[XeTeX] Microtypography?

Jonathan Kew jonathan_kew at sil.org
Sun May 14 22:44:48 CEST 2006

On 14 May 2006, at 8:02 pm, Geoffrey Alan Washburn wrote:

>> Before thinking of anything new, be sure to look closely at not only
>> Multiple Masters (which Adobe has largely abandoned)
> 	Yes, I've never worked with them, but some of my ideas are partly
> inspired about what I've read about them.
>> but also Apple's 'glyph variation' technology and other aspects
>> of AAT. There's a lot of cool stuff in there, at least in the
>> design and the low-level implementation, but it hasn't been
>> widely adopted either by font vendors or application developers.
> 	Is there a good reference you can point me to?

See Apple's TrueType reference manual, available at <http:// 
developer.apple.com/fonts/TTRefMan/>. Chapter 6 documents the actual  
table formats that control the variations (see 'fvar' and 'gvar', in  
particular). To make much sense of it, you probably need a fair  
understanding of the basic TrueType format, how glyph outlines are  
stored and rendered, etc. I think it's also helpful to have a grasp  
of the TrueType hinting mechanism, as there are some similarities  
between how the hinting language modifies outlines for grid-fitting  
and how the variation mechanism modifies them to change the style of  
the glyph.

Back in the System 7.x days of QuickDraw GX, Apple had a GUI tool  
called Mutator that could interactively create and edit glyph  
variations in a font; it was a bit temperamental but lots of fun to  
play with. Spending some time with Mutator and creating weight,  
width, or other variations in a font was a great way to get a better  
feel for how the technology actually behaved. I never came anywhere  
close to completing and shipping a font with variations, though--  
AFAIK, only a few were ever done (though some were really fun!), and  
only Skia is at all widespread. It might still be possible to run  
Mutator under Classic, with some system extension hackery.... been a  
while since I tried, though.

There may have been some background information in the Inside Mac:  
QuickDraw GX Typography book, too, but it's a long time since I  
looked at that. You can still find it among the "legacy technologies"  
documentation on Apple's site: <http://developer.apple.com/ 

Although I'm not aware of any current development of variation fonts,  
ATSUI (and CoreGraphics) support them, as you can see if you use Skia  
in XeTeX and vary the weight and width settings; or you can play with  
it interactively in Intaglio (from <http://www.purgatorydesign.com/ 
 >), and maybe a few other apps. (Do Pages and Keynote support  
variations, anyone? I don't have iWork so can't check on them.)

> 	I should probably actually look at some of the material on Graphite.

Might also be interesting, though Graphite does not at present have  
any features at all comparable to Multi Masters or AAT Variations.


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