Copyright (C) 1990, 1991, 1993, 1994 Aladdin Enterprises.  All rights reserved.
  
  This file is part of Aladdin Ghostscript.
  
  Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
  or distributor accepts any responsibility for the consequences of using it,
  or for whether it serves any particular purpose or works at all, unless he
  or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
  License (the "License") for full details.
  
  Every copy of Aladdin Ghostscript must include a copy of the License,
  normally in a plain ASCII text file named PUBLIC.  The License grants you
  the right to copy, modify and redistribute Aladdin Ghostscript, but only
  under certain conditions described in the License.  Among other things, the
  License requires that the copyright notice and this notice be preserved on
  all copies.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

This file, fonts.doc, describes the fonts and font facilities supplied
with Ghostscript.

For an overview of Ghostscript and a list of the documentation files, see
README.

About Ghostscript fonts
=======================

Most of Ghostscript's font files have a .gsf extension.  Each file defines
one (transformable) font specified in outline form.  They are ordinary
Type 1 PostScript outline fonts, and can be given to any PostScript
language interpreter; however, they are not compatible with Adobe Type
Manager or with tools that don't include a full PostScript language
interpreter.  Ghostscript also includes a few files with .pfa extension,
which *are* compatible with Adobe Type Manager.

The other font-related file that Ghostscript needs for proper operation is
a file called Fontmap.  This file maps font names (such as /Times-Roman)
to font file names (such as ptmr.gsf).

Most of the fonts supplied with Ghostscript are based on various public
domain bitmap fonts, primarily the ones supplied with the X11 distribution
from MIT, and on the public domain Hershey fonts.  The fonts are
distributed in the file `ghostscript-N.NNfonts.tar.Z'.  The bitmap-derived
fonts include the usual Helvetica, Times-Roman, and so on; see the file
`Fontmap' for the complete list, in the usual roman, italic, bold, and
bold italic styles (for the most part).  The Hershey fonts, on the other
hand, are quite different from traditional ones; the file `hershey.doc'
describes them in more detail.

The file gs_fonts.ps, which is loaded as part of Ghostscript
initialization, arranges to load fonts on demand using the information
from Fontmap.  If you want to preload all of the known fonts, invoke the
procedure
	loadallfonts
This is not done by default, since the fonts occupy about 50K each and there
are a lot of them.

Ghostscript fonts are actually ordinary Ghostscript programs: they use the
extension .gsf instead of .ps simply to be informative.  This convention
is only embodied in the Fontmap file: there is no code that knows about
it.

If you want to try out the fonts, prfont.ps contains code for printing a
sampler.  Load this program, by including it in the gs command line or by
invoking
	(prfont.ps) run
and then to produce a sampler of a particular font, invoke
	/fontName DoFont
e.g.
	/Times-Roman DoFont

About the Kanji fonts
---------------------

Mr. Tetsurou Tanaka of the Department of Engineering, University of Tokyo,
has created a set of free Kanji fonts that is freely available on the
Internet for anonymous FTP from moe.ipl.t.u-tokyo.ac.jp:/Font and is
distributed with Ghostscript.  Anyone can use these fonts as they are or
with some format translation, and redistribute them without reporting.  If
you redistribute them, you must inform the recipient that he can get the
original from the abovementioned FTP site, so that he could get the newest
version later.

The fonts include a README file in Japanese.  Here is some English
documentation supplied by Mr. Kiyotaka Sakai, also of the University of
Tokyo.

    The following four fonts are different styles of the same characters
    (JISX208). These fonts also needs wadalab-sym.tar.Z in common.

    wadalab-mincho-0-8.tar.gz
    wadalab-mincho-0-12.6.tar.gz
    wadalab-gothic-0-13.5.tar.gz
    wadalab-maru-0-8.4.tar.gz

    And the following two fonts are the other different styles of the same
    characters(JISX0212).

    wadalab-mincho-1-8.tar.gz
    wadalab-maru-1-8.tar.gz

    These fonts are postscript(type1) fonts. You can convert them to
    Metafont, Type1(PFA) font, TeX font(for japanese TeX), BDF font,
    Shotaikurabu font by using wftomf.c, wftopfa.c, wftodm.c, bdfmerge.c
    wftovf.c in tools directory.

