Windows timers are mechanisms that let you set one or more timers to be triggered at a specific number of milliseconds. If you set a timer to be triggered at a 1,000 millisecond interval, it triggers every second. When a timer triggers, it sends a WM_TIMER message to your application. You can use the Class Wizard to add a function to your application to handle this timer message.

Timer events are placed only in the application event queue if that queue is empty and the application is idle. Windows does not place timer event messages in the application event queue if the application is already busy. If your application has been busy and has missed several timer event messages, Windows places only a single timer message in the event queue. Windows does not send your application all the timer event messages that occurred while your application was busy. It doesn't matter how many timer messages your application may have missed; Windows still places only a single timer message in your queue.

When you start or stop a timer, you specify a timer ID, which can be any integer value. Your application uses this timer ID to determine which timer event has triggered, as well as to start and stop timers.

Creating the Project and Application

To create the application, follow these steps:

1. Create a new project, named TimerEvent, using the same AppWizard settings.

2. Choose SingleDocument

3. In the Step 6 , choose the base class as CFormView.

4. Select the Dialog from the Resources and the following controls as show in the Table.  

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TABLE CONTROL PROPERTY SETTINGS.

 

Object	Property	Setting
Static Text	ID	IDC_STATIC
	Caption	Current Time:
Edit Box	ID	IDC_CURRTIME
Static Text	ID	IDC_STATIC
	Caption	User Timer
Edit Box	ID	IDC_USERTIME
Static Text	ID	IDC_STATIC
	Caption	Task
Combo Box	ID	IDC_OPERATION
Button	ID	IDC_CANCEL
	Caption	Change Usertime
Button	ID	IDC_EXIT
	Caption	Exit

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Now, right click on the Combobox, go to properties window. Select the Tab DATA and enter the following data :

Lock

LogOff

ShutDown

Restart

Adding the Application Variables

You need to add a few variables to the controls. With the clock timer, you needed only a single variable for updating the clock display. Now you need to add a few other variables for the other controls, as listed in Table below.

 

CONTROL VARIABLES: 

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Object	Name	Category	Type
IDC_CANCEL	m_cCancel	Control	CButton
IDC_CURRTIME	m_sCurrtime	Value	CString
IDC_OPERATION	m_cOperation	Control	CComboBox
IDC_USERTIME	m_sUsertime	Value	CString
IDC_USERTIME	m_cUTime	Control	CEdit
IDC_EXIT	m_cExit	Control	CButton

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After you add all the variables using the Class Wizard,

 

Adding the Timer IDs:

#ifdef _DEBUG

#define new DEBUG_NEW

#undef THIS_FILE

static char THIS_FILE[] = __FILE__;

#endif

 

Add the following Code after this code in the TimerEventView.cpp:

 

#define  IDT_TIMER  WM_USER + 200 

int iHour,iMinute,iSecond;            // Global Variables

CString Label;               

BOOL Status=FALSE;  

 

Add the following Variables in the TimerEventView.h in the public section

 

UINT Timeval;

 

Add the following function definitions in the TimerEventView.h .After this comment write the following code.

 

Protected:

// Generated message map functions

 

afx_msg UINT  StartTimer (UINT TimerDuration);  // Start the Timer

afx_msg BOOL StopTimer (UINT TimerVal);           // Stop the Timer

afx_msg BOOL MyTask(CString strType);                 // Perform the Operation

afx_msg void OnCheck();                                               // Perform the Validation

afx_msg void OnUnlock();                                           // Unlock the System

 

 

Starting the Clock Timer:

To start the clock timer, you need to edit the OnInitUpdate function Add the new code:

void CShutEvtView::OnInitialUpdate()

{

            CFormView::OnInitialUpdate();

            GetParentFrame()->RecalcLayout();

            ResizeParentToFit();

 

/* My Code Starts Here*/

            m_cUTime.SetFocus();

            m_cCancel.EnableWindow(FALSE);

            Timeval=StartTimer(1000);

            SetWindowPos(&CWnd::wndTop, 670, 350, 0, 0, SWP_SHOWWINDOW|SWP_NOSIZE);

           

                       

}

 

THE StartTimer FUNCTION:

 

UINT  CTimerEventView::StartTimer (UINT TimerDuration)

 

    {

        UINT    TimerVal;

        TimerVal = SetTimer (IDT_TIMER, TimerDuration, NULL);  // Starting the Timer

        if (TimerVal == 0)

        {

              AfxMessageBox("Unable to obtain timer");

        }

      return TimerVal;

    }// end StartTimer

 

THE StopTimer FUNCTION:

 

BOOL CTimerEventView::StopTimer (UINT TimerVal)

   {

          if (!KillTimer (TimerVal))

          {

                                       return FALSE;

          }

          //    Place clean-up code following this point.

         return TRUE;

   } // end StopTimer

 

 

THE OnCancel FUNCTION:

 

void CTimerEventView::OnCancel()

{

            m_cUTime.EnableWindow(TRUE);            //Enabling the Shutdown Time Edit Control

            m_cExit.EnableWindow(TRUE);                                                //Enable Exit Button

            m_cOperation.EnableWindow(TRUE);           //Enable List Control

            Status=TRUE;

           

}

 

THE OnExit FUNCTION:

 

void CTimerEventView::OnExit()

{

            if(StopTimer(Timeval)==FALSE)

                        ::MessageBox(NULL,"Error While Killing the Timer","ShutEvt",1);

 

            ::PostQuitMessage(1);

}

THE OnUnlock FUNCTION:

 

void CTimerEventView::OnUnlock()

{

            WinExec("rundll32 user32.dll,LockWorkStation",1);  // Lock the System

}

THE OnCheck FUNCTION: This functions is to validate the date entered by user

 

void CTimerEventView::OnCheck()

{

            int iLHour,iLMinute;

            CString tmpTime,subTime;

 

            UpdateData();

           

            tmpTime=m_sUserTime;

            iLHour=tmpTime.Find(":",0);

            subTime=tmpTime.Left(iLHour);

            iHour=atoi(subTime);

           

            if(iLHour==2 && iHour>=0 && iHour<=24)

            {         

                        iLMinute=tmpTime.Find(":",iLHour);

                        subTime=tmpTime.Mid(iLHour+1);

                        subTime=subTime.Left(iLMinute);

                        iMinute=atoi(subTime);

                        if(iLMinute==2 && iMinute>=0 && iMinute<=60)

                        {

                                    iSecond=atoi(tmpTime.Right(2));

                                   

                                    if(iSecond>=0 && iSecond<=60)

                                    {

                                                m_cUTime.EnableWindow(FALSE);          

                                                m_cCancel.EnableWindow(TRUE);

                                                m_cExit.EnableWindow(FALSE);

                                                m_cOperation.EnableWindow(FALSE);

                                    }

                                    else

                                    ::MessageBox(NULL,"Enter the Date in  HH:MM:SS \n\n OR \n\n Seconds Should be between 0 and 60","ShutEvt",1);

                       

                        }

                        else

                                    ::MessageBox(NULL,"Enter the Date in HH:MM:SS\n\n OR \n\n Minutes Should be between 0 and 60","ShutEvt",1);

                                                           

            }

            else

                        ::MessageBox(NULL,"Enter the Date in HH:MM:SS \n\n OR \n\n Hour should be between 0 and 24","ShutEvt",1);

           

}

 

THE MyTask FUNCTION:

   This function is to perform the task selected by user from the CComboBox

 

BOOL CTimerEventView::MyTask(CString strType)

{

    HANDLE hToken;

    TOKEN_PRIVILEGES tkp;

   // Stop the timer before shutdown

            StopTimer(Timeval);

   // Get a token for this process.

