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Re: [CSS21] Concern about anonymous table objects and whitespace

From: fantasai <fantasai.lists@inkedblade.net>
Date: Thu, 22 Jan 2009 15:26:39 -0800
Message-ID: <497900AF.4010200@inkedblade.net>
To: Boris Zbarsky <bzbarsky@MIT.EDU>
CC: www-style@w3.org

Boris Zbarsky wrote:
>  > So, would a rule 4 added to the anonymous box generation rules
>  >   http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes
>  > that states
>  >
>  >   4. If a child T of a 'table', 'inline-table', 'table-row-group',
>  >       'table-header-group', 'table-footer-group', or 'table-row' box
>  >       is an anonymous inline box that contains only white space, then
>  >       it is treated as if it has "display: none".
>  >
>  > solve the problem?
>  >
>  > ~fantasai
> OK, I'm looking at this again.  This might solve the problem but 
> requires either various lookahead when constructing the rendering tree 
> or creating, analyzing, and then possibly (and in fact probably) 
> destroying rendering objects.  Further, it requires all this in the 
> common case (HTML tables).
> And I'm not even sure whether it solves the problem, because I can't 
> tell, by reading this rule, what the correct box tree is for:
>   <div style="display: table-row">
>     <span>AAA</span>
>     <span>BBB</span>
>   </div>
> Is there a space between the "AAA" and "BBB" or not?

Good point. The intent was for all consecutive boxes that are not an
internal table-* box to be considered as one unit. And if that unit is
composed entirely of white space then it is dropped. So that example
should generate a single table-cell just inside the table-row and,
probably, preserve all whitespace inside. Certainly it should preserve
the space between the two spans. So perhaps the intent is more closely
expressed by adding

   | 8. Any anonymous table-cell, table-row, table-row-group, table-header-group
   |    or table-footer-group whose contents are only anonymous boxes
   |    containing only white space are treated as if they had "display: none".

But that doesn't solve your lookahead problem there.

Can I get a bug #?

> The more I look at this section and think about implementing it, the 
> more poorly-thought-out it seems.  So I would like to propose alternate 
> anonymous box generation rules (loose phrasing; can write up formally if 
> desired):
> 1) Suppress all "misnested" boxes except 'table-row' inside 'table'.
> 2) Wrap runs of 'table-row' inside 'table' in a 'table-row-group'
>    (needed to deal with XHTML's not requiring a <tbody>).
> It feels like this would be much simpler to implement.  Interoperability 
> on this section is already quite poor, so making this change might 
> actually get us to CR faster.  The only question is whether it'll cause 
> website compat issues....  Are sites relying on the 
> currently-interoperable behavior?  If so, can we loosen the "suppress 
> everything" condition enough to allow those sites to keep operating 
> while still keeping the overall thing somewhat sane?

I agree with Tab,
   <ul style="display: table">
     <li style="display: table-cell"/>
     <li style="display: table-cell"/>
needs to work.

Received on Thursday, 22 January 2009 23:27:25 UTC

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