Visual C++ and MFC Programming 2nd Edition

Chapter 18: Progress-Based Controls Visual C++ and MFC Fundamentals

UINT SetTimer(UINT nIDEvent, UINT nElapse,

void (CALLBACK EXPORT* lpfnTimer)(HWND, UINT, UINT, DWORD));

This function call creates a timer for your application. Like the other controls, a timer

uses an identifier. This is passed as the nIDEvent argument. As mentioned already, when

it is accessed, a timer starts counting up to a set value. Once it reaches that value, it stops

and starts counting again. The nElapse argument specifies the number of milliseconds

that the timer must count before starting again. The lpfnTimer argument is the name of a

procedure that handles the timing event of the control. This argument can be set to

NULL, in which case the timing event would rest on the CWnd’s responsibility.

Practical Learning: Using Timer Controls

1. To create a timer, in the OnInitDialog() event, before the return line, type
   SetTimer(1, 200, 0);:

BOOL CRandShapesDlg::OnInitDialog()

{

CDialog::OnInitDialog();

// Set the icon for this dialog. The framework does this automatically

// when the application's main window is not a dialog

SetIcon(m_hIcon, TRUE); // Set big icon

SetIcon(m_hIcon, FALSE); // Set small icon

// TODO: Add extra initialization here

DlgWidth = GetSystemMetrics(SM_CXSCREEN);

DlgHeight = GetSystemMetrics(SM_CYSCREEN);

SetWindowPos(&wndTopMost, 0, 0, DlgWidth, DlgHeight,

SWP_SHOWWINDOW);

SetTimer(1, 200, 0);

return TRUE; // return TRUE unless you set the focus to a control

}

2. Save All

18.1.3..The Timer Messages and Methods...................................................

When a timer is accessed or made available, it starts counting. Once the nElapse value of

the CWnd::SetTimer() method is reached, its sends a WM_TIMER message to the

application.

We saw that a timer is initiated with a call to SetTimer(). When you do not need the

timer anymore, call the CWnd::KillTimer() method. Its syntax is:

BOOL KillTimer(int nIDEvent);

The nIDEvent argument identifies the timer that was created with a previous call to

SetTimer().