Question

我正在构建一个Windows Phone 8应用程序。我有一个UserControl，其内容应异步更新。我的模型实现了INotifyPropertyChanged。当我更新模型中的值时，它会传播到TextBox控件，但不会传播到UserControl的内容。我错过了哪个部分，或者它是不可能的？这是我的复制场景。

应用页面：

<phone:PhoneApplicationPage x:Class="BindingTest.MainPage">
  <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
    <Button Click="Button_Click" Content="Click" HorizontalAlignment="Left" Margin="147,32,0,0" VerticalAlignment="Top"/>
    <TextBlock  HorizontalAlignment="Left" Margin="69,219,0,0" TextWrapping="Wrap" Text="{Binding Bar}" VerticalAlignment="Top" Height="69" Width="270"/>
    <app:MyControl x:Name="Snafu" HorizontalAlignment="Left" Margin="69,319,0,0" Title="{Binding Bar}" VerticalAlignment="Top" Width="289"/>
  </Grid>
</phone:PhoneApplicationPage>

这是模型类（Foo）背后的代码

public partial class MainPage : PhoneApplicationPage
{
    Foo foo;
    // Constructor
    public MainPage()
    {
        InitializeComponent();
        foo = new Foo();
        ContentPanel.DataContext = foo;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        foo.Bar = "Gnorf";
    }
}

public class Foo : INotifyPropertyChanged
{
    string bar;
    public event PropertyChangedEventHandler PropertyChanged;
    void OnPropertyChanged(string name)
    {
        if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(name));
    }
    public Foo()
    {
        Bar = "Welcome";
    }
    public string Bar
    {
        get
        {
            return bar;
        }
        set
        {
            bar = value;
            OnPropertyChanged("Bar");
        }
    }
}

UserControl xaml

<UserControl x:Class="BindingTest.MyControl">
    <TextBox x:Name="LayoutRoot" Background="#FF9090C0"/>
</UserControl>

UserControl背后的代码

public partial class MyControl : UserControl
{
    public MyControl()
    {
        InitializeComponent();
    }
    public static readonly DependencyProperty TitleProperty = DependencyProperty.Register("Title", typeof(string), typeof(MyControl), new PropertyMetadata("", OnTitleChanged));
    static void OnTitleChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        MyControl c = (MyControl)d;
        c.Title = e.NewValue as String;
    }
    public string Title
    {
        get
        {
            return (string)GetValue(TitleProperty);
        }
        set
        {
            SetValue(TitleProperty, value);
            LayoutRoot.Text = value;
        }
    }
}

当我运行该示例时，UserControl TextBox将包含welcome。当我单击按钮时，常规TextBox将更新为Gnorf，但UserControl仍会显示Welcome。

我还发现，如果我只绑定到UserControl，则在调用set_DataContext时，PropertyChanged事件处理程序为null。 DataBinding基础结构似乎推断出对我的UserControl的绑定是一次性绑定而不是常规的单向绑定。有什么想法吗？

Answer 1

试试这个： -

 <app:UserControl1 x:Name="Snafu" Title="{Binding Bar,Mode=TwoWay}" />

我检查了它..这将有效.. :)

为什么我的依赖项属性更改不会传播到我的usercontrol

1 个答案: