.\"***************************************************************************
.\" Copyright 2018-2023,2024 Thomas E. Dickey                                *
.\" Copyright 1998-2007,2010 Free Software Foundation, Inc.                  *
.\"                                                                          *
.\" Permission is hereby granted, free of charge, to any person obtaining a  *
.\" copy of this software and associated documentation files (the            *
.\" "Software"), to deal in the Software without restriction, including      *
.\" without limitation the rights to use, copy, modify, merge, publish,      *
.\" distribute, distribute with modifications, sublicense, and/or sell       *
.\" copies of the Software, and to permit persons to whom the Software is    *
.\" furnished to do so, subject to the following conditions:                 *
.\"                                                                          *
.\" The above copyright notice and this permission notice shall be included  *
.\" in all copies or substantial portions of the Software.                   *
.\"                                                                          *
.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
.\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
.\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
.\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
.\" THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
.\"                                                                          *
.\" Except as contained in this notice, the name(s) of the above copyright   *
.\" holders shall not be used in advertising or otherwise to promote the     *
.\" sale, use or other dealings in this Software without prior written       *
.\" authorization.                                                           *
.\"***************************************************************************
.\"
.\" $Id: menu_hook.3x,v 1.34 2024/12/28 21:26:21 tom Exp $
.TH menu_hook 3X 2024-12-28 "ncurses 6.5" "Library calls"
.SH NAME
\fBmenu_hook\fP \-
set hooks for automatic invocation by applications
.SH SYNOPSIS
.nf
\fB#include <menu.h>
.PP
\fBint set_item_init(MENU *\fImenu\fP, Menu_Hook \fIfunc\fP);
\fBMenu_Hook item_init(const MENU *\fImenu\fP);
.PP
\fBint set_item_term(MENU *\fImenu\fP, Menu_Hook \fIfunc\fP);
\fBMenu_Hook item_term(const MENU *\fImenu\fP);
.PP
\fBint set_menu_init(MENU *\fImenu\fP, Menu_Hook \fIfunc\fP);
\fBMenu_Hook menu_init(const MENU *\fImenu\fP);
.PP
\fBint set_menu_term(MENU *\fImenu\fP, Menu_Hook \fIfunc\fP);
\fBMenu_Hook menu_term(const MENU *\fImenu\fP);
.fi
.SH DESCRIPTION
These functions make it possible to set hook functions to be called at various
points in the automatic processing of input event codes by \fBmenu_driver\fP.
.PP
The function \fBset_item_init\fP sets a hook to be called at menu-post time and
each time the selected item changes (after the change).
\fBitem_init\fP
returns the current item init hook, if any
.RI ( NULL
if there is no such hook).
.PP
The function \fBset_item_term\fP sets a hook to be called at menu-unpost time
and each time the selected item changes (before the change).
\fBitem_term\fP
returns the current item term hook, if any
.RI ( NULL
if there is no such hook).
.PP
The function \fBset_menu_init\fP sets a hook to be called at menu-post time and
just after the top row on the menu changes once it is posted.
\fBmenu_init\fP
returns the current menu init hook, if any
.RI ( NULL
if there is no such hook).
.PP
The function \fBset_menu_term\fP sets a hook to be called at menu-unpost time
and just before the top row on the menu changes once it is posted.
\fBmenu_term\fP returns the current menu term hook, if any
.RI ( NULL
if there is no such hook).
.SH RETURN VALUE
Routines that return pointers return
.I NULL
on error.
Other routines
return one of the following:
.TP 5
.B E_OK
The routine succeeded.
.TP 5
.B E_SYSTEM_ERROR
System error occurred (see \fBerrno\fP(3)).
.SH PORTABILITY
These routines emulate the System V menu library.
They were not supported on
Version 7 or BSD versions.
.SH AUTHORS
Juergen Pfeifer.
Manual pages and adaptation for new curses by Eric
S. Raymond.
.SH SEE ALSO
\fB\%curses\fP(3X),
\fB\%menu\fP(3X)