The preferred way to handle timing functions in ActionScript
3.0 is to use the Timer class (flash.utils.Timer), which can be
used to dispatch events whenever an interval is reached.
To start a
timer, you first create an instance of the Timer class, telling
it how often to generate a timer event and how many times to do
so before stopping.
For example, the following code creates a Timer instance that
dispatches an event every second and continues for 60 seconds:
var oneMinuteTimer:Timer = new Timer(1000, 60);
The Timer object
dispatches a TimerEvent object each time the given interval is reached.
A TimerEvent object’s event type is
timer
(defined
by the constant
TimerEvent.TIMER
). A TimerEvent
object contains the same properties as a standard Event object.
If the Timer instance is set to a fixed number of intervals,
it will also dispatch a
timerComplete
event (defined
by the constant
TimerEvent.TIMER_COMPLETE
) when
it reaches the final interval.
Here is a small sample application showing the Timer class in
action:
package
{
import flash.display.Sprite;
import flash.events.TimerEvent;
import flash.utils.Timer;
public class ShortTimer extends Sprite
{
public function ShortTimer()
{
// creates a new five-second Timer
var minuteTimer:Timer = new Timer(1000, 5);
// designates listeners for the interval and completion events
minuteTimer.addEventListener(TimerEvent.TIMER, onTick);
minuteTimer.addEventListener(TimerEvent.TIMER_COMPLETE, onTimerComplete);
// starts the timer ticking
minuteTimer.start();
}
public function onTick(event:TimerEvent):void
{
// displays the tick count so far
// The target of this event is the Timer instance itself.
trace("tick " + event.target.currentCount);
}
public function onTimerComplete(event:TimerEvent):void
{
trace("Time's Up!");
}
}
}
When the ShortTimer class is created, it creates a Timer instance
that will tick once per second for five seconds. Then it adds two
listeners to the timer: one that listens to each tick, and one that
listens for the
timerComplete
event.
Next, it starts the timer ticking, and from that point forward,
the
onTick()
method executes at one-second intervals.
The
onTick()
method simply displays the current
tick count. After five seconds have passed, the
onTimerComplete()
method
executes, telling you that the time is up.
When you run this sample, you should see the following lines
appear in your console or trace window at the rate of one line per
second:
tick 1
tick 2
tick 3
tick 4
tick 5
Time's Up!
