清除/清空Flex中的lineChart

Question

我有一個折線圖，帶有dateTime軸。我通過actionscript將數據提供者設置爲該線圖。圖形繪製完成。當我爲數據提供者分配一個空值以使圖形變爲空時，就會出現問題。

實際代碼類似於下面的代碼：

var actualValues:XMLList=flowChartDP.upFlows; 
var localSeries1:LineSeries = new LineSeries(); 
localSeries1.dataProvider = actualValues; 
localSeries1.yField = "flow"; 
localSeries1.xField = "time"; 
localSeries1.setStyle("form","curve"); 
var currentSeries1:Array =lineChart.series; 
currentSeries1.push(localSeries1); 
lineChart.series = currentSeries1; 
var actualValues2:XMLList=flowChartDP.downFlows; 
var localSeries2:LineSeries = new LineSeries(); 
localSeries2.dataProvider = actualValues2; 
localSeries2.yField = "flow"; 
localSeries2.xField = "time"; 
localSeries2.setStyle("form","curve"); 
var currentSeries2:Array =lineChart.series; 
currentSeries2.push(localSeries2); 
lineChart.series = currentSeries2; 

而且我會在samefashion到lineChart.Although正好被增加了兩個系列我想不會writung代碼這個作品的最好方式精細。 問題在於重置圖形。

我有一個按鈕，當點擊時： lineChart.dataprovider = null; lineChart.series = null;

但我的flash播放器（FP 10調試版）拋出了以下錯誤

TypeError: Error #1009: Cannot access a property or method of a null object reference. 
    at mx.charts::AxisRenderer/measureHorizontalGutters()[E:\dev\4.0.0\frameworks\projects\datavisualization\src\mx\charts\AxisRenderer.as:2275] 
    at mx.charts::AxisRenderer/calcRotationAndSpacing()[E:\dev\4.0.0\frameworks\projects\datavisualization\src\mx\charts\AxisRenderer.as:1889] 
    at mx.charts::AxisRenderer/adjustGutters()[E:\dev\4.0.0\frameworks\projects\datavisualization\src\mx\charts\AxisRenderer.as:1565] 
    at mx.charts.chartClasses::CartesianChart/updateAxisLayout()[E:\dev\4.0.0\frameworks\projects\datavisualization\src\mx\charts\chartClasses\CartesianChart.as:2133] 
    at mx.charts.chartClasses::CartesianChart/updateDisplayList()[E:\dev\4.0.0\frameworks\projects\datavisualization\src\mx\charts\chartClasses\CartesianChart.as:1391] 
    at mx.core::UIComponent/validateDisplayList()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\core\UIComponent.as:8531] 
    at mx.managers::LayoutManager/validateDisplayList()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:663] 
    at mx.managers::LayoutManager/doPhasedInstantiation()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:736] 
    at mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:1072] 

什麼解決的辦法？它不會拋出錯誤時

lineChart.series=null; 

被刪除。但聲明

lineChart.dataprovider=null; 

不使圖表爲空。

Answer 1

下面是我創建的一個簡單應用程序，用於重新創建您的問題。將dataProvider設置爲null會清除圖表，但對我來說沒有任何例外。運行它並看看。我說你的問題在別的地方。

<?xml version="1.0" encoding="utf-8"?> 
<s:Application 
    xmlns:fx="http://ns.adobe.com/mxml/2009" 
    xmlns:s="library://ns.adobe.com/flex/spark"    
    xmlns:mx="library://ns.adobe.com/flex/mx" > 

    <fx:Script><![CDATA[ 

     import mx.collections.ArrayCollection; 
     [Bindable] 
     public var expenses:ArrayCollection = new ArrayCollection([ 
      {Month:"Jan", Profit:2000, Expenses:1500, Amount:450}, 
      {Month:"Feb", Profit:1000, Expenses:200, Amount:600}, 
      {Month:"Mar", Profit:1500, Expenses:500, Amount:300} 
     ]); 


     protected function button1_clickHandler(event:MouseEvent):void 
     { 
      myChart.dataProvider = null; 

     } 

    ]]></fx:Script> 

    <s:layout> 
     <s:VerticalLayout /> 
    </s:layout> 


    <mx:Panel title="Line Chart"> 
     <mx:LineChart id="myChart" 
         dataProvider="{expenses}" 
         showDataTips="true" 
         > 
      <mx:horizontalAxis> 
       <mx:CategoryAxis 
        dataProvider="{expenses}" 
        categoryField="Month" 
        /> 
      </mx:horizontalAxis> 
      <mx:series> 
       <mx:LineSeries 
        yField="Profit" 
        displayName="Profit" 
        /> 
       <mx:LineSeries 
        yField="Expenses" 
        displayName="Expenses" 
        /> 
      </mx:series> 
     </mx:LineChart> 
     <mx:Legend dataProvider="{myChart}"/> 
    </mx:Panel> 

    <s:Button click="button1_clickHandler(event)" label="Clear" /> 

</s:Application>