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GROFF_FONT
!!!GROFF_FONT
NAME
DESCRIPTION
FILES
SEE ALSO
----
!!NAME


groff_font - format of groff device and font description files
!!DESCRIPTION


The groff font format is roughly a superset of the ditroff
font format. Unlike the ditroff font format, there is no
associated binary format. The font files for device
''name'' are stored in a directory __dev__''name.''
There are two types of file: a device description file
called __DESC__ and for each font ''F'' a font file
called ''F''. These are text files; there is no
associated binary format.


__DESC file format__


The DESC file can contain the following types of
line:


__res__ ''n''


There are ''n'' machine units per inch.


__hor__ ''n''


The horizontal resolution is ''n'' machine
units.


__vert__ ''n''


The vertical resolution is ''n'' machine
units.


__sizescale__ ''n''


The scale factor for pointsizes. By default this has a value
of 1. One ''scaled point'' is equal to one
point/''n''. The arguments to the __unitwidth__ and
__sizes__ commands are given in scaled
points.


__unitwidth__ ''n''


Quantities in the font files are given in machine units for
fonts whose point size is ''n'' scaled
points.


__prepro__ ''program''


Call ''program'' as a preprocessor.


__postpro__ ''program''


Use ''program'' as the postprocessor.


__tcommand__


This means that the postprocessor can handle the __t__
and __u__ output commands.


__sizes__ ''s1 s2...sn'' __0__


This means that the device has fonts at ''s1'',
''s2'',...''sn'' scaled points. The list of sizes must
be terminated by a __0__. Each __s__''i'' can also
be a range of sizes ''m''-''n''. The list can extend
over more than one line.


__styles__ ''S1 S2...Sm''


The first ''m'' font positions will be associated with
styles ''S1...Sm''.


__fonts__ ''n F1 F2 F3...Fn''


Fonts ''F1...Fn'' will be mounted in the font positions
''m''+1,...,''m''+''n'' where ''m'' is the
number of styles. This command may extend over more than one
line. A font name of __0__ will cause no font to be
mounted on the corresponding font position.


__family__ ''fam''


The default font family is ''fam''.


__use_charnames_in_special__


This command indicates that troff should encode named
characters inside special commands.


__pass_filenames__


requests that troff tells the driver the source file name
being processed. This is achieved by another tcommand:
__F__ ''filename''.


__charset__


This line and everything following in the file are ignored.
It is allowed for the sake of backwards
compatibility.


__print__ ''program''


Use ''program'' as the spooler program for printing. If
omitted, the __-l__ and __-L__ options of __groff__
are ignored.


The res, unitwidth, fonts and sizes lines are compulsory.
Other commands are ignored by __troff__ but may be used
by postprocessors to store arbitrary information about the
device in the DESC file.


Here a list of obsolete keywords which are recognized by
__groff__ but completely ignored: __spare1__,
__spare2__, __biggestfont__.


__Font file format__


A font file has two sections. The first section is a
sequence of lines each containing a sequence of blank
delimited words; the first word in the line is a key, and
subsequent words give a value for that key.


__name__ ''F''


The name of the font is ''F''.


__spacewidth__ ''n''


The normal width of a space is ''n''.


__slant__ ''n''


The characters of the font have a slant of ''n'' degrees.
(Positive means forward.)


__ligatures__ ''lig1 lig2...lign''
[[__0__]


Characters ''lig1'', ''lig2'',...,''lign'' are
ligatures; possible ligatures are __ff__, __fi__,
__fl__, __ffi__ and __ffl__. For backwards
compatibility, the list of ligatures may be terminated with
a __0.__ The list of ligatures may not extend over more
than one line.


__special__


The font is ''special''; this means that when a character
is requested that is not present in the current font, it
will be searched for in any special fonts that are
mounted.


Other commands are ignored by __troff__ but may be used
by postprocessors to store arbitrary information about the
font in the font file.


The first section can contain comments which start with the
__#__ character and extend to the end of a
line.


