UserPreferenceChangingEventHandler 委托

定义

命名空间:

Microsoft.Win32

程序集:

Microsoft.Win32.SystemEvents.dll

包:

Microsoft.Win32.SystemEvents v8.0.0

Source:

UserPreferenceChangingEventHandler.cs

表示用来处理 UserPreferenceChanging 事件的方法。

C#

public delegate void UserPreferenceChangingEventHandler(object sender, UserPreferenceChangingEventArgs e);

参数

sender

Object

事件源。 当 SystemEvents 类引发此事件时，此对象总是为 null。

e

UserPreferenceChangingEventArgs

包含事件数据的 UserPreferenceChangedEventArgs。

示例

下面的代码示例演示如何使用 UserPreferenceChangingEventHandler 类型监视 UserPreferenceChanging 事件。 此代码示例是为 SystemEvents 类提供的一个更大示例的一部分。

C#

using System;
using Microsoft.Win32;

public sealed class App 
{
    static void Main() 
    {         
        // Set the SystemEvents class to receive event notification when a user 
        // preference changes, the palette changes, or when display settings change.
        SystemEvents.UserPreferenceChanging += new 
            UserPreferenceChangingEventHandler(SystemEvents_UserPreferenceChanging);
        SystemEvents.PaletteChanged += new 
            EventHandler(SystemEvents_PaletteChanged);
        SystemEvents.DisplaySettingsChanged += new 
            EventHandler(SystemEvents_DisplaySettingsChanged);        

        // For demonstration purposes, this application sits idle waiting for events.
        Console.WriteLine("This application is waiting for system events.");
        Console.WriteLine("Press <Enter> to terminate this application.");
        Console.ReadLine();
    }

    // This method is called when a user preference changes.
    static void SystemEvents_UserPreferenceChanging(object sender, UserPreferenceChangingEventArgs e) 
    {
        Console.WriteLine("The user preference is changing. Category={0}", e.Category);
    }

    // This method is called when the palette changes.
    static void SystemEvents_PaletteChanged(object sender, EventArgs e)
    {
        Console.WriteLine("The palette changed.");
    }

    // This method is called when the display settings change.
    static void SystemEvents_DisplaySettingsChanged(object sender, EventArgs e)
    {
        Console.WriteLine("The display settings changed.");
    }
}

// This code produces the following output.
// 
//  This app is waiting for system events.
//  Press <Enter> to terminate this application.
//  Display Settings changed.
//  User preference is changing. Category=General

注解

创建 UserPreferenceChangingEventHandler 委托时，需要标识将处理该事件的方法。 若要将事件与事件处理方法相关联，请将委托的实例添加到事件。 除非删除委托，否则每当事件发生时，将调用事件处理方法。 有关事件处理程序委托的详细信息，请参阅 处理和引发事件。

扩展方法

适用于

另请参阅

• UserPreferenceChangingEventArgs
• UserPreferenceChanging
• SystemEvents