mftrace - Scalable Fonts for MetaFont

1 mftrace - Scalable PostScript Fonts for MetaFont

1.1 Introduction

mftrace is a small Python program that lets you trace a TeX bitmap font into a PFA or PFB font (A PostScript Type1 Scalable Font) or TTF (TrueType) font. It is licensed under the GNU GPL.

Scalable fonts offer many advantages over bitmaps, as they allow documents to render correctly at many printer resolutions. Moreover, Ghostscript can generate much better PDF, if given scalable PostScript fonts.

Versions prior to 1.0.5 were called `pktrace'.

1.2 Download

1.3 Required

mftrace is a thin Python wrapper around some other programs that do the real work: a tracing program and t1asm. To run mftrace you need:

1.4 Recommended

1.5 Red Hat

A RPM may be built by issuing 

     
             rpmbuild -tb mftrace-version.tar.gz

1.6 Debian GNU/Linux

Users of Debian unstable (and Debian 3.0 when it is released) can install all requirements by running (as root): 

     
         apt-get install mftrace

If you wish to also install the FontForge package to simplify and autohint the font, then run the command 

     
         apt-get install fontforge

1.7 Install

Install the prerequite packages. Then run 

     
         ./configure
         make install

in the mftrace directory. Run as follows: 

     
     mftrace cmr10

1.8 Invoking mftrace.

Command line options:

--formats=LIST
A comma-separated list of formats to generate. Choices include: AFM, PFA, PFB, TTF and SVG. Default is to generate a PFA file. Note that fontforge (formerly called pfaedit) needs to be installed in order to generate any format except PFA or PFB. For generating AFM you need either fontforge or ghostscript.
-e,--encoding=enc
Use encoding file enc. Encoding files used by mftrace are basically in the GhostScript/dvips format, but you may use a special .notavail glyph name in order to tell mftrace not to process a specific glyph. If this option is not specified, mftrace will try to determine the encoding file automatically, from the encoding specified in the TFM file.
--glyphs=list
Only process glyphs in list, which is a comma-delimited list of decimal numbers or ranges. 
            --glyphs 1-10,50,55,90-100

--gffile=name
= Take glyphs from file name.
--grid gridsize
Set reciprocal grid size in em units multiplied by ratio magnification/1000. For example --grid 10 --magnification 1000 will round coordinates of control points to 1/10 of em unit. Useful simultaneously with --noround option. Default gridsize value is 1, i. e. round to integer.
-h,--help
help on options.
-k,--keep
Retain all temporary files in the directory mftrace.dir/. This is useful for debugging problems.
--keep-trying
Try to continue if external programs called by mftrace fail. If METAFONT crashes with overflow errors, but nevertheless outputs a GF file, try to process its output as is (useful for some buggy fonts, see below). If potrace/autotrace fails to trace a specific character, first try it with a less smoothed curve, and if that fails, skip the character.

By default mftrace outputs trace-bug-FONTNAME-NUMBER.pbm and stops the process with a request to file a bugreport.

--magnification
The magnification to use for the PFA file. The default is 1000. The larger the more precise the PFA file will be. However, when magnification is too large METAFONT can crash with overflow errors.

Sadly, many MF fonts contain resolution checks 

            if dots_per_inch * design_size > 1500:
              ...

This check is susceptible to overflow errors. Such code should be reported as a bug, and changed to 

            if dots_per_inch > (1500 / design_size):
              ...

--noround
Don't round coordinates of control points to integer values. Useful simultaneously with --grid option. Disabled by default.
-o,--output-base=FILE
Output to FILE.pfa or FILE.pfb.
--simplify
Pass the font through FontForge for automatic simplification and hinting.
--tfmfile=FILE
Use file for the TFM file. This file is needed to determine at what resolution to run MetaFont.
-V,--verbose
Be verbose: print all commands as they are invoked. This is useful for debugging.
-v,--version
Print version number
--dos-kpath
Try to kludge up the paths coming from MikTeX for a cygwin environment. If this doesn't work, specify --tfmfile and --encoding manually.
-w,--warranty
show warranty and copyright
--potrace
use Potrace (default).
--autotrace
use AutoTrace.
-D,--define=symbol=value
Set the font info symbol to the given value. For example -DFamilyName=Foo sets the font family name to Foo.

Mftrace tries to fill in sensible values for the FontName, FamilyName, FullName and Weight fields. It does so by guessing values for the CM font series. For other fonts, it tries to read an AFM file (which is not likely to exist). Suggestions for a more generic way to handle this are welcome.

Mftrace uses kpathsea for finding fonts, so any kpathsea variable can be used to fine-tune which files should be loaded. For example, you can set MFINPUTS to specify which paths to search for .mf files.

Additional options may be passed to the backend program (potrace or autotrace) with the MFTRACE_BACKEND_OPTIONS environment variable.

1.9 Discussion

Why use mftrace over textrace? Textrace and mftrace are functionally similar. However, mftrace is quicker, more cleanly written and can be installed using standard methods. Additionally, textrace requires perl, ghostscript and dvips.

How about MetaFog? MetaFog operates directly on the curves that generate the bitmap font, its outlines will probably be smaller and better. However, MetaFog is a proprietary product: its source code is not available, and it will only run on a limited number of platforms.

How about MetaType1? MetaType1 is an approach that puts severe constraints on what may be done in a font program. It does not work for fonts containing overlaps and shaped pens.

How about FontForge itself? FontForge is an interactive editor, but it can be scripted. Since it supports bitmap tracing and TeX bitmap fonts, it is possible to duplicate the functionality of mftrace. However, out of the box, FontForge does not recognize TeX encodings.

1.10 Bugs and todo

Should you encounter any bug or problem, then please send a bugreport to Han-Wen Nienhuys.

1.11 Author

Han-Wen Nienhuys

1.12 Credits

Gf2pbm, the utility to convert a MetaFont GF file to a PBM file was based on Paul Vojta's Xdvi. The license notice is reproduced below.

Thanks to all bughunters and contributors: Andrey V. Panov, Geoffrey Alan Washburn, Julian Gilbey Günther Spahlinger, Richard Mahoney, Stanislav Brabec, and Thomas Bushnell BSG.

Copyright (c) 1990-1999 Paul Vojta

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL PAUL VOJTA BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

The rest of the package mftrace script itself is licensed under the GNU General Public License.

1.13 See also