Bool to Visibility converter for Windows Presentation Foundation

BoolVisibilityConverter.vb

' Converts true to Visibility.Visible and false to Visibility.Hidden (can be changed to Visibility Collapsed)
Public Class BoolVisibilityConverter
    Implements IValueConverter

    Public Function Convert(value As Object, targetType As Type, parameter As Object, culture As Globalization.CultureInfo) As Object Implements IValueConverter.Convert
        If Not targetType = GetType(Visibility) Then
            Throw New Exception("The target must be Visibility type")
        End If

        Dim valueAux As Nullable(Of Boolean) = CBool(value)

        If parameter IsNot Nothing AndAlso parameter.ToString() = "PreviewFound" Then
            Return If(valueAux.HasValue AndAlso valueAux.Value, Visibility.Hidden, Visibility.Visible)
        End If

        Return If(valueAux.HasValue AndAlso valueAux.Value, Visibility.Visible, Visibility.Hidden)
    End Function

    Public Function ConvertBack(value As Object, targetType As Type, parameter As Object, culture As Globalization.CultureInfo) As Object Implements IValueConverter.ConvertBack
        Return Nothing
    End Function
End Class