Before you can start using the drill down feature of RadChart, you'll need to implement Hierarchial View
. This document
will guide you through making sure your data is set up using ChartHierarchialViewDescriptor
objects. After doing this, you can use this document
as example code. It shows you how to layout your chart according to what level of data you are on.
Even though the example is with a BarChart, the same process is used for a pie chart. For instance, you notice the chart in the example first shows the car manufacturers "ToyYoda" and "Marda". This is your first level of hierarchial data. Then when you drill down it goes to the car model level and displays "Coolla" and "Veso".
I hope this clear it up for you, create the levels, then you can drill down.