[XeTeX] Multiple Master Fonts

[Jonathan Kew]

On 31 Mar 2005, at 12:52 am, Jonathan Nicholl wrote:

>> No. There won't be any OpenType Layout tables in LWFN-packaged fonts, 
>> they'd have to be repackaged as OTF/CFF in order to add those.
>>
>> And if there were GSUB/GPOS tables, and you load them in XeTeX using 
>> the ICU engine to get OT layout support, then you wouldn't have 
>> access to the MM axes, as that's provided through ATSUI.
>>
>> Sorry... you can't have both!
>
> This probably shows my ignorance of font technology: is it possible to 
> convert an Adobe MM font to the same format as Skia? That is a 
> multiple master font and it has exciting GSUB-like tables. Or are the 
> mechanisms for interpolation fundamentally different?

Skia isn't MM, it's an AAT variation font. Yes, it's a fundamentally 
different technology. Instead of interpolating between defined 
extremes, it extrapolates (in a controlled fashion) from a defined 
central point. But that's unimportant; ATSUI makes the AAT variation 
and Type 1 MM technologies work the same, as far as an application is 
concerned.

However, the "GSUB-like tables" are AAT tables, not OT layout tables; 
hence, they're recognized and processed by ATSUI, not by the ICU layout 
engine.

If you could repackage the LWFN MM fonts as Type 1 sfnts (like the 
T1Wrap tool does for .pfbs), and if you could then add AAT tables for 
the behaviors like small caps, swashes, ligatures, etc., then I expect 
it would all work. But (a) there are probably only a handful of people 
with a grasp of the various technologies and tools it would take to 
achieve this; and (b) chances are that the font licenses would prohibit 
it anyway.

> I'm sure that Jonathan is right: ATSUI support for Adobe MM fonts will 
> one day disappear. I still think that MM fonts are worth considering, 
> however. Remember that with command line tools like mmpfb  (from 
> http://www.lcdf.org/~eddietwo/type/) you can generate a perfectly 
> normal Type 1 font of any weight/width/optical size combination that 
> the font allows. In fact I never expected to use my MM fonts through 
> something like ATSUI. I wanted them for use with pdftex. I've got a 
> couple of folders with a very large number of generated font 
> instances. They weren't that much of a pain to generate (compared with 
> the usual hassle of installing fonts for use in TeX!) And they enable 
> very nice output.

Yes, you can do that. But you don't end up with all the nice OpenType 
features in your instances, so you still have to use all those legacy 
hacking methods to get at the "expert" stuff that OpenType could 
support automatically.

That's no reason not to use them, of course, if they give you the 
output you need; I just don't think it's a technology worth investing 
much time and effort in, as Adobe doesn't seem to think it has a 
future.

JK