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The last statement in the constructor in Listing 4 registers a CREATION_COMPLETE event handler on the Canvas object. You are already familiar with event listeners of this type. The code for thelistener is shown in its entirety in Listing 5.
private function creationCompleteHandler(
event:mx.events.FlexEvent):void{//Set the width and height of the Canvas object// based on the size of the bitmap in the smallSky
// image.this.width = Bitmap(smallSky.content).width;
this.height = Bitmap(smallSky.content).height;//Add the image to this Canvas object.this.addChild(smallSky);//Register a timer listener and start the timer
// running.timer.addEventListener(TimerEvent.TIMER, onTimer);
timer.start();} //end creationCompleteHandler As you learned in earlier lessons, this handler method is executed when the Canvas object has been fully created.
Nothing new here
There is nothing new in Listing 5. The code in Listing 5:
Beginning of the TIMER event handler
The event handler that is registered on the Timer object begins in Listing 6. This method is executed each time the Timer object fires an event.
public function onTimer(event:TimerEvent):void {//Update the loop counter.
loopCntr++;if (loopCntr == int.MAX_VALUE - 1) {
//Guard against numeric overflow.loopCntr = 0;
}//end if Update the loop counter
Among other things, the code in the Timer event handler maintains a count of the number of events that have been fired by the timer. Thecode in Listing 6 increments the timer each time the event-handler method is executed, and sets the value back to zero when it reaches a very large value toguard against binary overflow.
Play an occasional wind sound
According to the code in Listing 3, the Timer object will fire an event every 100 milliseconds, or ten times per second. That causes theevent handler to be called ten times per second.
The code in Listing 7 uses the modulus operator to identify every 25th call to the event handler. This occurs approximately once every 2.5 seconds,depending on the accuracy of the timer.
if ((loopCntr % 25 == 0)&&(Math.random()>0.75)){
wind.play();}//end if Let the wind blow: or maybe not
When the code in Listing 7 determines that 2.5 seconds have passed since the last attempt to play the wind sound, it gets a random value of type Number with a value between 0 and 1.0. If that random value is greater than 0.75, it calls the play method on the wind sound to cause the sound to be played once from start to finish.
One wind sound every ten seconds on average
Assuming that the random values are uniformly distributed, about one out of every four random values will be greater than 0.75. Therefore, the wind soundshould be played about once every ten seconds on average.
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