c# - NotifySourceUpdated & Binding.SourceUpdated 不工作

Question

我下面的事件 (OnSourceUpdated) 没有得到处理。

XAML:

    <StackPanel x:Name="MyStackPanel" 
                Orientation="Horizontal" 
                DockPanel.Dock="Top">
        <TextBox Text="{Binding Side, Mode=TwoWay}" 
                 Width="100"/>
        <TextBlock Background="Yellow" 
                   Text="{Binding Side, Mode=OneWay, 
                                  NotifyOnSourceUpdated=True}"
                   Width="100" 
                   SourceUpdated="OnSourceUpdated"
                   Binding.SourceUpdated="OnSourceUpdated"/>
    </StackPanel>

C#:

....
MyStackPanel.DataContext = new MyItemClass() { Side = "Test" };
....

private void OnSourceUpdated(Object sender, DataTransferEventArgs args)
{
    var i = args.Property;
}

public class MyItemClass : INotifyPropertyChanged
{
    private string _side;
    public string Side
    {
        get { return _side; }

        set 
        {
            _side = value;
            OnPropertyChanged("Side");
        }
    }

    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string propertyName)
    {
        if (this.PropertyChanged != null)
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    #endregion
}

我已完成所有相关设置，如 NotifyOnSourceUpdated & SourceUpdated & Binding.SourceUpdated 等

Answer 1

来自 msdn : Binding.SourceUpdated 附加事件在值从绑定(bind)目标传输到绑定(bind)源时发生，但仅适用于 NotifyOnSourceUpdated 值设置为 true 的绑定(bind)

在TextBlock的Binding中，没有从绑定(bind)目标(TextBlock.Text)到绑定(bind)源(Side)的值传递。因此无法触发 SourceUpdated。

相反，SourceUpdated 可以在第一次绑定(bind)时触发。实际上这里的目标绑定(bind) TextBox.Text 可以改变绑定(bind)源(Side)。