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Re: [Selectors4] :dir()

From: Alan Gresley <alan@css-class.com>
Date: Fri, 30 Sep 2011 21:49:55 +1000
Message-ID: <4E85ACE3.2020305@css-class.com>
To: Christoph Päper <christoph.paeper@crissov.de>
CC: W3C Style <www-style@w3.org>
On 30/09/2011 8:28 PM, Christoph Päper wrote:
> Daniel Glazman:
>> Le 30/09/11 10:57, Christoph Päper a écrit :
>>>
>>> When there is a small, fixed set of possible arguments one should
>>> consider not using arguments at all. That means, ‘:ltr’ etc. seem
>>> the better choice.
>>
>> Because the text direction is going to remain limited to
>> horizontal in the future? The set of directions is not small…
>
> It is not, it is. Anyhow, if the selector is supposed to be
> extensible in the future, a more appropriate design would be
> something like
>
> :direction(<line progression start>,<glyph progression start>)

BTW, can we please use 'inline base direction' (or 'base direction') and 
'block flow direction' (I did like 'block progression'). Also can we 
avoid 'glyph' period since we can not know how a glyph is orientated and 
it has no bearing on base direction or how block stack ('block flow 
direction').

> ⇒
>    :direction(top, left)  {/* eurographic */}
>    :direction(top, right) {/* semitographic */}
>    :direction(right, top) {/* sinographic */}
>    :direction(left, top)  {/* Mongolian */}
>    …

Chris, have you studied the writing-mode WD [1]. I ask because the use 
of 'eurographic' is indicating a language of European origin (like 
English, Latin, French, etc.). So for the first part you have 'top'. 
This would be say 'block flow direction' that begins at the top of the 
page. I would much prefer 'tb' as in the writing mode spec. Secondly, 
why is this value first. The initial direction that anything can go is 
left or right. A test to show this.

<!doctype html>

<div 
lang="en">lefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttorightlefttoright</div>

By convention (of thousands of years), any new line will appear below 
the former line which can be conceptualized as flowing downwards, line 
by line. These line can be separated into blocks, thus why we have block 
flow direction.

I will expand on this in a later message since this is important to know 
since it indicates what is visible and invisible in that bizarre thing 
called overflow (my visualization is shown in these messages [2] [3]).

So if we followed this building of base direction and flow, a logical 
way would be.

:direction(ltr, tb)  {/* eurographic */}

This would also allow for selection of 'inline base direction' and 
'block flow direction' individually.

:direction(ltr)  {/* eurographic, sinographic & Mongolian */}

:direction(tb)  {/* eurographic, & semitographic */}

> or, to deal with boustrophedon,
>
>    :direction(
>      <line progression start>,
>      <glyph progression start in first/odd line>,
>      <glyph progression start in second/even line>
>    )

Can you give example of this but avoid you use of 'line progression 
start' or 'glyph progression start'. Something that is not 'inline base 
direction' or 'block flow direction'

> or something more complex to deal with (in-/outwards,
> [counter]clockwise) spiral text etc. or block progression, which
> usually is the same as line progression.

I will assure you that concepts like 'line progression' and 'block 
progression' are very different (read writing-mode WD)

Alan


1. http://dev.w3.org/csswg/css3-writing-modes/
2. http://lists.w3.org/Archives/Public/www-style/2010Oct/0818.html
3. http://lists.w3.org/Archives/Public/www-style/2011Apr/0253.html



-- 
Alan Gresley
http://css-3d.org/
http://css-class.com/
Received on Friday, 30 September 2011 11:50:36 GMT

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