 {
     if (!m_image || m_isNeutered)
         return;
     m_image.clear();
     m_isNeutered = true;
 }
 
+// static
+ImageBitmap* ImageBitmap::take(ScriptPromiseResolver*, sk_sp<SkImage> image)
+{
+    return ImageBitmap::create(StaticBitmapImage::create(fromSkSp(image)));

[Justin Novosad, 2016/04/27 15:03:17]

You must determine whether 'image' is tainted with cross-origin data and call
setOriginClean() with the right value on the new StaticBitmapImage object. You
also need a layout test that creates a stream from a cross origin video source
and does a grab from it. To test that the tainting mechanism worked, you should
draw the grabbed ImageBitmap into a canvas and verify that calling
getImageData() on that canvas throws a SecurityError exception.

[mcasas, 2016/04/27 17:48:18]

|image| comes from a MediaStream so it's origin is
clean already. Moreover, the MS Video Track pixels
are already accessible on ToT by plugging it into a
<video> element, then reading it back via a <canvas>,
and the CORS test for the <video> tag says always
OK [1].

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/m...

+}
+
 PassOwnPtr<uint8_t[]> ImageBitmap::copyBitmapData(AlphaDisposition alphaOp)
 {
     SkImageInfo info = SkImageInfo::Make(width(), height(), kRGBA_8888_SkColorType, (alphaOp == PremultiplyAlpha) ? kPremul_SkAlphaType : kUnpremul_SkAlphaType);
     OwnPtr<uint8_t[]> dstPixels = copySkImageData(m_image->imageForCurrentFrame().get(), info);
     return dstPixels.release();
 }
 
 unsigned long ImageBitmap::width() const
 {
     if (!m_image)
@@ skipping 56 matching lines @@
 FloatSize ImageBitmap::elementSize(const FloatSize&) const
 {
     return FloatSize(width(), height());
 }
 
 DEFINE_TRACE(ImageBitmap)
 {
 }
 
 } // namespace blink