[luatex] Vital RTL issues in LuaTeX

Khaled Hosny khaledhosny at eglug.org
Fri Apr 10 13:51:32 CEST 2009

On Fri, Apr 10, 2009 at 01:27:57PM +0200, Yannis Haralambous wrote:
> Le 10 avr. 09 à 13:12, Khaled Hosny a écrit :
>> This has to be handled at a higher level, the engine don't know about
>> the directionality of individual characters, so you need to put  
>> numbers
>> inside {\textdir TRT } or write lua code that applies bidirectional
>> algorithm at node level.
> The engine knows about the directionality of each character since it is a 
> Unicode property on the character level, that's the whole idea of the 
> bidi algorithm.

I meant the current engine, which don't even have a Unicode character
property database. If it had to implement bidi algorithm, then it had to
implement Indic reordering, Thai line breaking, etc. I believe that the
whole point of having and embedded scripting language and opening up the
engine was to allow extending the engine using lua code, and not to hack
the engine except for the bare minimum requirement.


 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer
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