<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/11/04/positioning-labels-in-a-flex-piechart-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Script>
        <![CDATA[
            private function pieSeries_labelFunc(item:Object, field:String, index:Number, percentValue:Number):String {
                return item.@label + ": " + item.@data + " (" + percentValue.toFixed(2) + "%)";
            }
        ]]>
    </mx:Script>

    <mx:XML id="dp">
        <products>
            <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" />
        </products>
    </mx:XML>
    
    <mx:Array id="labelPositionArr">
        <mx:Object label="callout" />
        <mx:Object label="inside" />
        <mx:Object label="insideWithCallout" />
        <mx:Object label="none" />
        <mx:Object label="outside" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:Label text="labelPosition:" />
        <mx:ComboBox id="comboBox"
                dataProvider="{labelPositionArr}" />
    </mx:ApplicationControlBar>

    <mx:PieChart id="pieChart"
            dataProvider="{dp.product}"
            height="250"
            width="100%">
        <mx:series>
            <mx:PieSeries id="pieSeries"
                    field="@data"
                    labelPosition="{comboBox.selectedItem.label}"
                    labelFunction="pieSeries_labelFunc" />
        </mx:series>
    </mx:PieChart>

</mx:Application>