[XeTeX] Adobe Kepler Std: Extraneous space always inserted between left paren and f

John Was john.was at ntlworld.com
Sun Feb 21 13:17:11 CET 2010

Hello again

It was Khaled  Hosny who informed the list of this possibility in LuaTeX 
(which can also, it seems, handle Unicode input - I have never tried it). 
He wrote on 9 Nov. 2009:

Again, LuaTeX can actually do this, you can have a font feature file
(.fea) that, among other things, can define custom kerning table.

I did call up LuaTeX's online help and the .fea file seemed easy enough to 
create, at least for something as simple as kerning pairs.  However, for 
various reasons I want to stick with (plain) XeTeX.  I think most users 
notice slight blemishes in the kerning between certain recurrent pairs 
(which may only be recurrent because in their specialism they require some 
unusual combinations of characters), and the ability to fix it in an 
external file would enhance the appearance without getting involved in 
possibly illegal editing of the font itself.  An additional advantage would 
be that if the font manufacturer produces an improved version with (some of) 
the blemishes removed, one could then delete or amend the custom kerning 
table accordingly.

Incidentally, for the overtight apostrophe/closing quote in Adobe's Minion 
Pro I use:


\def’{\leavevmode \kern 1sp \hbox{'}}


\def”{\leavevmode \kern 1sp \hbox{''}}

(Of course, I have mapping=tex-text in the font call.) The tiny \kern 1sp 
seems enough to disable what must be mistaken instructions in Minion Pro's 
kerning tables.  But I don't think one could make ( or ) active as there are 
too many macros and packages that are likely to use these characters. 
(Might be worth a quick try though!)



----- Original Message ----- 
From: "Arno Trautmann" <arno.trautmann at gmx.de>
To: "Unicode-based TeX for Mac OS X and other platforms" <xetex at tug.org>
Sent: Sunday, February 21, 2010 12:44 PM
Subject: Re: [XeTeX] Adobe Kepler Std: Extraneous space always inserted 
between left paren and f

On 02/21/2010 09:55 AM, John Was wrote:
> Hello
> I strongly suspect it's in the kerning table of the font since Adobe's
> Minion Pro exhibits this to a small extent also (the visual effect isn't
> as much as a full space, but the parentheses are definitely too far from
> the adjacent character).  Perhaps something of a blindspot in whoever
> sets up the kerinng of Adobe's font (in Minion the spacing round the
> apostrophe is another flaw, rather worse than the parenthesis issue).
> In view of the fact that one isn't supposed to tinker with these
> commercial fonts, I've several times asked if one might have a custom
> ligature option in XeTeX that could be included in the font calls, so
> that just as one can say 'mapping=tex-text' one could say e.g.
> 'kerns=kernfile.KRN', the .KRN file containing any extra tweaks to the
> kerning that one cares to add, so that the font itself is left
> untouched.  This is possible in at least one implementation of TeX, but
> not (yet) in XeTeX - I think a few people at least said in the earlier
> thread that they would find it useful but I guess it hasn't been seen as
> a high priority.

Well, I’d really like that feature! I didn’t know that was possible at
all. What implementation are you talking about?

>  It is a nuisance, though, as you say, if an otherwise
> attractive font becomes unusable.

Yes, indeed. Maybe you could tweak the problem using the
XeTeXinterchartok mechanism. That would not be a very elaborate
solution, but it should work.


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