DOCUMENT:Q135873 15-MAY-2002 [visualc] TITLE :HOWTO: Add Tooltips for Controls on an MFC Modal Dialog Box PRODUCT :Microsoft C Compiler PROD/VER::2.1,2.2,4.0,4.1,4.2,4.2b,5.0,6.0 OPER/SYS: KEYWORDS:kbCmnCtrls kbCtrl kbDlg kbMFC kbToolTip KbUIDesign kbVC210 kbVC220 kbVC400 kbVC500 kbVC ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - The Microsoft Foundation Classes (MFC), used with: - Microsoft Visual C++, 32-bit Editions, versions 2.1, 2.2, 4.0, 4.1 - Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 4.2b, 5.0, 6.0 - Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 4.2b, 5.0, 6.0 - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 - Microsoft Visual C++.NET (2002) ------------------------------------------------------------------------------- SUMMARY ======= To make the CToolTipCtrl class work correctly, you must call the CToolTipCtrl::RelayEvent() function. This makes it possible for the mouse messages to be passed to the tooltip control. For a non-modal dialog box window in an MFC application, use the window's CWnd::PreTranslateMessage() function to call CToolTipsCtrl::RelayEvent(). However, for a modal dialog box, the CDialog::PreTranslateMessage() function is not called because modal dialog boxes have their own message loops. Therefore, to use CToolTipCtrl in a modal dialog box, you need a different approach. This article gives a step-by-step example that shows how to use the CToolTipCtrl class in a MFC modal dialog box, it involves adding two additional member variables to the application class and overwriting the CWinApp::ProcessMessageFilter() function for the application class. MORE INFORMATION ================ Step-by-Step Example -------------------- The following procedure generates a default MFC skeleton application and adds tooltips to the OK button on the About dialog box and the dialog box itself: 1. Use the Appwizard in Visual C++ to generate an MFC application, call it Tooltips, and use all the Appwizard default settings. 2. Include the header file in the stdafx.h file. NOTE: Do not do this step for Visual C++ .NET. 3. Add the following member variables to the CTooktipsApp class in the Tooltips.h file: class CTooltipsApp : public CWinApp { //... public: HWND m_hwndDialog; CToolTipCtrl* m_gpToolTip; //... }; 4. Initiate the two variables in the application's constructor to NULL: CTooltipsApp::CTooltipsApp() { m_hwndDialog = NULL; m_gpToolTip = NULL; } 5. Overwrite the CTooltipsApp:: ProcessMessageFilter() function as follows: BOOL CTooltipsApp::ProcessMessageFilter(int code, LPMSG lpMsg) { if (m_hwndDialog != NULL) if (lpMsg->hwnd == m_hwndDialog || ::IsChild(m_hwndDialog, lpMsg->hwnd)) { if (NULL != m_gpToolTip) m_gpToolTip->RelayEvent(lpMsg); } return CWinApp::ProcessMessageFilter(code, lpMsg); } 6. Use Classwizard to add a member variable for the OK button in the CAboutDlg class, and call it m_btOK. Also, add a m_pTooltip pointer to a CToolTipCtrl object: NOTE: For Visual C++ .NET you can add a memeber variable using the "Class View" right. (Click the AboutDialog calls, and then on Add menu, select Add Variable.) class CAboutDlg : public CDialog { public: CAboutDlg(); // Dialog Data //{{AFX_DATA(CAboutDlg) enum { IDD = IDD_ABOUTBOX }; CButton m_btOK; //}}AFX_DATA CToolTipCtrl* m_pTooltip; //... }; 7. Add code to the CAboutDlg class' constructor and destructor to initialize and release the tooltip object, you might also need to add a default destructor first: CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD) { m_pTooltip = NULL; } CAboutDlg::~CAboutDlg() { delete m_pTooltip; } 8. Overwrite the OnMouseMove() function of the CAboutDlg class to set up the tooltip control: void CAboutDlg::OnMouseMove(UINT nFlags, CPoint point) { //Set up the tooltip if (!m_pTooltip) { int rt; m_pTooltip = new CToolTipCtrl; rt = m_pTooltip->Create(this); ASSERT(rt!=0); ((CTooltipsApp*)AfxGetApp())->m_gpToolTip= m_pTooltip; rt = m_pTooltip->AddTool(this, "About Box"); ASSERT(rt!=0); rt = m_pTooltip->AddTool(&m_btOK,"OK Button"); ASSERT(rt!=0); m_pTooltip->Activate(TRUE); } CDialog::OnMouseMove(nFlags, point); } 9. Overwrite the OnInitDialog() function of the CAboutDlg class to pass the dialog's handle to the application: BOOL CAboutDlg::OnInitDialog() { CDialog::OnInitDialog(); ((CTooltipsApp*)AfxGetApp())->m_hwndDialog=m_hWnd; return TRUE; // return TRUE unless you set the focus to a control // EXCEPTION: OCX Property Pages should return FALSE } 10. Overwrite the PostNcDestroy() function of the CAboutDlg class to reset the variables in the application class: void CAboutDlg::PostNcDestroy( ) { CDialog::PostNcDestroy(); ((CTooltipsApp*)AfxGetApp())->m_hwndDialog= NULL; ((CTooltipsApp*)AfxGetApp())->m_gpToolTip= NULL; } 11. Rebuild the application and bring up the About dialog box, you will see the tooltips. Additional query words: ====================================================================== Keywords : kbCmnCtrls kbCtrl kbDlg kbMFC kbToolTip KbUIDesign kbVC210 kbVC220 kbVC400 kbVC500 kbVC600 kbFAQ kbGrpDSMFCATL Technology : kbAudDeveloper kbMFC Version : :2.1,2.2,4.0,4.1,4.2,4.2b,5.0,6.0 Issue type : kbhowto ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. 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