MFC - List Box

Quiz

A list box displays a list of items, such as filenames, that the user can view and select. A List box is represented by CListBox class. In a single-selection list box, the user can select only one item. In a multiple-selection list box, a range of items can be selected. When the user selects an item, it is highlighted and the list box sends a notification message to the parent window.

Here is the list of methods in CListBox class.

Sr.No.	Name & Description
1	AddString Adds a string to a list box.
2	CharToItem Override to provide custom WM_CHAR handling for owner-draw list boxes which don't have strings.
3	CompareItem Called by the framework to determine the position of a new item in a sorted owner-draw list box.
4	Create Creates the Windows list box and attaches it to the CListBox object.
5	DeleteItem Called by the framework when the user deletes an item from an owner-draw list box.
6	DeleteString Deletes a string from a list box.
7	Dir Adds filenames, drives, or both from the current directory to a list box.
8	DrawItem Called by the framework when a visualaspect of an owner-draw list box changes.
9	FindString Searches for a string in a list box.
10	FindStringExact Finds the first list-box string that matches a specified string.
11	GetAnchorIndex Retrieves the zero-based index of the current anchor item in a list box.
12	GetCaretIndex Determines the index of the item that has the focus rectangle in a multipleselection list box.
13	GetCount Returns the number of strings in a list box.
14	GetCurSel Returns the zero-based index of the currently selected string in a list box.
15	GetHorizontalExtent Returns the width in pixels that a list box can be scrolled horizontally.
16	GetItemData Returns the 32-bit value associated with the list-box item.
17	GetItemDataPtr Returns a pointer to a list-box item.
18	GetItemHeight Determines the height of items in a list box.
19	GetItemRect Returns the bounding rectangle of the list-box item as it is currently displayed.
20	GetListBoxInfo Retrieves the number of items per column.
21	GetLocale Retrieves the locale identifier for a list box.
22	GetSel Returns the selection state of a list-box item.
23	GetSelCount Returns the number of strings currently selected in a multiple-selection list box.
24	GetSelItems Returns the indices of the strings currently selected in a list box.
25	GetText Copies a list-box item into a buffer.
26	GetTextLen Returns the length in bytes of a list-box item.
27	GetTopIndex Returns the index of the first visible string in a list box.
28	InitStorage Preallocates blocks of memory for list box items and strings.
29	InsertString Inserts a string at a specific location in a list box.
30	ItemFromPoint Returns the index of the list-box item nearest a point.
31	MeasureItem Called by the framework when an ownerdraw list box is created to determine listbox dimensions.
32	ResetContent Clears all the entries from a list box.
33	SelectString Searches for and selects a string in a single-selection list box.
34	SelItemRange Selects or deselects a range of strings in a multiple-selection list box.
35	SetAnchorIndex Sets the anchor in a multiple-selection list box to begin an extended selection.
36	SetCaretIndex Sets the focus rectangle to the item at the specified index in a multipleselection list box.
37	SetColumnWidth Sets the column width of a multicolumn list box.
38	SetCurSel Selects a list-box string.
39	SetHorizontalExtent Sets the width in pixels that a list box can be scrolled horizontally.
40	SetItemData Sets the 32-bit value associated with the list-box item.
41	SetItemDataPtr Sets a pointer to the list-box item.
42	SetItemHeight Sets the height of items in a list box.
43	SetLocale Sets the locale identifier for a list box.
44	SetSel Selects or deselects a list-box item in a multiple-selection list box.
45	SetTabStops Sets the tab-stop positions in a list box.
46	SetTopIndex Sets the zero-based index of the first visible string in a list box.
47	VKeyToItem Override to provide custom WM_KEYDOWN handling for list boxes with the LBS_WANTKEYBOARDINPUT style set.

Here are some mapping entries for Listbox −

Message	Map entry	Description
LBN_DBLCLK	ON_LBN_DBLCLK( <id>, <memberFxn> )	The framework calls this member function when list item is double clicked.
LBN_KILLFOCUS	ON_LBN_KILLFOCUS( <id>, <memberFxn> )	The framework calls this member function immediately before losing the input focus.
LBN_SELCHANGE	ON_LBN_SELCHANGE( <id>, <memberFxn> )	The framework calls this member function when selection is changed.
LBN_SETFOCUS	ON_LBN_SETFOCUS( <id>, <memberFxn> )	The framework calls this member function after gaining the input focus.

Let us look into a simple example of List box by creating a new MFC dialog based application.

Step 1 − Once the project is created, you will see the TODO line which is the Caption of Text Control. Remove the Caption and set its ID to IDC_STATIC_TXT.

Step 2 − Drag List Box from the Toolbox.

Step 3 − Add the control variable for the Text control.

Step 4 − Add the Value variable for the Text control.

Step 5 − Add the control variable for the List Box control.

Step 6 − Add the event handler for the List Box control.

Step 7 − Select the LBN_SELCHANGE from the message type and enter name for the event handler.

Step 8 − Add one function, which will load the list box.

void CMFCListBoxDlg::LoadListBox() {
   CString str = _T("");
   for (int i = 0; i<10; i++) {

      str.Format(_T("Item %d"), i);
      m_listBox.AddString(str);
   }
}

Step 9 − Call the function from CMFCListBoxDlg::OnInitDialog() as shown in the following code.

BOOL CMFCListBoxDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();

   // Set the icon for this dialog. The framework does this automatically
   // when the application's main window is not a dialog
   SetIcon(m_hIcon, TRUE);       // Set big icon
   SetIcon(m_hIcon, FALSE);      // Set small icon

   // TODO: Add extra initialization here
   LoadListBox();
   return TRUE; // return TRUE unless you set the focus to a control
}

Step 10 − Here is the event handler implementation. This will display the current selected item from the List Box.

void CMFCListBoxDlg::OnLbnSelchangeList1() {
   // TODO: Add your control notification handler code here
   m_listBox.GetText(m_listBox.GetCurSel(),m_strItemSelected);
   UpdateData(FALSE);
}

Step 11 − When the above code is compiled and executed, you will see the following output.

Step 12 − When you select any item, it will be displayed on the Text Control.

mfc_windows_controls.htm

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