Re: AFM font handling corrected?

[Mats Bengtsson]

OK, I checked the Adobe Font Metrics File Format Specification
document (available at http://www.wotsit.org, for example) and
found the following statement:

====================================================================
3.2 Units of Measurement

All measurements in AFM, AMFM, and ACF M fi les are given in terms
of units equal to 1/1000 of the scale factor (point size) of the font
being used. To compute actual sizes in a document (in points; with
72 points = 1 inch), these amounts should be multiplied by
( scale factor of font ) / 1000.
==========================================================================

As far as I can understand, this means that the values should be
multiplied by 10/1000 for cmr10, right? Note that the definition
of point here is different from what TeX uses 1 inch = 72.27pt,
but that should only make a minor difference.

cmr10.afm and other AFM files can be found at CTAN in /fonts/cm/afm/.

I tried to quickly browse through the source code of afm2tfm that's
included in teTeX, but couldn't find the relevant parts.

   /Mats

Rune Zedeler wrote:
> Han-Wen Nienhuys wrote:
>
> > IIRC the 1000 in an AFM is relative to either the design size or the
> > baselineskip of the font. Isn't an em 10pt in cmr10? 
>
>
> I tried to (dirtily) hack afm.cc to multiply the sizes by 10 if the font 
> is CMR10.
> It does not give exactly the same results with and without the afm-file.
> Unfortunately I made a test file which produces bad results no matter if 
> the cmr afm-files are there or not. The result is worse with the 
> afm-files, but it is also wrong without them :-(
>
> \score {
>     \notes <
>     \context Staff \notes { c d e f g a b c' c d e f }
>     \context Lyrics \lyrics { this is a loooooooooooooooooooooooooong 
> test aaaa }
>     >
> }
>
>
> the long word overlaps the next word.
> Without the afm-files (i.e. on a tetex-system) it is approx "ng" that 
> overlaps, where as with the afm-files, "oong" overlaps.
> Can anybody else reproduce this bug?
>
> The bug is also there in 1.6, so 1.8 is not in danger :-)
>
> The font-metrics code really needs an intense look.
>
> -Rune

--
=============================================
        Mats Bengtsson
        Signal Processing
        Signals, Sensors and Systems
        Royal Institute of Technology
        SE-100 44  STOCKHOLM
        Sweden
        Phone: (+46) 8 790 8463                         
        Fax:   (+46) 8 790 7260
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