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A thread-safe timed message box

, 12 Feb 2001
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The system Message Box that is closed atuomatically after some time

What is the code for

This is for using the systems MessageBox (no extra dialog creation needed). After a time with no user-response the dialog is automatically closed. An optional text showing the time left to interact is provided. It's also a replacement for MSDN Q181934 (doesn't work)

Basics

Before calling MessageBox, a timer is installed. In the timer's callback-procedure the message-text from the box is replaced (optional).

When the box should be closed, a WM_COMMAND is posted to the MessageBox Window.

Timer-Callback

I decided to collect all the information corresponding to the MessageBox (title, Message, Flags ...) in a class. Then there is the problem that only a static timer-callback-procedure can be installed with the SetTimer()-function: one can not access the class-members (as it is static).

To solve this problem, I inserted a Map to store the classes corresponding to a timer-id:

Header:

class CDlgTimedMessageBox
{
public:
    // ...
    UINT         ShowMessageBox(BOOL *pbStoppedByUser=NULL);
    // ...
    static void  CALLBACK GlobalTimerProc(HWND hwnd, UINT uiMsg, 
                                          UINT idEvent, DWORD dwTime);
    void         LocalTimerProc(void);
    // ...
    static       CMapPtrToPtr        m_mapTimerIdToClassMe;

    // to call the messagebox within one line !
    static UINT  TimedMessageBox(...);

protected:
    UINT         m_idTimer;
};

Source:

UINT CDlgTimedMessageBox::ShowMessageBox(BOOL *pbStoppedByUser)
{
    // ...
    m_idTimer = ::SetTimer(NULL, 0, 1000, 
                    (TIMERPROC) CDlgTimedMessageBox::GlobalTimerProc);
    CDlgTimedMessageBox::m_mapTimerIdToClassMe.SetAt((void*)m_idTimer, 
                                                     this);
    // ...
    ::MessageBox(...)
    // ...
}

void CALLBACK CDlgTimedMessageBox::GlobalTimerProc(HWND hwnd, 
                               UINT uiMsg, UINT idEvent, DWORD dwTime)
{
    CDlgTimedMessageBox    *pMe = NULL;
    
    // Find the corresponding class by the timer-id
    CDlgTimedMessageBox::m_mapTimerIdToClassMe.Lookup((void*)idEvent, 
                                                       (void *&) pMe);
    
    if( pMe!=NULL )
        pMe->LocalTimerProc();
}

void CDlgTimedMessageBox::LocalTimerProc(void)
{
    // find the Message-Box-window

    // Calculate time since start
    
    if( too long running )
    {
        // Stop MessageBox
    }
    else
    {
        // replace text of MessageBox    
    }    
}

Finding the MessageBox

hWnd = ::GetWindow(::GetDesktopWindow(), GW_CHILD);
while( (hWnd!=NULL) && (m_hMsgBox==NULL) )
{
    pWnd = CWnd::FromHandle(hWnd);
    pWnd->GetWindowText(title);

    if( AfxIsDescendant(m_hParent, hWnd) && ::IsWindowVisible(hWnd) && 
        (m_Title.CompareNoCase(title)==0) )
    {
        m_hMsgBox = hWnd;
        break;
    }
    
    hWnd = ::GetWindow(hWnd, GW_HWNDNEXT);
}

 

Put it in one function

There is one function you can use to call the messagebox without creating a class-instance: CDlgTimedMessageBox::TimedMessageBox() does the rest for you!

UINT CDlgTimedMessageBox::TimedMessageBox(UINT flags, LPCTSTR ptszMessage, 
                          LPCTSTR ptszTitle, 
                          DWORD dwTimeout, UINT dDefaultReturn,
                          LPCTSTR ptszMessageTimer, HWND hwndParent, 
                          BOOL *pbStoppedByUser)
{
    CDlgTimedMessageBox    msgBox(flags, ptszMessage, ptszTitle, 
                                  dwTimeout, dDefaultReturn, 
                                  ptszMessageTimer, hwndParent);

    return msgBox.ShowMessageBox(pbStoppedByUser);
}

You can pass a BOOL * to get the info, if the user has pressed a button.

 

Thread-Safe

The map-access is enclosed by a CCriticalSection.

Sample

BOOL	stoppedByUser;
UINT	erg;

erg  = CDlgTimedMessageBox::TimedMessageBox(MB_YESNO|MB_ICONHAND, 
		"Please press a button", 
		"box-title", 
		5000, IDYES, 
		"\nin the next %lu sec !", 
		NULL, &stoppedByUser);

History

5.11.2000     posted to Code Project
14.11.2000   bugfixes for NT4
05.02.2001   bug reported when created with MBYES: defbutton then is IDCANCEL
05.02.2001   global function went to class-scope

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

Markus Loibl

Germany Germany
No Biography provided

Comments and Discussions

 
GeneralMy vote of 1 PinmemberSudhindra Sathya19-Nov-10 1:26 
QuestionHow to show other icons in the messagebox.. PinmemberJigar Mehta23-Nov-04 20:48 
GeneralCompiling errors Pinmembershalala7-Oct-03 21:11 
GeneralRe: Compiling errors Pinmembercristitomi21-Mar-07 6:35 
Generaltimed out MessageBox PinmemberXeena2-Oct-02 6:53 
Generalbottons PinmemberAnonymous17-Jun-02 5:29 
GeneralIf you like this then.... PinmemberAnonymous12-Mar-02 7:23 
General"Fire and Forget" addition PinmemberM.Lansdaal12-Feb-02 14:53 
GeneralTimer PinmemberJoachim12-Nov-01 2:59 
GeneralRe: Timer Pinmembermloibl12-Nov-01 21:10 
GeneralRe: Timer PinmemberAlfred Rohr22-Nov-01 5:04 
GeneralMemory Leaks Pinmembereljkmw22-Aug-01 17:53 
GeneralRe: Memory Leaks PinmemberAlan Adams28-Oct-04 11:04 
One leak which I saw when reviewing the code was that the m_idTimer was being reset to zero prior to calling CMapPtrToPtr::RemoveKey to remove the mapping from the m_mapTimerIdToClassMe list. So a very small amount being left in the m_mapTimerIdToClassMe list due to that.
 
-Alan
QuestionHOW? PinmemberTGWG6-Jul-01 7:00 
AnswerRe: HOW? PinmemberMLoibl17-Jul-01 20:50 
GeneralMissing include PinmemberAnonymous6-Jul-01 4:52 
GeneralAlways on top Pinmembernewbie22-Jun-01 3:20 
GeneralRe: Always on top PinmemberMLoibl17-Jul-01 20:56 
QuestionAfxIsDescendant() ? PinmemberPeter Sjöström28-Mar-01 5:58 
AnswerRe: AfxIsDescendant() ? PinmemberMLoibl28-Mar-01 20:10 
AnswerRe: AfxIsDescendant() ? PinmemberWes Jones17-Jul-01 13:19 
GeneralIcky global functions! PinmemberPaul Wolfensberger17-Nov-00 4:15 
GeneralRe: Icky global functions! PinmemberMLoibl5-Feb-01 3:51 
GeneralRe: Icky global functions! PinmemberMLoibl5-Feb-01 9:13 
GeneralCrashes immediately on NT4 PinmemberAnonymous13-Nov-00 1:40 
GeneralRe: Crashes immediately on NT4 PinmemberXYLiu13-Nov-00 2:55 
GeneralRe: Crashes immediately on NT4 PinmemberAnonymous13-Nov-00 7:18 
GeneralFixed PinmemberThe author (who forgot his pwd)14-Nov-00 0:49 

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