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
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