From: Richard Wordingham (email@example.com)
Date: Mon Aug 22 2005 - 15:02:54 CDT
Adam Twardoch wrote:
> Richard Wordingham wrote:
>> By the way, why can't font-encoded Tamil (e.g. using ASCII codes as a
>> hack) display be handled on Windows by a GSUB table that handles the
>> re-ordering? Or would that make it Level-2 anyway? Where can I find a
>> definition of 'Level-2'?
> GSUB tables don't handle the reordering in Indic languages. It's the
> responsibility of the OpenType Layout processor, e.g. Uniscribe.
So how do I get it to live up to its 'responsibility' to support an Indic
conlang living in the PUA? I'm not even sure that Burmese is supported yet.
I deliberately framed the question in terms of an encoding that Uniscribe
would not recognise as a complex script. It's not even clear to me whether
the feature 'ccmp' would be available, nor whether it can really be used to
effectively swap two glyphs. My doubts on the latter point arise because
Uniscribe has to maintain some sort of mapping between position and
characters to support selection, insertion and deletion. Using GSUB to do
the re-ordering in Devanagari might put quite a strain on the maintenance of
this mapping - Tamil would be simpler.
While it clearly looks like good practice to have a single per-script
definition of necessary re-orderings, in practice it is very inconvenient if
the user (or system administrator) cannot update the definitions. For
example, Microsoft has little incentive to modify Uniscribe to treat
independent Devanagari vowels as consonants (or, to be pedantic,
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