[whatwg] Canvas Path.addPath SVGMatrix not optimal?

[Rik Cabanier]

On Wed, Mar 19, 2014 at 2:22 PM, Justin Novosad <junov at google.com> wrote:

> On Wed, Mar 19, 2014 at 4:46 PM, Dirk Schulze <dschulze at adobe.com> wrote:
>
> > Hi,
> >
> > I just looked at the definition of Path.addPath[1]:
> >
> >     void addPath(Path path, SVGMatrix? transformation);
> >
> > SVGMatrix is nullable but can not be omitted all together. Why isn't it
> > optional as well? I think it should be optional, especially because
> > creating an SVGMatrix at the moment means writing:
> >
> >     var matrix = document.createElementNS('http://www.w3.org/2000/svg
> > ','svg').createSVGMatrix();
> >
> > Greetings,
> > Dirk
> >
> > [1]
> >
> http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#path
>
>
> I agree it should be optional, but just to play devil's advocate : you can
> create an identity SVGMatrix with a simpler bit of code. Just do this right
> after creating a canvas rendering context: var identity =
> context.currentTransform;
>

Hi Justin,

did Blink already expose this property?
As currently specified, this must return a live SVGMatrix object, meaning
that as you change the CTM on the 2d context, your reference to the
SVGMatrix should change as well. [1]

It's unlikely that you actually want this...
This API should be renamed to get/setCurrentTransform() and return a copy.

1:
http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-context-2d-currenttransform