wpf - 从 XAML 绑定(bind)到自定义依赖属性

Question

我已经实现了一个自定义 DependencyProperty 并希望从 XAML 绑定(bind)到它。出于某种原因，它不会在更新绑定(bind)源 (MainWindow.Test) 时更新。绑定(bind)源不是 DP 但会触发 PropertyChanged 事件。然而，更新适用于非自定义依赖属性

作品:

<TextBlock Text="{Binding Test}" />

不起作用:

<local:DpTest Text="{Binding Test}"/>

有什么想法吗？

---

DP实现如下:

using System;
using System.Windows;
using System.Windows.Controls;

namespace WpfApplication3
{
public partial class DpTest : UserControl
{
    public DpTest()
    {
        DataContext = this;
        InitializeComponent();
    }

    public string Text
    {
        get { return (string)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }

    public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof(string), typeof(DpTest), new PropertyMetadata(string.Empty, textChangedCallBack));

    static void textChangedCallBack(DependencyObject property, DependencyPropertyChangedEventArgs args)
    {
        int x = 5;
    }
}
}

使用方法如下:

<Window x:Class="WpfApplication3.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:local="clr-namespace:WpfApplication3" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:sys="clr-namespace:System;assembly=mscorlib" Title="MainWindow" Height="350" Width="525">
<StackPanel>
    <TextBlock Text="{Binding Test}"></TextBlock>
    <local:DpTest Text="{Binding Test}"></local:DpTest>
    <Button Click="Button_Click">Update</Button>
</StackPanel></Window>

带有绑定(bind)源的代码:

using System;
using System.Collections.Generic;
using System.Windows;
using System.ComponentModel;

namespace WpfApplication3
{
public partial class MainWindow : Window, INotifyPropertyChanged
{
    public MainWindow()
    {
        DataContext = this;
        InitializeComponent();
    }
    string _test;
    public string Test
    {
        get { return _test; }
        set
        {
            _test = value;
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("Test"));
            }
        }
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        Test = "Updatet Text";
    }
    public event PropertyChangedEventHandler PropertyChanged;
}
}

Answer 1

不要在 UserControls 上设置 DataContext = this;，这样，如果您假设 DataContext，所有实例绑定(bind)都将失败 被继承，因为这会阻止它并且也很不可见。在 UserControl 绑定(bind)中，您应该命名控件并执行 ElementName 绑定(bind)，或者使用 RelativeSource。

例如

<UserControl Name="control" ...>
     <TextBlock Text="{Binding Text, ElementName=control}"/>

<UserControl ...>
     <TextBlock Text="{Binding Text, RelativeSource={RelativeSource AncestorType=UserControl}}"/>