Flex ScrollView

/**
 * Author: Kevin Luo
 * Email: [email protected]
 * Description:
 * The passed in conponent can be scroll as iphone style;
 * */
package util
{
	import flash.display.DisplayObject;
	import flash.events.MouseEvent;
	import flash.events.TimerEvent;
	import flash.utils.Timer;
	import mx.containers.Canvas;

	public class ScrollView extends Canvas
	{
		private var _displayObj:DisplayObject;
		private var isMouseDown:Boolean=false;
		private var mDY:int;
		private var sY:int;
		private var eY:int;
		private var mDX:int;
		private var sX:int;
		private var eX:int;
		private var isDragging:Boolean=false;
		private var sTime:Number;
		private var eTime:Number
		private var inertialTimerY:Timer;
		private var inertialTimerX:Timer;
		private var speedY:Number;
		private var speedX:Number;
		private var a:int;

		public function get displayObj():DisplayObject
		{
			return this._displayObj;
		}

		public function ScrollView(value:DisplayObject, a:int=50)
		{
			super();
			this.horizontalScrollPolicy="off";
			this.verticalScrollPolicy="off";
			this._displayObj=value;
			this.a=a;
			this.addChild(value);
			this.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandle);
			this.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandle);
			this.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandle);
			this.inertialTimerY=new Timer(30);
			this.inertialTimerX=new Timer(30);
			this.inertialTimerY.addEventListener(TimerEvent.TIMER, inertialMovePieceY);
			this.inertialTimerX.addEventListener(TimerEvent.TIMER, inertialMovePieceX);
		}

		protected function mouseDownHandle(e:MouseEvent):void
		{
			this.isMouseDown=true;
			this.mDY=mouseY;
			this.mDX=mouseX;
			if (inertialTimerY.running)
				inertialTimerY.stop();
			if (inertialTimerX.running)
				inertialTimerX.stop();
		}

		protected function mouseUpHandle(e:MouseEvent):void
		{
			this.isDragging=false;
			this.isMouseDown=false;
			this.eTime=new Date().time;
			this.eY=mouseY;
			this.eX=mouseX;
			this.speedY=(eY - mDY) / (eTime - sTime) * a;
			this.speedX=(eX - mDX) / (eTime - sTime) * a;
			if (inertialTimerY.running)
				inertialTimerY.stop();
			if (inertialTimerX.running)
				inertialTimerX.stop();
			if (Math.abs(speedY) > 20)
			{
				inertialTimerY.start();
			}
			if (Math.abs(speedX) > 20)
			{
				inertialTimerX.start();
			}
		}

		private function mouseMoveHandle(e:MouseEvent):void
		{
			if (this.isMouseDown)
			{
				if (Math.abs(mouseY - mDY) > 3 || Math.abs(mouseY - mDX) > 3)
				{
					if (!this.isDragging)
					{
						sY=mouseY;
						sX=mouseX
						this.isDragging=true
						this.sTime=new Date().time;
					}
					this._displayObj.y=this._displayObj.y + (mouseY - sY);
					this._displayObj.x=this._displayObj.x + (mouseX - sX)
					this.sY=mouseY
					this.sX=mouseX
					if (this._displayObj.y > 0)
					{
						this._displayObj.y=0;
					}
					else if (this._displayObj.y < -(this._displayObj.height - this.height))
					{
						this._displayObj.y=-(this._displayObj.height - this.height)
					}
					if (this._displayObj.x > 0)
					{
						this._displayObj.x=0;
					}
					else if (this._displayObj.x < -(this._displayObj.width - this.width))
					{
						this._displayObj.x=-(this._displayObj.width - this.width)
					}
					if (this._displayObj.hasOwnProperty("selectedItem"))
					{
						this._displayObj["selectedItem"]=null;
					}
				}
			}
		}

		private function inertialMovePieceY(evt:TimerEvent):void
		{
			this._displayObj.y+=speedY;
			speedY=speedY * 0.9;
			if (this._displayObj.y > 0)
			{
				this._displayObj.y=0;
				inertialTimerY.stop()
			}
			else if (this._displayObj.y < -(this._displayObj.height - this.height))
			{
				this._displayObj.y=-(this._displayObj.height - this.height)
				inertialTimerY.stop()
			}
		}

		private function inertialMovePieceX(evt:TimerEvent):void
		{
			this._displayObj.x+=speedX;
			speedX=speedX * 0.9;
			if (this._displayObj.x > 0)
			{
				this._displayObj.x=0;
				inertialTimerX.stop()
			}
			else if (this._displayObj.x < -(this._displayObj.width - this.width))
			{
				this._displayObj.x=-(this._displayObj.width - this.width)
				inertialTimerX.stop()
			}
		}
	}
}