[whatwg] [Canvas] Behavior on non-invertable CTM
ian at hixie.ch
Tue Jul 23 14:11:10 PDT 2013
On Mon, 22 Jul 2013, Dirk Schulze wrote:
> > scale(0) is invalid, and should throw an exception.
> I don't think that we want to throw an exception on scale(0). No browser
> does that today. WebKit did it in some places in the past but removed
> the exceptions.
WebIDL says it should throw a TypeError, because it's missing an argument.
(Step 4 of the overload resolution algorithm). Firefox, Chrome, and Safari
all seem to do this.
> >> The second does setTransform(0,0,0,0,0,0), which should reset the CTM
> >> to a zero matrix (again, not invertible). IE, Opera and FF draw a
> >> line to 0,0 and close the path afterwards (which kind of makes sense,
> >> since the universe is convoluted to one point). WebKit refuses the
> >> lineTo command and closes the path as expected.
> > WebKit seems to just be wrong here, and the others right.
> Since this is not written in the spec
As far as I can tell, it _is_ written in the spec. scale(0,0) would reduce
all coordinates and lines and so forth to 0,0. That's what the spec
requires. I don't see the problem here.
Ian Hickson U+1047E )\._.,--....,'``. fL
http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,.
Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
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