How to add control bars to dialog boxes in MFC

In a Microsoft Foundation Classes (MFC) application, you can attach control bars such as status bars and toolbars to a frame window. However, for many applications a simple dialog box-based user interface is sufficient. MFC does not provide built-in support for adding control bars to dialog boxes.

DLGCBR32 is a sample application that demonstrates how to add a status bar and toolbar to a dialog box. In addition, it demonstrates a number of techniques related to using a modeless dialog box as the main window of an MFC application. The following files are available for download from the Microsoft Download Center:

Visual C++ 6.0

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Visual C++ .NET

Release Date: July 2, 2002

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To add a control bar to a dialog box, you must create the control bar as usual, and then make room for the control bar within the client area of the dialog box. For the control bar to function properly, the dialog box must duplicate some of the functionality of frame windows. If you want ON_UPDATE_COMMAND_UI handlers to work for the control bars, you also need to derive new control bar classes, and handle the WM_IDLEUPDATECMDUI message. If your dialog box is not the main window of your application, you will also need to modify its parent frame window to pass the WM_IDLEUPDATECMDUI message on to the dialog box's control bars.

To make room for a control bar within the client area of the dialog box, follow these steps in your dialog box's OnInitDialog() function:

1. Create the control bars.
2. Figure out how much room the control bars will take by using the reposQuery option of RepositionBars():

         CRect rcClientStart;
         CRect rcClientNow;
         GetClientRect(rcClientStart);
         RepositionBars(AFX_IDW_CONTROLBAR_FIRST,
                        AFX_IDW_CONTROLBAR_LAST,
                        0, reposQuery, rcClientNow);
   						

3. Move all the controls in your dialog box to account for space used by control bars at the top or left of the client area. If your dialog box contains a menu, you also need to account for the space used by the menu:

         CPoint ptOffset(rcClientNow.left - rcClientStart.left,
                          rcClientNow.top - rcClientStart.top);
   
         CRect  rcChild;
         CWnd* pwndChild = GetWindow(GW_CHILD);
         while (pwndChild)
         {
            pwndChild->GetWindowRect(rcChild);
            ScreenToClient(rcChild);
            rcChild.OffsetRect(ptOffset);
            pwndChild->MoveWindow(rcChild, FALSE);
            pwndChild = pwndChild->GetNextWindow();
         }
   						

4. Increase the dialog box window dimensions by the amount of space used by the control bars:

         CRect rcWindow;
         GetWindowRect(rcWindow);
         rcWindow.right += rcClientStart.Width() - rcClientNow.Width();
         rcWindow.bottom += rcClientStart.Height() - rcClientNow.Height();
         MoveWindow(rcWindow, FALSE);
   						

5. Position the control bars using RepositionBars().

To update the first pane of a status bar with menu item text, you must handle WM_MENUSELECT, WM_ENTERIDLE, and WM_SETMESSAGESTRING in your dialog box class. You need to duplicate the functionality of the CFrameWnd handlers for these messages. See the CModelessMain class in the sample program for examples of these message handlers.

To allow ON_UPDATE_COMMAND_UI handlers to work for other status bar panes and for toolbar buttons, you must derive new control bar classes and implement a message handler for WM_IDLEUPDATECMDUI. This is necessary because the default control bar implementations of OnUpdateCmdUI() assume the parent window is a frame window. However, it doesn't do anything but pass the parent window pointer on to a function which only requires a CCmdTarget pointer. Therefore, you can temporarily tell OnUpdateCmdUI() that the parent window pointer you are giving it is a CFrameWnd pointer to meet the compiler requirements. Here's an example: To pass WM_IDLEUPDATECMDUI messages on to dialog boxes other than the main window, save dialog pointers in your frame window class and create a WM_IDLEUPDATECMDUI handler in that class. The handler should send the WM_IDLEUPDATECMDUI message on to the dialog child windows by using CWnd::SendMessageToDescendants(). Then perform default processing for the message within the frame window.