WPF 添付イベント(Attached Event)実装例

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添付イベントの実装例を紹介します。

MainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
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;

namespace WpfApp3
{
/// <summary>
/// MainWindow.xaml の相互作用ロジック
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}

private void InputChangedHandler(object sender, RoutedEventArgs e)
{
Debug.WriteLine("InputChangedHanlder is called.");
}
}

public static class EventHelper
{
public static readonly DependencyProperty IsEventRaisingProperty =
DependencyProperty.RegisterAttached("IsEventRaising",
typeof(bool),
typeof(EventHelper),
new FrameworkPropertyMetadata(false, new PropertyChangedCallback(OnIsEventRaisingChanged)));

public static bool GetIsEventRaising(DependencyObject sender)
{
return (bool)sender.GetValue(IsEventRaisingProperty);
}

public static void SetIsEventRaising(DependencyObject sender, bool ier)
{
sender.SetValue(IsEventRaisingProperty, ier);
}

public static readonly RoutedEvent InputChangedEvent = EventManager.RegisterRoutedEvent(
"InputChanged",
RoutingStrategy.Bubble,
typeof(RoutedEventHandler),
typeof(EventHelper)
);

public static void AddInputChangedHandler(DependencyObject sender, RoutedEventHandler handler)
{
UIElement element = sender as UIElement;
if (element != null)
{
element.AddHandler(InputChangedEvent, handler);
}
}

public static void RemoveInputChangedHandler(DependencyObject sender, RoutedEventHandler handler)
{
UIElement element = sender as UIElement;
if (element != null)
{
element.RemoveHandler(InputChangedEvent, handler);
}
}

private static void OnIsEventRaisingChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
(sender as TextBox).TextChanged += (_s, _e) =>
{
(sender as TextBox).RaiseEvent(new RoutedEventArgs(InputChangedEvent));
};
}
}
}

MainWindow.xaml

<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WpfApp3"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
xmlns:Custom="http://infragistics.com/DockManager" x:Class="WpfApp3.MainWindow"
mc:Ignorable="d"
Title="MainWindow X" Height="350" Width="525">
<Grid>
<TextBox local:EventHelper.IsEventRaising="True"
local:EventHelper.InputChanged="InputChangedHandler"
/>
</Grid>
</Window>

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