bug in fontinst 1.801: duplicated kernings (was: ae fonts Q)

Bernd Raichle raichle@Informatik.Uni-Stuttgart.DE
Tue, 29 Sep 1998 14:28:11 +0200 (MET DST)

On Tue, 29 September 1998 13:01:29 +0100,
Lars Hellström <Lars.Hellstrom@math.umu.se> writes:
 > Alan Jeffrey wrote:
 > >I thought of doing this the first time around (have a \setkern and a
 > >\resetkern) but decided against it on grounds of running time: perhaps I
 > >was wrong...  or perhaps I'm misremembering.  Do you have an idea of
 > >whether there's a run-time cost associated with your fix?
 > The basic idea behind my fix is to change the routines under \etxtovpl that
 > writes kerning and ligature instructions to the VPL file so that they write
 > at most one kerning or ligature instruction for each pair of characters,
 > namely the one which would end up first in the VPL file.

Can you please keep it in such a way, that at most one kerning
instruction and at most one ligature instruction for each pair of
characters will be possible?  I.e., it will be still possible to have
one kern _and_ one ligature instruction for the same glyph pair?

Reason: This ``feature'' will be needed in the future.  Currently I'm
implementing a replacement of TeX's internal ligature and kerning
routines for the next e-TeX version.  The new ligature/kerning builder
is able to first create ligatures (ignoring all kerning instructions
in the font's lig/kern table) and then insert appropriate kerning
between the resulting char resp. ligature nodes (ignoring all ligature
instructions).  As one positive side effect of the new routines this
will allow you to insert kerning between two ligatures which is
currently not possible with TeX.  Another feature of the new
implementation will be the possibility to cleanly prevent the creation
of a ligature even if the ligature is declared in the font's lig/kern
table but in this case it will sometimes be necessary to add kerning
between the two glyphs.  Thus the ability to have a kerning _and_ a
ligature instruction for a glyph pair should be kept.


Bernd Raichle                                  "Le langage est source
Autor des `german.sty' (aktuell: v2.5e)         de malentendus"
					       (A. de Saint-Exupery)