Using interaction trigger to call visibility changed method WPF

Question

What I would like to figure out is two things, how to get a trigger occurring when a user control\'s visibility is changed and passing the value of visibility through as a p

Answer 1

First, we need to set TargetObject property to viewmodel/DataContext, because method to be invoked is available in the viewmodel :

......
<i:Interaction.Triggers>
    <i:EventTrigger EventName="IsVisibleChanged">
        <ei:CallMethodAction MethodName="VisibleTrigger" TargetObject="{Binding}"/>
    </i:EventTrigger>
</i:Interaction.Triggers>
......

Second, EventTrigger doesn't seems to work specifically with IsVisibleChanged event. So code snippet above works for other event, but not IsVisibleChanged. We can find a workaround in the answer to this SO question, by using PropertyChangedTrigger to listen to Visibility property changed, instead of listening to IsVisibleChanged event :

<i:Interaction.Triggers>
    <ei:PropertyChangedTrigger Binding="{Binding Visibility, ElementName=MyControlName}">
        <ei:CallMethodAction  MethodName="VisibleTrigger" TargetObject="{Binding}"/>
    </ei:PropertyChangedTrigger>
</i:Interaction.Triggers>

Third, CallMethodAction doesn't seems to provide a way to pass parameter to the method. To be able to invoke a method with parameter we better use InvokeCommandAction instead of CallMethodAction as suggested here and also suggested by @Rohit in your previous question.