SAMPLE: MDISubCl.exe Changes Background Color of MDI Client

ID: Q75002

The information in this article applies to:

Microsoft Windows Software Development Kit (SDK) for Windows versions 3.0, 3.1

SUMMARY

MDISubCl.exe demonstrates how to alter the default background color of an MDI client window by subclassing the MDI client window procedure and processing the WM_ERASEBKGND message. All other messages are passed to the original MDI client window procedure. Normally, a multiple-document interface (MDI) client window defines its background color to be the system color value COLOR_BACKGROUND+1, which is defined in the Windows SDK file WINDOWS.H. This value corresponds to the window background color defined by the user in the Control Panel.

MORE INFORMATION

The following file is available for download from the Microsoft Software Library:

 ~ MDISubCl.exe (size: 24085 bytes)

For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from Online Services

During processing of the WM_ERASEBKGND message, the class word that defines the MDI client's background color is altered using the SetClassWord() function. Then, control is passed to the original MDI client window procedure to paint and update the window. When control returns from the original MDI client window procedure, the MDI client's class word that defines the background color is set back to its original value so that other MDI applications currently running are not affected.

The following sample code from MDISubCl.exe is a sample window procedure that you can use to subclass the default MDI client window procedure:

   LONG FAR PASCAL MdiClientWndProc(hwnd, msg, wParam, lParam)
   HWND hwnd;
   WORD msg, wParam;
   LONG lParam;
   {
     LONG lRetCode;

     switch (msg)
       {
     case WM_ERASEBKGND:
       {
       HBRUSH hbrNew, hbrOld;
                                          // create a solid purple brush
       hbrNew = CreateSolidBrush(RGB(75, 45, 145));
                                       // set the class background color
       hbrOld = SetClassWord(hwnd, GCW_HBRBACKGROUND, hbrNew);
                      // let the old window procedure handle the message
       lRetCode = CallWindowProc(lpfnMDIClientOld, hwnd, msg, wParam,
                   lParam);
                                // set background back to original value
       SetClassWord(hwnd, GCW_HBRBACKGROUND, hbrOld);
       DeleteObject(hbrNew);         // all done with this, so delete it
       break;
       }

     default:
       lRetCode = CallWindowProc(lpfnMDIClientOld, hwnd, msg, wParam,
                   lParam);
       break;
       }
     return lRetCode;
   }

Additional query words: Keywords : kbcode kbfile kbsample kbMDI kbGrpUser kbWinOS310 kbWndw kbWinOS300

Last Reviewed: December 24, 1998