Vaadin Charts ChartType.AREA addLegendItemClickListener

Flow
1

ChartType.AREA has a cool feature that adjust the data displayed in the chart when an individual legend item is clicked.

However, the legend toggle feature fails after adding a LegendItemClickListener .

Simply adding the following causes the failure.

chart.addLegendItemClickListener(new LegendItemClickListener() {
@Override
public void onClick(LegendItemClickEvent event) {
}
});

Questions:

  1. Is addLegendItemClickListener adding a listener or setting the listener?
  2. Is this a bug?

I worked around the behavior by get the ListSeries object and simply series.setVisible(!series.isVisible());

2

Hi, It seems that you are not only one who have stumbled on this: http://dev.vaadin.com/ticket/16540

The issue is marked currently as an enhancement, but is almost a bug IMO… At least method should be named as setLegendItemClickListener if the current behaviour is not fixed.

3

Thank you for the response.

After running a test, multiple listeners can be added and receive messages using addLegendItemClickListener().

The trick is reproducing the default behavior, which requires maintaining series state, and re-establishing the visibility with the Listener. Example below.

chart.addLegendItemClickListener(new LegendItemClickListener() {
    @Override
    public void onClick(com.vaadin.addon.charts.LegendItemClickEvent event) {
        // Note, series data is maintained else where,
        // the getSeriers() in LegendItemClickEvent does not really contain the series data.
        // I think the bad verbiage throughout the Vaadin charts has lead to some confusion. 
        // Example getLabels() does not return labels.

        ListSeries data = series.get(event.getSeriesItemIndex());
        data.setVisible(!data.isVisible());
        
        ... do something useful...
    }
}
4

Hi malcom,

I had the same problem and solved it just the same way you did.
But sadly, in a pie chart you cannot do this, since there is no method in the API to toggle the visibility of a single DataSeriesItem. That’s why I marked my ticket
http://dev.vaadin.com/ticket/16540
 as enhancement. Feel free to comment on it.