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menu_driver(3X) 		  Library calls 		 menu_driver(3X)

NAME
     menu_driver - command-processing loop of the menu system

SYNOPSIS
     #include <menu.h>

     int menu_driver(MENU *menu, int c);

DESCRIPTION
     Once  a menu has been posted (displayed), you should funnel input events to
     it through menu_driver.  This routine has three major input cases:

     *	 The input is a menu navigation request.  Navigation request  codes  are
	 constants defined in menu.h, which are distinct from the key- and char-
	 acter codes returned by wgetch(3X).

     *	 The  input  is a printable character.	Printable characters (which must
	 be positive, less than 256) are checked according to the program's  lo-
	 cale settings.

     *	 The input is the KEY_MOUSE special key associated with an mouse event.

     The menu driver requests are as follows:

     REQ_LEFT_ITEM
	  Move left to an item.

     REQ_RIGHT_ITEM
	  Move right to an item.

     REQ_UP_ITEM
	  Move up to an item.

     REQ_DOWN_ITEM
	  Move down to an item.

     REQ_SCR_ULINE
	  Scroll up a line.

     REQ_SCR_DLINE
	  Scroll down a line.

     REQ_SCR_DPAGE
	  Scroll down a page.

     REQ_SCR_UPAGE
	  Scroll up a page.

     REQ_FIRST_ITEM
	  Move to the first item.

     REQ_LAST_ITEM
	  Move to the last item.

     REQ_NEXT_ITEM
	  Move to the next item.

     REQ_PREV_ITEM
	  Move to the previous item.

     REQ_TOGGLE_ITEM
	  Select/deselect an item.

     REQ_CLEAR_PATTERN
	  Clear the menu pattern buffer.

     REQ_BACK_PATTERN
	  Delete the previous character from the pattern buffer.

     REQ_NEXT_MATCH
	  Move to the next item matching the pattern match.

     REQ_PREV_MATCH
	  Move to the previous item matching the pattern match.

     If the second argument is a printable character, the code appends it to the
     pattern  buffer and attempts to move to the next item matching the new pat-
     tern.  If there is  no  such  match,  menu_driver	returns  E_NO_MATCH  and
     deletes the appended character from the buffer.

     If the second argument is one of the above pre-defined requests, the corre-
     sponding action is performed.

   Mouse Handling
     If  the  second argument is the KEY_MOUSE special key, the associated mouse
     event is translated into one of the above pre-defined requests.   Currently
     only  clicks  in the user window (e.g., inside the menu display area or the
     decoration window) are handled.

     If you click above the display region of the menu:

     *	 a REQ_SCR_ULINE is generated for a single click,

     *	 a REQ_SCR_UPAGE is generated for a double-click and

     *	 a REQ_FIRST_ITEM is generated for a triple-click.

     If you click below the display region of the menu:

     *	 a REQ_SCR_DLINE is generated for a single click,

     *	 a REQ_SCR_DPAGE is generated for a double-click and

     *	 a REQ_LAST_ITEM is generated for a triple-click.

     If you click at an item inside the display area of the menu:

     *	 the menu cursor is positioned to that item.

     *	 If you double-click an item a REQ_TOGGLE_ITEM is  generated  and  E_UN-
	 KNOWN_COMMAND	is  returned.	This return value makes sense, because a
	 double click usually means that an item-specific action should  be  re-
	 turned.   It is exactly the purpose of this return value to signal that
	 an application specific command should be executed.

     *	 If a translation into a request was done, menu_driver returns	the  re-
	 sult of this request.

     If  you  clicked  outside	the  user window or the mouse event could not be
     translated into a menu request an E_REQUEST_DENIED is returned.

   Application-defined Commands
     If the second argument is neither printable nor one of  the  above  pre-de-
     fined  menu  requests or KEY_MOUSE, the drive assumes it is an application-
     specific command and returns E_UNKNOWN_COMMAND.   Application-defined  com-
     mands should be defined relative to MAX_COMMAND, the maximum value of these
     pre-defined requests.

RETURN VALUE
     menu_driver return one of the following error codes:

     E_OK
	  The routine succeeded.

     E_SYSTEM_ERROR
	  System error occurred (see errno(3)).

     E_BAD_ARGUMENT
	  Routine detected an incorrect or out-of-range argument.

     E_BAD_STATE
	  Routine was called from an initialization or termination function.

     E_NOT_POSTED
	  The menu has not been posted.

     E_UNKNOWN_COMMAND
	  The menu driver code saw an unknown request code.

     E_NO_MATCH
	  Character failed to match.

     E_REQUEST_DENIED
	  The menu driver could not process the request.

PORTABILITY
     These  routines emulate the System V menu library.  They were not supported
     on Version 7 or BSD versions.  The support for mouse events is ncurses spe-
     cific.

AUTHORS
     Juergen Pfeifer.  Manual pages and adaptation for new  curses  by	Eric  S.
     Raymond.

SEE ALSO
     curses(3X), getch(3X), menu(3X)

ncurses 6.5			   2025-10-04			 menu_driver(3X)

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