[XeTeX] XETEX cannot access OpenType features in PUA?

[Peter Baker]

Aleks,

I don't have a solution to your problem, but thought I'd write in to say 
that I grabbed the font, opened it in FontForge and tested to make sure 
the OpenType features seemed to be working correctly there (they were). 
Then tried out your test file: saw the same problem you describe. I 
don't know what the problem is, but I don't think it has to do with the 
PUA or with putting a mark over an unencoded glyph: I've done that 
plenty of times in my fonts, and have had no problem.

So this is just by way of saying that I can confirm the problem, but it 
seems to me a real mystery.

Peter

On 11/25/2011 11:41 PM, Aleksandr Andreev wrote:
> Hello folks,
>
> I'm working on an implementation of a font for Znamenny Neumatic
> Notation in Unicode (see here:
> http://en.wikipedia.org/wiki/Znamenny_chant)
>
> Without getting too much into the details, I'll just state that the
> notation includes base characters (neumes) and diacritics (red marks
> or black marks). Sometimes, the neume may also change its shape, and
> this is controlled via control characters in the proposed standard.
>
> As the standard has yet to be proposed to Unicode, in the font the
> glyphs are currently mapped to the Private Use Area. For the
> implementation, the font makes heavy use of OpenType technology. In
> particular, anchor points define the positions of red marks and black
> marks over the neumes. The functions of control characters are handled
> via a Ligature Substitution.
>
> Now I'm writing up documentation for this standard in XeTeX.
>
> But, it appears that XeTeX is unable to handle these features. For
> example, consider this snippet:
>
> \documentclass[12pt,a4paper]{article}
> \usepackage{color}
> \usepackage{xunicode}
> \usepackage{xltxtra}
> \usepackage{fontspec}
> \defaultfontfeatures{Mapping=tex-text}
>
> \newfontfamily{\moo}{MezenetsUnicode}
>
> \begin{document}
>
> {\moo \color{red}{}}
>
> \end{document}
>
> The control character  is supposed to modify the neume   (sort of
> like a variation selector). Then, the diacritic  is supposed to be
> placed in accordance to the appropriate anchor point defined in the
> font.
>
> (None of these symbols will mean anything to you as you don't have the
> MezenetsUnicode font that I've designed. You can download it here if
> you wish to experiment:  http://www.ponomar.net/files/mezen_uni.ttf
>
> Please do not distribute this font -- it is only pre-beta software.)
>
> Instead, I see the neume, a box for the control character, and
> diacritic floating over nothing.
>
> The font is OK, as the same characters in Pango and FIrefox produce
> the desired results, so there is something wrong with the way XeTeX
> handles GSUB and GPOS in the PUA. Is this a bug?
>
> I'm running xelatex version 3.1415926-2.2-0.9995.2 on Ubuntu 11.10.
>
> Thanks for any insights,
>
> Aleks
>
>
>
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