Subject: Re: Indian Language in AbiWord
From: Andrew Dunbar (hippietrail@yahoo.com)
Date: Sat Dec 29 2001 - 05:11:40 CST
--- Tomas Frydrych <tomas@frydrych.uklinux.net>
wrote: >
>
>
> > > The bidi version of AW does two-character
> ligatures, i.e., it can do
> > > a+b-> c; we do not do more then two at the
> moment. In future we
> > > will probably use Pango (www.pango.org) which
> will take care of
> > > that. We also do basic
> initial/medial/final/isolate glyph shaping.
> > > However, all of this only if the alternate
> glyphs have separate
> > > codepoints in Unicode, and I am not sure Indic
> languages do).
> >
> > They don't. The alternate glyphs for the vowels do
> (one for the vowel in
> > isolation, and one for the vowel in combination
> with a consonant), but the
> > consonants don't. So if you have RKSSRI, that's
> stored in Unicode (which for
> > the Indic scripts is several copies of ISCII, 128
> codepoints each, at
> > different offsets) as RA VIRAMA KA VIRAMA SSA
> VIRAMA RI, and you have to turn
> > that into I KSS SLASHRA CANDRA, where I is the
> vowel that is written before
> > the consonant it comes after, KSS is a ligature
> that looks nothing like K or
> > SS, SLASHRA (of which there may need to be two or
> three variants) is a
> > vertical bar with a slash attached, and CANDRA
> (the first R) is a crescent in
> > the upper right corner. I has a codepoint, but KSS
> and SLASHRA do not.
> >
> > The rules are slightly different from one Nagari
> script to another. JI, for
> > example, has its own glyph in Gujarati, but not in
> Devanagari.
> >
>
> I think the only solution to this is to use a proper
> external renderer,
> such as Pango. I think when we start rewriting the
> layout engine
> after the 1.0 release, we need to start working on
> this as well, or at
> least examine the Pango api and make changes that
> would make
> it easier to plug it in at a later stage.
I think everybody has pretty much decided on using
Pango. But I'm not sure if anybody has looked into
the issues we have, what Pango can do, what platforms
Pango works on, what platforms we actually need Pango
on, etc. Perhaps Savant Shanti's time is best spent
looking into the details of Pango and how we might go
about making use of it. I'm pretty sure we don't need
pango on Win2000 and above for instance since it's
font rendering is already good enough. It is
probably also possible to use FreeType directly which
would be an XP solution since we would also be able
to use the same APIs on OpenType in Windows and I bet
Mac OSX also has matching APIs. I've tried to look
deeper into Pango several times but since I don't have
a system to install it on, I never really grokked it.
I think it's a good time for somebody to start looking
into this now so we have somewhere to start from after
1.0 is out.
Andrew Dunbar.
=====
http://linguaphile.sourceforge.net http://www.abisource.com
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