Question

I have the following radio button bound to the variable IsAllowed

<RadioButton Name="YesRadioButton" Margin="5,5,0,0" IsChecked="{Binding Path=IsAllowed, Mode=TwoWay}">Yes</RadioButton>

How can I make the No button to take the opposite value only using XAML ?

Answer 1

There is no Xaml-only solution. You could bind No using a reverse bool Converter though.

<local:NotConverter x:Key="notConverter"/>

{Binding IsAllowed, Mode=TwoWay, Converter=notConverter} 

public class NotConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Boolean result = false;
        if (value is Boolean)
            result = !((Boolean)value);
        return result;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Boolean result = false;
        if (value is Boolean)
            result = !((Boolean)value);
        return result;
    }
}