Re: [css3-text-layout] New editor's draft - margin-before/after/start/end etc.

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From: "Zack Weinberg" <zweinberg@mozilla.com>
Sent: Saturday, May 29, 2010 2:03 PM
To: "Andrew Fedoniouk" <news@terrainformatica.com>
Cc: "HåkonWiumLie" <howcome@opera.com>; <www-style@w3.org>
Subject: Re: [css3-text-layout] New editor's draft - 
margin-before/after/start/end etc.

> "Andrew Fedoniouk" <news@terrainformatica.com> wrote:
>>
>> Correct, "dir" is a DOM attribute here.
>>
>> Precise algorithm of determination of :ltr,:rtl and :ttb values is
>> this: Start from the element itself and walk through child-parent
>> chain until you will find DOM element with defined "dir" attribute.
>> If value of the "dir" is "rtl" then set :rtl to true and reset all
>> other directionality pseudo-classes like :ltr and :ttb.
>
> Consider the complete HTML5 document
>
> <!doctype html>
> <p>This text is mostly in English, but contains a Hebrew
>    quotation: <q>אבגabcדה</q>.  There is an English word embedded
>    in the quotation.</p>
>
> What, if anything, would be matched by :ltr here?  :rtl?  Why, or why
> not?

The document you've provided does not contain any explicit "dir"
declaration so neither :ltr nor :rtl is true.

UA may or may not set implicit @dir value for the content
depending on OS directionality but it is up to UA I think.

In practical UI applications (e.g. this one
http://en.wikipedia.org/wiki/Norton_Internet_Security )
we use explicit @dir declarations.

>
> Does your answer change if the Unicode explicit directional codes
> (U+202A through U+202E) appear anywhere in the document, either as HTML
> entities or as literal characters?
>
> Does your answer change if the right-to-left characters are not
> well-nested relative to element boundaries, e.g. <q>אבגabcד</q>ה ?
>

I don't think that guessing :rtl or :ltr values by using particular
character runs is a good idea at all.

E.g. there is a task of presenting file names or URLs in UI.
Think about file name in e.g. Hebrew but with ".htm" extension.
Usually this is treated as <div dir="ltr"> so overall directionality is
still LTR.  To be short: :ltr and :rtl are explicitly @dir based.

Is this the answer?

-- 
Andrew Fedoniouk

http://terrainformatica.com

Received on Saturday, 29 May 2010 21:41:24 UTC