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.TH FONT 9.5
.CT 2 comm_term
.SH NAME
font \- jerq font layouts
.SH SYNOPSIS
.B #include <jerq.h>
.br
.B #include <font.h>
.PP
.B typedef struct Fontchar Fontchar;
.br
.B typedef struct Font Font;
.PP
.B extern Font defont;
.SH DESCRIPTION
A
.I Font
is a character set, stored as a single
Bitmap
with the characters
placed side-by-side.
It is described by the following data structures.
.IP
.EX
.ta +.5i +\w'unsigned char bottom; 'u
typedef struct Fontchar {
short x; /* left edge of bits */
unsigned char top; /* first non-zero scan-line */
unsigned char bottom; /* last non-zero scan-line */
char left; /* offset of baseline */
unsigned char width; /* width of baseline */
} Fontchar;
typedef struct Font {
short n; /* number of chars in font */
char height; /* height of bitmap */
char ascent; /* top of bitmap to baseline */
long unused;
Bitmap *bits; /* where the characters are */
Fontchar info[n+1]; /* n+1 character descriptors */
} Font;
.EE
.PP
Characters in
.L bits
abut exactly, so the displayed width of the character
.I c
is
.BI Font.info[ c +1].x\ -\ Font.info[ c ].x .
The first
.L left
columns of pixels in a character overlap the previous character.
The upper left corner of the nonempty columns appears at
.RB ( x, 0)
in the bitmap.
.L Width
is the distance to move horizontally after drawing a character.
The font bitmap has a fixed
.LR height ;
parameters
.L top
and
.L bottom
may speed up the copying of a character.
.PP
Characters are positioned by their upper left corners.
.PP
Fonts are stored on disk in binary with byte
order that of the terminal.
First in the file is the Font structure
with
.B bits
elided.
The data for the bitmap follows.
The header for the bitmap must be inferred from
.B Font.height
and
.BR Font.info[Font.n].x .
.SH EXAMPLES
.EX
Fontchar *i = f->info + c;
bitblt(f->bits, Rect(i->x, i->top, (i+1)->x, i->bottom),
&display, Pt(p.x+i->left, p.y+i->top), fc);
p.x += i->width;
.EE
.ns
.IP
Copy character
.I c
from font
.I f
to point
.I p
with Code
.B F_XOR
or
.BR F_OR .
.PP
For Code
.LR F_STORE ,
use
.LR "Rect(i->x, 0, (i+1)->x, f->height)" .
.SH SEE ALSO
.IR jf (9.1),
.IR string (9.3),
.IR getfont (9.1)
.SH BUGS
The
.L unused
field is used, by
.IR getfont (9.1).
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