Re: DestroyWindow() not destroying child windows

From:
"PaulH" <paul.heil@gmail.com>
Newsgroups:
microsoft.public.vc.atl
Date:
31 Oct 2006 11:58:37 -0800
Message-ID:
<1162324717.624245.92480@e3g2000cwe.googlegroups.com>
Alexander Nickolov wrote:

Why do you expect your method to be called? It'd only
be called if your code did the destruction control by control.
Instead, Windows does the destruction for you by sending
WM_DESTROY to all of your controls. Your classes won't
know about that fact naturally, unless you subclass those
controls.

Besides, you have a clear programmatic error if your wrappers
do not get reinitialized. Are you by chance using static or
global variables?

--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://www.mvps.org/vcfaq
=====================================

"PaulH" <paul.heil@gmail.com> wrote in message
news:1162002872.050847.275460@k70g2000cwa.googlegroups.com...

Alexander Nickolov wrote:

How do you know they aren't being destroyed? Do you
subclass them?

--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://www.mvps.org/vcfaq
=====================================

"PaulH" <paul.heil@gmail.com> wrote in message
news:1161878716.976991.105390@i3g2000cwc.googlegroups.com...

I have a WTL SDI program where the views can change. To accomplish
this, a SwitchView() function is called and the view to switch to is
specified:

DIALOGS m_CurView; //DIALOGS is an enum with identifiers for each view
std::map<DIALOGS, CBase*> m_mViews;

BOOL CMainFrame::SwitchView(DIALOGS dlg)
{

   if (m_mViews[m_CurView]->BaseIsWindow())
       m_mViews[m_CurView]->BaseDestroyWindow();

   m_CurView = dlg;
   m_hWndClient = m_mViews[m_CurView]->BaseCreate(m_hWnd);
   if (!m_mViews[m_CurView]->BaseIsWindow())
       return FALSE;

   RECT rcWnd = {0};
   GetClientRect(&rcWnd);
   m_mViews[m_CurView]->BaseMoveWindow(&rcWnd, FALSE);
   m_mViews[m_CurView]->BaseShowWindow(SW_SHOW);
   m_mViews[m_CurView]->BaseSetFocus();

   return TRUE;
}

This destroys the current view and creates the requested view. But,
when the DestroyWindow() is called on the current view, the child
windows (such as CStatics) don't get the WM_DESTROY message, so when I
return to the dialog, I get all kinds of nasty failures.

Each view class derives from a CBaseViewT class so that I can specify
them generically in the CMainFrm. (as above in the SwitchView()
function).

class CBase
{
public:
   virtual BOOL BasePreTranslateMessage(MSG* pMsg) = 0;
   virtual HWND BaseCreate(HWND hWndParent, LPARAM dwInitParam = NULL)
= 0;
   virtual BOOL BaseMoveWindow(LPCRECT lpRect, BOOL bRepaint = TRUE) =
0;
   virtual BOOL BaseDestroyWindow() = 0;
   virtual HWND BaseSetFocus() = 0;
   virtual BOOL BaseIsWindow() = 0;
   virtual BOOL BaseShowWindow(int nCmdShow) = 0;
};

template <class T>
class CBaseViewT : public CBase
{
   //...Implementation of virtual functions in CBase() that just call
the CWindow() counterparts
   // For Example:
   BOOL BaseDestroyWindow()
   {
       T* pT = static_cast<T*>(this);
       return pT->DestroyWindow();
   };
};

Can anybody tell me why the child windows of the views aren't being
properly destroyed?

Thanks,
PaulH


I put a breakpoint on CWindow::DestroyWindow()
Also, when the parent class is re-created and it processes its DDX_MAP,
the controls get bypassed because their m_hWnd isn't NULL.

-Paul


No, no statics or globals being used. I agree there's a programmatic
error, that's what I'm trying to track down.
Why do I expect which of my methods to be called?
I expect to see the CWindow::OnDestroy() method to be called because
that's what each of the controls is wrapped with since they're WTL. Is
this what you mean by subclassing?

Thanks,
-Paul

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