SetTimer
The SetTimer
function creates a timer with the specified time-out value.
UINT SetTimer(
|
HWND hWnd, |
// handle of window
for timer messages |
|
UINT nIDEvent, |
// timer identifier |
|
UINT uElapse, |
// time-out value |
|
TIMERPROC lpTimerFunc |
// address of timer
procedure |
|
); |
|
Parameters
hWnd
Identifies
the window to be associated with the timer. This window must be owned by the
calling thread. If this parameter is NULL, no window is associated with the
timer and the nIDEvent parameter is ignored.
nIDEvent
Specifies a
nonzero timer identifier. If the hWnd parameter is NULL, this parameter
is ignored.
uElapse
Specifies the
time-out value, in milliseconds.
lpTimerFunc
Points to the
function to be notified when the time-out value elapses. For more information
about the function, see TimerProc.
If lpTimerFunc
is NULL, the system posts a WM_TIMER message to the application queue. The hwnd
member of the message s MSG
structure contains the value of the hWnd parameter.
Return Values
If the
function succeeds, the return value is an integer identifying the new timer. An
application can pass this value, or the string identifier, if it exists, to the
KillTimer
function to destroy the timer. If the function fails to create a timer, the
return value is zero.
Remarks
An application
can process WM_TIMER messages by including a WM_TIMER case statement in the
window procedure or by specifying a TimerProc callback function when
creating the timer. When you specify a TimerProc callback function, the DispatchMessage
function simply calls the callback function instead of the window procedure.
Therefore, you need to dispatch messages in the calling thread, even when you
use TimerProc instead of processing WM_TIMER.
The wParam
parameter of the WM_TIMER message contains the value of the nIDEvent
parameter.
See Also