[XeTeX] Small Caps?

[Jonathan Kew]

There are actually two different things you'll want to look into: 
"features" and "variations".

Features (and feature settings) are the more common. Essentially these 
are options that cause substitution (globally or contextually) of 
certain glyphs for others. So things like small caps, word-final 
swashes, archaic forms, flourishes, ligatures, etc., are all examples 
of font features.

You can see the feature and setting names supported by a font using the 
Font panel (e.g., in TextEdit -- or even in TeXShop -- though it's not 
immediately obvious. You need to make the panel wide enough for the 
"Collections" column to appear, along with the additional controls 
underneath it. Press on the "gear" icon and you'll get a popup menu 
allowing you to access the Typography panel. This shows you (and lets 
you change) the feature settings (if any) of the current font.

Variations (in AAT terminology) are a different thing: this refers to 
fonts like Skia (there aren't many others) where the outlines of the 
individual glyphs can be varied along one or more "axes of variation" 
such as weight, width, optical size, or others. The standard Fonts 
panel doesn't seem to offer any way to access variations. If you 
install the developer tools, you can run WorldText (installed into 
/Developer/Applications/Utilities/Built Examples/), which has an 
extended Typography palette (still accessed through the "secret" 
control in the Fonts panel) that also shows Variations -- though it 
doesn't give you any clue as to the actual numeric values to use.

I believe that if you have Type 1 Multiple Master fonts such as Minion 
installed, you can use the variation syntax in XeTeX to control these, 
too; e.g.,
	\font\myfont="MinionMM Italic:weight=200;optical size=9" at 9pt
or something like that (not sure of the naming, I don't have it here on 
my PowerBook).

Clearly, all this is more than a little untidy. Apple needs to do some 
work to make font  variations accessible in OS X applications in 
general, and as for hiding the Typography palette behind a "magic" 
control in the Fonts panel, that many users may never discover.... 
well, what were they thinking? Don't they want people to use any of 
this neat stuff?

Meanwhile, I've considered a couple of things. The old TeXGX 
application, pre-OS X, had a "Font Information" window that listed the 
supported feature settings and variations for any selected font, so 
that users could tell what would work in a \font command. It would be 
fairly straightforward, I think, to build a little utility for OS X 
that could display similar details.

Another possibility would be to add some kind of \XeTeXfontinformation 
extension to XeTeX processor itself, so that a TeX document could 
explore the available options for a given font. This seems attractive 
as a route to implementing flexible documents that take advantage of 
whatever features are available. However, I'm not sure it's really 
quite as useful as it first seems, because of the open-ended and highly 
font-specific nature of feature names. There are too many possible ways 
a font designer might choose to name any particular feature, and I 
suspect that hand-crafted, font-specific tables of some kind will be 
the only realistic way to support these things.

Jonathan

On 24 Apr 2004, at 10:00 am, Bruno Voisin wrote:

>> Can anyone comment on the feasibility of creating a macro for
>> use with XeTeX to provide faked small caps (i.e. real capitals
>> would be rendered at full size in the current font and lower case
>> letters would be rendered as capitals in a slightly smaller size)?  
>> How
>> would one go about this?
>
> That prompts actually another question: how is it possible to know the
> different "variations" available for a given font, such as the
> "variations" used in FontSample.tex?
> I wondered about this when trying to build a XeLaTeX logo using a small
> caps "a". I tried naively, for Lucida Grande, to invoke "Lucida
> Grande:Letter Case=Small Caps", with no luck. I remember Jonathan 
> telling
> there is no unified naming scheme, for example some fonts may use 
> "Letter
> Case= Caps and Small Caps" instead, etc. I imagine this implies, for
> example, that for some fonts small caps are even not available at all.
> Unfortunately Apple's font pane does not list these "variations". I
> started to browse through the typography section of Apple's 
> documentation
> site, but gave up after a couple of minutes. Not being a developer, as
> soon as classes NSSomething are mentioned I get lost...
> Bruno
>
>
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