WPF 依赖属性

依赖属性，它是注册到 Hastable 里面去了。依赖属性默认属性变更通知功能。

▲ 点击按钮 Traget 显示

XAML：

<Window x:Class="WPF_P128.MainWindow"
        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:WPF_P128"
        mc:Ignorable="d"
        Title="DependencyProperty" Height="160" Width="260">
    <Grid>
        <StackPanel>
            <TextBlock Text="Source:" Margin="5 5 5 0"/>
            <TextBox x:Name="textBox1" BorderBrush="Black" Margin="5 0 5 0"/>
            <TextBlock Text="Target:" Margin="5 5 5 0"/>
            <TextBox x:Name="textBox2" BorderBrush="Black" Margin="5 0 5 0"/>
            <Button Content="OK" Margin="5" Click="Button_Click"/>
        </StackPanel>
    </Grid>
</Window>

DependencyObject 类内有两个方法：object GetValue(DependencyProperty dp)
和 Void SetValue(DependencyProperty dp, object o)

C# Behind：

namespace WPF_P128
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            Student stu = new Student();
            stu.SetValue(Student.NameProperty, textBox1.Text);
            textBox2.Text = (string)stu.GetValue(Student.NameProperty);
        }
    }

    public class Student:DependencyObject
    {
        public static readonly DependencyProperty NameProperty =
            DependencyProperty.Register("Name", typeof(string), typeof(Student));
    }
}

增加绑定功能：

namespace WPF_P128
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            // 增加绑定方式
            stu = new Student();
            Binding binding = new Binding("Text") { Source = textBox1 };
            BindingOperations.SetBinding(stu, Student.NameProperty, binding);
        }

        private Student stu = null;

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            // 直接赋值，取值
            //Student stu = new Student();
            stu.SetValue(Student.NameProperty, textBox1.Text);
            textBox2.Text = (string)stu.GetValue(Student.NameProperty);

            // 弹窗显示绑定属性值
            MessageBox.Show(stu.GetValue(Student.NameProperty).ToString());
        }
    }

    public class Student:DependencyObject
    {
        // 依赖属性
        public static readonly DependencyProperty NameProperty =
            DependencyProperty.Register("Name", typeof(string), typeof(Student));
    }    
}

▲ 运行效果

再包装一下：

namespace WPF_P128
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            // 增加绑定方式
            stu = new Student();
            Binding binding = new Binding("Text") { Source = textBox1, UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged };
            //BindingOperations.SetBinding(stu, Student.NameProperty, binding);
            stu.SetBinding(Student.NameProperty, binding);
            textBox2.SetBinding(TextBox.TextProperty, new Binding(nameof(stu.Name)) { Source = stu });
        }

        private Student stu = null;

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            // 直接赋值，取值
            //Student stu = new Student();
            //stu.SetValue(Student.NameProperty, textBox1.Text);
            //textBox2.Text = (string)stu.GetValue(Student.NameProperty);

            // 弹窗显示绑定属性值
            MessageBox.Show(stu.GetValue(Student.NameProperty).ToString());
        }
    }

    public class Student:DependencyObject
    {
        // 依赖属性
        public static readonly DependencyProperty NameProperty =
            DependencyProperty.Register("Name", typeof(string), typeof(Student));

        // CLR 属性包装
        public string Name
        {
            get { return (string)GetValue(NameProperty); }
            set { SetValue(NameProperty, value); }
        }

        // SetBinding 包装
        public BindingExpressionBase SetBinding(DependencyProperty dp, BindingBase binding)
        {
            return BindingOperations.SetBinding(this, dp, binding);
        }
    }    
}

运行效果：

▲ 运行效果

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参考： 《WPF 深入浅出》 - P138