Flex---实现画图板功能

<?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>