Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!JHUNIX.BITNET!cal
From: cal@JHUNIX.BITNET (cal)
Newsgroups: comp.laser-printers
Subject: ditroff metrics
Keywords: ditroff, metrics, Transcript, troff
Message-ID: <8910100244.AA08879@crayola.cs.UMD.EDU>
Date: 6 Oct 89 20:18:30 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Johns Hopkins University - HCF
Lines: 108
Approved: laser-lovers@brillig.umd.edu


     
     
We use troff (ditroff) and Adobe's Transcript package for most of our
printing. I have written or modified a number of Postscript fonts for
non-European languages and have gotten them up and running in ditroff.
The only problem that I have yet to figure out a solution to arises,
apparently, in how ditroff does its metrics work.
   Due to the number of characters in the fonts I have developed, som
of the characters have had to be encoded in high ascii position and
called with the ditroff string \(xx (xx replaced with the 2 character
code for the desired character). Each character in the font has its
own metrics value in the Postscript prologue file and in the
corresponding afm (Adobe font metrics) file. This latter file is
converted to a ditroff font description file with the afmdit program
supplied with Transcript. All of these files have the correct metrics
information for all characters in the fonts. The problem comes with
ditroff takes the original troff coded file and produces the
intermediary ditroff file. In that file, the high ascii (and only the
high ascii) characters of my fonts are not given the metrics value
from the ditroff font description file for that font, but the metrics
of the character of the same ascii position in the Times-Roman font
(the default font for ditroff). The low ascii characters are spaced
correctly, so ditroff is finding the font description file, and all of
the characters, low and high ascii, are printing correctly, with the
exception of the messed up spacing of the high ascii characters. If
anyone has an explanation, or better a solution to this problem, I
would greatly appreciate knowing about it.
   Appended here are some samples of the various files illustrating
the situation in case my explanation above is not clear enough. For
anyone already familiar with these files, I apologize for this.
However, if there is something wrong in these files that I have
overlooked, seeing the pieces of code below might prompt a solution.
     
Steve Bennett
cal@jhunix
     
     
Postscript (from Syriac prologue file)
     
        Encoding        % ditroff octal
        dup 66 /bP put  % B
        dup 77 /mP put  % M
        dup 162 /bF put % \(ct    242
        dup 174 /TB put % \(fi    256
     
        Metrics
        /bP 912 def
        /mP 816 def
        /bF 614 def
        /TB 896 def
     
     
from Syriac AFM file
     
        C 66 ; WX 912 ; N B ; B 0 -24 912 360 ;
        C 77 ; WX 816 ; N M ; B 0 -200 816 448 ;
        C 162 ; WX 614 ; N cent ; B 0 0 564 360 ;
        c 174 ; WX 896 ; N fi ; B 0 -336 896 768 ;
     
     
Ditroff description file Syriac font
        (the metric value for each character -- 2nd column -- is derived by
        dividing the Postscript value by 5)
     
        B       182 2 0102      B
        M       163 2 0115      M
        ct      123 2 0242      cent
        fi      179 2 0256      fi
     
     
Ditroff values in Times-Roman font description file for same characters
     
        B       133 2 0102      B
        M       178 2 0115      M
        ct      100 0 0242      cent
        fi      111 2 0256      fi
     
     
Section of troff file and ditroff file (done at 25 point so that the
        character size matches the unitwidth of our printer.)
     
  (troff)
        .fp 4 sy        \" sy is name of downloaded font
        \f1 B\(ct\(fiMB
        \f4 B\(ct\(fiMB
     
  (ditroff)
        x font 4 sy
        f1                      Printing Times Roman line
        H555
        wV792
        50Bh133Cct
        h100Cfi
        h111cM
        h178cB
        n216 0
        H555
        wf4                     Printing Syriac line
        V1008
        50Bh186Cct              186 is correct for Syriac "B", 133 in Times
        h100Cfi                 Should be 123, not 100
        h111cM                  Should be 179, not 111
        h163cB                  163 correct for Syriac "M", 178 in Times
        n216 0
        x trailer
        V6336
        x stop