[XeTeX] strande behavior of Linux Libertine fonts with optio Fractions=On

[mskala at ansuz.sooke.bc.ca]

On Thu, 13 Jan 2011, Fr. Michael Gilmary wrote:
> >   I couldn't find the source code for the OpenType features
> > in Latin Modern Roman;

> Voilà!
>
> > > > otfinfo -f lmroman10-regular.otf

I'd been hoping for the source code as such - i.e. the *.fea files.
Looking at the substitution tables after they're compiled into the *.otf
files can be difficult with a complicated feature like arbitrary-length
fractions; the table format isn't designed to be human-readable.

Nonetheless, I did take a look at the tables for Latin Modern Roman in
FontForge, and it appears to me that it's just substituting precomposed
glyphs - so that "one fraction two" will become "onehalf" and so on, but
it won't work on arbitrary fractions with a large number of digits.  I
haven't dug into Junicode myself, but Alexey Kryukov's posting suggests
that that's how Junicode does it as well.  The problem is in the
interaction between arbitrary-length fractions and digit sequences that
are not fractions:  I don't think it's possible to support
arbitrary-length fractions and also leave non-fraction digit sequences
untouched.
-- 
Matthew Skala
mskala at ansuz.sooke.bc.ca                 People before principles.
http://ansuz.sooke.bc.ca/