FONT(6) FONT(6)
NAME
font, subfont - external format for fonts and subfonts
SYNOPSIS
#include <libg.h>
DESCRIPTION
Fonts and subfonts are described in cachechars(2).
External fonts are described by a plain text file that can
be read using rdfontfile. The format of the file is a header
followed by any number of subfont range specifications. The
header contains two numbers: the height and the ascent, both
in pixels. The height is the inter-line spacing and the
ascent is the distance from the top of the line to the base-
line. These numbers are chosen to display consistently all
the subfonts of the font. A subfont range specification
contains two or three numbers and a file name. The numbers
are the inclusive range of characters covered by the sub-
font, with an optional starting position within the subfont,
and the file name names an external file suitable for
rdsubfontfile. The minimum number of a covered range is
mapped to the specified starting position (default zero) of
the corresponding subfont. If the subfont file name does
not begin with a slash, it is taken relative to the direc-
tory containing the font file. Each field must be followed
by some white space. Each numeric field may be C-format
decimal, octal, or hexadecimal.
External subfonts are represented in a more rigid format
that can be read and written using rdsubfontfile and
wrsubfontfile (see subfalloc(2)). The format for subfont
files is: a bitmap containing character images, followed by
a subfont header, followed by character information. The
bitmap has the format for external bitmap files described in
bitmap(6). The subfont header has 3 decimal strings: n,
height, and ascent. Each number is right-justified and
blank padded in 11 characters, followed by a blank. The
character info consists of n+1 6-byte entries, each giving
the Fontchar x (2 bytes, low order byte first), top, bottom,
left, and width. The x field of the last Fontchar is used
to calculate the bitmap width of the previous character; the
other fields in the last Fontchar are irrelevant.
Note that the convention of using the character with value
zero (NUL) to represent characters of zero width (see
bitblt(2)) means that fonts should have, as their zeroth
character, one with non-zero width.
FILES
Page 1 Plan 9 (printed 12/21/24)
FONT(6) FONT(6)
/lib/font/bit/* font directories
SEE ALSO
graphics(2), bitblt(2), cachechars(2), subfalloc(2)
Page 2 Plan 9 (printed 12/21/24)