[XeTeX] Microtypography?

[Jonathan Kew]

On 11 May 2006, at 3:34 pm, Will Robertson wrote:

>>> and *fairly* sure that OpenType can do it
>>> as well.
>>
>> I don't recall seeing this in the OpenType spec, but I'm less
>> familiar with that.
>
> Took me a second to find it: feature 'opbd' "Optical bounds":
>    <http://www.microsoft.com/typography/otspec/features_ko.htm#opbd>

Aha, thanks! Seen any fonts that provide this, though? I haven't --  
not even the Adobe Pro fonts I've got.

>> Actually, when working with ATSUI on OS X, XeTeX uses a hybrid of TeX
>> and ATSUI justification.
>
> Yes, I've seen this and been quite upset with it :(
> I don't suppose there's a way to turn it off?

Sorry, not at present; you get XeTeX's best attempt at providing  
whatever the AAT font designer specified. (Hey, font designers are  
supposed to be good at this kind of typographic detail!) But I can  
imagine that you might like an option to turn it off at times.

> Anyway, I'm surprised that the the combination of XeTeX and ATSUI
> works for beginning-of-line and end-of-line interactions -- I thought
> the contextuals in this area (Hoefler Text Italics' swashes, for
> example) were fairly broken at this stage and assumed that margin
> kerning would be similarly non-functional.

I think it would be at least somewhat functional if the AAT 'opbd'  
table were present, but I don't have any such font and so it's not  
something I've paid any real attention to.

Some day I'd like to do a more thorough job of all the line-boundary  
stuff; I have some ideas how it could be done, but it'll take some  
work and there's potentially a performance hit for taking those extra  
variables into account. Mostly, though, it just hasn't been top  
priority because it's not needed for most "normal" text setting.

JK