Flex中如何利用showLabelVertically属性控制ColumnChart上Column

<?xml version="1.0"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">
 
    <mx:Style>
        @font-face {
            src: local("Arial");
            fontFamily: ArialEmbedded;
        }
 
        ColumnChart {
            fontFamily: ArialEmbedded;
        }
    </mx:Style>
 
    <mx:Script>
        <![CDATA[
            import mx.charts.series.items.ColumnSeriesItem;
            import mx.charts.ChartItem;
            import mx.charts.chartClasses.Series;
            import mx.charts.chartClasses.IAxis;
            import mx.utils.ObjectUtil;
 
            private function linearAxis_labelFunc(item:Object,prevValue:Object,axis:IAxis):String {
                return currencyFormatter.format(item);
            }
 
            private function categoryAxis_labelFunc(item:Object,axis:CategoryAxis,categoryItem:Object):String {
                var datNum:Number = Date.parse(item);
                var tempDate:Date = new Date(datNum);
                return shortDateFormatter.format(tempDate).toUpperCase();
            }
 
            private function columnSeries_labelFunc(element:ChartItem,series:Series):String {
                var csi:ColumnSeriesItem = ColumnSeriesItem(element);
                var ser:ColumnSeries = ColumnSeries(series);
 
                var datNum:Number = Date.parse(csi.item.@date);
                var tempDate:Date = new Date(datNum);
                return fullDateFormatter.format(tempDate);
            }
        ]]>
    </mx:Script>
 
    <mx:DateFormatter id="shortDateFormatter" formatString="DD" />
    <mx:DateFormatter id="fullDateFormatter" formatString="MMM D,YYYY" />
    <mx:CurrencyFormatter id="currencyFormatter" precision="2" />
 
    <mx:XMLListCollection id="dp">
        <mx:source>
            <mx:XMLList>
                <quote date="8/1/2007" open="40.29" close="39.58" />
                <quote date="8/2/2007" open="39.4" close="39.52" />
                <quote date="8/3/2007" open="39.47" close="38.75" />
                <quote date="8/6/2007" open="38.71" close="39.38" />
                <quote date="8/7/2007" open="39.08" close="39.42" />
                <quote date="8/8/2007" open="39.61" close="40.23" />
                <quote date="8/9/2007" open="39.9" close="40.75" />
                <quote date="8/10/2007" open="41.3" close="41.06" />
                <quote date="8/13/2007" open="41" close="40.83" />
                <quote date="8/14/2007" open="41.01" close="40.41" />
                <quote date="8/15/2007" open="40.22" close="40.18" />
                <quote date="8/16/2007" open="39.83" close="39.96" />
                <quote date="8/17/2007" open="40.18" close="40.32" />
                <quote date="8/20/2007" open="40.55" close="40.74" />
                <quote date="8/21/2007" open="40.41" close="40.13" />
                <quote date="8/22/2007" open="40.4" close="40.77" />
                <quote date="8/23/2007" open="40.82" close="40.6" />
                <quote date="8/24/2007" open="40.5" close="40.41" />
                <quote date="8/27/2007" open="40.38" close="40.81" />
            </mx:XMLList>
        </mx:source>
    </mx:XMLListCollection>
 
    <mx:ApplicationControlBar dock="true">
        <mx:CheckBox id="checkBox"
                label="showLabelVertically:"
                labelPlacement="left"
                selected="true" />
    </mx:ApplicationControlBar>
 
    <mx:ColumnChart id="columnChart"
            showDataTips="true"
            dataProvider="{dp}"
            width="100%"
            height="100%"
            showLabelVertically="{checkBox.selected}">
 
        <!-- vertical axis -->
        <mx:verticalAxis>
            <mx:LinearAxis baseAtZero="false"
                    labelFunction="linearAxis_labelFunc" />
        </mx:verticalAxis>
 
        <!-- horizontal axis -->
        <mx:horizontalAxis>
            <mx:CategoryAxis id="ca"
                    categoryField="@date"
                    title="August 2007"
                    labelFunction="categoryAxis_labelFunc" />
        </mx:horizontalAxis>
 
        <!-- horizontal axis renderer -->
        <mx:horizontalAxisRenderers>
            <mx:AxisRenderer axis="{ca}"
                    canDropLabels="true" />
        </mx:horizontalAxisRenderers>
 
        <!-- series -->
        <mx:series>
            <mx:ColumnSeries displayName="Open"
                    xField="@date"
                    yField="@open"
                    labelFunction="columnSeries_labelFunc"
                    labelPosition="outside">
            </mx:ColumnSeries>
        </mx:series>
 
        <!-- series filters -->
        <mx:seriesFilters>
            <mx:Array />
        </mx:seriesFilters>
    </mx:ColumnChart>
 
</mx:Application>