- From: Sam Weinig <weinig@apple.com>
- Date: Tue, 7 Sep 2010 22:32:36 -0700
In 4.8.11.1 the spec does state:
"Except where otherwise specified, for the 2D context interface, any method call with a numeric argument whose value is infinite or a NaN value must be ignored."
-Sam
On Sep 7, 2010, at 9:41 PM, Boris Zbarsky wrote:
> Consider this testcase:
>
> <!doctype html>
> <html>
> <body>
> <canvas id="c" width="200" height="200"></canvas>
> <script>
> try {
> var c = document.getElementById("c"),
> t = c.getContext("2d");
> t.moveTo(100, 100);
> t.lineTo(NaN, NaN);
> t.lineTo(50, 25);
> t.stroke();
> } catch (e) {alert(e); }
> </script>
> </body>
> </html>
>
> Behavior in the spec seems to be undefined (in particular, no mention is made as to what the canvas API functions are supposed to do if non-finite values are passed in). Behavior in browsers is:
>
> Presto: Throws NOT_SUPPORTED_ERR on that lineTo(NaN, NaN) call.
> Gecko: Throws DOM_SYNTAX_ERR on that lineTo(NaN, NaN) call.
> Webkit: Silently ignores the lineTo(NaN, NaN) call, and then
> draws a line from (100,100) to (50, 25).
>
> Seems like the spec needs to define this.
>
> -Boris
>
> P.S. This isn't a hypothetical issue; this came up in a page that was trying to graph things using canvas and ending up with divide-by-0 all over the place. It "worked" in webkit (though not drawing the right thing, so much). It failed to draw anything in Presto or Gecko.
Received on Tuesday, 7 September 2010 22:32:36 UTC