[whatwg] Singular CTM and currentTransform

[Dirk Schulze]

On Mar 25, 2014, at 8:46 PM, Rik Cabanier <cabanier at gmail.com> wrote:

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> On Tue, Mar 25, 2014 at 12:35 PM, Justin Novosad <junov at google.com> wrote:
> On Tue, Mar 25, 2014 at 3:15 PM, Rik Cabanier <cabanier at gmail.com> wrote:
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> I agree. That issue has the same root problem as currentTransform.
> It would be nice to get closure.
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> 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?
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> 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.
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> 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.
> 
> Great to hear!
> I volunteer to update the Firefox implementation if we can get consensus. (see https://bugzilla.mozilla.org/show_bug.cgi?id=931587) 

Speaking for WebKit, support for changing the spec from me as well. Doing it according to the spec would be difficult, if possible at all in WebKit.

Greetings,
Dirk

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> Note that Firefox is still non-compliant if there's a non-invertible matrix during filling/stroking/clipping
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> > 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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