[FLEX-32979] Plotting a curved line in a chart will throw a run time error if all of the data points in a data provider have the same x/y values

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Adobe Flex SDK 4.5 (Release)
• Component/s: Charts
• Environment: Affected OS(s): All OS Platforms; Language Found: English
• Assignee: Unassigned
• Reporter: Adobe JIRA
• Created: 27/May/11 02:37
• Updated: 11/Sep/11 23:29

Description

Steps to reproduce:
1. Run following code

<?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" >
<mx:LineChart width="100%" height="100%">
<mx:series>
<mx:LineSeries form="curve" xField="a" yField="b" dataProvider="{[

{a:1,b:1}

,

{a:1,b:1}

]}"/>
</mx:series>
</mx:LineChart>
</s:Application>

Actual Results:
TypeError: Error #1010: A term is undefined and has no properties.
at mx.charts.chartClasses::GraphicsUtilities$/drawPolyLine()[E:\dev\4.x\frameworks\projects\datavisualization\src\mx\charts\chartClasses\GraphicsUtilities.as:327]
at mx.charts.renderers::LineRenderer/updateDisplayList()[E:\dev\4.x\frameworks\projects\datavisualization\src\mx\charts\renderers\LineRenderer.as:119]
at mx.skins::ProgrammaticSkin/validateDisplayList()[E:\dev\4.x\frameworks\projects\framework\src\mx\skins\ProgrammaticSkin.as:503]
at mx.managers::LayoutManager/validateDisplayList()[E:\dev\4.x\frameworks\projects\framework\src\mx\managers\LayoutManager.as:663]
at mx.managers::LayoutManager/doPhasedInstantiation()[E:\dev\4.x\frameworks\projects\framework\src\mx\managers\LayoutManager.as:718]
at mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:\dev\4.x\frameworks\projects\framework\src\mx\managers\LayoutManager.as:1072]

Expected Results:
No RTE, Chart to display.

Workaround (if any):
current workaround is to set our own line renderer on line series instances, which traps the exception. This fix is not ideal since there is a small chance we may end up swallowing genuine errors with problems in our own code/data:
public class CustomLineRenderer extends LineRenderer
{

override protected function updateDisplayList(unscaledWidth:Number,
unscaledHeight:Number):void
{
// The line renderer uses mx.charts.chartClasses.GraphicsUtilities to plot a curve.
// This class has a bug when rendering curves, if it manages to receive render data too
// early in the creation of the chart.
//
// Our work around here is to trap the runtime error, since the chart will successfully render
// on the next frame.
try

{ super.updateDisplayList(unscaledWidth,unscaledHeight); }

catch(e:Error)

{ // We are swallowing this error so we don't take out the entire layout manager. }

}
}

Identified Cause:

The drawPolyLine method in mx.charts.chartClassess.GraphicsUtilities class contains a loop to skip over coincident points when dealing with curved lines:
start = originalStart;
var innerEnd:int = end - incr;
// Check for coincident points at the head of the list.
// We'll skip over any of those
while (start != end)
{
if (pts[start + incr][hProp] != pts[start][hProp] ||
pts[start + incr][vProp] != pts[start][vProp])

{ break; }

start += incr;
}