The second section contains one or two subsections. It must
contain a ''charset'' subsection and it may also contain
a ''kernpairs'' subsection. These subsections can appear
in any order. Each subsection starts with a word on a line
by itself.


The word __charset__ starts the charset subsection. The
__charset__ line is followed by a sequence of lines. Each
line gives information for one character. A line comprises a
number of fields separated by blanks or tabs. The format
is


''name metrics type code'' [[''entity_name'']
[[__--__ ''comment'']


''name'' identifies the character: if ''name'' is a
single character ''c'' then it corresponds to the groff
input character ''c''; if it is of the form
__\__''c'' where c is a single character, then it
corresponds to the groff input character __\__''c'';
otherwise it corresponds to the groff input character
__[[__''name''__]__ (if it is exactly two characters
''xx'' it can be entered as ____''xx''). Groff
supports eight bit characters; however some utilities has
difficulties with eight bit characters. For this reason,
there is a convention that the name __char__''n'' is
equivalent to the single character whose code is ''n .''
For example, __char163__ would be equivalent to the
character with code 163 which is the pounds sterling sign in
ISO Latin-1. The name __---__ is special and indicates
that the character is unnamed; such characters can only be
used by means of the __N__ escape sequence in
__troff__.


The ''type'' field gives the character type:


1


means the character has an descender, for example,
p;


2


means the character has an ascender, for example,
b;


3


means the character has both an ascender and a descender,
for example, (.


The ''code'' field gives the code which the postprocessor
uses to print the character. The character can also be input
to groff using this code by means of the __N__ escape
sequence. The code can be any integer. If it starts with a
__0__ it will be interpreted as octal; if it starts with
__0x__ or __0X__ it will be intepreted as
hexadecimal.


The ''entity_name'' field gives an ascii string
identifying the glyph which the postprocessor uses to print
the character. This field is optional and has been
introduced so that the html device driver can encode its
character set. For example, the character `[[Po]' is
represented as `''


Anything on the line after the encoding field resp. after
`--' will be ignored.


The ''metrics'' field has the form:


''width''[[__,__''height''[[__,__''depth''[[__,__''italic_correction''[[__,__''left_italic_correction''[[__,__''subscript_correction'']]]]]


There must not be any spaces between these subfields.
Missing subfields are assumed to be 0. The subfields are all
decimal integers. Since there is no associated binary
format, these values are not required to fit into a variable
of type __char__ as they are in ditroff. The ''width''
subfields gives the width of the character. The
''height'' subfield gives the height of the character
(upwards is positive); if a character does not extend above
the baseline, it should be given a zero height, rather than
a negative height. The ''depth'' subfield gives the depth
of the character, that is, the distance below the lowest
point below the baseline to which the character extends
(downwards is positive); if a character does not extend
below above the baseline, it should be given a zero depth,
rather than a negative depth. The ''italic_correction''
subfield gives the amount of space that should be added
after the character when it is immediately to be followed by
a character from a roman font. The
''left_italic_correction'' subfield gives the amount of
space that should be added before the character when it is
immediately to be preceded by a character from a roman font.
The ''subscript_correction'' gives the amount of space
that should be added after a character before adding a
subscript. This should be less than the italic
correction.


A line in the charset section can also have the
format


''name'' ____


This indicates that ''name'' is just another name for the
character mentioned in the preceding line.


The word __kernpairs__ starts the kernpairs section. This
contains a sequence of lines of the form:


''c1 c2 n''


This means that when character ''c1'' appears next to
character ''c2'' the space between them should be
increased by ''n''. Most entries in kernpairs section
will have a negative value for ''n''.
!!FILES


__/usr/share/groff/1.17.2/font/dev__''name''__/DESC__


Device description file for device ''name''.


__/usr/share/groff/1.17.2/font/dev__''name''__/__''F''


Font file for font ''F'' of device
''name''.
!!SEE ALSO


groff_out(5), troff(1).
----
13 pages link to groff_font(5):
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Last edited on Tuesday, June 4, 2002 12:30:37 am by "perry"
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