In MFC, the MDICLIENT window is stored in a public HWND
member variable (
m_hwndMDIClient) in the
CMDIFrameWnd class.
CMDIFrameWnd is the base class of the
CMainFrame class in an AppWizard-generated MDI application.
To
subclass the MDICLIENT window, you must perform the following three steps
:
- Use ClassWizard to derive a class from CWnd that is named CMDIClientWnd.
- Add theGetSuperWndProcAddr() function to CMDIClientWnd.
- Use CMDIClientWnd to subclass the MDICLIENT window.
After you have subclassed the MDICLIENT window with
CMDIClientWnd, message handlers and other functions can be placed in the
CMDIClientWnd class.
Here is more detailed information about each of the steps:
- Use ClassWizard to derive a class from CWnd that is named CMDIClientWnd.
For details on how to derive a class using
ClassWizard, see the User's Guide documentation on ClassWizard, specifically
the "Adding a New Class" section.
Note Visual Studio .NET does not have ClassWizard. Instead, use the Add Class dialog box to access the MFC Class Wizard. For more information
see the MSDN topic "Where Are ClassWizard and WizardBar in Visual C++ .NET?" - Add the GetSuperWndProcAddr() function to CMDIClientWnd.
Note You only have to perform this step if you are using 16-bit
versions of Visual C++, not 32-bit. The 32-bit versions of Visual C++ implement
this functionality for you.
Once the class has been created, add the
following prototype to the header file:
public:
WNDPROC* GetSuperWndProcAddr();
WNDPROC* CMDIClientWnd::GetSuperWndProcAddr() {
static WNDPROC NEAR pfnSuper = NULL;
return &pfnSuper;
}
- Use CMDIClientWnd to subclass the MDICLIENT window in the CMDIFrameWnd class (typically CMainFrame).
To the CMainFrame class, add a public variable of type CMDIClientWnd that is named m_wndMDIClient. Then modify OnCreate for CMainFrame as follows:
int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
if (CMDIFrameWnd::OnCreate(lpCreateStruct) == -1)
return -1;
if (!m_wndMDIClient.SubclassWindow (m_hWndMDIClient)) { // Add
TRACE ("Failed to subclass MDI client window\n"); // Add
return (-1); // Add
} // Add
...
}
After completing these three steps, you can use ClassWizard to
add message handlers to
CMDIClientWnd similar to the one below. This changes the background color of
MDICLIENT.
Note In Visual Studio .NET, you can add a message handler by selecting
CMDIClientWnd in
ClassView and in
Properties under
Messages choose WM_ERASEBKGND message handler method (“
OnEraseBkgnd”).
BOOL CMDIClientWnd::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;
}
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