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.  The height is the inter-line spacing and the ascent is the distance from the top of the line to the baseline.  These numbers are chosen to display consistently all the subfonts of the font.  A subfont range specification contains two numbers and a file name.  The numbers are the inclusive range of characters covered by the subfont, and the file name names an external file suitable for rdsubfontfile. The minimum number of a covered range is mapped to character zero of the corresponding subfont. If the subfont file name does not begin with a slash, it is taken relative to the directory 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. 

SEE ALSO

graphics(2), bitblt(2), cachechars(2), subfalloc(2)

Plan 9  —  January 03, 1993