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RadChartView: Legend

In this article, you will learn to use the built-in legend in RadChartView for Android.

Example

You can start from the BarSeries example and add a second instance of the BarSeries with stack combine mode. Then you need to set their legend title and create a new instance of RadLegendView. RadLegendView needs a legend provider which will provide the data. You can use RadCartesianChartView as a LegendProvider:

    barSeries1.setCombineMode(ChartSeriesCombineMode.STACK);
    barSeries2.setCombineMode(ChartSeriesCombineMode.STACK);

    barSeries1.setLegendTitle("first");
    barSeries2.setLegendTitle("second");

    RadLegendView legendView = new RadLegendView(this);
    legendView.setLegendProvider(chartView);

    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(460,100);
    params.setMargins(10,10,10,10);
    legendView.setLayoutParams(params);

    LinearLayout linearLayout = new LinearLayout(this);
    linearLayout.setOrientation(LinearLayout.VERTICAL);

    linearLayout.addView(legendView);
    linearLayout.addView(chartView);

    ViewGroup rootView = (ViewGroup)findViewById(R.id.container);
    rootView.addView(linearLayout);

    barSeries1.CombineMode = ChartSeriesCombineMode.Stack;
    barSeries2.CombineMode = ChartSeriesCombineMode.Stack;

    barSeries1.LegendTitle = "first";
    barSeries2.LegendTitle = "second";

    RadLegendView legendView = new RadLegendView (this);
    legendView.LegendProvider = chartView;

    LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(460,100);
    layoutParams.SetMargins(10,10,10,10);
    legendView.LayoutParameters = layoutParams;

    LinearLayout linearLayout = new LinearLayout(this);
    linearLayout.Orientation = Android.Widget.Orientation.Vertical;

    linearLayout.AddView(legendView);
    linearLayout.AddView(chartView);

    ViewGroup rootView = (ViewGroup)FindViewById(Resource.Id.container);
    rootView.AddView(linearLayout);

Here's the result:

Orientation

The default behaviour of the RadLegendView is to show the legend items vertically. However you can change the orientation of the items to horizontal with:

   legendView.setLegendOrientation(LienarLayout.HORIZONTAL);

   legendView.LegendOrientation = LinearLayout.HORIZONTAL;

The posible values for the orientation are:

• LienarLayout.HORIZONTAL
• LienarLayout.VERTICAL

Scrolling

By default the scroll of the legend items is disabled. In order to enable the horizontal and vertical scroll you can use:

   legendView.setCanScrollHorizontally(true);
   legendView.setCanScrollVertically(true);

   legendView.CanScrollHorizontally = true;
   legendView.CanScrollVertically = true;

Finally, the legend for the pie chart is a little bit different. The pie series does not have a legend title because each point in the series means something different, the title is taken from the data points with a name binding. For example:

    PieSeries series = new PieSeries();
    // This assumes that the data models have a getter with
    // the signature public String getName().
    series.setNameBinding(new PropertyNameDataPointBinding("Name"));

    PieSeries series = new PieSeries();
    // This assumes that the data models have a property with
    // the signature public string Name { get; }.
    series.NameBinding = new PropertyNameDataPointBinding("Name");