[XeTeX] Macro for kerning adjustment

[Jonathan Kew]

On 7 Mar 2008, at 4:46 pm, Sven Siegmund wrote:

> Hello,
>
> I have to write phonetic transcriptions which involve nasalized glide
> [w]. So I have to have a sequence of e.g. [auwa] where all the letters
> have a tilde for nasalization above them.
>
> There are single unicode characters for a, e, i, o, u, y with tilde,
> so I use them. However, a w with tilde above is afaik not defined in
> unicode 5.0.

(Nor will it be in any future version of Unicode.)

> The solution is to write "w" followed by the U+0303
> COMBINING TILDE.

Yes, that is the standard way to represent it.

> I use Gentium font and with Gentium this renders as a
> w with a tilde which is far too right above.

Because Gentium does not (currently) have OpenType code to position  
diacritics nicely. (This should be supported in a future release of  
the font.)

> So I adjusted the kerning
> manually by "\kern-0.085em{}" My sequence of nasalized [auwa] has now
> the source code of:
>
> [ãũw\kern-0.085em{}̃\kern+0.085em{}ã]
> (you can hardly see the combining tilde because it combines with "}")
> So there is \kern-0.085em between w and combining tilde and a  
> corresponding
> ̃\kern+0.085em{} between the combining tilde and ã to make them  
> again
> properly kerned.
>
> This works ok for me, but I don't want to do this manually. I will
> have to write the nasalized w a plenty of times and would like to know
> how can I set xelatex up in a way it automatically will kern the
> sequence w + combining tilde like this (and therafter switch to normal
> kerning again)

Are you strongly committed to using Gentium? The simplest solution at  
this point would be to use a font (such as Charis SIL) that has  
diacritic positioning support. (If you're on a recent Windows system,  
I think this is supported by Microsoft's core fonts, too.)

JK