 

   if (!OpenProcessToken(GetCurrentProcess(),

        TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &hToken))

      return( FALSE );

 

   // Get the LUID for the shutdown privilege.

 

   LookupPrivilegeValue(NULL, SE_SHUTDOWN_NAME,

        &tkp.Privileges[0].Luid);

 

   tkp.PrivilegeCount = 1;  // one privilege to set   

   tkp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;

 

   // Get the shutdown privilege for this process.

 

   AdjustTokenPrivileges(hToken, FALSE, &tkp, 0,

        (PTOKEN_PRIVILEGES)NULL, 0);

 

   if (GetLastError() != ERROR_SUCCESS)

      return FALSE;

 

   // Shut down the system and force all applications to close.

 

  // if (!ExitWindowsEx(EWX_POWEROFF | EWX_POWEROFF | EWX_FORCE, 0))

  

   if(strType=="LogOff")

   {

                        if(!ExitWindowsEx(EWX_LOGOFF | EWX_FORCE, 0))

                  return FALSE;

   }

   else if(strType=="ShutDown")

   {

                        if(!ExitWindowsEx(EWX_SHUTDOWN|EWX_POWEROFF| EWX_FORCE, 0))

                  return FALSE;

   }

   else if(strType=="Restart")

   {

                        if(!ExitWindowsEx(EWX_REBOOT| EWX_FORCE, 0))

                  return FALSE;

   }

 

   return TRUE;

}

 

THE OnSelchangeOperation FUNCTION: 

   Add this function through ClassWizard for the Comboxbox Control.(CBN_SELCHANGE)

 

void CTimerEventView::OnSelchangeOperation()

{

            Status=FALSE;

            int Selection=m_cOperation.GetCurSel();

                        OnCheck();

            m_cOperation.GetLBText(Selection,Label);

}

 

Handling the Clock Timer Event

Now that you've started a timer, you need to add the code to handle the timer event message. You can do this by following these steps:

1. Using the Class Wizard, add a variable to the IDC_STATIC control of type CString named m_sCurrtime.

2. Using the Class Wizard, add a function to handle the WM_TIMER message for the CTimerEvent object.

3. Edit the OnTimer function, adding the following code:

THE OnTimer FUNCTION.

 

void CTimerEventView::OnTimer(UINT nIDEvent)

{

            CTime ct=CTime::GetCurrentTime();

            char *str=new char[10];

 

            UpdateData();

            m_sCurrtime.Format("%d : %d : %d ",ct.GetHour(),ct.GetMinute(),ct.GetSecond());

            UpdateData(FALSE);

           

            if(iHour==ct.GetHour() && iMinute==ct.GetMinute() && iSecond==ct.GetSecond() && Label=="Lock" && Status==FALSE)

 

            {

                        OnUnlock();

m_cUTime.EnableWindow(TRUE);            //Enabling the Shutdown Time Edit Control

                        m_cExit.EnableWindow(TRUE);                                                //Enable Exit Button

                        m_cOperation.EnableWindow(TRUE);           //Enable List Control

                        //StopTimer(Timeval);

                        Status=TRUE;

            }

           

            if(iHour==ct.GetHour() && iMinute==ct.GetMinute() && iSecond==ct.GetSecond() && Label=="LogOff" && Status==FALSE)

            {

                        MyTask ("LogOff");

            }

           

            if(iHour==ct.GetHour() && iMinute==ct.GetMinute() && iSecond==ct.GetSecond() && Label=="ShutDown" && Status==FALSE)

            {

                        MyTask ("ShutDown");

            }

            if(iHour==ct.GetHour() && iMinute==ct.GetMinute() && iSecond==ct.GetSecond() && Label=="Restart" && Status==FALSE)

            {

                        MyTask ("Restart");

            }

 

            delete [] str;

            CFormView::OnTimer(nIDEvent);

}

 

Download the Sample Project here.