package {
	import flash.display.*;
	import flash.text.*;
	import flash.events.*;
	
	public class MyAnimation extends MovieClip {
		
		// Properties
		var myCircle:Sprite;
		var moveX:Number = 10;
		var moveY:Number = 10;
		var pausedMovie:Boolean = false;
		var oldX:Number;
		var oldY:Number;
		var friction:Number = .9;
		var gravity:Number = .5;

		// Constructor
		public function MyAnimation() {
			myCircle = new Sprite();
			myCircle.graphics.lineStyle(5,0x000000);
			myCircle.graphics.beginFill(0xCCCCCC);
			myCircle.graphics.drawCircle(0,0,25);
			addChild(myCircle);
			
			myCircle.x = 100;
			myCircle.y = 150;
			
			addEventListener(Event.ENTER_FRAME, moveCircle);
			myButton.addEventListener(MouseEvent.CLICK, stopOnEveryFrame);
			myCircle.addEventListener(MouseEvent.MOUSE_DOWN, startDragging);
		}
		
		public function startDragging(e:MouseEvent) {
			stage.addEventListener(MouseEvent.MOUSE_UP, stopDragging);
			removeEventListener(Event.ENTER_FRAME, moveCircle);
			myCircle.startDrag();
			addEventListener(Event.ENTER_FRAME, trackVelocity);
		} //startDragging
		
		public function stopDragging(e:MouseEvent) {
			stage.removeEventListener(MouseEvent.MOUSE_UP, stopDragging);
			myCircle.stopDrag();
			addEventListener(Event.ENTER_FRAME, moveCircle);
			removeEventListener(Event.ENTER_FRAME, trackVelocity);
		} //stopDragging
		
		public function trackVelocity(e:Event){
			moveX = myCircle.x - oldX;
			moveY = myCircle.y - oldY;
			oldX = myCircle.x;
			oldY = myCircle.y;
		}
		
		public function stopOnEveryFrame(e:MouseEvent) {
			if(pausedMovie){ 
				addEventListener(Event.ENTER_FRAME, moveCircle);
				pausedMovie = false;
			} else {
				removeEventListener(Event.ENTER_FRAME, moveCircle);
				pausedMovie = true;
			}
		}

		// Methods
		public function moveCircle(e:Event):void{
			moveY = moveY + gravity;

			if(myCircle.x > stage.stageWidth ||  myCircle.x < 0){
				moveX = -moveX*friction;  //change direction
			}     
			if(myCircle.y > stage.stageHeight ||  myCircle.y < 0){
				moveY = -moveY*friction;  //change direction
			}    

			myCircle.x = myCircle.x + moveX;
			myCircle.y = myCircle.y + moveY*gravity;
		}


	}
}