Q151662: HOWTO: How To Disable Tabs in CPropertySheet

Article: Q151662
Product(s): Microsoft C Compiler
Version(s): winnt:4.0,4.1
Operating System(s): 
Keyword(s): kbMFC kbPropSheet KbUIDesign kbVC kbGrpDSMFCATL
Last Modified: 06-MAY-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1 
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SUMMARY
=======

This article describes how to disable tabs in a CPropertySheet so the user is
not allowed to activate the tab. To accomplish this behavior, you can do the
following:

- Handle the TCN_SELCHANGING notification in the sheet and save the index of
  the current tab.

- Handle the TCN_SELCHANGE notification in the sheet and call GetActiveIndex()
  to determine if you want the page disabled.

- If you want the page disabled, post a PSM_SETCURSEL message to the sheet
  using the index that was saved in TCN_SELCHANGING.

The sample code below shows how to implement an EnablePage() function that allows
you to enable and disable pages.

MORE INFORMATION
================

Because there is no way to gray out the text in the tab of the disabled page,
append "Disabled" to the tab label to inform the user that the page is
disabled.

Instead of posting a PSM_SETCURSEL message in the handler for TCN_SELCHANGE to
activate a different page, you can accomplish this behavior in OnSetActive() for
a CPropertyPage.

If OnSetActive() returns FALSE, it tries to activate the next tab. The method
described above allows you to reactivate the previously active tab.

Sample Code
-----------

     // This sample disables page #2 of a property sheet.

     // We need to include this file so we can use CMap
     #include <afxtempl.h>

     class CMySheet : public CPropertySheet
     {
     protected:
         // we save the current page in TCN_SELCHANGING
         int m_nLastActive;
         // list of indexes of disabled pages
         CMap <int, int&, int, int&> m_DisabledPages;
     public:
         void EnablePage (int nPage, BOOL bEnable = TRUE);
     ...
     };

     BOOL CMySheet::OnInitDialog()
     {
         // OnInitDialog() must be called before EnablePage()
         // or GetTabControl() will fail.
         BOOL bReturn = CPropertySheet::OnInitDialog();
         // disable page #2
         EnablePage (1, FALSE);
         return bReturn;
     }

     void CMySheet::EnablePage (int nPage, BOOL bEnable)
     {
         // if we want to enable the page
         if (bEnable)
         {
             // remove the index from the map
             m_DisabledPages.RemoveKey (nPage);
             // take out " - Disabled" from tab label
             CTabCtrl* pTab = GetTabControl();
             ASSERT (pTab);
             TC_ITEM ti;
             char szText[100];
             ti.mask = TCIF_TEXT;
             ti.pszText = szText;
             ti.cchTextMax = 100;
             VERIFY (pTab->GetItem (nPage, &ti));
             char * pFound = strstr (szText, " - Disabled");
             if (pFound)
             {
                 *pFound = '\0';
                 VERIFY (pTab->SetItem (nPage, &ti));
             }
         }
         // if we want to disable it
         else
         {
             // add the index to the map
             m_DisabledPages.SetAt (nPage, nPage);
             // add " - Disabled" to tab label
             CTabCtrl* pTab = GetTabControl();
             ASSERT (pTab);
             TC_ITEM ti;
             char szText[100];
             ti.mask = TCIF_TEXT;
             ti.pszText = szText;
             ti.cchTextMax = 100;
             VERIFY (pTab->GetItem (nPage, &ti));
             strcat (szText, " - Disabled");
             VERIFY (pTab->SetItem (nPage, &ti));
         }
     }

     BOOL CMySheet::OnNotify(WPARAM wParam, LPARAM lParam, LRESULT* pResult)
     {
         NMHDR* pnmh = (NMHDR*)lParam;
         // tab is about to change
         if (TCN_SELCHANGING == pnmh->code)
             // save the current page index
             m_nLastActive = GetActiveIndex ();
         // tab has been changed
         else if (TCN_SELCHANGE == pnmh->code)
         {
             // get the current page index
             int nCurrentPage = GetActiveIndex ();
             // if current page is in our map of disabled pages
             if (m_DisabledPages.Lookup (nCurrentPage, nCurrentPage))
             // activate the previous page
             PostMessage (PSM_SETCURSEL, m_nLastActive);
         }
         return CPropertySheet::OnNotify(wParam, lParam, pResult);
     }

     /* Compile options needed: default
     */ 

Additional query words: 4.00 4.10 CPropertySheet CPropertyPage disable

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Keywords          : kbMFC kbPropSheet KbUIDesign kbVC kbGrpDSMFCATL 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:4.0,4.1
Issue type        : kbhowto

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