Animating a Flex PieChart control’s rotation when a user clicks on an item

In a previous example, “Rotating a Flex PieChart control when a user clicks on an item”, we looked at changing a PieChart’s rotation when the user clicked on a pie wedge. In the following example, we look at how to add a nice animation effect with some easing to make the effect a bit more smooth.

Full code after the jump.


<?xml version="1.0" encoding="utf-8"?>
<!-- -->
<mx:Application xmlns:mx=""

            import mx.effects.easing.*;
            import mx.charts.series.items.PieSeriesItem;

            private function pieChart_itemClick(evt:ChartItemEvent):void {
                var item:PieSeriesItem = evt.hitData.chartItem as PieSeriesItem;
                var degrees:Number = radiansToDegrees(item.startAngle);
                var arr:Array = [];
                if (checkBox.selected) {
                    arr[item.index] = 0.2;
                pieSeries.perWedgeExplodeRadius = arr;
                pieSeries.startAngle -= degrees;


            private function radiansToDegrees(radians:Number):Number {
                return radians * (180 / Math.PI);

    <mx:XMLListCollection id="dp">
                <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:ApplicationControlBar dock="true">
        <mx:CheckBox id="checkBox"
                label="Use perWedgeExplodeRadius:"
                selected="true" />

    <mx:PieChart id="pieChart"
            <mx:PieSeries id="pieSeries"
                    <mx:SeriesInterpolate duration="1500"
                            easingFunction="{Elastic.easeOut}" />
                    <mx:DropShadowFilter />

    <mx:Legend dataProvider="{pieChart}" direction="horizontal" />


View source is enabled in the following example.

But remember kids, just because you can add easing, doesn’t mean you always should! ;)

11 thoughts on “Animating a Flex PieChart control’s rotation when a user clicks on an item

  1. Very Cool! I did notice that depending on where you click and after the animation the datatip is not updated and hovers over the wrong piece of pie.

    Neat effect though.

  2. Amazing, i have a request, beside the source code can you give me the xml files ? i mean the data of the chart.

  3. fidi,

    There aren’t any external XML files. The chart uses an mx:XMLListCollection as a data provider. All the required code should either be posted above, or you can right-click the Flex SWF and select “View Source” from the context menu.


  4. Dear peterd,

    Its very good example which helped me a lot and I am a very beginner to this and i started doing this flex charts using php mysql and outputting this as xml data but it could not able to do that could u help me out on this….

  5. Hi,
    I love this example. Thanks a lot! However, I have a question. When I changed the data provider to be XML from a server call, dp.refresh() was no longer defined. What’s the equivalent of refresh() for XML? I suspect that some redisplay event is being called. And now that I can’t redisplay my data, the piechart is not spinning anymore.
    Thank you,
    David :)

  6. @ David: Just call the dataprovider in the script.

    here an example:


    This line i call after my remotedataobject is loaded.

    in remoteobject:
    <mx:method name=”getStatistics” result=”getStatisticresults( event );” />

    The Function getStatisticresults:

    private function getStatisticresults(e:ResultEvent):void {
    showDataEffect=”seriesInterpolate” help you to see a nice reload-animation (<mx:PieSeries …)

    <mx:SeriesInterpolate id=”seriesInterpolate” duration=”1500″ />

    Best Regards from Austria

  7. Hi Peter , Excellent
    It saved my time a lot .
    But If you have some time , Could you please provide the same impact for the combo box event . I mean to say I have a combobox with Product 1, Product 2 …. . If I select any product , it should get react exactly the same whatever you did.

    Thanks again for your help

  8. Hi Alex,
    I cant see the colours in the legend of pichart.i am using flash builder 4.5. can you help me with this??. thanks for the help. Great Post!

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