Fetching and changing the current item

The current item is the item where your end-user is positioned on the screen. Unless it is invisible, this item is highlighted and the cursor rests on the item. To have your application program set or determine the current item, you use the following functions.

SYNOPSIS

   int set_current_item (menu, item)
   MENU  menu;
   ITEM  item;
   

   ITEM  current_item (menu)
   MENU  menu;
   

   int item_index (item)
   ITEM  item;

The function item_index takes an item pointer argument and returns the index to that item in the item pointer array. The value of this index ranges from 0 through N-1, where N is the total number of items connected to the menu.

Because the menu driver satisfies ETI-defined item navigation requests automatically, your application program need not call set_current_item, unless you want to implement additional item navigation requests for your application. You may, for instance, want a request to jump to a particular item or an item, say, two items down from the current one on the menu page.

When a menu is created by new_menu or the items associated with a menu are changed by set_menu_items, the current item is set to the first item of the menu.

As an example of set_current_item, the following function sets the current item of menu m to the first item of the menu:

   int set_first_item (m) /* set current item to first
       item */
   MENU *  m;
   {
   	ITEM ** i = menu_items (m);
   	return set_current_item (m, i[0]);
   }

As an example of current_item, the following routine checks if the first menu item is the current one:

   int first_item (m)  /* check if current item is first
       item */
   MENU * m;
   {
   	ITEM * i = current_item (m);
   	return item_index (i) == 0;
   }

E_SYSTEM_ERROR

system error

E_BAD_ARGUMENT

NULL menu pointer or item not connected to menu

E_BAD_STATE

called from initialization or termination routines

Function item_index returns -1 if the item pointer is NULL or the item is not connected to a menu.