PropertyChangedTrigger For Multiple Properties? - wpf

Question

Is there a way to create PropertyChangedTrigger for multiple properties that all share the same conditions, for the sake of redundancy, without specifying the conditions repeatedly for each PropertyChangedTrigger?
For example, when PropertyA, PropertyB and PropertyC change, I want a command to execute in my ViewModel.

Answer 1

I was thinking of something like extending the PropertyChangedClass and adding a dependency property of a an observable collection of Bindings. But it turned out I'm not very knowledgeable in how Bindings are monitored.
Then I saw some of old code and saw Multibinding. I thought it could work. And it did with a MultiValueConverter that just increments a static field. I'm not sure if this is the best solution but this worked.
First the MultiValueConverter:
public class IncrementOnPropertyChangedMultiConverter:IMultiValueConverter
{
static uint _counter=0;
#region IMultiValueConverter Members
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
_counter = _counter < uint.MaxValue ? _counter + 1 : 0;
return _counter;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
#endregion
}
Then in XAML you just add a MultiBinding instead of Binding in the PropertyChangedTrigger.
<i:Interaction.Triggers>
<ei:PropertyChangedTrigger>
<ei:PropertyChangedTrigger.Binding>
<MultiBinding Converter="{StaticResource IncrementOnPropertyChangedMultiConverter}">
<Binding Path="Property1" />
<Binding Path="Property2" />
<Binding Path="PropertyN" />
</MultiBinding>
</ei:PropertyChangedTrigger.Binding>
<i:Interaction.Behaviors>
<ei:ConditionBehavior>
<ei:ConditionalExpression>
<ei:ComparisonCondition LeftOperand="{Binding Property1}"
Operator="Equal"
RightOperand="{Binding Property2}" />
</ei:ConditionalExpression>
</ei:ConditionBehavior>
</i:Interaction.Behaviors>
<ei:ChangePropertyAction PropertyName="Background"
Value="Transparent" />
</ei:PropertyChangedTrigger>
<i:Interaction.Triggers>