[XeTeX] misplaced diacritical marks

[Khaled Hosny]

On Tue, Aug 31, 2010 at 09:21:32AM -0400, Fr. Michael Gilmary wrote:
> David J. Perry wrote:
> 
> 
> >The following minimal example works for me (Windows, MiKTeX 2.7)
> >with marks correctly placed.  I happen to have the Unicode values
> >for the diacritics memorized, so I just typed them in, but you
> >could equally well paste the actual characters from BabelMap or
> >Character Viewer or whatever utility you have.
> 
> 
> This will work, as long as you have a font with the /combining/
> glyphs --- in this case: "combining dot below" and "combining
> macron", as Junicode does. But not all fonts have them. E.g., Minion
> Pro does not have both of those /combining/ glyphs --- but it /does/
> have a macron and a dot below. In which case, maybe the only way to
> obtain the desired result is the cumbersome definition posted
> yesterday (which comes from Juan Acevedo from XeTeX archives 25 Aug
> 2008 ... which he found on earlier posts by Musa Furber and Jonathan
> Kew from the archives of 11 Feb. 2005, I think).

In an ideal world, fonts should have proper GPOS anchors for positioning
arbitrary combining marks, and sometimes this is only way to get proper
output as there isn't a pre-composed form (and, as a matter of policy,
Unicode is not adding any new pre-composed forms), but almost all fonts
fail on that, fortunately TeX can still provide workarounds for that.

Regards,
 Khaled

-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer