Q103786: HOWTO: Change Window Background Color with Foundation Classes

Article: Q103786
Product(s): Microsoft C Compiler
Version(s): winnt:1.0,2.0,2.1,4.0
Operating System(s): 
Keyword(s): 
Last Modified: 07-MAY-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5, 1.51, 1.52 
   - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1, 4.0 
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SUMMARY
=======

To change the background color for a CView, CFrameWnd, or CWnd object, process
the WM_ERASEBKGND message. The sample code below demonstrates how to do this.

MORE INFORMATION
================

Sample Code
-----------

      BOOL CSampleView::OnEraseBkgnd(CDC* pDC)
     {
        // Set brush to desired background color
        CBrush backBrush(RGB(255, 128, 128));

        // Save old brush
        CBrush* pOldBrush = pDC->SelectObject(&backBrush);

        CRect rect;
        pDC->GetClipBox(&rect);     // Erase the area needed

        pDC->PatBlt(rect.left, rect.top, rect.Width(), rect.Height(),
            PATCOPY);
        pDC->SelectObject(pOldBrush);
        return TRUE;
     }

To change the background color for a CMDIFrameWnd, you must subclass the multiple
document interface (MDI) client window (window in the client area of
CMDIFrameWnd) and process the WM_ERASEBKGND message. For more information about
the MDI client window in an MDI application, see chapter 18 in "Programming
Windows 3.1 - Third Edition" by Charles Petzold. For an example that shows how
to subclass the MDICLIENT window, please see the article in the Microsoft
Knowledge Base:

  Q129471 HOWTO: Subclass the MDICLIENT by Using MFC

To change the background color of an MDI client window (client area of a
CMDIFrameWnd), perform the following steps using an AppWizard-generated
application:

1. Create a generic CWnd class with ClassWizard.

2. Add a member variable, using the type of the CWnd class from step 1, to the
  CMainFrame class.

3. In the CMainFrame's OnCreate member function, after the call to the base
  class CMDIFrameWnd::OnCreate(), add a call to SubclassWindow(). For example:

        if (!m_wndNewClient.SubclassWindow(m_hWndMDIClient))
        {
          TRACE("Failed to subclass MDI client window\n");
          return -1;      // fail to create
        }

  m_hWndMDIClient is the member variable of CMDIFrameWnd that contains the
  handle to the MDI client window. Also, replace "m_wndNewClient" with the data
  member that you created in step 2.

4. Whenever a window is subclassed, the GetSuperWndProcAddr() member function
  for the CWnd needs to be overridden to provide storage for the old window
  procedure's address. To do that, add the following function to the
  implementation of the CWnd class created in step 1:

        WNDPROC* CNewClientWnd::GetSuperWndProcAddr()
        {
           static WNDPROC NEAR pfnSuper = NULL;
           return &pfnSuper;
        }

  NOTE: Replace "CNewClientWnd" above with the name of your class.

  For more information on subclassing windows using the Microsoft Foundation
  Classes, please see the following materials:

   - "Class Library Reference" for functions CWnd::SubclassWindow(),
     CWnd::GetSuperWndProcAddr(), and CWnd::SubclassDlgItem()

   - Query on the following words in the Microsoft Knowledge Base:

  subclass and sample and mfc

   - See the CTRLTEST MFC sample application that is provided with Visual C++
     for Windows and Visual C++ 32-bit Edition.

   - See the article titled "Subclassing Windows with the Microsoft Foundation
     Class Library" on the Microsoft Developer Network (MSDN) CD.

5. Override the WM_ERASEBKGND message for the generic CWnd class, using the code
  listed above.

To change the background color of a CFormView object, either process the
WM_ERASEBKGND message and use the code above or process the WM_CTLCOLOR message
to change the background color.

For more information on changing the background color of a dialog box by
processing the WM_CTLCOLOR message, please query on the following words in the
Microsoft Knowledge Base:

  changing and background and color and MFC

Additional query words:

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbMFC
Version           : winnt:1.0,2.0,2.1,4.0
Issue type        : kbhowto

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