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.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/11/22/animating-a-flex-piechart-controls-rotation-when-a-user-clicks-on-an-item/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            import mx.effects.easing.*;
            import mx.charts.series.items.PieSeriesItem;
            import mx.charts.events.ChartItemEvent;

            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;

                dp.refresh();
            }

            private function radiansToDegrees(radians:Number):Number {
                return radians * (180 / Math.PI);
            }
        ]]>
    </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:ApplicationControlBar dock="true">
        <mx:CheckBox id="checkBox"
                label="Use perWedgeExplodeRadius:"
                labelPlacement="left"
                selected="true" />
    </mx:ApplicationControlBar>

    <mx:PieChart id="pieChart"
            dataProvider="{dp}"
            showDataTips="true"
            itemClick="pieChart_itemClick(event);"
            height="100%"
            width="100%">
        <mx:series>
            <mx:PieSeries id="pieSeries"
                    field="@data"
                    nameField="@label">
                <mx:showDataEffect>
                    <mx:SeriesInterpolate duration="1500"
                            easingFunction="{Elastic.easeOut}" />
                </mx:showDataEffect>
                <mx:filters>
                    <mx:DropShadowFilter />
                </mx:filters>
            </mx:PieSeries>
        </mx:series>
    </mx:PieChart>

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

</mx:Application>

View source is enabled in the following example.

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

Tagged as: easingFunction, perWedgeExplodeRadius, startAngle