In order to conform to MS-DOS naming restrictions, we have renamed the
original font files as follows:
	Name		Original name
	----		-------------
	got013-5.taz	wadalab-gothic-0-13.5.tar.gz
	mar08-4.taz	wadalab-maru-0-8.4.tar.gz
	mar18.taz	wadalab-maru-1-8.tar.gz
	min012-6.taz	wadalab-mincho-0-12.6.tar.gz
	min08-4.taz	wadalab-mincho-0-8.4.tar.gz
	min18.taz	wadalab-mincho-1-8.tar.gz
	sym-4.taz	wadalab-sym.4.tar.gz

Platform fonts
==============

Starting with release 2.6.1, Ghostscript uses whatever font technology is
provided by the system on which it runs, by using the system's API for
displaying text.  On MS Windows this may be TrueType, or it may be ATM;
Ghostscript neither knows nor cares.  Note that Ghostscript does not
contain a TrueType rasterizer, so it cannot read disk files containing
TrueType fonts; don't put the names of TrueType font files (.FON or .TTF
or .PTF whatever they are called) in Ghostscript's Fontmap.

The PostScript language specifies that fonts are data structures with
particular contents (e.g., they include a bounding box for the font, an
Encoding vector for specifying the character set, etc.), and it is fairly
common for PostScript files to make use of this fact; also, characters can
be used as clipping regions, and can be arbitrarily rotated, skewed,
expanded/condensed, etc. algorithmically.  Most of this information is
available in one form or another from the underlying graphics system, but
one crucial piece is not: the actual scalable outlines of the characters,
which Ghostscript needs in order to implement clipping with character
shapes and to implement arbitrarily transformed characters.  Consequently,

	Ghostscript needs the scalable outlines of any font mentioned
	in a document, and will load them from the disk (.PFA, .PFB, or
	.GSF file) in the usual way, even if it uses the platform's font
	machinery for displaying the characters.

To make matters worse, platforms use different names for their standard
fonts.  For example, the Times Roman font, for which PostScript files use
the name "Times-Roman", may be known as "Times-Roman", "Times Roman", "Tms
Rmn", "Times New Roman", or "TimesNewRoman".  The name may even be
completely different: the usual Helvetica-equivalent TrueType font is
called "Arial".  Now, it is possible to cope with this situation by
introducing aliases in Fontmap, but there are two reasons why the
current Ghostscript release does not do this:

	1) Naming in different systems is so unstandardized that there
does not seem to be a small set of alternative names that is likely to
cover most of the situations.  All 5 of the above names for Times Roman
have been seen in Windows and OS/2 environments, depending on system
version, TrueType vs.  ATM, and other unknown factors.

	2) Each alias takes up a substantial amount of space (several
hundred bytes) at run time.  If each of the standard 35 fonts has 3
additional aliases, this might amount to 50K of wasted space.  This is a
lot on a PC, although running under Windows in enhanced mode, it might not
be a problem.

If you don't seem to be getting nice characters on the screen under MS
Windows, you can try adding aliases to the Fontmap, according to the
documentation found there.

Adding your own fonts
=====================

Ghostscript can use any Type 1 or Type 3 font that is acceptable to other
PostScript language interpreters.  Ghostscript also provides a way to
construct a Type 1 font from a bitmap font in BDF format, which is a
popular format in the Unix world.

If you want to add fonts of your own, you must edit Fontmap to include an
entry for your new font at the end.  The format for entries is documented
in the Fontmap file.  Since later entries in Fontmap override earlier
entries, any fonts you add will supersede the corresponding fonts supplied
with Ghostscript.

