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