WPF中的依赖属性

1.创建项目后下载两个NuGet程序包

2.创建一个MyButton类继承Button

MyButton类如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;namespace WPF练习15依赖属性
{public class MyButton : Button{// 普通属性//public int CornerRadius { get; set; }// 依赖属性的包装器：其实就是一个普通属性// 依赖属性需要使用普通属性包装起来。public CornerRadius CornerRadius{get{return (CornerRadius)GetValue(CornerRadiusProperty);}set{SetValue(CornerRadiusProperty, value);}}/*a、依赖属性所属的类必须继承至DependencyObject类，b、依赖属性的声明开头默认 public static readonly,c、依赖属性的命名以Property结尾，建议：包装器名称+Propertyd、使用DependencyProperty.Register静态方法注册。e、Register方法的三个参数（1、依赖属性包装器的名字，2、依赖属性保存值得类型，3、指明依赖属性的宿主类型）*/public static readonly DependencyProperty CornerRadiusProperty =DependencyProperty.Register("CornerRadius",typeof(CornerRadius),typeof(MyButton),new PropertyMetadata(default(CornerRadius), CornerRadiusPropertyCallback));// 当CornerRadiusProperty依赖属性发生变化时，处理一些业务逻辑// d依赖对象，此依赖属性属于哪个控件？MyButtonprivate static void CornerRadiusPropertyCallback(DependencyObject d, DependencyPropertyChangedEventArgs e){MyButton button = (MyButton)d;button.Content = e.NewValue.ToString();}// 普通属性private Brush myBackground;public Brush MyBackground{get { return myBackground; }set{myBackground = value;OnBackgroundChanged();}}// 普通事件public event EventHandler BackgroundChanged;private void OnBackgroundChanged(){BackgroundChanged?.Invoke(this, EventArgs.Empty);}// 路由事件:  公开静态只读的 public static readonly，这一点和依赖属性类似// 需要使用RoutedEvent来定义public static readonly RoutedEvent MyClickEvent = EventManager.RegisterRoutedEvent("MyClick",RoutingStrategy.Bubble,  // 使用的路由策略：冒泡（从内层元素向外层元素执行）  直连（只执行本元素）， 隧道（捕获，挖洞）// 路由事件使用的委托类型RoutedEventHandler public delegate void RoutedEventHandler(object sender, RoutedEventArgs e);typeof(RoutedEventHandler),typeof(MyButton));// 路由事件的包装器，用一个普通事件来包装一下路由事件。public event RoutedEventHandler MyClick{add { AddHandler(MyClickEvent, value); }  // 添加事件remove { RemoveHandler(MyClickEvent, value); }  // 移除事件}// 设置一下MyClick事件的执行时机，在点击的执行// 调用MyBackground1ChangedEventprotected override void OnClick(){// 路由事件的参数对象。是哪一个路由事件的参数呢？RoutedEvent = MyClickEventRoutedEventArgs e = new RoutedEventArgs(){RoutedEvent = MyClickEvent,};this.RaiseEvent(e);  // 触发路由事件MyClickEvent}}
}

3.创建MainWindowViewModel

MainWindowViewModel代码如下：

using CommunityToolkit.Mvvm.ComponentModel;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;namespace WPF练习15依赖属性.ViewModels
{public class MainWindowViewModel: ObservableObject{private CornerRadius cornerRadius = new CornerRadius(10);public CornerRadius CornerRadius{get { return cornerRadius; }set { SetProperty(ref cornerRadius, value); }}}
}

MainWindow.xaml.cs代码如下：

using System;
using System.Collections.Generic;
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 WPF练习15依赖属性
{/// <summary>/// MainWindow.xaml 的交互逻辑/// </summary>public partial class MainWindow : Window{public MainWindow(){InitializeComponent();}private void myButton_BackgroundChanged(object sender, EventArgs e){MyButton myButton = (MyButton)sender;Console.WriteLine("修改了MyBackground属性");Console.WriteLine(myButton.MyBackground.ToString());}private void myButton_MyClick(object sender, RoutedEventArgs e){MessageBox.Show(e.RoutedEvent.Name);}}
}