Re: Luatex (actually Aleph) and Bidi_Mirrored chars in RTL mode

From: "Idris Samawi Hamid" <ishamid@colostate.edu>
To: "mailing list for ConTeXt users" <ntg-context@ntg.nl>
Subject: Re: Luatex (actually Aleph) and Bidi_Mirrored chars in RTL mode
Date: Mon, 09 Jun 2008 19:07:29 -0600	[thread overview]
Message-ID: <op.uciderdlnx1yh1@your-b27fb1c401> (raw)
In-Reply-To: <20080609012128.GA8011@khaled-laptop>

Hi Khaled,

On Sun, 08 Jun 2008 19:21:28 -0600, Khaled Hosny <khaledhosny@eglug.org>  
wrote:

> Luatex does not mirror characters that has a Bidi_Mirrored property when
> the text direction is set to RTL (TRT in Aleph), according to
> http://unicode.org/reports/tr9/#Mirroring, the different types of
> parenthesis that has Bidi_Mirrored property should be mirreored in RTL
> mode, but this isn't what I get. Is this a bug, feature, or am I missing
> some thing?

In addition to the comments by Arthur, Hans:

This issue needs to be looked at in the larger context of bidi in luatex.  
For example, we need a flexible model to implement Bidirectional Character  
Types. For example, we need an option that will recognize certain  
character-types as RL and switch directions accordingly -- that is,  
automatically switch \textdir, within a given paragraph, in accordance  
with the directionality of the word-string. This needs a well thought-out  
model so that we can map the Unicode specification to our \texdir \pardir  
functionality...

So the whole directionality issue needs to be looked at carefully, in  
addition to temporary patches like \setcharactermirroring[1]

OTOH: SC Unipad gets this right is perhaps the ideal to strive for...  
Indeed, it implements unicode better than any text application of which I  
am aware...

Also, we need not be too slavish: The Yudit author has pointed out areas  
where the bidi algorithm makes no sense or is deficient:

http://www.yudit.org/bidi/surprise.html

So this all needs careful thought. On my list...

Best wishes
Idris

-- 
Professor Idris Samawi Hamid, Editor-in-Chief
International Journal of Shi`i Studies
Department of Philosophy
Colorado State University
Fort Collins, CO 80523
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