DependencyProperty使用中的3个场景，讨论PropertyChangedCallback

最新推荐文章于 2024-09-20 10:10:00 发布

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最新推荐文章于 2024-09-20 10:10:00 发布

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本文链接：https://blog.youkuaiyun.com/luminji/article/details/16984629

本文探讨了Silverlight中控件的数据绑定机制，通过三种不同的绑定方式对比，展示了依赖属性及属性更改回调的使用方法。当直接设置依赖属性或通过DataContext进行绑定时，属性更改回调的触发情况有所不同。

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1：项目结构图

2：控件SilverlightControl1

前台：

后台：

    public partial class SilverlightControl1 : UserControl
    {
        public SilverlightControl1()
        {
            InitializeComponent();
        }

        public static readonly DependencyProperty StudentProperty = DependencyProperty.Register("Student", typeof(Student), typeof(SilverlightControl1), new PropertyMetadata(new PropertyChangedCallback(xxx)));

        public Student Student
        {
            get
            {
                return (Student)GetValue(StudentProperty);
            }
            set
            {
                SetValue(StudentProperty, value);
                
            }
        }

        static void xxx(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            MessageBox.Show("sss");
        }
    }

3：调用方

前台：

后台：

    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();
        }

        Student student1 = new Student() { StudentName = "hzh" + DateTime.Now.ToFileTime(), Age = 99 };
        Student student2 = new Student() { StudentName = "lmj" + DateTime.Now.ToFileTime(), Age = 99 };
        Student student3 = new Student() { StudentName = "lh" + DateTime.Now.ToFileTime(), Age = 99 };

        //初始化
        private void Button_Click(object sender, RoutedEventArgs e)
        {
            //采用非绑定机制
            uc1.Student = student1;
            //采用非绑定机制，对DataContext赋值
            uc2.DataContext = student2;
            //采用绑定机制
            uc3.DataContext = student3;
        }

        //改Model值
        private void Button_Click1(object sender, RoutedEventArgs e)
        {
            student1.StudentName = "lmj" + DateTime.Now.ToString();
            student1.Age = 90;
            student2.StudentName = "hzh" + DateTime.Now.ToString();
            student2.Age = 90;
            student3.StudentName = "hzh" + DateTime.Now.ToString();
            student3.Age = 90;
        }

        //更换Model
        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            student1 = new Student() { StudentName = "hzh" + DateTime.Now.ToFileTime(), Age = 99 };
            student2 = new Student() { StudentName = "lmj" + DateTime.Now.ToFileTime(), Age = 99 };
            student3 = new Student() { StudentName = "lh" + DateTime.Now.ToFileTime(), Age = 99 };
        }
    }

4：结论

无论是第一种方式，还是第三种方式，都能触发PropertyChangedCallback，而如果调用采用第二种方式，则不会触发PropertyChangedCallback。

源码：SilverlightApplication320110609.rar