Re: OpenType support in Pango

[Antoine Leca <Antoine Leca renault fr>]

Owen Taylor wrote:
> 
> > > It's probably a day or so additional work to get positioning of
> > > accents working. A really sophisticated use of OpenType like the
> > > OpenType Indic spec would require considerably more work.
> 
> Pango actually has Indic rendering code for a large range of languages
> usingn BDF fonts (thanks to Robert Brady), and this is again based
> on the descriptions in the Unicode specfication, so that's probably
> a good start.

Probably, but I do not believe it complies nicely with OT indic...
OTOH, the goal is to have Indic rendered, so it may be another valuable
path! And Indic OT fonts are not very frequent these days, contrary to
what MS may have envisionned...

 
> I don't think that the amount of new code that needs to be written to
> get the OT Indic spec working is actually that big, the reason why I
> think it is a significant amount of work (a week or two, anyways) is
> that there are a lot of things that can go wrong:
> 
>  - It has a large number of lookups that interact in complex ways,

Right. And last time I looked at this, the scheme used in FT1 was not
very easy to use, because the lockups (from 4 to 14, usually) are to be
applied to limited runs of glyphs rather than complete strings, which
means a lot of managing for small pieces, which seems to me the reverse
of FT1 OT aims (but I confess I never gave it a try to see what is
the real performance hit: implement even a part of the specs appears
to me too much a job to allow toying :-( ).

 
>  - These lookups use quite a bit of the OpenType layout spec.
> 
>  - The set of languages that is covered is big so testing is hard.

What do you mean here ?
 
>  - There are certainly missing details from the spec that will
>    take some experimentation to figure out.

I believe that the support for scripts other than Nagari and Tamil
is still unfinished at Microsoft (particularly for the most complex
ones like Malayalam) ;-)

 
Antoine