menu_driver(3X)                                   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; either the input is a menu navi-
       gation request, it's a printable ASCII character or it  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 ASCII character, the
       code appends it to the pattern buffer and attempts to move
       to the next item matching the new pattern.  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 corresponding action is performed.

       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  decora-
       tion  window)  are handled. If you click above the display
       region of the menu, a REQ_SCR_ULINE is generated,  if  you
       doubleclick  a  REQ_SCR_UPAGE  is  generated  and  if  you
       tripleclick a REQ_FIRST_ITEM is generated.  If  you  click
       below  the  display region of the menu, a REQ_SCR_DLINE is
       generated, if you doubleclick a REQ_SCR_DPAGE is generated
       and  if  you  tripleclick a REQ_LAST_ITEM is generated. 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 at  an  item  a  REQ_TOGGLE_ITEM  is  generated  and
       E_UNKNOWN_COMMAND  is  returned.  This  return value makes
       sense, because a double click usually means that an  item-
       specific  action should be returned. It's exactly the pur-
       pose 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 result of this
       request.   If  you  clicked outside the user window or the
       mouse event couldn't be translated into a menu request  an
       E_REQUEST_DENIED is returned.

       If  the second argument is neither printable ASCII nor one
       of the above pre-defined menu requests or  KEY_MOUSE,  the
       drive  assumes  it  is an application-specific command and
       returns E_UNKNOWN_COMMAND.   Application-defined  commands
       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).

       E_BAD_ARGUMENT
            Routine detected an incorrect or  out-of-range  argu-
            ment.

       E_BAD_STATE
            Routine was called from an initialization or termina-
            tion 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.

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

NOTES
       The header file <menu.h> automatically includes the header
       files <curses.h>.

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

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

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