[whatwg] Singular CTM and currentTransform

Justin Novosad junov at google.com
Tue Mar 25 12:35:47 PDT 2014

On Tue, Mar 25, 2014 at 3:15 PM, Rik Cabanier <cabanier at gmail.com> wrote:
> I agree. That issue has the same root problem as currentTransform.
> It would be nice to get closure.
> Justin, you hinted that you would be willing to follow the spec which
> would make you match Firefox and IE.
> Are still planning on doing that?

I'm in a holding pattern. I prepared a code change to that effect, but then
there was talk of changing the spec to skip path primitives when the CTM is
not invertible, which I think is a good idea. It would avoid a lot of
needless hoop jumping on the implementation side for supporting weird edge
cases that have little practical usefulness.

Right now, there is no browser interoperability when using non-invertible
CTMs, and the web has been in this inconsistent state for a long time.  The
fact that this issue has never escalated (AFAIK) is a strong hint that no
one out there really cares about this use case, so we should probably just
go for simplicity. Maklng path primitives and draw calls no-ops when the
CTM is non-invertible is simple to spec, implement, test, and understand
for developers.

> Note that Firefox is still non-compliant if there's a non-invertible
> matrix during filling/stroking/clipping
>> > PS: This is one reason I prefer a getter over an attribute because the
>> > getter does not return a mutable (live) SVGMatrix. But even than the
>> > problem above is not fully solved of course.

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