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  1. PO
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    <p>Thanks for everyone's help, I finally figured it out.</p> <p>I am binding to a strongly typed DataSet, so the enumerations are stored as type System.Byte and not System.Enum. I happened to notice a silent binding casting exception in my debug output window which pointed me to this difference. The solution is the same as above, but with the ValueProperty being of type Byte instead of Enum.</p> <p>Here is the CheckBoxFlagsBehavior class repeated in its final revision. Thanks again to Ian Oakes for the original implementation!</p> <pre><code>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 byte GetValue(DependencyObject obj) { return (byte)obj.GetValue(ValueProperty); } // end GetValue public static void SetValue(DependencyObject obj, byte value) { obj.SetValue(ValueProperty, value); } // end SetValue public static readonly DependencyProperty ValueProperty = DependencyProperty.RegisterAttached("Value", typeof(byte), typeof(CheckBoxFlagsBehaviour), new UIPropertyMetadata(default(byte), 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 &amp; mask) != 0, null); ((CheckBox)d).IsChecked = (value &amp; 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 &amp; mask) == 0) { value = (byte)(value + mask); } } else { if ((value &amp; mask) != 0) { value = (byte)(value - mask); } } pi.SetValue(dataItem, value, null); } } // end IsCheckedChanged private static object GetUnderlyingDataItem(object o) { return o is DataRowView ? ((DataRowView)o).Row : o; } // end GetUnderlyingDataItem } // end class CheckBoxFlagsBehaviour </code></pre>
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    1. POHow can you two-way bind a checkbox to an individual bit of a flags enumeration?
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    1. USSteve Cadwallader
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      1. VTUpMod
    1. COThis seems awfully complex - why wouldn't a simple value converter do the job?
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      1. USDaniel Paull
    2. COA value converter is great for one-way binding, but when it comes to two-way binding the ConvertBack falls apart because you can't know what the other bits are set to in order to return a valid value.
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      1. USSteve Cadwallader
 

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