.\"	$NetBSD: menu_driver.3,v 1.9 2017/07/03 21:32:50 wiz Exp $
.\"
.\" Copyright (c) 1999
.\"	Brett Lymn - blymn@baea.com.au, brett_lymn@yahoo.com.au
.\"
.\" This code is donated to The NetBSD Foundation by the author.
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.Dd September 10, 1999
.Dt MENU_DRIVER 3
.Os
.Sh NAME
.Nm menu_driver
.Nd main menu handling function
.Sh LIBRARY
.Lb libmenu
.Sh SYNOPSIS
.In menu.h
.Ft int
.Fn menu_driver "MENU *menu" "int c"
.Sh DESCRIPTION
The
.Fn menu_driver
function is the guts of the menu system.
It takes the commands passed
by c parameter and performs the requested action on the menu given.
The following commands may be given to the menu driver:
.Pp
.Bl -tag -width REQ_CLEAR_PATTERN -compact
.It Command
Action
.It REQ_LEFT_ITEM
Sets the new current item to be the item to the left of the current
item.
.It REQ_RIGHT_ITEM
Sets the new current item to be the item to the rights of the current
item.
.It REQ_UP_ITEM
Sets the new current item to be the item above the current item.
.It REQ_DOWN_ITEM
Sets the new current item to be the item below the current item.
.It REQ_SCR_ULINE
Scroll the menu one line towards the bottom of the menu window.
The new current item becomes the item immediately above the current item.
.It REQ_SCR_DLINE
Scroll the menu one line towards the top of the menu window.
The new current item becomes the item immediately below the current item.
.It REQ_SCR_DPAGE
Scroll the menu one page towards the bottom of the menu window.
.It REQ_SCR_UPAGE
Scroll the menu one page towards the top of the menu window.
.It REQ_FIRST_ITEM
Set the current item to be the first item in the menu.
.It REQ_LAST_ITEM
Set the current item to be the last item in the menu.
.It REQ_NEXT_ITEM
Set the new current item to be the next item in the item array after
the current item.
.It REQ_PREV_ITEM
Set the new current item to be the item before the current item in the
items array.
.It REQ_TOGGLE_ITEM
If the item is selectable then toggle the item's value.
.It REQ_CLEAR_PATTERN
Clear all the characters currently in the menu's pattern buffer.
.It REQ_BACK_PATTERN
Remove the last character from the pattern buffer.
.It REQ_NEXT_MATCH
Attempt to find the next item that matches the pattern buffer.
.It REQ_PREV_MATCH
Attempt to find the previous item that matches the pattern buffer.
.El
If
.Fn menu_driver
is passed a command that is greater than MAX_COMMAND then the command
passed is assumed to be a user defined command and
.Fn menu_driver
returns E_UNKNOWN_COMMAND.
Otherwise if the command is a printable
character then the character represented by the command is placed at
the end of the pattern buffer and an attempt is made to match the
pattern buffer against the items in the menu.
.Sh RETURN VALUES
The functions return one of the following error values:
.Pp
.Bl -tag -width E_UNKNOWN_COMMAND -compact
.It Er E_OK
The function was successful.
.It Er E_SYSTEM_ERROR
There was a system error during the call.
.It Er E_BAD_ARGUMENT
One or more of the arguments passed to the function was incorrect.
.It Er E_NOT_POSTED
The menu is not posted.
.It Er E_UNKNOWN_COMMAND
The menu driver does not recognize the request passed to it.
.It Er E_NO_MATCH
The character search failed to find a match.
.It Er E_NOT_CONNECTED
The item is not connected to a menu.
.It Er E_REQUEST_DENIED
The menu driver could not process the request.
.El
.Sh SEE ALSO
.Xr curses 3 ,
.Xr menus 3
.Sh NOTES
The header
.Pa <menu.h>
automatically includes both
.Pa <curses.h>
and
.Pa <eti.h> .