On Tue, Dec 12, 2006 at 08:56:06PM +0600, Christopher Fynn wrote: > > Rich Felker wrote: > > >Whether it's possible to support all combinations efficiently, I don't > >know. The OpenType system is very poorly designed from what I can > >tell. In the Tibetan fonts I've examined, rather than just saying > >"character U+0F62 needs to use an alternate glyph when followed by any > >of {list here} combining characters", there are individual ligature > >combination tables for each pairing. Whether this is just lack of > >understanding on the font designer's part or fundamental limitations > >of OpenType, I'm not sure. > > Although you can build Tibetan stacks using contextual substitutions > I've found through trial and error that it is generally much more > efficient to have pre-composed consonant stacks and simple > (non-contextual) GSUB lookups. You will probably still need some > contextual lookups for vowel marks and for a few variant forms of stacks > - especially in cursive style Tibetan - but having a lot of contextual > substitution lookups in a Tibetan font seems to slow everything to a > crawl especially with long documents.
OK, so basically it's a workaround for poor OpenType implementations. Got it. Thanks for the explanation. BTW, I heard there was a mailing list specifically for Tibetan font/script issues. Is that still active, and if so, how can I subscribe? Rich -- Linux-UTF8: i18n of Linux on all levels Archive: http://mail.nl.linux.org/linux-utf8/