In the PC world, Type 1 fonts are customarily given names ending in .PFA
or .PFB.  Ghostscript can use these directly; you just need to make the
entry in Fontmap.  If you are going to use a commercial Type 1 font (such
as fonts obtained in conjunction with Adobe Type Manager) with
Ghostscript, please read carefully the license that accompanies the font;
Aladdin Enterprises takes no responsibility for any possible violations of
such licenses.

Converting BDF fonts
--------------------

If you want to convert a BDF file to a scalable outline, use the program
bdftops.ps (and invoking shell script bdftops.bat or bdftops).  Run the
shell command
	bdftops <BDF_file_name> [<AFM_file1_name> ...] <your_gsf_file_name>
	  <font_name> <uniqueID> [<XUID>] [<encoding_name>]
e.g.,
	bdftops pzdr.bdf ZapfDingbats.afm pzdr.gsf
	  ZapfDingbats 4100000 1000000.1.41
(Obviously, you would enter this all on one line; the example is split so
it will fit on the page.)  Then make an entry for the .gsf file in Fontmap
as described above.  You may find it helpful to read, and to add an entry
to, the fonts.mak file, which is a makefile for converting the standard
Ghostscript fonts.

For developers only
===================

The rest of this document is very unlikely to be of value to ordinary
users.

Contents of fonts
-----------------

A Ghostscript font is a dictionary with a standard set of keys as follows.
The keys marked with a * have the same meanings as in P*stScr*pt fonts;
those marked with # have the same meanings as in Adobe Type 1 fonts.  Note
that FontName is required, and StrokeWidth is required for all stroked or
outlined fonts.

*	- FontMatrix <array>: the transformation from character
	  coordinates to user coordinates.

*	- FontType <integer>: the type of the font, either 1 or 3.

*	- FontBBox <array>: the bounding box of the font.

*	- Encoding <array>: the map from character codes to character
	  names.

*	- FontName <name>: the name of the font.

*	- PaintType <integer>: an indication of how to interpret the
	  character description from CharInfo.

*	- StrokeWidth <number>: the stroke width for outline fonts.

*	- FontInfo <dictionary>: additional information about the font
	  (optional, not used by the standard Ghostscript software).

*	- UniqueID <integer>: a unique number identifying the font.

*	- BuildChar <procedure>: the procedure for showing a character
	  (not required in type 1 fonts).

#	- CharStrings <dictionary>: the map from character names to character
	  descriptions (relevant only in type 1 fonts).

#	- Private <dictionary>: additional information used by the
	  algorithms for rendering outlines fonts (relevant only in type 1
	  fonts).

The format of values in the CharStrings and Private dictionaries are
described in the Adobe Type 1 Font Format book.

Precompiling fonts
------------------

You can compile any Type 1 font into C and link it into the Ghostscript
executable.  (Type 1 fonts include any font whose name ends with .pfa or
.pfb, and it also includes all the Ghostscript .gsf fonts except for the
Hershey fonts.)  This doesn't have any effect on rendering speed, but it
eliminates the time for loading the font dynamically, which may make a big
difference in total rendering time, especially for multi-page documents.
(Because of RAM and compiler limitations, you should only use compiled
fonts on MS-DOS systems if you are using a 32-bit compiler such as Watcom
C/386 or djgpp; you will run out of memory if you use compiled fonts with
the Borland compiler.)  Fonts that have been precompiled and linked in
this way do not need to appear in the Fontmap, although if they do appear
there, no harm is done.

The utility for precompiling fonts is called font2c.  Note that font2c is
a PostScript language program, so you must have Ghostscript already
running to be able to run font2c; you must also have entries in the
Fontmap for the fonts you want to compile.  For example, to precompile
the Times-Italic font,
	font2c Times-Italic ptmri.c
where the first argument is the font name and the second is the name of
the .c file.  You can use any file name you want, as long as it ends in
.c.  It doesn't have to be limited to 8 characters, unless your operating
system requires this.  We suggest that you use names xxxx.c, where
xxxx.gsf or xxxx.pfa is the name of the font file in the Fontmap file,
just so you don't have to keep track of another set of names.  (If you are
running on a VMS platform, or another platform where the C compiler has a
limit on the length of identifiers, you must do something slightly more
complicated; see the section 'Platforms with identifier length limits'
below.  Also, on VMS, you must put quotes "" around the font name so that
the VMS command processor doesn't convert the name to lower case.)

