Re: Adding a view to MDI, by hand, special requirements ???

Scot T Brennecke <>
Mon, 24 Aug 2009 03:22:31 -0500
You're doing things the hard way here. Note that the child frame is not to be a direct child of the main frame. There is another
window, known as the MDICLIENT, which is the child of the main frame, and the parent of the child frames.

Look at the MFC source code in the CMultiDocTemplate::OpenDocumentFile and CDocTemplate::CreateNewFrame functions, found in
docmulti.cpp and doctempl.cpp, respectively Once you understand how these functions open the initial document, frame and view, it
will become more clear how to extend that to open new child frames with other views on the same document.

FHDB wrote:

VS2008, XP
I have been trying without success to add a view to a MDI program. The goal
is: for a document, two active views, each displayed in separate windows,
both constantly updated. The Microsoft chart indicates the view is a child of
a window, so the code is intended to:

1. Create a child frame of the application mainframe.
2. Creat a view and make it a child of the above child frame.
3. Add the view to the document.

It appears that while walking the views, MFC doesn't like the hWnd of the
view. The view was created by the wizard.

BOOL CdualDoc::AddFloatView()
    CMDIFrameWnd* pMainWnd = (CMDIFrameWnd*)AfxGetApp()->m_pMainWnd;
     CMDIChildWnd* pParentFrame = new CMDIChildWnd;
    CRect rect(200, 200, 600, 600);
    pParentFrame->Create(_T("CMDIChildWnd"), _T("Points"),
    HWND h_Parent = pParentFrame->m_hWnd;
    FloatView* pFloatView = new FloatView;
    HWND h_View = pFloatView->m_hWnd;
    SetParent( h_View, h_Parent );
    this->AddView( pFloatView );
    pFloatView->SetScrollSizes( MM_TEXT, CSize(100, 100) );

Fails in doccore.cpp at ASSERT(::IsWindow(pView->m_hWnd));

void CDocument::UpdateFrameCounts()
     // assumes 1 doc per frame
    // walk all frames of views (mark and sweep approach)
    POSITION pos = GetFirstViewPosition();
    while (pos != NULL)
        CView* pView = GetNextView(pos);
        if (pView->IsWindowVisible()) // Do not count invisible windows.
            CFrameWnd* pFrame = pView->GetParentFrame();
            if (pFrame != NULL)
                pFrame->m_nWindow = -1; // unknown

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