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RE: Expected behavior of background-clip property on the html element?

From: Sylvain Galineau <sylvaing@microsoft.com>
Date: Wed, 12 Jan 2011 16:03:26 +0000
To: fantasai <fantasai.lists@inkedblade.net>, Alan Gresley <alan@css-class.com>
CC: "Cathy.Chan@nokia.com" <Cathy.Chan@nokia.com>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <045A765940533D4CA4933A4A7E32597E2AADA0BD@TK5EX14MBXC111.redmond.corp.microsoft.com>
> From: www-style-request@w3.org [mailto:www-style-request@w3.org] On
> Behalf Of fantasai
> Sent: Tuesday, January 11, 2011 11:21 PM
> To: Alan Gresley
> Cc: Cathy.Chan@nokia.com; www-style@w3.org
> Subject: Re: Expected behavior of background-clip property on the html
> element?
> 
> On 01/11/2011 11:03 PM, Alan Gresley wrote:
> > On 12/01/2011 5:13 PM, fantasai wrote:
> >> The spec says:
> >>
> >> http://www.w3.org/TR/css3-background/#background-clip
> >>
> >> # background-clip ... determines the <dfn>background painting
> area</dfn>.
> >> # ...
> >> # Note that the root element has a different background painting area.
> >> # See "The backgrounds of special elements."
> >>
> >> http://www.w3.org/TR/css3-background/#special-backgrounds
> >>
> >> # The background of the root element becomes the background of the
> >> canvas # and its <em>background painting area</em> extends to cover
> >> the entire # canvas
> >>
> >> Exactly what is not clear?
> >
> > Interesting how this is implemented. I ask you what browser handles this
> correct?
> 
> Given the above-quoted spec text, the entire canvas, aside from the blue
> dots of the html border and the white background of the body box which is
> just high enough to contain the word "test", should be gray.
> 
> I fail to understand why this is not clear from the spec. Perhaps you can walk
> me through an interpretation of the spec that gets you a different answer?

Fwiw, my own interpretation:

What should be done in the absence of the background-clip property is clear. 
Whether background-clip values (other than its initial value) should have an 
effect on the result - it applies to 'all elements', after all - and what that effect 
could/should be is less obvious. 

The background-clip section does note that the root has a different painting area
but neither it nor the special background section explain what the effect of 
background-clip is, if any. We learn that the canvas is the background painting 
area; but it's not explicitly stated whether that is the only BPA for root i.e.for
all values of background-clip. It seems that way, and one can suspect that's the
case, but implementations currently appear to disagree.

I'm sure I've missed something but it seems safe at this point to say this could be
clarified. 

Nitpick: should the reference to the special background section in background-clip
be a note ? It looks normative to me.
Received on Wednesday, 12 January 2011 16:04:14 GMT

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