Routed Tunnel Events in wpf

Question

I have got a question to wpf community here. I am kind of not able to understand Routing Tunnel Events. In my application, I have got a window which contains a tool bar. Window also contains usercontrols. There are some controls in Tool bar like view which are used to Hide / unhide usercontrols (Views) like in Visual Studio.

I have custom routed tunnel event in windows control. I raise custom event when a button is clicked on toolbar (hide / unhide). I need to hide a expander in child usercontrol (which has a name like "Expander 1") when button is clicked.

Can some one tell me how can I capture the raised event in the child user control?

Thanks.

Code window :

public partial class MainWindow : Window
    {
        private static readonly RoutedEvent HideShowMitigationEvent;

        static MainWindow()
            {
            HideShowMitigationEvent = EventManager.RegisterRoutedEvent("HideShowMitigation",
                RoutingStrategy.Tunnel, typeof(RoutedEventHandler), typeof(MainWindow));
            }

        public MainWindow()
            {
            InitializeComponent();
            }

        // The Standard .Net optional event wrapper
        // This is required if we want to register the event handler in XAML       
        public event RoutedEventHandler HideShowMitigation
            {
            add { AddHandler(HideShowMitigationEvent, value); }
            remove { RemoveHandler(HideShowMitigationEvent, value); }
            }

        // Raise the event. overidden from UIElement       
        protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
            {
           // RaiseEvent(new RoutedEventArgs(HideShowMitigationEvent, this));
            }


        public static ExploredRisks _rootName { get; set; }

        public MainWindow(GeneralTree<string> rawTreeData, Excel.Worksheet sheet,Excel.Workbook Wb)
        {

            //prepares the visual tree for other views
            PrepareVisualTree visualTree = new PrepareVisualTree(rawTreeData, sheet);
            _rootName = visualTree.getVisualTree();
            var l_vm = new MainViewModel();
            l_vm.Load(_rootName);
           TreeListViewMultiColumned view = new TreeListViewMultiColumned( RiskViewModel.CreateTestModel(visualTree.getVisualTree()),sheet,Wb);


            base.DataContext = l_vm;
            InitializeComponent();

        }

        private void UIPanel_Loaded(object sender, RoutedEventArgs e)
        {

        }


        private void RibbonCheckBox_Checked(object sender, RoutedEventArgs e)
        {

           RaiseEvent(new RoutedEventArgs(HideShowMitigationEvent, this));
        }

        private void SimpleClickEventHandlingCode(object sender, RoutedEventArgs e)
            {
            //Expander exp = ((MainWindow)(e.OriginalSource)).RiskProperties.MitigationArea; 
                RoutedEventArgs args = new RoutedEventArgs();
                args.RoutedEvent = HideShowMitigationEvent;
                 RaiseEvent(args);
            }
    }
}

Window Xaml:

<Window>


       <Ribbon x:Name="RibbonWin"  SelectedIndex="0">
             <RibbonTab Header="Views" KeyTip="H">
                <!-- Home  group-->
                <RibbonGroup x:Name="ViewsGroup" Header="Views">
                    <RibbonCheckBox Label="Mitigation" IsChecked="{Binding IsChecked, Mode=TwoWay}" Checked="RibbonCheckBox_Checked" PreviewMouseDown="SimpleClickEventHandlingCode"/>
                    <RibbonCheckBox Label="Properties" IsChecked="{Binding IsChecked, Mode=TwoWay}" Checked="RibbonCheckBox_Checked" />
                </RibbonGroup>
            </RibbonTab>
        </Ribbon>
  <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*" />
            </Grid.ColumnDefinitions>
            <UI:TreeListViewMultiColumned x:Name="RiskProperties"  Grid.Column="0"  />
        </Grid>
</Window>

Manu Meyer Manu Meyer · Accepted Answer · 2014-05-06T08:42:19

I think I have to to clarify on WPF Routed Events before I suggest a solution:

In WPF there is a new concept of Routed Events. Routed Events are Events that are passed along the logical tree.

Example: Lets look at what happens when you click a button on your UI. First, you will get a PreviewLeftMouseButtonDown event that occurs on the MainWindow and is then passed down the element tree from parent to child until it reaches the button that has been clicked. -> This process (from parent to child) is called Tunneling

Second, you will get a LeftMouseButtonDown event that occurs on the button and is passed up the element tree until it reaches the MainWindow. -> This process (from child to parent) is called Bubbling

As far as I understand you want to open the expander on the click of the button. IMHO using routed events for this is not the appropriate approach.

I think you can solve your use case with a little XAML. Here is what I suggest:

You use a ToggleButton in the Toolbar (this ensures that the user can see the state of the button, e.g. pressed or not pressed.)
You use DataBinding to bind the ToggleButtons IsChecked Property to the Expanders IsExpanded property.

Check the following (highly simplified) sample:

<Grid>
  <StackPanel>
     <ToggleButton x:Name="openExpanderBtn" Width="100" Height="30" Margin="20" Content="Click to Open" />
     <Expander Width="150" Height="200" IsExpanded="{Binding ElementName=openExpanderBtn, Path=IsChecked}" >
        <Expander.Header>
           This is my Header
        </Expander.Header>
        This is my Body
     </Expander>
  </StackPanel>

Remark: It just came to my mind that this only works if the UserControl is under your control. If this is the case: fine, else I will describe another solution. Rgds MM

Routed Tunnel Events in wpf

1 Answers