Two way percentage formatted binding in WPF

Question

I have this textbox:

It correctly displays 0.05 as 5

Answer 1

You need to write a custom converter. NOTE: this one assumes that the values are stored in the range 0 to 100 rather than 0 to 1.

public object Convert(object value, Type targetType, object parameter,
                      System.Globalization.CultureInfo culture)
{
    if (string.IsNullOrEmpty(value.ToString())) return 0;

    if (value.GetType() == typeof(double)) return (double)value / 100;

    if (value.GetType() == typeof(decimal)) return (decimal)value / 100;    

    return value;
}

public object ConvertBack(object value, Type targetType, object parameter,
                          System.Globalization.CultureInfo culture)
{
    if (string.IsNullOrEmpty(value.ToString())) return 0;

    var trimmedValue = value.ToString().TrimEnd(new char[] { '%' });

    if (targetType == typeof(double))
    {
        double result;
        if (double.TryParse(trimmedValue, out result))
            return result;
        else
            return value;
    }

    if (targetType == typeof(decimal))
    {
        decimal result;
        if (decimal.TryParse(trimmedValue, out result))
            return result;
        else
            return value;
    }
    return value;
}

The call it like this: