flex初级画图板2

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical" creationComplete="init()">
	<mx:Script>
		<![CDATA[
			import mx.binding.utils.BindingUtils;
			import mx.managers.CursorManager;

			private var mX:Number;
			private var mY:Number;
			private var IsDown:Boolean=false;
			[Bindable] public var _lineSize:int=3;
			[Bindable] public var _lineColor:uint=0xff0000;

			private function init():void{
				myPanel.addEventListener(MouseEvent.MOUSE_DOWN,downHandler);
				myPanel.addEventListener(MouseEvent.MOUSE_MOVE,moveHandler);
				myPanel.addEventListener(MouseEvent.MOUSE_UP,upHandler);
				BindingUtils.bindProperty(this,"_lineSize",hs,"value");
				BindingUtils.bindProperty(this,"_lineColor",cp,"selectedColor");
			}

			private function downHandler(e:MouseEvent):void{
				IsDown=true;
				mX=myPanel.mouseX;
				mY=myPanel.mouseY;
			}
			
			private function upHandler(e:MouseEvent):void{
				IsDown=false;
			}

			private function moveHandler(e:MouseEvent):void{
				if(IsDown){
					var x:Number = myPanel.mouseX;
					var y:Number = myPanel.mouseY;
					myPanel.graphics.lineStyle(_lineSize,_lineColor,1);
					myPanel.graphics.moveTo(mX,mY);
					myPanel.graphics.lineTo(x,y);
					mX=x;
					mY=y;
				}
			}
		]]>
	</mx:Script>
	<mx:Panel width="100%" height="100%">
		<mx:Canvas id="myPanel" x="113.5" y="83" width="100%" height="90%" buttonMode="true" borderStyle="outset">
		</mx:Canvas>
		<mx:Button label="清空" click="myPanel.graphics.clear();"/>
		<mx:HSlider id="hs" value="{_lineSize}"/>
		<mx:ColorPicker id="cp" selectedColor="{_lineColor}"/>
	</mx:Panel>
</mx:Application>