[XeTeX] OpenType and Character variants

[Jonathan Kew]

On 17/7/12 12:58, Lorna Priest wrote:
> Can someone give me the proper incantation to access Character variants
> (cv01, cv44, etc)? (I'm not using fontspec, just XeTeX) .
>
> Currently, I have:
>
> \def\testSS#1{
>
> \font\x="#1" at 14pt \x
>
> This shows the font “#1”. \SStext\par}
>
>
> \def\testCV#1{
>
> \font\x="#1" at 21pt \x
>
> This shows the font “#1”. \CVtext\par}
>
>
> \def\SStext{Flying Dogstarman}
>
> \def\CVtext{\beginR ممم م ݦݦݦ ݦ ݥݥݥ ݥ م ممم\endR}
>
>
> \testSS{Gabriola:+ss06}
>
> \testCV{Scheherazade:script=arab:+cv44=1}
>
>
> The Stylistic Sets in Gabriola are displaying properly. We've added
> Character Variants (as cvxx) to Scheherazade and are trying to test them
> in XeTeX (they do work in the new version of Firefox so I'm sure they
> are implemented correctly, I just can't figure out what to type to get
> them in XeTeX.
>
> I've tried "+cv44", "+cv44=0", "+cv44=1", "+cv44,1" and none of those
> work. What am I missing?
>

Hi Lorna,

Sorry, it won't work: the opentype engine in xetex doesn't support 
enabling/disabling additional features in conjunction with 
complex-script shaping; that's only supported in the "generic" shaper 
used for Latin and other simple scripts.

Language-specific forms (e.g. separate 'locl' features under different 
opentype language systems) should work with complex scripts, so that's 
one approach that allows some support for variants, but you can't access 
cvXX or ssXX features there.

The best chance of fixing this will be if xetex is updated some day to 
use the new harfbuzz engine, but there's no immediate prospect of that, 
I'm afraid.

JK