public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            double ActualWidth  = 400;
            double ActualHeight = 160;


            ReadOnlyContinuousCollection <StockTransaction> tickCollection =
                (ReadOnlyContinuousCollection <StockTransaction>)value;

            if (tickCollection.Count == 0)
            {
                return(null);
            }

            double priceMin = Math.Min(PreviousClosingPrice, tickCollection.Min(t => t.Price));
            double priceMax = Math.Max(PreviousClosingPrice, tickCollection.Max(t => t.Price));

            double tickMin = tickCollection.Min(t => t.TimeStamp.Ticks);
            double tickMax = tickCollection.Max(t => t.TimeStamp.Ticks);

            double yScale = ActualHeight / (priceMax - priceMin);
            double xScale = ActualWidth / Math.Min((tickMax - tickMin), _fiveMinuteWindow);

            StockTransaction[] querySource = tickCollection.ToArray(); // turn CLINQ off
            var newPoints =
                from tick in querySource
                select new Point
            {
                X = (tick.TimeStamp.Ticks - tickMin) * xScale,
                Y = (ActualHeight - (tick.Price - priceMin) * yScale)
            };

            return(new PointCollection(newPoints.ToArray()));
        }