Adding a Behavior via a style

Asked May 09 '14 at 10:02

Active May 09 '14 at 11:20

Viewed 965 times

How would I add a behavior via a style in WPF?

Specifically, I need to add a behavior to a TreeViewItem via the ItemContainerStyle.

<TreeView.ItemContainerStyle>
    <Style TargetType="{x:Type TreeViewItem}">
        <Style.Setters>
            <Setter Property="i:Interaction.Behaviors">
                <Setter.Value>
                    <behaviors:MyBehavior/>
                </Setter.Value>
            </Setter>
        </Style.Setters>
    </Style>
</TreeView.ItemContainerStyle>

But at runtime, I get this:

System.Windows.Markup.XamlParseException: 'Set property 'System.Windows.Setter.Property' threw an exception.' Line number '422' and line position '34'. ---> System.ArgumentNullException: Value cannot be null. Parameter name: property at System.Windows.Setter.CheckValidProperty(DependencyProperty property) at......

There are also errors in the designer:

The property "Behaviors" is not a DependencyProperty. To be used in markup, non-attached properties must be exposed on the target type with an accessible instance property "Behaviors". For attached properties, the declaring type must provide static "GetBehaviors" and "SetBehaviors" methods.

edited May 09 '14 at 11:20

asked May 09 '14 at 10:02

RBT

Can you show the ItemContainerStyle you have so far? – Gayot Fow May 09 '14 at 10:03
@GarryVass I've added what I would *like* to do. – RBT May 09 '14 at 10:43
Are you getting this error at runtime? – user3455395 May 09 '14 at 10:52
@user3455395 I tell a lie, I think this is Resharper "helping" me. Builds OK. – RBT May 09 '14 at 10:54
Updated with the runtime error – RBT May 09 '14 at 11:04
The designer error is key. So let's see the declaration of your attached property, including the name spaces... – Gayot Fow May 09 '14 at 11:22
Possible duplicate: http://stackoverflow.com/questions/1647815/how-to-add-a-blend-behavior-in-a-style-setter – user3411327 May 09 '14 at 12:07
@user3411327 Yup, good spot. That works perfectly, even though it is a pain to have to go through so much to do something so simple. – RBT May 09 '14 at 12:42

Adding a Behavior via a style

0 Answers0