Adds ability to perform bitwise operations using a checkbox. (WPF)

BitFlagBehaviour.cs

    using System;
    using System.Windows;
    using System.Windows.Controls;

    /// <summary>
    /// Adds ability to perform bitwise operations using a checkbox.
    /// </summary>
    public class BitFlagBehaviour : DependencyObject
    {
        /// <summary>
        /// Returns true if the value contains the checked value. If either are null, then it returns null. 
        /// Otherwise it return false.
        /// </summary>
        /// <param name="value"></param>
        /// <param name="checkedValue"></param>
        /// <returns></returns>
        static bool? IsChecked(int? value, int? checkedValue)
        {
            return (value & checkedValue) == checkedValue;
        }

        /// <summary>
        /// Sets the checked value onto the value by performing a bitwise Or operation.
        /// </summary>
        /// <param name="value"></param>
        /// <param name="checkedValue"></param>
        /// <returns></returns>
        static int? SetValue(int? value, int? checkedValue)
        {
            return (value | checkedValue);
        }

        /// <summary>
        /// Unsets the checked value by performing a bitwize And Not operation.
        /// </summary>
        /// <param name="value"></param>
        /// <param name="checkedValue"></param>
        /// <returns></returns>
        static int? UnsetValue(int? value, int? checkedValue)
        {
            return (value & ~checkedValue);
        }

        /// <summary>
        /// Extracts the value and checkedvalue from the checkbox.
        /// </summary>
        /// <param name="element"></param>
        /// <param name="value"></param>
        /// <param name="checkedValue"></param>
        static void GetValues(CheckBox element, out int? value, out int? checkedValue)
        {
            value = null;
            checkedValue = null;

            if (element.GetValue(BitFlagBehaviour.ValueProperty) != null)
            {
                value = (int)element.GetValue(BitFlagBehaviour.ValueProperty);
            }

            if (element.GetValue(BitFlagBehaviour.CheckedValueProperty) != null)
            {
                checkedValue = (int)element.GetValue(BitFlagBehaviour.CheckedValueProperty);
            }
        }

        #region Value property implementation

        public static readonly DependencyProperty ValueProperty = DependencyProperty.RegisterAttached("Value"
                                                                , typeof(object), typeof(BitFlagBehaviour)
                                                                , new PropertyMetadata(null, BitFlagBehaviour.Value_Changed));

        public static object GetValue(CheckBox element)
        {
            return element.GetValue(BitFlagBehaviour.ValueProperty);
        }

        public static void SetValue(CheckBox element, object value)
        {
            element.SetValue(BitFlagBehaviour.ValueProperty, value);
        }

        static void Value_Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            CheckBox element = (CheckBox)d;
            int? value, checkedValue;
            BitFlagBehaviour.GetValues(element, out value, out checkedValue);
            element.IsChecked = BitFlagBehaviour.IsChecked(value, checkedValue);
        }

        #endregion

        #region CheckedValue property implementation

        public static readonly DependencyProperty CheckedValueProperty = DependencyProperty.RegisterAttached("CheckedValue"
                                                                , typeof(object), typeof(BitFlagBehaviour)
                                                                , new PropertyMetadata(null, BitFlagBehaviour.CheckedValue_Changed));

        public static object GetCheckedValue(CheckBox element)
        {
            return element.GetValue(BitFlagBehaviour.CheckedValueProperty);
        }

        public static void SetCheckedValue(CheckBox element, object value)
        {
            element.SetValue(BitFlagBehaviour.CheckedValueProperty, value);
        }

        static void CheckedValue_Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            CheckBox element = (CheckBox)d;
            element.Checked -= CheckBox_Checked;
            element.Checked += CheckBox_Checked;
            element.Unchecked -= CheckBox_Unchecked;
            element.Unchecked += CheckBox_Unchecked;
        }

        static void CheckBox_Unchecked(object sender, RoutedEventArgs e)
        {
            CheckBox element = (CheckBox)sender;
            int? value, checkedValue;
            BitFlagBehaviour.GetValues(element, out value, out checkedValue);
            element.SetValue(BitFlagBehaviour.ValueProperty, BitFlagBehaviour.UnsetValue(value, checkedValue));
        }

        static void CheckBox_Checked(object sender, RoutedEventArgs e)
        {
            CheckBox element = (CheckBox)sender;
            int? value, checkedValue;
            BitFlagBehaviour.GetValues(element, out value, out checkedValue);
            element.SetValue(BitFlagBehaviour.ValueProperty, BitFlagBehaviour.SetValue(value, checkedValue));
        }

        #endregion
    }