MFC MDI tab activation

Question

Hi,

I have an MDI application. In case , there are several documents open and I close one, the newly activated document is the last one in the frame , not the last one I visited. How do I force the application to activate a document my choice after a random one was closed.

Answer 1

You could reinvent the wheel and add a resizable, docking tab control to your application.  You would have complete programmatical control over your tabs.  It requires some understanding of dockable panes and you may have to renovate your app so it's a design issue.

Here are the links: note the remarks and examples.

http://msdn.microsoft.com/en-us/library/bb982549(v=vs.110).aspx

http://msdn.microsoft.com/en-us/library/bb984302.aspx

Here's how I did it:

// CreateTabControl - Creates the tab control.

BOOL CTheApp::CreateTabControl(int nID)
{

	CRect rectDummy;
	bp_dock->GetWindowRect(&rectDummy);
	bp_dock->ScreenToClient(&rectDummy);
	
	if (!m_wndTabs.Create(CMFCTabCtrl::STYLE_3D_ROUNDED_SCROLL, rectDummy, bp_dock, nID, CMFCTabCtrl::LOCATION_TOP, false))
	{
		AfxMessageBox("Failed to create the tab control.");
		return false;  
	}

	m_wndTabs.EnableAutoColor();
	m_wndTabs.EnableActiveTabCloseButton();
	m_wndTabs.EnableTabDocumentsMenu();
	m_wndTabs.SetActiveTabBoldFont();
	m_wndTabs.SetFlatFrame(false, true);
	m_wndTabs.SetDrawFrame();
	m_wndTabs.EnableTabSwap(true);

	created_tab_control = true;

	return true;

} // CreateTabControl(...)

bp_dock is the basepane/mdiclient.

For reasons similar to yours I decided to make the conversion, but it has added a lot of time to my project.

---

PAC

Answer 2

Thanks PAC!

Answer 3

I think there is much simpler solution, in agreement with my MEMC approach.

Any time active tab changes, CMFCBaseTabCtrl object send a message to the MDI client area window. Since default implementation of CMDIClientAreaWnd does not handle this message, tab object attempts to notify main window by sending the same message from FireChangingActiveTab.

Handling this message allows controlling what tab is activated. The message is AFX_WM_CHANGING_ACTIVE_TAB.

To insert the handler in VS 2010 or 2012 you can use Class Wizar. Since this is registered message, choose Messages tab and click on Add Custom Message. . .button at the bottom of the wizard dialog and enter AFX_WM_CHANGING_ACTIVE_TAB message.

In VS 2008 and earlier do this in the CMainFrame header file (as protected):

	afx_msg LRESULT OnAfxWmChangingActiveTab(WPARAM wParam, LPARAM lParam);

In the implementation file, insert macro:

BEGIN_MESSAGE_MAP(CMainFrame, CMDIFrameWndEx)
	. . .
	ON_REGISTERED_MESSAGE(AFX_WM_CHANGING_ACTIVE_TAB, &CMainFrame::OnAfxWmChangingActiveTab)
	. . .
END_MESSAGE_MAP()

Insert following implementation:

LRESULT CMainFrame::OnAfxWmChangingActiveTab(WPARAM wParam, LPARAM lParam)
{
	CMFCTabCtrl* pTab = (CMFCTabCtrl*)lParam;

	int iTabsCount = pTab->GetTabsNum();

	// removed?
	if(m_iCurrentTabCount <= iTabsCount)
	{
		m_iCurrentTabCount = iTabsCount;
		return 0;
	}

	m_iCurrentTabCount = iTabsCount;

	CWnd *pWnd = pTab->GetActiveWnd();
	if(NULL == pWnd)
	{
		// determine what tab you want to activate
		// I used tab #1 just for demonstration purpose
		pTab->SetActiveTab(1);

		// do not allow any further tab activation
		return 1;
	}

	return 0;
}

I did not code any error checking or checking if tab you want to activate is within tab count. It is up to you to come up with the logic of determining next active tab. Instead I used arbitrary number 1 for the demo and testing purpose.

By the way: MEMC means Minimum Coding Maximum Effect.

---

JohnCz

Answer 4

Thanks John! Long live the MEMC!!

Answer 5

You are very welcome, glad to be of help. Good luck.

---

JohnCz Please consider voting if you find this post helpful.