WPF Attached event

Code behind:

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;

using Microsoft.Win32;

using System.Globalization;

 

namespace WpfApplication54

{

/// <summary>

/// Interaction logic for MainWindow.xaml

/// </summary>

public partial class MainWindow : Window

{

public MainWindow()

{

InitializeComponent();

this.AddHandler(AttachedEventTest.NeedsCleaningEvent, new RoutedEventHandler((object o, RoutedEventArgs e) => { MessageBox.Show("from window"); }));

// use true to handle this event too in MainWindow level though e.handled is marked as true in grid_NeedsCleaning method.

//this.AddHandler(AttachedEventTest.NeedsCleaningEvent, new RoutedEventHandler((object o, RoutedEventArgs e) => { MessageBox.Show("from window"); }), true);

}

 

private void button1_Click(object sender, RoutedEventArgs e)

{

this.grid.RaiseEvent(new RoutedEventArgs(AttachedEventTest.NeedsCleaningEvent));

}

 

private void grid_NeedsCleaning(object sender, RoutedEventArgs e)

{

MessageBox.Show("from grid");

//e.Handled = true;

}

}

 

// for this case, note that, if NeedsCleaningEvent's RoutingStrategy is Bubble, the order of windows pop up is: from grid -> from window(frist catched by grid, then window);

// if NeedsCleaningEvent's RoutingStrategy is Tunnel, the order of windows pop up is: from window -> from grid;

public class AttachedEventTest

{

// below is the pattern of AttachedEvent, it uses the same method RegisterRoutedEvent as non-attached event.

// the Add*Handler and Remove*Handler are must, xaml will use it when setting attached event for an element in xaml.

public static readonly RoutedEvent NeedsCleaningEvent = EventManager.RegisterRoutedEvent("NeedsCleaning", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(AttachedEventTest));

 

public static void AddNeedsCleaningHandler(DependencyObject d, RoutedEventHandler handler)

{

UIElement uie = d as UIElement;

if (uie != null)

{

uie.AddHandler(AttachedEventTest.NeedsCleaningEvent, handler);

}

}

public static void RemoveNeedsCleaningHandler(DependencyObject d, RoutedEventHandler handler)

{

UIElement uie = d as UIElement;

if (uie != null)

{

uie.RemoveHandler(AttachedEventTest.NeedsCleaningEvent, handler);

}

}

}

}

 

Xaml:

 

<Window x:Class="WpfApplication54.MainWindow"

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

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

Title="MainWindow" Height="350" Width="525"

xmlns:local="clr-namespace:WpfApplication54">

<Grid x:Name="grid" local:AttachedEventTest.NeedsCleaning="grid_NeedsCleaning" >

<Button Content="Button1" Click="button1_Click" Height="23" HorizontalAlignment="Left" Margin="174,118,0,0" Name="button1" VerticalAlignment="Top" Width="75" />

</Grid>

</Window>