How to bind RadioButtons to an enum?

Question

I\'ve got an enum like this:

public enum MyLovelyEnum
{
    FirstSelection,
    TheOtherSelection,
    YetAnotherOne
};

I got a property in

Answer 1

This work for Checkbox too.

public class EnumToBoolConverter:IValueConverter
{
    private int val;
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        int intParam = (int)parameter;
        val = (int)value;

        return ((intParam & val) != 0);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        val ^= (int)parameter;
        return Enum.Parse(targetType, val.ToString());
    }
}

Binding a single enum to multiple checkboxes.

Answer 2

Based on the EnumToBooleanConverter from Scott. I noticed that the ConvertBack method doesn't work on the Enum with flags code.

I've tried the following code:

public class EnumHasFlagToBooleanConverter : IValueConverter
    {
        private object _obj;
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            _obj = value;
            return ((Enum)value).HasFlag((Enum)parameter);
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (value.Equals(true))
            {
                if (((Enum)_obj).HasFlag((Enum)parameter))
                {
                    // Do nothing
                    return Binding.DoNothing;
                }
                else
                {
                    int i = (int)_obj;
                    int ii = (int)parameter;
                    int newInt = i+ii;
                    return (NavigationProjectDates)newInt;
                }
            }
            else
            {
                if (((Enum)_obj).HasFlag((Enum)parameter))
                {
                    int i = (int)_obj;
                    int ii = (int)parameter;
                    int newInt = i-ii;
                    return (NavigationProjectDates)newInt;

                }
                else
                {
                    // do nothing
                    return Binding.DoNothing;
                }
            }
        }
    }

The only thing that I can't get to work is to do a cast from int to targetType so I made it hardcoded to NavigationProjectDates, the enum that I use. And, targetType == NavigationProjectDates...

---

Edit for more generic Flags Enum converter:

    public class FlagsEnumToBooleanConverter : IValueConverter {
        private int _flags=0;
        public object Convert(object value, Type targetType, object parameter, string language) {
            if (value == null) return false;
            _flags = (int) value;
            Type t = value.GetType();
            object o = Enum.ToObject(t, parameter);
            return ((Enum)value).HasFlag((Enum)o);
        }

        public object ConvertBack(object value, Type targetType, object parameter, string language)
        {
            if (value?.Equals(true) ?? false) {
                _flags = _flags | (int) parameter;
            }
            else {
                _flags = _flags & ~(int) parameter;
            }
            return _flags;
        }
    }

Answer 3

You can create the radio buttons dynamically, ListBox can help you do that, without converters, quite simple.

The concrete steps are below:

• create a ListBox and set the ItemsSource for the listbox as the enum MyLovelyEnum and binding the SelectedItem of the ListBox to the VeryLovelyEnum property.
• then the Radio Buttons for each ListBoxItem will be created.

• Step 1: add the enum to static resources for your Window, UserControl or Grid etc.

    <Window.Resources>
        <ObjectDataProvider MethodName="GetValues"
                            ObjectType="{x:Type system:Enum}"
                            x:Key="MyLovelyEnum">
            <ObjectDataProvider.MethodParameters>
                <x:Type TypeName="local:MyLovelyEnum" />
            </ObjectDataProvider.MethodParameters>
        </ObjectDataProvider>
    </Window.Resources>

• Step 2: Use the List Box and Control Template to populate each item inside as Radio button

    <ListBox ItemsSource="{Binding Source={StaticResource MyLovelyEnum}}" SelectedItem="{Binding VeryLovelyEnum, Mode=TwoWay}" >
        <ListBox.Resources>
            <Style TargetType="{x:Type ListBoxItem}">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate>
                            <RadioButton
                                Content="{TemplateBinding ContentPresenter.Content}"
                                IsChecked="{Binding Path=IsSelected,
                                RelativeSource={RelativeSource TemplatedParent},
                                Mode=TwoWay}" />
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </ListBox.Resources>
    </ListBox>

The advantage is: if someday your enum class changes, you do not need to update the GUI (XAML file).

References: https://brianlagunas.com/a-better-way-to-data-bind-enums-in-wpf/