Re: [NTG-context] Small caps problem/bug with some fonts

19 Sep 2009

      Barry Schwartz wrote:
...
Hans Hagen  skribis:
...
but even then, if a font is not clear about issues, then one can get 
unwanted side effects (the frac feature for instance is often quite 
bugged and can only be applied selectively)
Yeah, I think trying to be fancy with contextual substitutions is a
bit like getting drunk. I'm not even sure why there was a "frac" tag
when it was originally intended to be converted to "numr" and "dnom"
tags.
(I just looked at
http://www.microsoft.com/typography/otspec160/features_fj.htm#frac
to see what it says nowadays and now want to go get drunk.)
actually the frac featurs, like most features is a rather generic one 
and as such it should work out of the box (some of the justitication 
features use gpos and/or assume specific renderer support, and some of 
that is rather undefined)

so, its not that frac itself is the problem dealing with in the engine, 
because if so, many features would be a problem, it's just that font 
makers stick to a couple of simple rules like:

(1) replace all
       <digits> <slash> <digits>
     by
       <sup digits> <overlapping frac slash> <sub digits>

(1) replace all
       <digits> <slash> <digits>
     by
       <sup digits> <overlapping frac slash> <sub digits>

and if they have rule 2, it will mess up things like a/b

of course it can be properly dealt with ... just make proper rules

now, one reason that metafont kind of design tools never were accepted 
as basic tool for font design is that designers are no programmers; and 
one needs programmers (or at least some of the related mindset) to make 
the more complex ot fonts (or one needs teams)

actually, as many fonts do have the sup/sub digits its rather trivial to 
provide proper frac's in mkiv but till now i had no reason (time, 
project, etc) for doing it

i fear the moment when designers start giving me rules like "use this or 
that font and turn on those features" assuming dtp like control and 
tweaking of the text (one reason for spending much time on fonts in mkiv 
is that it will give me control over bad behaving fonts; think of wrong 
glyph to unicode mapping and such)

Hans

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