CSplitterWnd and OnSize

From: Michael Chisholm (chisholm_at_mitre.org)
Date: 07/22/04 

Date: Thu, 22 Jul 2004 15:06:11 -0400

I've seen people complain about the following problem in many posts.
Others all seem to answer with the same solution--which does not work.
Perhaps it worked in an earlier version of the libraries... I don't
know. But I still have the problem, and would like a (nice) workaround.
  I'm sure I can work around it in an ugly way, but I would like to know
the "right" way to do this. I have Visual Studio .NET 2003 (Microsoft
Visual C++ .NET 69462-270-0000007-18596)

My main frame uses a CSplitterWnd in its client area. I want to control
how the panes resize when the user resizes the main frame. But
CMainFrame::OnSize() is being called before the CSplitterWnd is
completely created, so it is in an inconsistent state, and the
operations I need to do on it cause the program to crash (NULL pointers
get dereferenced). I need a way to determine whether the splitter is
"ready" for me to do stuff with it. The only "solution" I've seen
posted is to call CSplitterWnd::GetSafeHwnd() and compare to NULL. But
that method returns a non-NULL value even when the splitter is not
ready, so it does not work. FWIW, the code is below (the crash is in
the first GetRowInfo() call). Any help would be appreciated.

BOOL CMainFrame::OnCreateClient(LPCREATESTRUCT lpcs, CCreateContext*
pContext)
{
   // TODO: Add your specialized code here and/or call the base class
// return CFrameWnd::OnCreateClient(lpcs, pContext);

   if (!splitter.CreateStatic(this, 2, 1))
     return FALSE;

...etc...
}

void CMainFrame::OnSize(UINT nType, int cx, int cy)
{
   CFrameWnd::OnSize(nType, cx, cy);

   // TODO: Add your message handler code here
   if (splitter.GetSafeHwnd()!=NULL)
   {
     CRect r;
     GetClientRect(&r);

     int upperRowHeight, utemp;
     int lowerRowHeight, ltemp;
     splitter.GetRowInfo(0, upperRowHeight, utemp);
     splitter.GetRowInfo(1, lowerRowHeight, ltemp);

     //preserve the height of the lower pane if possible
     upperRowHeight = r.bottom - lowerRowHeight;

     splitter.SetRowInfo(0, upperRowHeight, utemp);
     splitter.RecalcLayout();
   }
}

Andy