How To Add Toolbars and Tooltips to ActiveX Controls

MORE INFORMATION

Visual C++ provides two methods to create a toolbar. The article desribes how to create a toolbar resource using the Resource Editor. If you already have a bitmap resource, please refer to the online documentation "Converting Bitmaps to Toolbars" for converting your bitmap resource to a toolbar resource.

Steps are shown below:

1. Use the MFC ActiveX Control Wizard to generate an MFC ActiveX control.
2. Create a Toolbar resource in the control's project.
3. Add a tooltip string resource for each button in the toolbar. These tooltip string resources will be loaded in the TTN_NEEDTEXT notification code handler.
4. Add a WH_GETMESSAGE hook callback function to the ActiveX control- derived class. The hook procedure is in charge of calling the application's PreTranslateMessage(), and this results in the call to FilterToolTipMessage(), which activates tooltips. A hook procedure is needed because the ActiveX control is just like an inproc server[ASCII 151]no message pump is found:

         HHOOK hHook = NULL;
   
         // Hook procedure for WH_GETMESSAGE hook type.
         LRESULT CALLBACK GetMessageProc(int nCode, WPARAM wParam, LPARAM
            lParam)
         {
           // Switch the module state for the correct handle to be used.
           AFX_MANAGE_STATE(AfxGetStaticModuleState( ));
   
           // If this is a keystrokes message, translate it in controls'
           // PreTranslateMessage().
           LPMSG lpMsg = (LPMSG) lParam;
   
           if( (nCode >= 0) &&
             PM_REMOVE == wParam &&
             AfxGetApp()->PreTranslateMessage(lpMsg))
           {
              lpMsg->message = WM_NULL;
              lpMsg->lParam = 0L;
              lpMsg->wParam = 0;
           }
   
   
          // Passes the hook information to the next hook procedure in
          // the current hook chain.
          return ::CallNextHookEx(hHook, nCode, wParam, lParam);
         }
   					

5. Create the toolbar window (a CToolBar class), which is a child window of the ActiveX control. This is done in response to WM_CREATE message. In addition, WM_CREATE message handler is also a good place to install the WH_GETMESSAGE hook procedure.

         int CCToolBarCtrl::OnCreate(LPCREATESTRUCT lpCreateStruct)
         {
            if (COleControl::OnCreate(lpCreateStruct) == -1)
               return -1;
   
            // Create a CToolBar window which is a child of ActiveX control.
            if (!m_ToolBar.Create(this,
                  WS_CHILD | WS_VISIBLE | CBRS_TOP | CBRS_TOOLTIPS) ||
                 !m_ToolBar.LoadToolBar(IDR_TOOLBAR))
               {
                  TRACE0("Failed to create toolbar\n");
                  return -1;      // fail to create
               }
   
            // Toolbar has to have TBSTYLE_TOOLTIPS style. Otherwise,
            // notification handler for TTN_NEXTTEXT won't be called.
            m_ToolBar.ModifyStyle (0, TBSTYLE_TOOLTIPS);
   
            // Move the toolbar so it is VISIBLE on the screen.
            CRect rc;
            GetClientRect(&rc);
            rc.bottom = rc.top + 34;
            m_ToolBar.MoveWindow(&rc);
   
            // Because ActiveX control is an inproc server, it does not have a
            // message pump. So, messages to child windows created by the
            // ActiveX control are not going to be received by the control.
            // Thus, we set up a message hook to call PreTranslateMessage().
            // This results in the call to FilterToolTipMessage(), which
            // activates tooltips.
            hHook = ::SetWindowsHookEx(
               WH_GETMESSAGE,
               GetMessageProc,
               AfxGetInstanceHandle(),
               GetCurrentThreadId());
            ASSERT (hHook);
   
            return 0;
         }
   					

6. Uninstall the message hook function in response to WM_DESTROY message:

         void CCToolBarCtrl::OnDestroy()
         {
            // Remove the message hook function.
            VERIFY (::UnhookWindowsHookEx (hHook));
   
            COleControl::OnDestroy();
         }
   					

7. Add a TTN_NEEDTEXTW (for Unicode notification code) or TTN_NEEDTEXTA (for ANSI notification code) notification handler to the ActiveX control-derived class. Load the tooltip string to be displayed in this notification code handler:

         BEGIN_MESSAGE_MAP(CCToolBarCtrl, COleControl)
            //{{AFX_MSG_MAP(CCToolBarCtrl)
            ON_WM_CREATE()
            ON_COMMAND(ID_BUTTON1, OnButton1) // first button on toolbar
            ON_COMMAND(ID_BUTTON2, OnButton2) // second button on toolbar
            ON_COMMAND(ID_BUTTON3, OnButton3) // third button on toolbar
            ON_WM_DESTROY()
            //}}AFX_MSG_MAP
            ON_OLEVERB(AFX_IDS_VERB_PROPERTIES, OnProperties)
   
            // ANSI notification code (for Windows 95)
            ON_NOTIFY_EX_RANGE(TTN_NEEDTEXTA, 0, 0xFFFF, OnToolTipNotify)
   
            // Unicode notification code (for NT)
            ON_NOTIFY_EX_RANGE(TTN_NEEDTEXTW, 0, 0xFFFF, OnToolTipNotify)
         END_MESSAGE_MAP()
   
         // Notification handler for tooltips - determine which tooltip
         // string resource to be displayed.
         BOOL CCToolBarCtrl::OnToolTipNotify(
            UINT id, NMHDR * pNMHDR, LRESULT * pResult)
         {
            TOOLTIPTEXTA* pTTTA = (TOOLTIPTEXTA*) pNMHDR;
            TOOLTIPTEXTW* pTTTW = (TOOLTIPTEXTW*) pNMHDR;
   
            int strid = 0;
            switch (pNMHDR->idFrom)
            {
            case ID_BUTTON1:
               strid = IDS_BUTTON1;
               break;
   
            case ID_BUTTON2:
               strid = IDS_BUTTON2;
               break;
   
            case ID_BUTTON3:
               strid = IDS_BUTTON3;
               break;
            }
   
     if (strid)
          {
             *pResult = 0;
     
             CString str;
             str.LoadString(strid);
     
             #define _countof(array) (sizeof(array)/sizeof(array[0]))
     
             #ifndef _UNICODE
             if (pNMHDR->code == TTN_NEEDTEXTA)
             lstrcpyn(pTTTA->szText, str, _countof(pTTTA->szText));
             else
             _mbstowcsz(pTTTW->szText, str, _countof(pTTTW->szText));
             #else
             if (pNMHDR->code == TTN_NEEDTEXTA)
             _wcstombsz(pTTTA->szText, str, _countof(pTTTA->szText));
             else
             lstrcpyn(pTTTW->szText, str, _countof(pTTTW->szText));
             #endif
     
              return TRUE;
           }
   
            return FALSE;
         }
    
   					

(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Yeong- Kah Tam, Microsoft Corporation.