Adds SVGImageElement as a CanvasImageSource

third_party/WebKit/Source/core/svg/SVGImageElement.cpp

Index: third_party/WebKit/Source/core/svg/SVGImageElement.cpp
diff --git a/third_party/WebKit/Source/core/svg/SVGImageElement.cpp b/third_party/WebKit/Source/core/svg/SVGImageElement.cpp
index 99f083eae214dccc6296751d4afa06fb065655c7..d224e051dc6a346534c75b456fd0c91d7a0e0645 100644
--- a/third_party/WebKit/Source/core/svg/SVGImageElement.cpp
+++ b/third_party/WebKit/Source/core/svg/SVGImageElement.cpp
@@ -195,6 +195,10 @@ Node::InsertionNotificationRequest SVGImageElement::insertedInto(
   return InsertionDone;
 }
 
+FloatSize SVGImageElement::sourceDefaultSize() {
+  return FloatSize(0, 0);

[fs, 2017/03/07 22:01:25]

To be somewhat equivalent with the HTMLImageElement version, I think this would
be something like:

if (layoutObject())
  return toLayoutSVGImage(layoutObject())->objectBoundingBox().size();
SVGLengthContext lengthContext(this);
return FloatSize(m_width->currentValue()->value(lengthContext),
                 m_height->currentValue()->value(lengthContext));

I wonder if these width/heights shouldn't be the <canvas> width/height - reading
step 3 of https://html.spec.whatwg.org/multipage/scripting.html#drawing-images

[fserb, 2017/03/08 18:31:59]

Thanks for the code snippet, I'll implement it like this.

Regarding the spec thing, those functions are messed up
(sourceWidth/sourceHeight). They are not called by the CanvasImageSource code
path at all (they are used for BitmapImageSource). On the canvas side, we always
get called through getSourceImageForCanvas() which receives a
"defaultObjectSize" (which is the canvas size) -- I've added tests to make sure
that step 3 works (it's the 6th id on the test, iirc). Since those are not used
for the actual canvas rendering, I interpreted them as "the inherit dimension of
the image" and therefore I think your code makes sense (but I'll go over it
again for Bitmap source, maybe even remove it completely). 

Does this make sense to you?

[fs, 2017/03/08 18:57:16]

Ok (ImageBitmapSource though, right?). Codesearch seems to only show them being
called in modules/shapedetection though. Did it miss something?
If they are indeed only used by the shapedetection code, it makes perfect sense
to revisit later. So, if you want to go with the above, that would be fine with
me. I suspect that these are buggy/broken though, and should probably be
replaced/removed.

[fserb, 2017/03/21 19:15:22]

yep. Only for shapedetection, (which I assumed is only used for
ImageBitmapSource, no?)
Anyway, moot point. I've used your snippet and will look into those again for
ImageBitmapSoure.

[fs, 2017/03/21 21:05:41]

Acknowledged.

+}
+
 const AtomicString SVGImageElement::imageSourceURL() const {
   return AtomicString(hrefString());
 }