PRB: MFC SAVER Sample Does Not Run Correctly Under Windows 98

• Microsoft Visual C++, 32-bit Editions, versions 5.0, 6.0

SYMPTOMS

When you configure the MFC SAVER sample in Control Panel, it does not run correctly under Windows 98. When you click Preview or Configuration for the screen saver, nothing happens.

CAUSE

The problem is caused by a coding error in the MFC sample. The MatchOption() function performs a string comparison instead of a character comparison.

RESOLUTION

To resolve this problem so you can preview and configure the screen saver in the Control Panel, change the existing MatchOption() and InitInstance() functions as follows:

BOOL MatchOption(LPTSTR lpsz, TCHAR ch)
{
    if (lpsz[0] == '-' || lpsz[0] == '/')
        lpsz++;

    if (lpsz[0] == ch)
        return TRUE;

    return FALSE;
}

///////////////////////////////////////////////////////////////////////////// 
// CSaverApp initialization.
BOOL CSaverApp::InitInstance()
{
    // Standard initialization.
    // If you are not using these features and want to reduce the size
    // of your final executable, you should remove from the following
    // the specific initialization routines you do not need.

    Enable3dControls();
    SetRegistryKey(_T("MFC Screen Savers Inc."));

    if (__argc == 1 || MatchOption(__argv[1], _T('c')))
        DoConfig();

    else if (MatchOption(__argv[1], _T('p')))
    {
        CWnd* pParent = CWnd::FromHandle((HWND)atol(__argv[2]));
        ASSERT(pParent != NULL);
        CDrawWnd* pWnd = new CDrawWnd();
        CRect rect;
        pParent->GetClientRect(&rect);
        pWnd->Create(NULL, WS_VISIBLE|WS_CHILD, rect, pParent, NULL);
        m_pMainWnd = pWnd;
        return TRUE;
    }
    else if (MatchOption(__argv[1], _T('s')))
    {
        CSaverWnd* pWnd = new CSaverWnd;
        pWnd->Create();
        m_pMainWnd = pWnd;
        return TRUE;
    }

    return FALSE;
} 

MORE INFORMATION

Steps to Reproduce Behavior

BOOL MatchOption(LPTSTR lpsz, LPTSTR lpszOption)
{
    if (lpsz[0] == '-' || lpsz[0] == '/')
        lpsz++;

    if (lstrcmpi(lpsz, lpszOption) == 0) // This fails on Windows 98.
        return TRUE;

    return FALSE;
}

///////////////////////////////////////////////////////////////////////////// 
// CSaverApp initialization.
BOOL CSaverApp::InitInstance()
{
  // Standard initialization.
  // If you are not using these features and you want to reduce the size
  // of your final executable, you should remove from the following
  // the specific initialization routines you do not need.
    Enable3dControls();
    SetRegistryKey(_T("MFC Screen Savers Inc."));

    if (__argc == 1 || MatchOption(__argv[1], _T("c")))
        DoConfig();

    else if (MatchOption(__argv[1], _T("p")))
    {
        CWnd* pParent = CWnd::FromHandle((HWND)atol(__argv[2]));
        ASSERT(pParent != NULL);
        CDrawWnd* pWnd = new CDrawWnd();
        CRect rect;
        pParent->GetClientRect(&rect);
        pWnd->Create(NULL, WS_VISIBLE|WS_CHILD, rect, pParent, NULL);
        m_pMainWnd = pWnd;
        return TRUE;
    }
    else if (MatchOption(__argv[1], _T("s")))
    {
        CSaverWnd* pWnd = new CSaverWnd;
        pWnd->Create();
        m_pMainWnd = pWnd;
        return TRUE;
    }

    return FALSE;
} 

REFERENCES

Visual C++ Help for SAVER sample

(c) Microsoft Corporation 1999, All Rights Reserved. Contributions by Nathan Manis, Microsoft Corporation.

Additional query words:

Keywords : kbMFC kbVC500 kbVC600 kbSampleProd
Version : winnt:5.0,6.0
Platform : winnt
Issue type : kbprb