A timer (the Xt Intrinsics term is TimeOut) is a procedure that is invoked when a specified time interval has elapsed. This function can be used to add or remove a timer. To register a timer routine for a specified interval, use the WtTimer function in the application with the ADD parameter.

timerid = WtTimer("ADD", interval, timer, [client_data])

The interval parameter specifies the time interval, in milliseconds, until the PV-WAVE procedure timer callback timer is invoked. The WtTimer routine, unlike the Xt TimeOut function, restarts itself when the timer callback procedure is called. To stop the timer, use the following command in the timer callback:

status=WtTimer("REMOVE", timerid)

The application can optionally use the client_data procedure to specify some application-defined data to be passed to the timer callback procedure when the callback is invoked. If client_data is a local variable (defined only in the current procedure), a copy of that variable is created and passed (passed by value). If client_data is a global variable (defined in a Common Block), it is passed by reference.

The form of Widget Toolbox timer procedures is:

PRO TimerProc, widget, client_data, nparams, timerid, time

where:

common timer, tid

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.

id=WtTimer("ADD", 100, 'TimerCallback', my_data)

PRO TimerCallback, wid, client_data, nparams, timer_id, interval

COMMON timer, tid

tid = timer_id

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END