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ref: d09cf07a82cf4ffb846a31d0384e774b4c4661e1
dir: /man/2/prefab-0intro/

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.TH PREFAB-INTRO 2
.SH NAME
Prefab: intro \- Interactive TV tookit
.SH SYNOPSIS
.EX
include "draw.m";
include "prefab.m";
prefab := load Prefab Prefab->PATH;
.EE
.SH DESCRIPTION
The
.B Prefab
module contains components for building graphics objects suitable for
Interactive Television (ITV) applications using infrared remote controls.
Using the
.B Draw
module's operations
for simple text and images
(see
.IR draw-intro (2)),
the toolkit can group individual items,
treat those groups as units, and then activate the
items on command.
The other user interface toolkit,
.IR tk (2),
provides facilities for keyboard- and mouse-driven applications.
.PP
The objects on the screen are of type
.BR Compound ,
each of which occupies a unique window on the
display and contains objects of type
.BR Element .
An
.B Element
may be a single object or a list of further
.BR Elements ,
to build hierarchically structured components.
.PP
.B Prefab
defines
.B Environ
and
.B Style
types that specify the appearance of objects: their colours, fonts,
backgrounds, and so on.
A
.B Style
gives font and colour information, while
an
.B Environ
identifies the
.B Screen
upon which the items will be displayed and the
.B Style
in which they will be drawn.
.PP
Applications should allocate
.B Elements
and
.B Compounds
only through the appropriate member functions, as described in the corresponding
sections of the manual.
Items created with regular Limbo
definitions will not work properly.
Moreover, except where indicated,
applications should not modify the data members directly.
Although the type definitions make data members visible,
the members should usually be treated as read-only data.
.SH SOURCE
.B /libinterp/prefab.c
.br
.B /libprefab/*.c
.SH SEE ALSO
.IR draw-intro (2),
.IR ir (2)