Routed Events【pluralsight】

Routing Strategies:

• Direct
• Bubbling
• Tunneling

WHy use them?

• Any UIElement can be a listener
• Common handlers
• Visual Tree Communication
• Event Setter and Event Trigger

Routed Event Example:

<Window x:Class="CustomControlDemo.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        Title="MainWindow"

        Width="350"

        Height="220"

        ButtonBase.Click="Window_Click">　　　//listen to the RoutedEvent：ButtonBase.Click and handle RoutedEvent using Window_Click

    <Grid>

        <StackPanel Margin="20" ButtonBase.Click="StackPanel_Click">　　　//listen to the RoutedEvent：ButtonBase.Click and handle RoutedEvent using StackPanel_Click

            <Border BorderBrush="Red" BorderThickness="5">

                <TextBlock Margin="5"

                           FontSize="18"

                           Text="This is a TextBlock" />

            </Border>

            <Button Margin="10"

                    Click="Button_Click"　　//handle the Button.Click event using Button_Click handler

                    Content="Click me" />

        </StackPanel>

    </Grid>

</Window>

 

namespace CustomControlDemo

{

    /// <summary>

    /// Interaction logic for MainWindow.xaml

    /// </summary>

    public partial class MainWindow : Window

    {

        public MainWindow()

        {

            InitializeComponent();

        }



        private void Button_Click(object sender, RoutedEventArgs e)

        {

　　　　　　　　//Button层的event handler，由于ButtonBase.Click是routedEvent所以可以向上bubble

        }



        private void StackPanel_Click(object sender, RoutedEventArgs e)

        {

　　          

　　　　　　　　e.Handled = true;　　//StackPanel层的event handler，不继续向上传

　　 e.Handled = false;　　//StackPanel层的event handler，继续向上传

        }



        private void Window_Click(object sender, RoutedEventArgs e)

        {

　　　　　　   //Window层的event handler，已传到最上层

        }

    }

}

我们也可以不在xaml写handler，直接用后台控制

namespace CustomControlDemo

{

    /// <summary>

    /// Interaction logic for MainWindow.xaml

    /// </summary>

    public partial class MainWindow : Window

    {

        public MainWindow()

        {

            InitializeComponent();

            AddHandler(Button.ClickEvent, new RoutedEventHandler(Window_Click), true);  //即使e.Handled = true;我们也要routedevent继续传到window层

        }



        private void Button_Click(object sender, RoutedEventArgs e)

        {

　　　　　　　　//Button层的event handler，由于ButtonBase.Click是routedEvent所以可以向上bubble

        }



        private void StackPanel_Click(object sender, RoutedEventArgs e)

        {

　　　　　　　　e.Handled = true;

        }



        private void Window_Click(object sender, RoutedEventArgs e)

        {

　　　　　　  

        }

    }

}    

 Custom Routed Events

• register your event
• choose your routing strategy
• provide add and remove CLR wrapper
• Raise your event