RE: canvas origin?

> On 07/04/2011 22:14, Anton Prowse wrote:

> > I suppose the canvas origin is where the top-left corner of the margin
> > area box of the root element would be if it had position:static, and the
> > ICB's top-left corner is incident with that point.
> 
> That was rather careless.  How about: ...if it had position:static and 
> non-auto margin-left, in ltr mode; and in rtl mode it's the top-right 
> corners and margin-right that we consider.

Thank
 you for your response. I'm not clear about your stipulation about 
margin-left having to be "non-auto". Can you explain what you mean by 
this? 

By saying "non-auto", are you implying that it's 
permissible for the left-margin property of the html element to be 
specified as any positive or negative number, so that the canvas origin 
would then be wherever the top-left corner of the html (root) block is? 
(assuming ltr mode) For example, if I do html: {margin-left: -50px}, 
would the canvas origin be 50px to the left of the top left corner of 
the viewport? And since the ICB is coincident with that point, its top 
left corner would be at that point as well? The problem with this is 
that it means that the ICB would be larger than the viewport (when the 
spec says that the ICB is the same dimensions as the viewport). This is 
because the right margin edge of the html block extends to the right 
edge of the viewport, which must mean that the ICB (html's containing 
block) extends to the right edge as well. I'm finding this very 
confusing.

> > This should probably be made a little clearer in the spec.

I agree. How can we make that happen? 

> Date: Thu, 7 Apr 2011 22:44:25 +0200
> From: prowse@moonhenge.net
> To: www-style@w3.org
> CC: zxcv_890@hotmail.com
> Subject: Re: canvas origin?
> 
> On 07/04/2011 22:14, Anton Prowse wrote:
> > On 04/04/2011 23:19, Jack Smiley wrote:
> >>
> >> Referring to section 10.1 Definition of "containing block",
> >>
> >> "For continuous media, [the ICB] has the dimensions of the viewport
> >> and is anchored at the canvas origin..."
> >>
> >> I
> >> don't see the term "canvas origin" defined anywhere in the spec. Where
> >> is the canvas origin and what is the implication of having the ICB
> >> anchored to it?
> >
> > I suppose the canvas origin is where the top-left corner of the margin
> > area box of the root element would be if it had position:static, and the
> > ICB's top-left corner is incident with that point.
> 
> That was rather careless.  How about: ...if it had position:static and 
> non-auto margin-left, in ltr mode; and in rtl mode it's the top-right 
> corners and margin-right that we consider.
> 
> > This should probably be made a little clearer in the spec.
> 
> ;-)
> 
> 
> Cheers,
> Anton Prowse
> http://dev.moonhenge.net