How To Disable Tabs in CPropertySheet

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

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.

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

Keywords          : kbcode kbMFC KbUIDesign kbVC 
Version           : 4.00 4.10
Platform          : NT WINDOWS 
Issue type        : 

Last Reviewed: July 29, 1999