[XeTeX] new use of alternate glyphs and how to turn them off

[Khaled Hosny]

On Sat, Oct 16, 2010 at 09:46:58PM +0100, Jonathan Kew wrote:
> On 16 Oct 2010, at 21:17, Fr. Michael Gilmary wrote:
> 
> > Hi Everyone:
> > 
> > I've noticed that since installing MacTeX2010, some alternate glyphs are selected without my permission! They're lovely, to be sure, but it's really a control issue for me ....
> > 
> > Is this a new feature of fontspec? or ?
> > 
> > Here's the example from a document compiled some time ago (June of 09 ... which was TL08) and you'll see the difference with the capital Q.
> > 
> > I haven't noticed any other changes. This is loaded with:
> > 
> > \defaultfontfeatures{Mapping=tex-text}
> > \setmainfont[Numbers={Proportional,OldStyle}]{Garamond Premier Pro}
> > 
> > The Q alternate only has a GID and no unicode point.
> > 
> > otfinfo -v GaramondPremrPro.otf
> > Version 2.000;PS 2.000;hotconv 1.0.50;makeotf.lib2.0.16970
> > 
> 
> The swash Q (which seems to be used only when it is followed by 'u') is a "contextual alternate" in Garamond Premier Pro. This feature is supposed to be active by default, according to the OpenType spec (see <http://www.microsoft.com/typography/otspec/features_ae.htm#calt>), but was not enabled in the older version of xetex.

I thought 'calt' is not on by default for Latin script, per the other MS
page:
http://www.microsoft.com/typography/otfntdev/standot/features.aspx

I have always been confused what to believe; the recommendations of
individual features (like the one you cited) or the script specific
pages like this one, but the little research that I did was more in the
side of script specific pages.

Regards,
 Khaled

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