C++ DropDownList::Length方法代码示例

	/**
	 * Create a dropdown menu.
	 * @param parent        Parent window.
	 * @param list          Dropdown item list.
	 * @param selected      Index of the selected item in the list.
	 * @param button        Widget of the parent window doing the dropdown.
	 * @param instant_close Close the window when the mouse button is raised.
	 * @param position      Topleft position of the dropdown menu window.
	 * @param size          Size of the dropdown menu window.
	 * @param wi_colour     Colour of the parent widget.
	 * @param scroll        Dropdown menu has a scrollbar.
	 * @param widget        Widgets of the dropdown menu window.
	 */
	DropdownWindow(Window *parent, const DropDownList *list, int selected, int button, bool instant_close, const Point &position, const Dimension &size, Colours wi_colour, bool scroll)
			: Window(&_dropdown_desc)
	{
		assert(list->Length() > 0);

		this->position = position;

		this->CreateNestedTree();

		this->vscroll = this->GetScrollbar(WID_DM_SCROLL);

		uint items_width = size.width - (scroll ? NWidgetScrollbar::GetVerticalDimension().width : 0);
		NWidgetCore *nwi = this->GetWidget<NWidgetCore>(WID_DM_ITEMS);
		nwi->SetMinimalSize(items_width, size.height + 4);
		nwi->colour = wi_colour;

		nwi = this->GetWidget<NWidgetCore>(WID_DM_SCROLL);
		nwi->colour = wi_colour;

		this->GetWidget<NWidgetStacked>(WID_DM_SHOW_SCROLL)->SetDisplayedPlane(scroll ? 0 : SZSP_NONE);

		this->FinishInitNested(0);
		CLRBITS(this->flags, WF_WHITE_BORDER);

		/* Total length of list */
		int list_height = 0;
		for (const DropDownListItem * const *it = list->Begin(); it != list->End(); ++it) {
			const DropDownListItem *item = *it;
			list_height += item->Height(items_width);
		}

		/* Capacity is the average number of items visible */
		this->vscroll->SetCapacity(size.height * (uint16)list->Length() / list_height);
		this->vscroll->SetCount((uint16)list->Length());

		this->parent_wnd_class = parent->window_class;
		this->parent_wnd_num   = parent->window_number;
		this->parent_button    = button;
		this->list             = list;
		this->selected_index   = selected;
		this->click_delay      = 0;
		this->drag_mode        = instant_close;
		this->instant_close    = instant_close;
		this->left_button_state = _left_button_down;
	}

/**
 * Show a dropdown menu window near a widget of the parent window.
 * The result code of the items is their index in the \a strings list.
 * @param w             Parent window that wants the dropdown menu.
 * @param strings       Menu list, end with #INVALID_STRING_ID
 * @param selected      Index of initial selected item.
 * @param button        Button widget number of the parent window \a w that wants the dropdown menu.
 * @param disabled_mask Bitmask for disabled items (items with their bit set are displayed, but not selectable in the dropdown list).
 * @param hidden_mask   Bitmask for hidden items (items with their bit set are not copied to the dropdown list).
 * @param width         Width of the dropdown menu. If \c 0, use the width of parent widget \a button.
 */
void ShowDropDownMenu(Window *w, const StringID *strings, int selected, int button, uint32 disabled_mask, uint32 hidden_mask, uint width)
{
	DropDownList *list = new DropDownList();

	for (uint i = 0; strings[i] != INVALID_STRING_ID; i++) {
		if (!HasBit(hidden_mask, i)) {
			*list->Append() = new DropDownListStringItem(strings[i], i, HasBit(disabled_mask, i));
		}
	}

	/* No entries in the list? */
	if (list->Length() == 0) {
		delete list;
		return;
	}

	ShowDropDownList(w, list, selected, button, width);
}