Re: [css3-writing-modes] a third option for implementing logical properties

?--------------------------------------------------
From: "David Hyatt" <hyatt@apple.com>
Sent: Sunday, October 24, 2010 9:29 AM
To: "John Daggett" <jdaggett@mozilla.com>
Cc: "L. David Baron" <dbaron@dbaron.org>; <www-style@w3.org>
Subject: Re: [css3-writing-modes] a third option for implementing logical 
properties

> On Oct 24, 2010, at 9:16 AM, John Daggett wrote:
>
...
>> Vertical
>> text layout has lots of features that make it quite distinct from
>> horizontal text layout, I think limiting authors to a "directionally
>> abstract" solution is a mistake.
>>
>
> I have never said that the logical properties are all that is needed.  I 
> am not opposed to a way of writing style rules based off the writing mode. 
> I just don't think anyone has suggested a good way to do that yet.
>


I cannot see how declarations like this:

fieldset {
  display: block;
  -webkit-margin-start: 2px;
  -webkit-margin-end: 2px;
  -webkit-padding-before: 0.35em;
  -webkit-padding-start: 0.75em;
  -webkit-padding-end: 0.75em;
  -webkit-padding-after: 0.625em;
  border: 2px groove ThreeDFace
}

will help to define that fieldset for ttb-ltr writing systems. Even more -
this declaration is I suspect just wrong for TTB writings.

----

We can postulate that in any case CSS will need directionality
"sensors" - pseudo-classes that are sensitive to view/content
directional flags.

I think that we can split the problem into two subjects:

1) To define system of directional pseudo-classes.
   It could be simple set as:

  :ltr;
  :rtl;
  :ttb-ltr;
  :ttb-rtl;

  These classes are getting their values from view settings
  and can be overridden in markup by using @dir attribute
  on the element or one of its parents.

2) If there is a real need for logical properties then we can consider
proposition for authors to use either CSS preprocessors like the LESS
or probably for us to think about use of constants or variables in
CSS again.

In any case CSS so far is a set of *physical*, concrete properties.
These properties define different styles of rendering of the DOM
for different environments. I mean that CSS is already a
definition of concrete layout for (logical, semantic) system of
DOM elements and attributes. Addition of logical layer to the
CSS itself will change the nature of CSS.


-- 
Andrew Fedoniouk.

http://terrainformatica.com

Received on Sunday, 24 October 2010 20:46:48 UTC