How to dynamically remove legend in charts using Jasper reports?

Question

How to dynamically remove the legend from a chart using the Jasper report API?

I have a chart to display dynamically based on some configurations, which includes the legend as a option, so if legend is unchecked I need to hide or remove the legend form the chart. Is there any function available in the API which can do that?

Answer 1

Here there is a method setShowLegend(Boolean)

You can obtain the chart this way (I haven't tested it, so there might be some issues):

InputStream is = this.getClaa().getResourceAsStream(jasperFilePath);
JasperReport jasperReport = (JasperReport) JRLoader.loadObject(is);
JRChart chart = (JRChart) report.getDetail().getElementByKey("chart");
chart.setShowLegend(Boolean.FALSE);

Answer 2

I think that the JasperReport description syntax (the XML tags composing the jrxml file) do not let you do such a thing.

Here is a pie chart description with legend (default) :

<pieChart>
    <chart isShowLegend="true">
     <reportElement x="19" y="18" width="518" height="196"/>
     <chartTitle/>
     <chartSubtitle/>
     <chartLegend/>
    </chart>
    <pieDataset>
     <keyExpression><![CDATA[$F{name}]]></keyExpression>
     <valueExpression><![CDATA[$F{value}]]></valueExpression>
     <labelExpression><![CDATA["<"+$F{name}+">"]]></labelExpression>
    </pieDataset>
    <piePlot>
     <plot/>
     <itemLabel color="#000000" backgroundColor="#FFFFFF"/>
    </piePlot>
</pieChart>

and here the same chart without legend :

<pieChart>
    <chart isShowLegend="false">
     <reportElement x="19" y="18" width="518" height="196"/>
     <chartTitle/>
     <chartSubtitle/>
     <chartLegend/>
    </chart>
    <pieDataset>
     <keyExpression><![CDATA[$F{name}]]></keyExpression>
     <valueExpression><![CDATA[$F{value}]]></valueExpression>
     <labelExpression><![CDATA["<"+$F{name}+">"]]></labelExpression>
    </pieDataset>
    <piePlot>
     <plot/>
     <itemLabel color="#000000" backgroundColor="#FFFFFF"/>
    </piePlot>
</pieChart>

The only difference is the isShowLegend attribute in the chart tag. (You can access it in the chart properties panel in iReport).

But this attribute is a value, and you can't use a expression such as :

$P{DISPLAY_LEGEND}.booleanValue();

Where DISPLAY_LEGEND would be a parameter of the report (type is java.lang.Boolean)

---

If you really want to realise a such thing, following trick should work:

Define you graph to time. One with legend and one without. Graph should be overlapped. (you can do so by coping the concerned tag directly in the XML text)

After that edit the print when expression property of each graph, in oder that just one of the 2 graph is printed, depending of a condition.

Here is the result example with my DISPLAY_LEGEND parameter. (but it could be an other condition, also calculated. Important is that the two conditions are symmetric)

<pieChart>
    <chart isShowLegend="true">
     <reportElement x="19" y="18" width="518" height="196">
      <printWhenExpression><![CDATA[$P{DISPLAY_LEGEND}]]></printWhenExpression>
     </reportElement>
     <!-- end of the chart definition-->
    </chart>
    <!-- pieDataset and piePlot-->
</pieChart>
<pieChart>
    <chart isShowLegend="false">
     <reportElement x="19" y="18" width="518" height="196">
      <printWhenExpression><![CDATA[new Boolean(!$P{DISPLAY_LEGEND}.booleanValue())]]></printWhenExpression>
     </reportElement>
     <!-- end of the chart definition-->
    </chart>
    <!-- pieDataset and piePlot-->
</pieChart>

---

I also wanted to mention that you can access the the JFreeChart Object during the report generation. Here some forum posts, that helped me doing so :

• display value beside each point on a line graph
• How to put "Label" in Line Graph?
• Customizing a chart - for newbies!