IColorizerValueProvider Interface

((TreeMapColorizerBase)treeMapControl1.Colorizer).ValueProvider = new ColorizerValueProvider();
//...
public class ColorizerValueProvider : IColorizerValueProvider {
    double IColorizerValueProvider.GetValue(IHierarchicalItem item, int itemIndex) {
        DataRowView row = item.Tag as DataRowView;
        if (row != null)
            return (double)row["HPI"];
        return 0;
    }
}

CType(treeMapControl1.Colorizer, TreeMapColorizerBase).ValueProvider = New ColorizerValueProvider()
'...
Public Class ColorizerValueProvider
    Inherits IColorizerValueProvider

    Private Function GetValue(ByVal item As IHierarchicalItem, ByVal itemIndex As Integer) As Double
        Dim row As DataRowView = TryCast(item.Tag, DataRowView)
        If row IsNot Nothing Then Return CDbl(row("HPI"))
        Return 0
    End Function
End Class