WPF 链绑定

我想创建一个像这样的链绑定：我有一个用户控件，在具有类似依赖属性的窗口内具有依赖属性。我想将用户控件的依赖属性绑定到窗口的依赖属性。

我创建了一个示例项目来演示我的问题：

用户控件1 XAML：

<UserControl x:Class="WpfApplication1.UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d"
             d:DesignHeight="300" d:DesignWidth="300" DataContext="{Binding RelativeSource={RelativeSource Self}}">
    <Grid>
        <Label Content="{Binding Caption}"/>
    </Grid>
</UserControl>

用户控件1 C#：

public partial class UserControl1 : UserControl
  {
    public static readonly DependencyProperty CaptionProperty = DependencyProperty.Register("Caption", typeof(string), typeof(UserControl1));
    public string Caption
    {
      get { return (string)GetValue(CaptionProperty); }
      set { SetValue(CaptionProperty, value); }
    }

    public UserControl1()
    {
      InitializeComponent();
    }
  }

主窗口 XAML：

<Window xmlns:WpfApplication1="clr-namespace:WpfApplication1"  x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" DataContext="{Binding RelativeSource={RelativeSource Self}}">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Label Content="{Binding Caption, Mode=OneWay}"/>
        <WpfApplication1:UserControl1 x:Name="uc" Caption="{Binding Caption, Mode=OneWay}"  Grid.Row="1"/>
    </Grid>
</Window>

主窗口 C#：

public partial class MainWindow : Window
  {
    public static readonly DependencyProperty CaptionProperty = DependencyProperty.Register("Caption", typeof(string), typeof(MainWindow));
    public string Caption
    {
      get { return (string)GetValue(CaptionProperty); }
      set { SetValue(CaptionProperty, value); }
    }

    public MainWindow()
    {
      InitializeComponent();
      (new Thread(() => { Thread.Sleep(2000); Dispatcher.Invoke(() => { uc.Caption = "YYY"; Caption = "XXX"; }); })).Start();
    }
  }

问题是，当我将 Caption 设置为（窗口的）“XXX”时，我希望它也通知用户控件并更新其 Caption，但事实并非如此。我想避免附加依赖属性并尽可能避免代码隐藏。有任何想法吗？

感谢您的任何努力。

问题出在你的绑定上。默认情况下，绑定会查找控件的 DataContext 属性上的属性。每个绑定都有一个源，在您的情况下，它是控件的 DataContext 属性。因此您的绑定正在评估 DataContext.Caption。您真正想要的是创建绑定源，即具有 Caption 属性的窗口。因此，如下所示更改代码。我在我的机器上测试了它并且它有效。请记住初始化窗口的 Caption 属性。

new:

<UserControl x:Class="WpfApplication1.UserControl1"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300">
<Grid>
    <Grid>
        <Label Content="{Binding Path=Caption, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=UserControl}}"/>
    </Grid>
</Grid>

new:

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:current="clr-namespace:WpfApplication1"
    Title="MainWindow" Height="350" Width="525" >
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition/>
    </Grid.RowDefinitions>
    <Label Content="{Binding Caption, Mode=OneWay, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Window}}"/>
    <current:UserControl1 x:Name="uc" Caption="{Binding Path=Caption, Mode=OneWay, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Window}}"  Grid.Row="1"/>
</Grid>