Re: Making necessary OpenType features on by default

["Idris Samawi Hamid ادريس سماوي حامد" <ishamid@colostate.edu>]

On Sun, 22 Feb 2009 13:54:51 -0700, Khaled Hosny <khaledhosny@eglug.org>  
wrote:

>>> http://www.microsoft.com/typography/otfntdev/arabicot/features.htm
>>>
>>> :-)
>>
>> watch the "The standard order for applying Arabic features encoded in
>> OpenType fonts" ... an earlier mkiv otf handler did this but then we
>> found out that it violates the otf 'any order possible' rule so now we
>> do just the order as we encounter it (and even then it took us a while
>> to figure out where/how to avoid interferences); so ... it's up to the
>> font designer (or technician)
>
> IIRC, the 'ccmp' should be applied before any other lookup, the rest are
> applied as they are ordered in the font, at least this makes sense more.

It is not the order of the features, but the order of the lookups that  
really counts here. So, more precisely, the lookups in ccmp should be  
defined in the font before all other lookups.

See also

http://www.microsoft.com/typography/otfntdev/arabicot/shaping.htm
http://www.microsoft.com/typography/otfntdev/arabicot/default.htm

>> now, having init, medi, fina, isol, rlig enabled might be the default,
>> but for instance arabtype output looks much better when instead of rlig
>> we use calt/clig etc so, in that case the defaults would bot be the best
>> choice; again an argument for a database approach
>
> Arabic Typesetting is a quit a special case font, though I believe that
> 'calt' and 'clig' should be on by default for any font.

That's just it, there are so many exceptional cases it's not trivial to  
define a rule. Again, Scheherazade seems appropriate as a place to  
start... I will try to find some time in the next month to work on this,  
or someone can start and Hans and I can complete the module.

>> there are even fonts out there that have the right gsub/gpos info but
>> lack the feature being listed in the script/lang dictionary which is
>> complicating live even more; maybe we should assume that the renderers
>> of ms and adobe have some additional built in heuristics of using
>> specific fonts
>
> Any links to such fonts? Looks interesting.

Hans may be referring to hybrids like Traditional Arabic....

Best wishes
Idris

-- 
Professor Idris Samawi Hamid, Editor-in-Chief
International Journal of Shi`i Studies
Department of Philosophy
Colorado State University
Fort Collins, CO 80523
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : https://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________