如何将复选框双向绑定到标志枚举的单个位？

对于那些喜欢WPF绑定挑战的人：

我有一个几乎可行的例子，可以将CheckBox双向绑定到标志枚举的单个位（感谢Ian Oakes，原来的MSDN帖子）。但问题是绑定的行为表现为单向（从UI到DataContext，而不是反过来）。因此，CheckBox实际上没有初始化，但如果切换它，则数据源会正确更新。附上了定义一些附加依赖属性的类，以启用基于位的绑定。我注意到即使强制更改DataContext，也从未调用ValueChanged。

我尝试过的：更改属性定义顺序，使用标签和文本框来确认DataContext是否向外部冒泡更新，任何合理的FrameworkMetadataPropertyOptions（AffectsRender，BindsTwoWayByDefault），明确设置Binding Mode= TwoWay，在墙上撞头，将ValueProperty更改为EnumValueProperty以防冲突。

任何建议或想法都将非常感谢，感谢您提供的一切！

枚举：

[Flags]
public enum Department : byte
{
    None = 0x00,
    A = 0x01,
    B = 0x02,
    C = 0x04,
    D = 0x08
} // end enum Department

XAML用法：

CheckBox Name="studentIsInDeptACheckBox"
         ctrl:CheckBoxFlagsBehaviour.Mask="{x:Static c:Department.A}"
         ctrl:CheckBoxFlagsBehaviour.IsChecked="{Binding Path=IsChecked, RelativeSource={RelativeSource Self}}"
         ctrl:CheckBoxFlagsBehaviour.Value="{Binding Department}"

类：

///
/// A helper class for providing bit-wise binding.
///

public class CheckBoxFlagsBehaviour { private static bool isValueChanging; public static Enum GetMask(DependencyObject obj) { return (Enum)obj.GetValue(MaskProperty); } // end GetMask public static void SetMask(DependencyObject obj, Enum value) { obj.SetValue(MaskProperty, value); } // end SetMask public static readonly DependencyProperty MaskProperty = DependencyProperty.RegisterAttached("Mask", typeof(Enum), typeof(CheckBoxFlagsBehaviour), new UIPropertyMetadata(null)); public static Enum GetValue(DependencyObject obj) { return (Enum)obj.GetValue(ValueProperty); } // end GetValue public static void SetValue(DependencyObject obj, Enum value) { obj.SetValue(ValueProperty, value); } // end SetValue public static readonly DependencyProperty ValueProperty = DependencyProperty.RegisterAttached("Value", typeof(Enum), typeof(CheckBoxFlagsBehaviour), new UIPropertyMetadata(null, ValueChanged)); private static void ValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { isValueChanging = true; byte mask = Convert.ToByte(GetMask(d)); byte value = Convert.ToByte(e.NewValue); BindingExpression exp = BindingOperations.GetBindingExpression(d, IsCheckedProperty); object dataItem = GetUnderlyingDataItem(exp.DataItem); PropertyInfo pi = dataItem.GetType().GetProperty(exp.ParentBinding.Path.Path); pi.SetValue(dataItem, (value & mask) != 0, null); ((CheckBox)d).IsChecked = (value & mask) != 0; isValueChanging = false; } // end ValueChanged public static bool? GetIsChecked(DependencyObject obj) { return (bool?)obj.GetValue(IsCheckedProperty); } // end GetIsChecked public static void SetIsChecked(DependencyObject obj, bool? value) { obj.SetValue(IsCheckedProperty, value); } // end SetIsChecked public static readonly DependencyProperty IsCheckedProperty = DependencyProperty.RegisterAttached("IsChecked", typeof(bool?), typeof(CheckBoxFlagsBehaviour), new UIPropertyMetadata(false, IsCheckedChanged)); private static void IsCheckedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { if (isValueChanging) return; bool? isChecked = (bool?)e.NewValue; if (isChecked != null) { BindingExpression exp = BindingOperations.GetBindingExpression(d, ValueProperty); object dataItem = GetUnderlyingDataItem(exp.DataItem); PropertyInfo pi = dataItem.GetType().GetProperty(exp.ParentBinding.Path.Path); byte mask = Convert.ToByte(GetMask(d)); byte value = Convert.ToByte(pi.GetValue(dataItem, null)); if (isChecked.Value) { if ((value & mask) == 0) { value = (byte)(value + mask); } } else { if ((value & mask) != 0) { value = (byte)(value - mask); } } pi.SetValue(dataItem, value, null); } } // end IsCheckedChanged ///

    /// Gets the underlying data item from an object.
    ///

///The object to examine. /// The underlying data item if appropriate, or the object passed in. private static object GetUnderlyingDataItem(object o) { return o is DataRowView ? ((DataRowView)o).Row : o; } // end GetUnderlyingDataItem } // end class CheckBoxFlagsBehaviour