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 form  navigation  request.   Navigation  request  codes  are  constants
           defined  in <form.h>, which are distinct from the key- and character codes returned by
           wgetch.

       •   The input is a printable character.  Printable characters  (which  must  be  positive,
           less than 256) are checked according to the program's locale 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  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.

   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_UNKNOWN_COMMAND  is
           returned.  This return value makes sense, because a double click usually means that an
           item-specific action should be returned.  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 result 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-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 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.

SEE ALSO

       ncurses(3NCURSES), menu(3MENU), getch(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 support for mouse events is ncurses specific.

AUTHORS

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

                                                                                    driver(3MENU)