using System;
using System.Globalization;
using System.Windows.Data;
using System.Windows.Media;

namespace WPFToolKit
{
    public abstract class BaseBoolConverter<T> : IValueConverter
    {
        public T True { set; get; }
        public T False { set; get; }
        protected virtual T Convert(bool value, Type targetType, object parameter, CultureInfo culture)
        {
            return value ? True : False;
        }
        protected virtual bool ConvertBack(T value, Type targetType, object parameter, CultureInfo culturae)
        {
            if (Equals(value, True))
                return true;
            else if (Equals(value, False))
                return false;
            else
                throw new ArgumentOutOfRangeException(nameof(value));
        }

        object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return Convert((bool)value, targetType, parameter, culture);
        }

        object IValueConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return ConvertBack((T)value, targetType, parameter, culture);
        }
    }
    public class BoolToBrushConverter : BaseBoolConverter<Brush> { }
    public class BoolToBoolConverter : BaseBoolConverter<bool> {}
    public class BoolToNegativeConverter : BoolToBoolConverter
    {
        public BoolToNegativeConverter() { True = false; False = true; }
    }
}

<Window x:Class="WPFToolKit.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WPFToolKit"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525"
        DataContext="{StaticResource MainModel}">
    <Window.Resources>
        <local:BoolToBrushConverter x:Key="BoolToBrushConverter" 
                                    True="Red"
                                    False="Green"/>
    </Window.Resources>
    <Grid>
        <Border Width="100" Height="100" Background="{Binding BoolValue, Converter={StaticResource BoolToBrushConverter}}"/>
    </Grid>
</Window>