[XeTeX] Minion Pro Sylistic Alternates in Win32 XeTeX

[Jonathan Kew]

On 21 Mar 2007, at 10:45 pm, Adam Twardoch wrote:

> Jonathan,
>
> this brings me to the question: does XeTeX offer a way to preserve
> kerning across text runs where a different OpenType Layout feature is
> activated?

Not currently.

> For example, if I choose to typeset arbitrary slash fractions
> by switching on the "numr" (numerators) feature to a run of digits,  
> then
> type a fraction bar and then another run of digits with the "dnom"
> (denominators) applied. When there are kerning pairs defined in the  
> font
> between the numerator glyphs and the fraction, or between the fraction
> and the denominator glyphs -- is there a way that those kerning pairs
> are correctly applied in XeTeX? A similar case would be if I choose to
> apply the "sups" (superscripts) or "sinf" (scientific inferiors)  
> feature
> to a set of letters that immediately follow some normal letters, and
> there are kerning pairs defined between the normal and the superscript
> or inferior glyphs. Another example would be if I typeset an
> all-uppercase headline and choose to apply the "swsh" (swash)  
> feature to
> one of the letters.
>
> What would be the best way to do it, if it is at all possible?

I can't think of a way to achieve this in today's XeTeX. Changing  
OpenType features requires a new \font definition at the TeX level,  
and there is no way for kerning (or other layout features) to be  
applied across a (logical) font change; this breaks the text run  
within which layout features occur.

Yes, this is a shortcoming; maybe it'll change one day. Suggested  
patches are welcome! :)

JK