Generic routed event handler to command behavior
Imagine that you need to handle from the ViewModel the
SelectedIndexChanged
of a WPF TreeView
, currently the only way (without using any particular framework) is to build your own behavior to achieve that, or bind, via a style the IsSelected
property of the node to a property of the view model, but in this second case the side effect is that to find the selected item you need to visit the whole tree.<TreeView Margin="5" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
ItemsSource="{Binding Path=MyListOfElements}">
<i:Interaction.Behaviors>
<behaviors:Handle RoutedEvent="TreeView.SelectedItemChanged"
WithCommand="{Binding Path=MyAmazingCommand}"
PassingIn="$args.NewValue" />
</i:Interaction.Behaviors>
<TreeView.ItemTemplate>
<!-- omitted -->
</TreeView.ItemTemplate>
</TreeView>
As you can imagine the value of the
NewValue
property of the event arguments is passed as the command parameter to the command, we currently support as placeholder:$args
: the routed event arguments;$this
: the WPF element the behavior is attached to;$source
: the source of the routed event;$originalSource
: the original source of the routed event;
- the event identified by the
RoutedEvent
property must be a valid WPFRoutedEvent
. - the bound command identified by the
WithCommand
property must be a validICommand
,AutoCommandBinding
is not supported.
The behavior is defined in the
http://schemas.radicalframework.com/windows/behaviors
xml namespace.Last modified 1yr ago