How to retrieve the size and position of the initial document of the MDI interface of an MFC application?

Question

https://1drv.ms/u/c/506e10ab962c3b92/EdScY7Cq2RdOgKdPdjCBTecB_WZLBYTT1GtuvO5klbFXbg?e=Su7LFP

Above should be a public link to the project.

At this point there is a dimensioning problem with the overlay window. So far I would like to cover just the client area of the child window. How can that be done?

Answer 1

SetWindowPos takes client coordinates (relative to parent window), not screen coordinates. So does CWnd::CreateEx.

GetDlgItem(AFX_IDW_PANE_FIRST) on an MDI main Frame returns its m_wndClientArea, in which you can drag child frames around. It is not an MDI child.

GetClientRect returns the client area's location relative to the window itself. For m_wndClientArea and views. it is basically the window itself minus borders.

I see you handled OnMDIActivate (good) but I don't see how you handled moving/resizing of the child frame/splitter.

Answer 2

void CChildFrame::OnSize(UINT nType, int cx, int cy)
{
    CMDIChildWndEx::OnSize(nType, cx, cy);
    // Get the active view
    CView* pView = GetActiveView();
    if (pView)
    {
        // Try to cast to your specific view class
        CMFCMDIOverlayWndExample002View* pMyView = DYNAMIC_DOWNCAST(CMFCMDIOverlayWndExample002View, pView);
        if (pMyView)
        {
            // Get the main frame window
            CMainFrame* pMainFrame = DYNAMIC_DOWNCAST(CMainFrame, AfxGetMainWnd());
            if (pMainFrame)
            {
                pMainFrame->PrintActiveViewClientRect();
            }
        }
    }
}
void CChildFrame::OnMDIActivate(BOOL bActivate, CWnd* pActivateWnd, CWnd* pDeactivateWnd)
{
    CMDIChildWndEx::OnMDIActivate(bActivate, pActivateWnd, pDeactivateWnd);
    if (bActivate)
    {
        // Get the active view
        CView* pView = GetActiveView();
        if (pView)
        {
            // Try to cast to your specific view class
            CMFCMDIOverlayWndExample002View* pMyView = DYNAMIC_DOWNCAST(CMFCMDIOverlayWndExample002View, pView);
            if (pMyView)
            {
                // Get the main frame window
                CMainFrame* pMainFrame = DYNAMIC_DOWNCAST(CMainFrame, AfxGetMainWnd());
                if (pMainFrame)
                {
                    pMainFrame->PrintActiveViewClientRect();
                }
            }
        }
    }
}


void CMainFrame::CreateOrUpdateOverlayOverActiveView()
{
	CMDIChildWnd* pChild = MDIGetActive();
	if (!pChild) return;
	CView* pView = pChild->GetActiveView();
	if (!pView) return;
	CMFCMDIOverlayWndExample002View* pMyView = DYNAMIC_DOWNCAST(CMFCMDIOverlayWndExample002View, pView);
	if (!pMyView) return;
	CRect clientRect = pMyView->GetClientRectOfView();
	CPoint topLeft = clientRect.TopLeft();
	CPoint bottomRight = clientRect.BottomRight();
	int width = clientRect.Width();
	int height = clientRect.Height();
	pMyView->ClientToScreen(&topLeft);
	pMyView->ClientToScreen(&bottomRight);
	RECT screenRect = { topLeft.x, topLeft.y, bottomRight.x, bottomRight.y };
	if (!::IsWindow(m_hOverlayWnd))
	{
		static bool bClassRegistered = false;
		if (!bClassRegistered)
		{
			WNDCLASS wc = { 0 };
			wc.lpfnWndProc = OverlayWndProc; // Static WNDPROC defined above
			wc.hInstance = AfxGetInstanceHandle();
			wc.lpszClassName = _T("OverlayWindowClass");
			wc.hbrBackground = (HBRUSH)GetStockObject(GRAY_BRUSH);
			RegisterClass(&wc);
			bClassRegistered = true;
		}
		m_hOverlayWnd = ::CreateWindowEx(
			WS_EX_LAYERED | WS_EX_TRANSPARENT | WS_EX_TOOLWINDOW,
			_T("OverlayWindowClass"),
			_T("Overlay"),
			WS_POPUP,
			screenRect.left, screenRect.top,
			screenRect.right, screenRect.bottom,
			nullptr, nullptr, AfxGetInstanceHandle(), nullptr);
		if (!m_hOverlayWnd)
		{
			TRACE("Overlay creation failed, Error: %d\n", ::GetLastError());
			return;
		}
		::SetLayeredWindowAttributes(m_hOverlayWnd, 0, 128, LWA_ALPHA);
		::ShowWindow(m_hOverlayWnd, SW_SHOWNOACTIVATE);
		::UpdateWindow(m_hOverlayWnd);
	}
	::SetWindowPos(
		m_hOverlayWnd, HWND_TOPMOST,
		screenRect.left, screenRect.top,
		width, height,
		SWP_NOACTIVATE | SWP_SHOWWINDOW);
}
void CMainFrame::PrintActiveViewClientRect()
{
	CreateOrUpdateOverlayOverActiveView();
	// Get the active MDI child window
	CMDIChildWnd* pChild = MDIGetActive();
	if (!pChild)
		return;
	// Get the active view
	CView* pView = pChild->GetActiveView();
	if (!pView)
		return;
	// Try to cast to your specific view class
	CMFCMDIOverlayWndExample002View* pMyView = DYNAMIC_DOWNCAST(CMFCMDIOverlayWndExample002View, pView);
	if (!pMyView)
		return;
	// Get the client rectangle using your new function
	CRect rect = pMyView->GetClientRectOfView();
	// Print to the console
	std::cout << "Active View Client Rect: left=" << rect.left
		<< ", top=" << rect.top
		<< ", right=" << rect.right
		<< ", bottom=" << rect.bottom
		<< ", width=" << rect.Width()
		<< ", height=" << rect.Height()
		<< std::endl;
}

If this relative dogma is followed there should be a correctly sized overlay window showing up.

This is what the resultant overlay window should look like.