Besides running font2c, you must arrange things so that the file will be
compiled from C to machine code, and linked into the executable.  All
environments except VMS use the same procedure for this, which we will now
describe.  (For VMS environments, see the directions in the file make.doc,
and ignore the rest of this section.)

First, you must add the compiled fonts "feature" to your
platform-specific makefile.  On MS-DOS systems, you edit tc.mak,
bc.mak, bcwin.mak, msc.mak, or watc.mak; on Unix systems, you edit
makefile.  Find the definition of FEATURE_DEVS in the makefile, e.g.,
	FEATURE_DEVS=filter.dev dps.dev
Add ccfonts.dev on the end, e.g.,
	FEATURE_DEVS=filter.dev dps.dev ccfonts.dev

Next, you must add the specific fonts to the generic makefile.  On MS-DOS
systems, you edit gs.mak; on Unix systems, you edit makefile.  Find the
line in the relevant makefile that says
	ccfonts1_=ncrr.$(OBJ)
Edit this to add your compiled font file names, e.g.,
	ccfonts1_=ncrr.$(OBJ) ptmri.$(OBJ)
If the line gets too long, add another line of the same form, e.g.,
	ccfonts2_=ptmb.$(OBJ)
Just below this, you will find a line that says
	ccfonts1=Courier
Add your own fonts to the end of this line, e.g.,
	ccfonts1=Courier Times_Italic
Notice that you must replace `-' by `_' in the font name.  Again, if
the line gets too long, add another line of the same form, e.g.,
	ccfonts1=Courier
	ccfonts2=Times_Italic
Now find the lines that say
	ncrr.$(OBJ): ncrr.c $(CCFONT)
		$(CCCF) ncrr.c
Add a similar pair of lines for each font, separating these entries from
the existing entries and from each other by a blank line.  (The makefile
includes lines for a few more fonts than this already.)  In our example,
	ncrr.$(OBJ): ncrr.c $(CCFONT)
		$(CCCF) ncrr.c

	ptmri.$(OBJ): ptmri.c $(CCFONT)
		$(CCCF) ptmri.c

Finally, run `make'.  The executable will now include the fonts you added.
They will be present in FontDirectory when Ghostscript starts up.

Note that ncrr.c, ptmr.c, etc. are not supplied with the Ghostscript
fileset, since they are quite large and can easily be recreated using
the font2c program as described above.

Precompiling fonts on platforms with identifier length limits
-------------------------------------------------------------

On some platforms, the C compiler and/or linker have a limit on the number
of significant characters in an identifier.  On such platforms, you must
do a little extra work.

Let N be the maximum number of significant characters in an identifier
(typically 31).  For each font whose name is longer than N-5 characters,
pick an arbitrary identifier that we will call the "short name".  This can
be any string you want, as long as it contains only letters, digits, and
underscores; is no longer than N-5 characters; and is not the same as any
other font name or short name.  A good choice for this would be to use the
name of the C file.  (There is no harm in doing this for fonts with names
shorter than N-5 characters, it's just not necessary.)

You must do two different things for fonts that require a short name.
First, you must supply the short name as a third argument to the font2c
program.  For example, to compile NewCenturySchlbk-BoldItalic using the
short name "pncbi",
	font2c NewCenturySchlbk-BoldItalic pncbi.c pncbi
Then when you add the font to the gsaddmod line in the makefile, use the
short name, not the actual font name, e.g.,
	ccfonts2=pncbi
instead of
	ccfonts2=NewCenturySchlbk_BoldItalic
Everything else is as described above.

This procedure doesn't change the name of the font in the Fontmap, or as
seen from within Ghostscript; it's just a workaround for a limitation of
some older compilers.