flex 饼图缓动

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
<mx:Script>
	<![CDATA[
	import mx.charts.series.items.PieSeriesItem;
	import mx.charts.events.ChartItemEvent;
	import mx.effects.easing.*;

		private function c(event:ChartItemEvent):void{
			var item:PieSeriesItem=event.hitData.chartItem as PieSeriesItem;
			var rad:Number=item.startAngle*(180/Math.PI);
			var arr:Array=[];
			arr[item.index]=0.2;  
			pieSeries.perWedgeExplodeRadius=arr; //离开的距离
			//pieSeries.startAngle-=rad;   //设置起始位置
		}
	]]>
</mx:Script>
 <mx:XMLListCollection id="dp">
        <mx:source>
            <mx:XMLList>
                <product label="Product 1" data="3" />
                <product label="Product 2" data="1" />
                <product label="Product 3" data="4" />
                <product label="Product 4" data="1" />
                <product label="Product 5" data="5" />
                <product label="Product 6" data="9" />
            </mx:XMLList>
        </mx:source>
    </mx:XMLListCollection>
	<mx:PieChart x="136" y="28" id="piechart1" dataProvider="{dp}" showDataTips="true" itemClick="c(event)" width="543" height="428">
		<mx:series>
			<mx:PieSeries  id="pieSeries" displayName="Series 1" field="@data" nameField="@label">
				<mx:showDataEffect>
					<mx:SeriesInterpolate duration="2000" easingFunction="{Elastic.easeOut}"/>
				</mx:showDataEffect>
			</mx:PieSeries>
		</mx:series>
	</mx:PieChart>
	<mx:Legend dataProvider="{piechart1}" x="732" y="413"/>
</mx:Application>