private static void OnMissingValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            IsolineGraphBase owner = (IsolineGraphBase)d;

            owner.UpdateDataSource();
        }
        private static void OnLineThicknessChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            IsolineGraphBase graph = (IsolineGraphBase)d;

            graph.OnLineThicknessChanged();
        }
        private static void OnDataSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            IsolineGraphBase owner = (IsolineGraphBase)d;

            owner.OnDataSourceChanged((DataSource)e.OldValue, (DataSource)e.NewValue);
        }