DRAW-FONT(2) DRAW-FONT(2)
NAME
Font - character images for Unicode text
SYNOPSIS
include "draw.m";
draw := load Draw Draw->PATH;
Font: adt
{
name: string;
height: int;
ascent: int;
display: ref Display;
open: fn(d: ref Display, file: string): ref Font;
build: fn(d: ref Display, name, desc: string): ref Font;
width: fn(f: self ref Font, str: string): int;
};
DESCRIPTION
The Font type defines the appearance of characters drawn
with the Image.text primitive (see draw-image(2)). Fonts are
usually read from files and are selected based on their
size, their style, the portion of Unicode space they repre-
sent, and so on.
Fonts are built from a series of subfonts that define con-
tiguous portions of the Unicode character space, such as the
ASCII or the Greek alphabet. Font files are textual
descriptions of the allocation of characters in the various
regions of the Unicode space; see font(6) for the format.
Subfonts are not visible from Limbo.
A default font, named *default*, is always available.
The type incorporates:
ascent, height
These define the vertical sizes of the font, in
pixels. The ascent is the distance from the font
baseline to the top of a line of text; height
gives the interline spacing, that is, the distance
from one baseline to the next.
name This field identifies the font, either the name of
the file from which the font was read, or
"*default*" for the default font.
display Tells on which display the font resides.
Page 1 Plan 9 (printed 11/18/24)
DRAW-FONT(2) DRAW-FONT(2)
open(d, file)
The open method creates a Font by reading the con-
tents of the named file. Fonts are cached, so an
open request may return a pointer to an existing
Font, without rereading the file. The name
"*default*" always describes a defined font.
Fonts are created for an instance of a Display
object, even though the creation functions are in
type Font.
build(d, name, desc)
Build creates a Font object by reading the
description from the string desc rather than a
file. Name specifies the name of the font to be
created.
f.width( str )
The width method returns the width in pixels that
str would occupy if drawn by Image.text in the
Font f.
Page 2 Plan 9 (printed 11/18/24)