HOWTO: Change Window Background Color with Foundation Classes

ID: Q103786

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

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:

Create a generic CWnd class with ClassWizard.

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

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.

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.

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 :
Version : winnt:1.0,2.0,2.1,4.0
Platform : winnt
Issue type : kbhowto