I'm not sure that's this solution is still working now (Q1 2013 SP1).
I have try to implement something like that's in my application and Provider.LegendInfos do not return anything.
Anyway I reach the same result by handling the VisualItemCreating event of the RadChartView.ChartElement.LegendElement.
I think that's Telerik could improve this feature by adding the two property "IsVisibleInLegend" and "LegendTitle" to PieDataPoint. We will have a more unified behaviour. It will be perfect if we could bind directly this property in PieSerie with something like a "LegendMember" property !
Last but not least... Telerik should update the Demo Application "First Look" of the "ChartViewGroup" because this sample is still using an old fashionned custom control for managing the legend.
Don't think your customer are interested in writing three dedicated class for displaying a piechart with a relevent legend. As long as Microsoft ChartControl could make it in three line of code :-)
' This call is required by the designer.
' Add any initialization after the InitializeComponent() call.
'Handle the VisualItemCreating of the legend
(e.LegendItem.Element, PiePointElement).DataPoint.DataItem, BoundObject).PropertyMember