[XeTeX] OpenType Math kerning (cut-ins)

[Jonathan Kew]

On 28 Oct 2009, at 09:43, Joel C. Salomon wrote:

> Consider the attached files (requires a recent version of
> unicode-math).  There does not seem to be any kerning of f_k, even in
> Cambria Math where it's most obviously needed.
>
> I recall from Rhatigan's TUG 2008 presentation "Three typefaces for
> mathematics" (based on his thesis; see
> <http://ultrasparky.org/school/pdf/DanielRhatigan_Dissertation.pdf>,
> pp. 36–37) that OpenType Math fonts have somewhat complicated  
> kerning
> (cut-ins) for super-/sub-scripts.  Is support for these implemented in
> XɘTeX?

Not at the moment. I think this would require some kind of extension  
to TeX's model for positioning the super- and subscripts. Currently,  
XeTeX just attempts to use the OpenType font within the existing TeX  
math-layout model, which is somewhat more limited.

The Cambria example does look bad, though; it would be nice to improve  
this.

JK