<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
			   xmlns:s="library://ns.adobe.com/flex/spark" 
			   xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600">
	
	<fx:Script>
		<![CDATA[
			
			// GLOBAL VARIABLES
			public var t:Timer; // our timer
			public var direction:int = -1; // keeps track of up/down direction
			
			/**
			 * startTimer function is called when the button is pressed.
			 * It starts a timer of limited length and adds some EventListeners 
			 * to the Timer.
			 * **/
			protected function startTimer(event:MouseEvent):void
			{
				t=new Timer(5,100); // create timer events every 5ms, only tick 100 times
				t.addEventListener(TimerEvent.TIMER,go); // call 'go' when the timer starts
				t.addEventListener(TimerEvent.TIMER_COMPLETE,end); // call 'end' when the timer is done
				t.start(); // start the timer
			}
			
			/**
			 * go function is called every time the timer ticks.
			 * It moves an image up/down, checking so it doesn't go
			 * out of bounds.
			 * **/
			protected function go(event:TimerEvent):void
			{
				myImage.y+=2*direction; // move up/down 2
				
				if (myImage.y<0 || myImage.y>600) // checking boundaries
					direction*=-1; // direction = -direction;
			}
			
			/**
			 * end() function is called when the timer is done. It changes
			 * the source of our displayed image.
			 * **/
			protected function end(event:TimerEvent):void
			{
				myImage.source="http://www.cs.cmu.edu/~anind/dey.big.jpg";
			}
			
		]]>
	</fx:Script>
	
	<fx:Declarations>
		<!-- Place non-visual elements (e.g., services, value objects) here -->
	</fx:Declarations>
	<s:Button x="43" y="227" width="116" height="56" label="Start Timer" click="startTimer(event)"/>
	<s:Image id="myImage" x="233" y="143" width="104" height="96" source="http://upload.wikimedia.org/wikipedia/en/thumb/8/81/HCII_logo.svg/200px-HCII_logo.svg.png"/>
</s:Application>