flex 画板

<?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>