Re: How to add a CWnd subclass object to a CDialog?

From:

"Doug Harrison [MVP]" <dsh@mvps.org>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 04 Mar 2009 22:07:37 -0600

Message-ID:

<0ljuq41l4kuqk033mlkvcp1ancqdbm7i37@4ax.com>

On Wed, 4 Mar 2009 19:42:46 -0800 (PST), fifth <Buddhist.CHinA@gmail.com>
wrote:

I have subclassed a CWnd, then I want to add it to a main CDialog.

I coded like this,

BOOL CMainDialog::OnInitDialog()
{
   CDialog::OnInitDialog();

   // TODO: Add extra initialization here
   m_myWnd = new CMyWnd(this);

In MFC-land, the usual way is to make the variable an object instead of a
pointer and to use two-phase initialization to create the HWND part.

   return TRUE; // return TRUE unless you set the focus to a control
}

CMyWnd::CMyWnd(CWnd* pParent)
{
   RECT rect;
   pParent->GetWindowRect(&rect);
   RECT myrect;
   myrect.left = rect.left + 5;
   myrect.top = rect.top + 5;
   myrect.right = rect.right - 5;
   myrect.bottom = rect.bottom - 30;

   Create(_T("CMyWnd"), _T("MyWnd"), WS_CHILD | WS_VISIBLE |
WS_BORDER, myrect, pParent, IDC_CMyWnd);
}

However, the inner window did't showed up as expected, did I miss sth?

The GetWindowRect function returns screen coordinates, but child window
positions are specified in terms of client coordinates. So replace the
GetWindowRect call with GetClientRect; note also that rect.left and
rect.top are zero by definition for client area coordinates. Finally, there
are probably better ways to determine the offsets than pulling magic
numbers such as 5 and 30 out of a hat. See GetSystemMetrics for a start.

--
Doug Harrison
Visual C++ MVP