System.Windows.Forms.MenuTracker.GetNextItem C# (CSharp) Method

		static MenuItem GetNextItem (Menu menu, ItemNavigation navigation)
		{
			int pos = 0;
			bool selectable_items = false;
			MenuItem item;

			// Check if there is at least a selectable item
			for (int i = 0; i < menu.MenuItems.Count; i++) {
				item = menu.MenuItems [i];
				if (item.Separator == false && item.Visible == true) {
					selectable_items = true;
					break;
				}
			}

			if (selectable_items == false)
				return null;

			switch (navigation) {
			case ItemNavigation.First:

				/* First item that is not separator and it is visible*/
				for (pos = 0; pos < menu.MenuItems.Count; pos++) {
					item = menu.MenuItems [pos];
					if (item.Separator == false && item.Visible == true)
						break;
				}

				break;

			case ItemNavigation.Last: // Not used
				break;

			case ItemNavigation.Next:

				pos = menu.SelectedItem == null ? - 1 : menu.SelectedItem.Index;

				/* Next item that is not separator and it is visible*/
				for (pos++; pos < menu.MenuItems.Count; pos++) {
					item = menu.MenuItems [pos];
					if (item.Separator == false && item.Visible == true)
						break;
				}

				if (pos >= menu.MenuItems.Count) { /* Jump at the start of the menu */
					pos = 0;
					/* Next item that is not separator and it is visible*/
					for (; pos < menu.MenuItems.Count; pos++) {
						item = menu.MenuItems [pos];
						if (item.Separator == false && item.Visible == true)
							break;
					}
				}
				break;

			case ItemNavigation.Previous:

				if (menu.SelectedItem != null)
					pos = menu.SelectedItem.Index;

				/* Previous item that is not separator and it is visible*/
				for (pos--; pos >= 0; pos--) {
					item = menu.MenuItems [pos];
					if (item.Separator == false && item.Visible == true)
						break;
				}

				if (pos < 0 ) { /* Jump at the end of the menu*/
					pos = menu.MenuItems.Count - 1;
					/* Previous item that is not separator and it is visible*/
					for (; pos >= 0; pos--) {
						item = menu.MenuItems [pos];
						if (item.Separator == false && item.Visible == true)
							break;
					}
				}

				break;

			default:
				break;
			}

			return menu.MenuItems [pos];
		}