[FLEX-32996] CLONE -NPE in AxisRenderer when stacked column chart has one data item

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: Adobe Flex SDK Previous
• Component/s: Charts
• Environment: Affected OS(s): All OS Platforms; Language Found: English
• Assignee: Unassigned
• Reporter: Adobe JIRA
• Created: 05/Jul/11 10:09
• Updated: 25/Aug/11 04:51

Description

I have been unable to create a simple test-case that reproduces this error, but I think a code inspection shows a problem. I've also been unable to get any help with a workaround on the Adobe forums or flexcoders.
The error is a null pointer exception when a stacked column chart has a single data item.

In AxisRenderer.as (line 2200 in sdk3.3) we find a reference to "lastLabel" which will be null if there is only one label, because it is computed as _labels[1].

Excerpt from AxisRenderer.calcStaggeredSpacing:

lastLabel = _labels[1];

if (adjustable.left == false)

{ staggeredScale = Math.min( staggeredScale, staggeredleftGutter / (firstLabel.width / 2)); }

if (adjustable.right == false)

{ staggeredScale = Math.min( staggeredScale, staggeredrightGutter / (lastLabel.width / 2)); // (me) Here's where the NPE occurs. }

Stack Crawl:

__________

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at mx.charts::AxisRenderer/calcStaggeredSpacing()[C:\work\flex\dmv_automation\proj ects\datavisualisation\src\mx\charts\AxisRenderer.as:2200]
at mx.charts::AxisRenderer/calcRotationAndSpacing()[C:\work\flex\dmv_automation\pr ojects\datavisualisation\src\mx\charts\AxisRenderer.as:1591]
at mx.charts::AxisRenderer/adjustGutters()[C:\work\flex\dmv_automation\projects\da tavisualisation\src\mx\charts\AxisRenderer.as:1331]
at mx.charts::AxisRenderer/set gutters()[C:\work\flex\dmv_automation\projects\datavisualisation\src\mx\charts\ AxisRenderer.as:803]
at mx.charts.chartClasses::CartesianChart/updateAxisLayout()[C:\work\flex\dmv_auto mation\projects\datavisualisation\src\mx\charts\chartClasses\CartesianChart.as:2 032]
at mx.charts.chartClasses::CartesianChart/updateDisplayList()[C:\work\flex\dmv_aut omation\projects\datavisualisation\src\mx\charts\chartClasses\CartesianChart.as: 1359]
at mx.core::UIComponent/validateDisplayList()[C:\autobuild\3.3.0\frameworks\projec ts\framework\src\mx\core\UIComponent.as:6351]
at mx.managers::LayoutManager/validateDisplayList()[C:\autobuild\3.3.0\frameworks\ projects\framework\src\mx\managers\LayoutManager.as:622]
at mx.managers::LayoutManager/doPhasedInstantiation()[C:\autobuild\3.3.0\framework s\projects\framework\src\mx\managers\LayoutManager.as:695]
at Function/http://adobe.com/AS3/2006/builtin::apply()
at mx.core::UIComponent/callLaterDispatcher2()[C:\autobuild\3.3.0\frameworks\proje cts\framework\src\mx\core\UIComponent.as:8633]
at mx.core::UIComponent/callLaterDispatcher()[C:\autobuild\3.3.0\frameworks\projec ts\framework\src\mx\core\UIComponent.as:8573]

Context from AxisRenderer:

(Note: the second branch of the if statement is executing, thus adjustment.bottom is false which leads to the code path with the bug.)

public function set gutters(value:Rectangle):void
{
var correctedGutters:Rectangle = value;

// This check will rarely succeed, because _gutters
// have been tweaked to represent placement.
if (_gutters &&
_gutters.left == correctedGutters.left &&
_gutters.right == correctedGutters.right &&
_gutters.top == correctedGutters.top &&
_gutters.bottom == correctedGutters.bottom)

{ _gutters = correctedGutters; return; }

else
{
adjustGutters(value,

{ left: false, top: false, right: false, bottom: false }

);
}
}

I am building the series list dynamically, it's a stacked column chart, and for me the bug occurs when there is one series and one data point.

I haven't been able to trigger the bug with the following example, which has a similar structure to my actual code.

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical" xmlns:local="*">

<mx:Script>
<![CDATA[
import mx.charts.series.ColumnSeries;
import mx.charts.chartClasses.Series;

[Bindable]
public var seriesList:Array = [];

public function buildSeriesList(seriesList:Array):Array {

var chartSeries:Array = new Array();

var index:int = 0;
for each (var series:Object in seriesList)

{ var columnSeries:ColumnSeries = new ColumnSeries(); columnSeries.dataProvider = series.items; columnSeries.dataFunction = myDataFunction; columnSeries.displayName = series.category; chartSeries.push( columnSeries ); }

return chartSeries;
}

private function categoryProvider(seriesList:Array):Array

{ if (seriesList && seriesList.length > 0) return (seriesList[0]).items; return null; }

private function myDataFunction(series:Series, item:Object, fieldName:String):Object {
if(fieldName == "yValue")

{ return item.value; }

else if(fieldName == "xValue")

{ return item.category; }

else
return null;
}

public function shortCategoryLabel(source:String):String

{ return source; }



public function longCategoryLabel(source:String):String { return source; }

private function onRefresh(event:Event):void {
this.seriesList = [ { category: "cat1" , items: [

{ category: "Default Business Unit", value:574.1 }

] }];
}

]]
>
</mx:Script>

<mx:Button label="Refresh" click="onRefresh(event)" />

<mx:ColumnChart height="100%"
width="100%" type="stacked" series="

{this.buildSeriesList(this.seriesList)}

">

<mx:horizontalAxis>
<mx:CategoryAxis id="bottomAxis2" title="Horizontal Axis"
dataProvider="

{this.categoryProvider(this.seriesList)}

"
categoryField="category"
/>
</mx:horizontalAxis>

<mx:verticalAxis>
<mx:LinearAxis id="leftAxis2" title="Vertical Axis"/>
</mx:verticalAxis>

<mx:verticalAxisRenderers>
<mx:AxisRenderer
placement="left" styleName="verticalAxisRenderer"
axis="

{leftAxis2}

" verticalAxisTitleAlignment="vertical"
/>
</mx:verticalAxisRenderers>

<mx:horizontalAxisRenderers>
<mx:AxisRenderer
placement="bottom"
axis="

{bottomAxis2}

" verticalAxisTitleAlignment="flippedVertical"
>
</mx:AxisRenderer>
</mx:horizontalAxisRenderers>

</mx:ColumnChart>

</mx:Application>