Unicode Font Woes

Sivakatirswami katir at hindu.org
Tue Sep 13 21:51:45 EDT 2005

OK I'll look at these... I think in the interests of helping RunRev,  
we all need to be aware of an underlying cross plaftorm issue of  
which I am informed onl yesterday as follows by  professor in  
Switzerland who is helping me on this matter. which is: many fonts  
will "apparently" work on the Mac, but are actually meant only to be  
properly rendered with the Windows Uniscribe, but not the Mac ATSUI  
engine... to wit:

   Dr. Kalyanasundaram writes:

"But there is a practical problem here. Most of the GIST Tamil Unicode
fonts distributed free are meant for use on Windows PCs. Rendering of
Tamil glyphs in Unicode is done differently in Windows (use a rendering
enginecalled UNISCRIBE) as compared to Apple Mac (Mac uses ATSUI
search engine to deal with Open Truetype fonts for Unicode.

Thus for use on Mac OS X platform, Open TTF fonts of Windows are to
be "repacked" for use under ATSUI engine. Without this tinkering and
repacking, composite glyphs of Tamil are not displayed correctly -
you see only a linear rendering, as the way in which Unicode text is
saved in the file (mei followed by modifier signs and not the composite
glyph themselves). On Mac, like CDAC fonts GSUB tables that are in  
the font file are
not used and you will see linear mode display."

This may be the issue with bug 2489 where the problem is composite  
character modifiers--additional "matras" we call them in Indic  
languages... small extra bits and pieces that are hooked onto regular  
characters... i.e. there is *nothing* Run rev can do to fix this...  
if the user has, unwittingly pulled Windows OpenType font onto his  
Mac, thinking that that is should work just fine. (As I myself have  
just done...)

Of course, Rev should render the font as other mac apps do... albeit  
with those extra matras ("Diacriticals") not being proper placed  
under ATSUI...

I'm off to FontLab to import and re-export some of these and see what  


On Sep 13, 2005, at 4:56 AM, Devin Asay wrote:

> Sivakatirswami,
> I have a suspicion that your Unicode problems are related to a  
> larger issue that affects unicode rendering in general. If you  
> haven't already, consider voting for Bugzilla bugs 2489, 2493,  
> 2497, 2998, 3022, 3023 and 3085. There may be others. The more  
> votes we get on these issues, the sooner they will get attention.
> Devin
> Devin Asay
> Humanities Technology and Research Support Center
> Brigham Young University
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