'宣言
Public Class _PiePlotDataLabelViewLayout(Of TPlotView As IBarCartesianPlotView) Inherits _RadialCartesianPlotDataLabelViewListLayoutPolicy(Of TPlotView) Implements IPlotDataLabelViewListLayoutPolicy
public class _PiePlotDataLabelViewLayout<TPlotView> : _RadialCartesianPlotDataLabelViewListLayoutPolicy<TPlotView>, IPlotDataLabelViewListLayoutPolicy where TPlotView: IBarCartesianPlotView