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| driver(3MENU) | driver(3MENU) |
NAME¶
menu_driver - command-processing loop of the menu systemSYNOPSIS¶
#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.