Inverted bool to radio button from dataContext to userControl

Question

How can I bind an inverted value of a bool in my xaml?

I know, I know, there are a lot of q&a about this, but there aren't any about a specific case: when the converter is in a view model and the radio button in a user control.

how can I correctly refer to the main window view model data context? In other case I used the code I've posted, but in this case I don't get how to use it.

UPDATE CODE:

namespace ***.ViewModel
{
    [ValueConversion(typeof(bool), typeof(bool))]
    public class InverseBooleanConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter,
            System.Globalization.CultureInfo culture)
        {
            if (targetType != typeof(bool))
                throw new InvalidOperationException("The target must be a boolean");
            return !(bool)value;
        }
        public object ConvertBack(object value, Type targetType, object parameter,
            System.Globalization.CultureInfo culture)
        {
            throw new NotSupportedException();
        }
    }
        class MainWindowViewModel : MyClass.UtilityClasses.ViewModelBase
    {
        public MainWindowViewModel(){
            SaveCommand = new DelegateCommand(SaveData, CanSave );
            UndoCommand = new DelegateCommand(UndoActions, CanSave);
            [...]

    }
....
}

ANOTHER CODE UPDATE:

In my xaml, I have a devexpress GridControl where I list my observableCollection from db. When I click one element, a layout group is populated with the relative data.

In this layout group, I have:

<StackPanel Margin="0" Orientation="Horizontal" VerticalAlignment="Center" HorizontalAlignment="Left">
    <RadioButton Content="{DynamicResource Locale}" Margin="10,0,0,0" x:Name="rd_LOCALE" VerticalAlignment="Center" IsChecked="{Binding Path=REMOTO, Converter={StaticResource InverseBooleanConverter}}" GroupName="Location" Panel.ZIndex="9" TabIndex="10" />
    <RadioButton Content="{DynamicResource Remoto}" Margin="10,0,6,0" x:Name="rd_REMOTO" VerticalAlignment="Center" IsChecked="{Binding REMOTO}" GroupName="Location" Panel.ZIndex="10" TabIndex="11" Tag="PRISMA" />
</StackPanel>

WhenI change from one record to another, the converter gives me error... why? It fails the "if (targetType != typeof(bool))" row. So I tried to change that like:

if (value.getType() != typeof(bool))

but in this way, without fails nothing in the code, it put the wrong value in the radiobutton!

Answer 1

You need to make sure that the value converter is referenced in the XAML

<UserControl.Resources>
    <myproject:InverseBooleanConverter x:Key="InverseBooleanConverter" />
</UserControl.Resources>

where my project is the namespace in which the value converter class is defined