Re: Arabic with LuaTeX vs. XeTeX

[Hans Hagen <pragma@wxs.nl>]

Idris Samawi Hamid wrote:

> But at this stage of development, only pure OpenType fonts will be  
> supported out of the box. For example: Traditional Arabic, which comes  
> with XP, has OpenType tables but depends on Uniscribe instead of OpenType  
> for, eg, making marks exceptions to the contextual analysis. Since the  
> mark exception was not added to the GSUB table, voweled text appears  
> unjoined in Trad. Arabic processed by luaTeX.

one problem there is that the open type spec is not always clear which 
in turn can mean that apps do things different or maybe even know how to 
deal with certain fonts; another problem is that there is no prescribed 
behaviour ... ok, some dtp app can claim that version n+3 supports this 
or that feature, or adapts automatically to this or that situations but 
if that's then the 'standard' there is no reason why version n+1 should 
not have supported it (or should have been tagged as bugged)

> I suppose we (=Hans) could add some "spell-checking" to the otf analyzer,  
> but that's dangerous and needs some careful thought. Maybe we can come up  
> with various "spell-checking" options that could be turned on and off, so  
> that old-technology (Nadeem is 1998), platform-dependent (like Nadeem and  
> Trad. Ar.) fonts can be used.

we can add all kind of checking and compensation and make them pseudo 
features and then have them enabled based on info that we keep in a font 
database (like .. this font lacks this or that and therefore we need to 
enable such or so; of this feature in font foo is bugged so we disable it)

> In any case, we want to stay as platform-independent as possible. So for  
> AAT, we may need to wait at least till someone (maybe one of you?) can  
> come up with a spec so that we can implement a cross-platform solution for  
> AAT.

Hans

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