inabox/inabox.wpf/Converters/RelativeFontSize.cs

using System.Globalization;
using System.Windows.Data;

namespace InABox.WPF
{
    public class RelativeFontSize : IValueConverter
    {
        // Create a ratio property 
        // allows the converter to be used for different font ratios
        public double Ratio { get; set; }

        public object Convert(object value, Type targetType, object parameter,
            CultureInfo culture)
        {
            // add input parameter testing as needed.
            var originalFontSize = (double)value;
            var alteredFontSize = originalFontSize * Ratio;

            return alteredFontSize;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}