[whatwg] Canvas spec issues

Ian Hickson ian at hixie.ch
Fri May 11 16:18:21 PDT 2007

On Mon, 26 Mar 2007, Philip Taylor wrote:
> A couple of points that are unclear and are causing differences between 
> current implementations (which is presumably a bad thing):
> "interface HTMLCanvasElement" says "attribute long width;". #reflect 
> says "If a reflecting DOM attribute is a signed integer type (long) then 
> the content attribute must be parsed according to the rules for parsing 
> signed integers first", which seems to apply in this case. But the 
> canvas section says of width/height, "The rules for parsing non-negative 
> integers must be used to obtain their numeric values". Hence, conflict.
> Also, "canvas.width = -1" is acceptable for a signed long, but doesn't 
> make sense here. (After setting that, Firefox gives canvas.width==0, 
> Opera gives 300, Safari gives -1.)

Changed to unsigned.

> And some minor issues with the text:
> "DOMString toDataURL();" has the link stretching across the brackets.
> In "interface CanvasRenderingContext2D", it looks like
> "HTMLCanvasElement canvas;" should be "readonly attribute
> HTMLCanvasElement canvas;" (because everything else has "attribute",
> and the comment says it's readonly).

Oops, the newline moved a bit too far there. Fixed.

> "When the context is created, the transformation matrix must initially 
> be the identity transform. It may then be adjusted using the three 
> transformation methods" - but there are now five (not three) 
> transformation methods (scale, rotate, translate, transform, 
> setTransform).


> In Compositing, "darker" says "destination images" while all the others 
> say "destination image".


Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
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