Classic Chart getting Null Paint Exception in X-Trace and Mark modes

Ignition
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1

I am currently using the Classic Chart’s configureChart() function to change the color of the data points if it is outside of a user-defined spec limit. It is currently working as expected.

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image989×387 37.6 KB

However, when I go into X-Trace or Mark mode, I get this error

java.lang.IllegalArgumentException: Null 'paint' argument.
	at org.jfree.chart.annotations.XYTextAnnotation.setPaint(XYTextAnnotation.java:222)
	at com.inductiveautomation.factorypmi.application.components.chart.runtime.AutoAnnotateXYPlot.draw(AutoAnnotateXYPlot.java:634)
	at org.jfree.chart.JFreeChart.draw(JFreeChart.java:1227)
...

This is the code I am using in my configureChart()

	from org.jfree.chart.renderer.xy import XYLineAndShapeRenderer
	from java.awt import Color
	
	specData = self.SpecData
	
	if specData.getRowCount() == 0:
		rend = XYLineAndShapeRenderer()
	else:
		highVal = specData.getValueAt(0, 1)
		lowVal = specData.getValueAt(0, 2)
		class myRenderer(XYLineAndShapeRenderer):
			def getItemPaint(self, row, column):
				val = self.getPlot().getDataset(0).getYValue(row, column)
				if val > highVal or val < lowVal:
					return Color.red
				else:
					return Color.blue
		rend = myRenderer()	
		
	chart.getXYPlot().setRenderer(rend)

Is there something I am missing in my overridden getItemPaint() method to cause it to send a null value?

2

Update: I have tried testing getItemPaint() by having it always return Color.blue. This still causes the null paint exception. When I don’t override the getItemPaint() method at all, this exception does not happen. Am I not allowed to override this method? What could possibly be happening on Ignition’s backend to change that value to null?

3

What exact version are you using? Your line numbers don’t match up with mine in the current codebase, so I can’t see exactly which path we’re following to end up sending a null.

What’s happening, broadly, is that we’re trying to send a color to the annotation, and the annotation itself (vanilla JFreeChart code) is guarding against a null paint.

4

I am using 8.0.12.

5

This is our code that’s ultimately returning null and assigning it to the annotation object:
image

It looks like the call getSeriesPaint on your subclassed renderer is where the null is coming from. Try overriding getSeriesPaint in your subclass as well.

1 Like
6

This works, thank you so much!

7

Can someone expand on this and show where in the @Zachary_Zipper's you would need to override getSeriesPaint? I'm assuming you make another definition like below:

def getSeriesPaint(self, row, column)

When I did that, it says it needs three arguments and only 2 given, example below:

def getSeriesPaint(self, row, column):
	valx = plot.getDataset().getXValue(row, column)
	valy = plot.getDataset().getYValue(row, column)
	if valx > 6:
		return Color.RED
	else:
		return Color.GREEN
8

getSeriesPaint would accept self and one additional argument series (an integer). Not as convenient as a row/column.

9

I’m having trouble on constructing the code for this. For simplicity, I’m working with just a single series, so zero (0) is what I’m assuming I can use.

10

Ok, so it seems it was as simple as writing this:

def getSeriesPaint(self, series):
	return Color.BLACK

It didn’t matter what I put in the 2nd argument as long as it had a string. It doesn’t accept an integer itself. What this did was return the color to the trace or mark label font.