CDockablePane in CMDIChildWndEx

[mesajflaviu]

I have an MDI app, built in VS2008. On some childframes, I have inserted some CDockablePane. But I have a probem: <b>They don't know to save their state and position</b>. The CDockablePane's ones that is part of CMainFrame know how to save their state and position without any written code, through CDockingManager class ...

But this is not the case, when CDockablePane is part of CChildFrame ...

I have tried this: https://stackoverflow.com/questions/...49341#39449341

not worked.

I have tried this:

int CChildFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
..........
	CDockState state;
	state.LoadState(_T("MyDockPane"));
	SetDockState(state);

	return 0;
}

and

void CChildFrame::OnDestroy()
{
	CDockState state;
	GetDockState(state);
	state.SaveState(_T("MyDockPane"));

	CMDIChildWndEx::OnDestroy();
}

I also tried this:

int CChildFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
	if (CMDIChildWndEx::OnCreate(lpCreateStruct) == -1)
		return -1;

	// enable Visual Studio 2005 style docking window behavior
	CDockingManager::SetDockingMode(DT_SMART);
	// enable Visual Studio 2005 style docking window auto-hide behavior
	EnableAutoHidePanes(CBRS_ALIGN_ANY);

	CMDIChildWndEx::m_bEnableFloatingBars = TRUE;

	// Create properties window
	CString strPropertiesWnd;
	BOOL bNameValid = strPropertiesWnd.LoadString(IDS_PROPERTIES_WND);
	ASSERT(bNameValid);
	if(! m_wndProperties.Create(strPropertiesWnd, this, CRect(0, 0, 200, 200), TRUE, ID_VIEW_PROPERTIESWND, WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN | CBRS_LEFT | CBRS_FLOAT_MULTI))
	{
		TRACE(_T("Failed to create Properties window\n"));
		return FALSE; // failed to create
	}
	if(! m_wndFilter.Create(_T("Filter"), this, CRect(0, 0, 200, 200), TRUE, 0, WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN | CBRS_LEFT | CBRS_FLOAT_MULTI))
	{
		TRACE(_T("Failed to create Properties window\n"));
		return FALSE; // failed to create
	}

	SetDockingWindowIcons(theApp.m_bHiColorIcons);

	AddPane(&m_wndFilter);
	AddPane(&m_wndProperties);
	m_wndFilter.EnableDocking(CBRS_ALIGN_ANY);
	m_wndProperties.EnableDocking(CBRS_ALIGN_ANY);
	DockPane(&m_wndFilter);
	CDockablePane* pTabbedBar = NULL;
	m_wndProperties.AttachToTabWnd(&m_wndFilter, DM_SHOW, TRUE, &pTabbedBar);
	EnableAutoHidePanes(CBRS_ALIGN_ANY);

	m_dockManager.LoadState(theApp.GetRegSectionPath(_T("ChildFrame")));
	m_dockManager.SetDockState();

	return 0;
}

and

void CChildFrame::OnDestroy()
{
	if(! m_wndProperties.IsFloating() && 
		! m_wndFilter.IsFloating())
	m_dockManager.SaveState(theApp.GetRegSectionPath(_T("ChildFrame")));

	CMDIChildWndEx::OnDestroy();
}

but sometimes I get memory leaks:

Detected memory leaks!
Dumping objects ->
f:\dd\vctools\vc7libs\ship\atlmfc\src\mfc\afxpanecontainer.cpp(2382) : {27179} client block at 0x0267BEC8, subtype c0, 156 bytes long.
a CPaneContainer object at $0267BEC8, 156 bytes long
Object dump complete.
The program '[8876] Model.exe: Native' has exited with code 0 (0x0).

and

DestroyWindow in CWnd::~CWnd; OnDestroy or PostNcDestroy in derived class will not be called.

is there any solution to save/restore the pane's from child frame ?

I attach here a sample code that illustrate the problem ...

[AvDav]

It passed a long time since I am not engaged in MFC-related development. However, as from what, I remember, during that timescale, you need to release any resource you have created in your application. For example, if it would the drawing facility like device context, there's a necessity to release it after acquiring its handle. The same technique is applicable here.

[mesajflaviu]

Thank you for your interest. Yes, I would clean any resources, if I would allocate it ... but in this case, I allocate no resources ...

[mesajflaviu]

I think I have found the problem: in the creation of m_wndFilter, I didn't put an distinct ID, but 0. Soon as I identified with ID, everything work ok, with the solution:

	m_dockManager.LoadState(theApp.GetRegSectionPath(_T("ChildFrame")));
	m_dockManager.SetDockState();

and

m_dockManager.SaveState(theApp.GetRegSectionPath(_T("ChildFrame")));

[ovidiucucu]

Two related remarks:

1. To easily find the source of memory leaks in MFC, put this code on top of each implementation (.cpp) file:

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

See also: How to detect memory leaks in MFC?

2. If you find in the output window

Warning: calling DestroyWindow in CWnd::~CWnd; OnDestroy or PostNcDestroy in derived class will not be called.

or

Warning: calling DestroyWindow in CDialog::~CDialog -- OnDestroy or PostNcDestroy in derived class will not be called.

means that an object of CWnd-derived or CDialog-derived class, is being destroyed without previously destroy the window. As a consequence if you handled WM_DESTROY message or overrode PostNcDestroy, they will never called.
One solution to get rid this issue by calling DestroyWindow in the derived class destructor (of course if the window is not yet destroyed).

[mesajflaviu]

Ovidiu, thank you for your observations.

The funny thing here is that I get rid of these ML and warnings, solving the problem: when I create the pane, I give him a real ID, not 0 ... I am thinking that inside of MFC code is searching for the pane ID, and as long as it didn't found this ID, the resources were not freed ... I guess.