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Re: [CSS21] Can column boxs span multiple columns?

From: Simon Sapin <simon.sapin@kozea.fr>
Date: Wed, 30 Nov 2011 12:28:23 +0100
Message-ID: <4ED61357.4020005@kozea.fr>
To: www-style@w3.org
Le 29/11/2011 18:24, fantasai a écrit :
> On 11/17/2011 01:57 AM, Simon Sapin wrote:
>> Le 16/11/2011 20:04, fantasai a écrit :
>>> Huh, that seems pretty wrong. I'd expect the <col> element to just
>>> generate
>>> multiple column boxes.
>>
>> After some experiments with backgrounds and borders, it seems to be
>> what browsers do. (Small detail: Gecko adds borders to
>> each boxes generated by the same <col>, but webkit does not draw the
>> border in-between them.)
>>
>> It is also consistent with what HTM4 says about the width attribute.
>> I’ll implement it this way in WeasyPrint.
>>
>> I’d write up proposed changes to the spec to make this clearer and
>> more explicit, but would they be useful?
>
> Yep!

The only section about how elements generate boxes for tables is 17.5 
Visual layout of table content. The section seems misnamed as non-visual 
user agents also need to generate boxes.

I propose adding to the first paragraph:

"""
Each element generates one box, except for table-column elements which 
generate as many table-column box as the number of column they span. 
Cells that span multiple rows or columns still generate only one box. 
(Although CSS 2.1 does not define how the number of spanned rows or 
columns is determined, a user agent may have special knowledge about the 
source document; a future update of CSS may provide a way to express 
this knowledge in CSS syntax.)
"""

The sentence in parenthesis is moved from the 5th point of the ordered 
list. It implicitly also affects table-column elements that may span 
multiple columns, but I’m not sure how to make this explicit.

The whole chapter needs clarification between elements and boxes (as 
well as "objects" in 17.2.1 ?) but this is a bigger issue.

Side issue: 17.5 says that "These rules do not apply to HTML 4 or 
earlier HTML versions; HTML imposes its own limitations on row and 
column spans."
Does that mean that they apply to HTML5?

Regards,
-- 
Simon
Received on Wednesday, 30 November 2011 11:29:12 GMT

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