[dev-context] Re: BiDi in ConTeXt

Adam Lindsay atl at comp.lancs.ac.uk
Fri Nov 12 00:39:11 CET 2004


Idris Samawi Hamid said this at Thu, 11 Nov 2004 14:37:58 -0700:

>Hi Adam, & thnx for cc'ing me.

(Well, only natural: I was looking thru m-gamma to see how things were
being used, and it had your name all over it.)

>> I just started thinking about further language support within ConTeXt now
>> that the XeTeX-ConTeXt "basics" are done. XeTeX doesn't have the same
>> character/line directionality control that is apparently in Omega, but it
>> does control Right/Left typesetting fairly well.
>
>I've been out of the loop on all things TeX for a while now (demands of my 
>profession and other matters). I have a couple of general questions:
>
>1. What exactly is the aim and purpose of XeTeX?

http://scripts.sil.org/xetex
XeTeX is an updating of GXTeX. It is an amalgamation of eTeX with Unicode
and Apple's advanced typography APIs, and is therefore Mac OS X only.
Once cross-platform-ness is sacrificed, there are a lot of interesting
benefits. Font installation issues drop to nearly zero--it has access to
all fonts on the system--and Apple ships the systems with a fairly
impressive array of intelligent fonts. The native Unicode support unlocks
a lot of ConTeXt's stored multilingual potential, too.

>2. Since its apparently based on eTeX, and since bidi seems to be of 
>interest, why not integrate it with the Aleph project, also eTeX-based 
>(with an eye towards ConTeXt), and which already has the bidi stuff 
>implemented rather well?

I doubt it's headed that way, but Jonathan Kew, the developer, may well
be swayed by certain of Omega's paragraph/text directionality constructs.
I don't know it well enough, but William Adams seems to have a hand in
the Omega pie, and is represented in the XeTeX community.

>> In particular, it makes a fairly big deal of its implementation of the
>> eTeX beginR/beginL extensions. They seem to work fairly well in demos
>> I've seen and simplistic tests I've done.
>>
>> I was wondering about the bigger issues in terms of BiDi support, though.
>> Do people want an interface that mimics Omega's \pardir command? Or is
>> there a more simple/focussed/specific way?
>
>If the idea is a kind of BiDi-Light (just paragraph and text), then 
>implementing a subset of Aleph's functionality (such as \pardir and 
>textdir) seems like a good way to go.
>
>> (I imagine I don't see a single \beginR in ConTeXt's source code because
>> it relies heavily on proper font support, probably beyond what the TFM
>> system usually offers.)
>
>which is where we will need Aleph and Bidi-Full

The (too hidden) implication from me was that XeTeX does offer automatic
text directionality, driven by the script and/or Unicode page. Noticing
Hebrew in a default font, I tried spelling Aleph-Dalet-Mem in the middle
of a roman paragraph, and it naturally (no markup needed) came out MDA.
(Hans, incidentally, is a little disturbed by this sort of cleverness.)

>Is Giuseppe aware of all of this (I assume he's on dev-context)?

Actually, looking at the distro list, it looks like he isn't! hi!
-- 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 Adam T. Lindsay, Computing Dept.     atl at comp.lancs.ac.uk
 Lancaster University, InfoLab21        +44(0)1524/510.514
 Lancaster, LA1 4WA, UK             Fax:+44(0)1524/510.492
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