[whatwg] Compatibility problems with HTML5 Canvas spec.

Ian Hickson ian at hixie.ch
Sun Feb 3 02:07:28 PST 2008

On Fri, 1 Feb 2008, Oliver Hunt wrote:
> All the transform operations define the behaviour if given inf, but not 
> NaN

Fixed recently.

> The behaviour of inf and nan arguments is undefined for arguments to the
> gradient constructors and shadow offsets.

Fixed, I believe. Let me know if I missed something.

> I think it should be explicit that negative width/height are allowed on the
> rect methods (which appears to be the case based on my reading)

Is the current text not explicit enough?

> The behaviour of inf and NaN arguments is undefined for any of the path 
> functions.

There's a paragraph near the top of the 2D context section now that 
explains this in general for all methods.

> I would think the a 0 dimension in the source rect for drawImage, and 
> the like should fail silently, but i need to check what existing 
> implementations actually do.
> Unfortunately I don't really know what the best behaviour would be in 
> these cases -- i tend to prefer failing silently, but i think we should 
> at least look at what existing implementions already do.

Do let me know if you think the spec should change.

> Finally, although only tangentially related, i think we should provide 
> the ability to selectively blit only a subregion of an ImageData object.


Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

More information about the whatwg mailing list