[email protected] skrev:
On Sat 22nd May, 2010 at 00:11, [email protected] seems to have written:
On Fri 21st May, 2010 at 17:59, Lars Hellström seems to have written:
Dr. Clea F. Rees skrev:
I am trying to update CFRLatinModern for version 2.004 of Latin Modern
(included in TL 2009 which I recently updated to). While I'm at it, I
was hoping to resolve some of the issues which I or others raised about
the earlier version of the package. (The aim of the package is to make
various features of the fonts, especially different styles of figures,
easily accessible in LaTeX.)
The following is bugging me a lot: when using the small-caps version of
the font, accent placement for characters which must be created "on
the fly" are wrong. Not only are the accents too low for the small-caps
themselves, they are too low for the capital letters as well. So if I'm
using T1 encoding, \^A is fine but \^W and \^Y are not; similarly for
\^a versus \^w and \^y.
I don't expect these characters to look great because TeX is creating
them on the fly, but my package creates output markedly worse than that
produced by using lmodern itself and I cannot figure out why. The
accents are placed much lower so they run into the letter below.
This isn't a problem for the non-small-caps variants of the fonts - the
output produced by my package doesn't look any worse than that output
by lmodern for these characters.
I did notice that fontdimen 10 and 12 differ in lmr10.afm and
Numbered fontdimens in AFMs? News to me, unless you mean AFM keywords
corresponding to acccapheight and maxheight.
Probably I'm explaining badly. There are a bunch of lines starting:
Comment TFM fontdimen <number>: <number> (text)
OK, that was news to me, and your explanation is reasonably clear.
lmcsc10.afm. These are both smaller in the case of lmcsc10.afm which
seems odd. But I'm assuming this is just my ignorance since lmodern is
obviously based on these dimensions and everything works fine there.
One fontdimen that is likely to be important is xheight (fontdimen
5), as TeX's \accent primitive assumes the accent character specified
is in the proper position for a glyph with \height{}=xheight. If for
example the smallcaps xheight is larger than the regular xheight, but
you're using the regular accent in the smallcaps font, then you would
get the effect that it is placed too low.
grep XHeight lmr10.afm lmcsc10.afm gives:
lmr10.afm:XHeight 430.55556
lmcsc10.afm:XHeight 513.88889
grep xheight lmr10.afm lmcsc10.afm gives:
lmr10.afm:Comment TFM fontdimen 5: 4.3055 (xheight)
lmcsc10.afm:Comment TFM fontdimen 5: 4.3055 (xheight)
So would fontinst be using the first or the second?
Fontinst uses the first, i.e., the xheight that the AFM file formally
states. AFM Comment's are just ignored.
This difference is probably the root of your problems; with a larger
xheight in lmcsc than in lmr, TeX thinks it needs to raise the accent
less in the former than in the latter.
Regarding fontdimen 12 (which I think is "max height" based on the
It is in T1-encoded fonts (and several other newer text font
encodings). Math fonts may require it to be something else.
afm), the dimension is smaller in lmcsc10.afm than in lmr10.afm but
larger in ec-lmcsc10.tfm than in ec-lmr10.tfm:
lmr10.afm:Comment TFM fontdimen 12: 11.27 (non-standard: max
height)
lmcsc10.afm:Comment TFM fontdimen 12: 11 (non-standard: max
height)
ec-lmr10.tfm: (PARAMETER D 12 R 0.932001)
ec-lmcsc10.tfm: (PARAMETER D 12 R 0.933001)
Are those TFMs which come with the latin modern fonts? Curious, in that
case, that they have two different values.
On the other hand, when I use fontinst to generate tfms, I end up with
this dimension being larger for lmr10 than lmcsc10:
clmr8t10.pl: (PARAMETER D 12 R 1.127)
clmcsc8t10.pl: (PARAMETER D 12 R 1.1)
That's the same as in the AFM lines you quote, so it looks as though
you at least have these right.
A remark on the varying magnitudes of these numbers: PLs and TFMs tend
to take 1 length unit as equal to the font size. AFMs, and fontinst
internally, use 1000 length units equal to the font size. The AFM
comments quoted seem to use pt as length unit, which for a 10pt font
means 10 length units is equal to the font size.
All of which leaves me suspecting that I really don't understand even
the bits of this I previously thought I did understand. The
relationship between the afms and tfms when I generate the tfms using
fontinst makes sense to me, but how do the dimensions end up not only
differing in the tfms included with Latin Modern but actually reversing
relationships such as "greater than" and "less than"?!
>
I assumed that the tfms provided in Latin Modern would be derived from
the afms but now I'm wondering if that's so...
One would expect that they are at least generated from the same source,
but the fact that the AFMs contain hints about what would be good TFM
fontdimens, which the TFMs don't seem to care about, indicates there is
something odd about the toolchain producing these files.
Any idea about what tool produced the AFMs? I can imagine e.g.
Fontforge being "smart" enough to know about TeX fontdimens and trying
to compute proper values for them, whereas I think the lmodern fonts
were generated using a MetaPost-based tool that may well have a
separate TFM-generation capability. In that case, the TFMs may actually
be closer to the designers' intentions.
Lars Hellström
