Developing a MultiSelector

using System.Windows.Markup;
using System.Windows.Data;
using System.Windows.Media;
using System.Windows;

namespace SelectionAreaSample
{
    public sealed class EllipseGeometryConverter : MarkupExtension, IMultiValueConverter
    {
        public override object ProvideValue(System.IServiceProvider serviceProvider)
        {
            return this;
        }

        #region IMultiValueConverter Members

        public object Convert(object[] values, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return new EllipseGeometry(new Rect((Point)values[0], (Point)values[1]));
        }

        public object[] ConvertBack(object value, System.Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new System.NotImplementedException();
        }

        #endregion
    }

}