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Re: [css3-writing-modes] Inlines and logical properties

From: Alan Gresley <alan@css-class.com>
Date: Thu, 14 Oct 2010 02:18:39 +1100
Message-ID: <4CB5CDCF.5030104@css-class.com>
To: David Hyatt <hyatt@apple.com>
CC: "www-style@w3.org list" <www-style@w3.org>
David Hyatt wrote:
> I've noticed a problem with logical properties as they relate to inlines.
> 
> For a vertical-lr block, the before side of the block is the left and the after 
> side is the right.
> 
> 
> However the "top" of a line and "bottom" of a line in a vertical-lr block are 
> typically flipped relative to the block (see the rotated block above).  The 
> "top" of the line is on the "after" side of the block and the "bottom" of the 
> line is on the "before" side of the block.
> 
> My question is, "What do before and after mean on an inline?"  Technically the 
> inline's writing-mode value is also vertical-lr, so if you obey that to the 
> letter, "before" is the "bottom" side of the line.  However if you were to 
> switch to a horizontal-tb writing mode, the "after" side becomes the "bottom" 
> side of the line.


Correct. I have raised this here [1] [2] and created a test case [3].


> If the purpose of these logical properties is to allow you to switch between 
> writing modes seamlessly then this seems like a problem to me.


Yes when we have vertical-lr languages which can also be horizontal-lr


> For example, trying to use borders to do an underline on a span, e.g., 
> border-after: 1px dotted blue would have to become border-before:1px dotted blue 
> in a vertical-lr block.
> 
> My suggestion would be to make before/after map to top/bottom for horizontal 
> lines and right/left for vertical lines.
> 
> dave


The only problem with that is most vertical Japanese and Chinese 
scripts are vertical-rl which fall back to horizontal-lr if vertical 
text is not supported.


1. <http://lists.w3.org/Archives/Public/www-style/2010Oct/0014.html>
2. <http://lists.w3.org/Archives/Public/www-style/2010Oct/0017.html>
3. <http://css-class.com/test/css/text/mongolian-script-horz-vert.htm>



-- 
Alan http://css-class.com/

Armies Cannot Stop An Idea Whose Time Has Come. - Victor Hugo
Received on Wednesday, 13 October 2010 15:19:11 GMT

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