Bug 24668 – Canvas arc gives exceptions on r<0

• Status: RESOLVED
• Resolution: DUPLICATE
• Component: DOM

[Dirk Schulze]

Our canvas code gives exceptions on r<0 for arc. This behavior matches the spec, but breaks some sites like this above.

[Dirk Schulze]

Created attachment 28720 [details]
silent return for r<0

patch

[Darin Adler]

What’s our strategy on this for canvas? If the spec is wrong I think we need to get the spec fixed too, and not just change our implementation. Have we been doing this same type of thing for other canvas issues?

[Dirk Schulze]

It's ok to return if r<0, but there is no need to throw an exception here. The same for arcTo.
It's maybe the best way to adjust the spec.

[Eric Seidel (no email)]

Comment on attachment 28720 [details]
silent return for r<0

We should match the spec.  Even if that means the spec should be changed here.  This change would also require a test case (preferably a new js-style test).

I suggest you add a test to check our behavior regardless.  Then at least we know when we change our behavior later to match any changes in the spec.

[Oliver Hunt]

Comment on attachment 28720 [details]
silent return for r<0

dirk and i already discussed this -- he's going to email whatwg's mailing list to get the spec changed.

[Oliver Hunt]

Comment on attachment 28720 [details]
silent return for r<0

Oh, needs a layout test :D

[Dirk Schulze]

Sorry for my absence. I'll upload a layout test in the next days.

[Eric Seidel (no email)]

Comment on attachment 28720 [details]
silent return for r<0

Marking as r- due to lack of layout test.

[Dirk Schulze]

Ian Hixie denied the change of the spec. (for the moment ;-))

http://www.nabble.com/Canvas---Exception-on-arc-with-negative-radius-td22748785.html

[Dirk Schulze]

Opened a bug in bugzilla.mozilla.org (https://bugzilla.mozilla.org/show_bug.cgi?id=491150). Let's see their opinion.

[Dirk Schulze]

*** This bug has been marked as a duplicate of bug 37176 ***