How to change a chart in Jaspersoft Studio or create your own? - jasper-reports

Question

I need to insert a graph in Jaspersoft, which contains the last 24 energy consumptions of a person to print it on an invoice. I'm programming in Java.
With each invoice will come different consumption values, which must respect the fixed size of the graph, and develop the size of its bars based on the highest consumption to keep proportion with the rest of the consumption.
I have developed the model that I attached in the image in Java with Graphics 2D and it is very laborious, I would like to do it in JasperSoft to generate a report, but as much as I explore the properties of the bar graph, I cannot obtain something similar.
I've seen on Google that Jaspersoft can use some modified JFreeChart charts to add to their themes, but I can't find any documentation to investigate how this is done.
Jaspersoft's documentation is very brief and doesn't say much about how to do what I need.
Can someone help me with this problem, either by sending me a link with examples or more complete documentation?

Answer 1

If you already have Java code to render the chart to Graphics2D, the best approach is to leverage what you have in JasperReports. You can do that by wrapping your code into an implementation of the net.sf.jasperreports.renderers.Renderable interface, and using an instance of your implementation as image expression in the report.
A slightly trickier part is collecting the data from the report and passing it to the chart renderer. That can be done with a couple of variables that collect the values into a map (for instance).
The chart renderer implementation would look something like this:
public class ChartRenderer extends AbstractRenderer implements Graphics2DRenderable {
private final Map<String, Number> data;
public ChartRenderer(Map<String, Number> data) {
this.data = data;
}
#Override
public void render(JasperReportsContext jasperReportsContext, Graphics2D grx, Rectangle2D rectangle)
throws JRException {
//render the data as a chart onto the Graphics2D instance
}
}
Then in the report you would have variables to collect the data:
<variable name="ChartData" class="java.util.LinkedHashMap" calculation="System">
<initialValueExpression>new java.util.LinkedHashMap()</initialValueExpression>
</variable>
<variable name="ChartDataPut" class="java.lang.Object">
<variableExpression>$V{ChartData}.put($F{KeyField}, $F{ValueField})</variableExpression>
</variable>
And an image to display the chart:
<image>
<reportElement ... />
<imageExpression>new ChartRenderer($V{ChartData})</imageExpression>
</image>