Hi Kevin,
Currently a pie chart can display only a single series. We have plans to implement support for multiple pie series for "doughnut" charts, but at this point it's not a top priority.
It is possible to emulate this feature using two pie charts (please see the code below). This is a workaround though, so it has some limitations - first it doesn't work for real 3D charts (works for 2D and for 3D in ortho 2D projection), and second - cannot be used along with the non-overlapping pie labels mode.
private void Form1_Load(object sender, EventArgs e)
{
nChartControl1.Panels.Clear();
// first chart (outer)
NPieChart pieChart1 = new NPieChart();
nChartControl1.Charts.Add(pieChart1);
NPieSeries series1 = new NPieSeries();
pieChart1.Series.Add(series1);
series1.LabelMode = PieLabelMode.Center;
series1.Values.AddRange(new double[]{10, 20, 15});
series1.PieStyle = PieStyle.Ring;
series1.InnerRadius = new NLength(30, NRelativeUnit.ParentPercentage);
series1.Radius = new NLength(50, NRelativeUnit.ParentPercentage);
series1.FillStyles[0] = new NColorFillStyle(Color.IndianRed);
series1.FillStyles[1] = new NColorFillStyle(Color.Goldenrod);
series1.FillStyles[2] = new NColorFillStyle(Color.OliveDrab);
// second chart (inner)
NPieChart pieChart2 = new NPieChart();
nChartControl1.Charts.Add(pieChart2);
NPieSeries series2 = new NPieSeries();
pieChart2.Series.Add(series2);
series2.LabelMode = PieLabelMode.Center;
series2.Values.AddRange(new double[] { 7, 4, 8 });
series2.PieStyle = PieStyle.Ring;
series2.InnerRadius = new NLength(10, NRelativeUnit.ParentPercentage);
series2.Radius = new NLength(30, NRelativeUnit.ParentPercentage);
series2.FillStyles[0] = new NColorFillStyle(Color.IndianRed);
series2.FillStyles[1] = new NColorFillStyle(Color.Goldenrod);
series2.FillStyles[2] = new NColorFillStyle(Color.OliveDrab);
}
Best Regards,
Nevron Support Team