IMul​​tiValueConverter中提到DependencyProperty的例外情况

Question

我正在尝试在列表框中获取图像，提供iMultiValueConverter的路径，在后台线程中执行：

<Image>
  <Image.Source>
    <MultiBinding Converter="{StaticResource UriToBitmapConverter}">
      <MultiBinding.Bindings>
        <Binding RelativeSource="{RelativeSource Self}" />
        <Binding Source="{Binding ImagePath}" />  
      </MultiBinding.Bindings>
    </MultiBinding>
  </Image.Source>
</Image>

和

public class UriToBitmapConverter : IMultiValueConverter 
{
    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)    
    {
        if (values[1] == null) return null;

        BitmapImage BI= null;
        Image image = values[0] as Image;
        string mypath = values[1] as string;
        FileStream fileStream = new FileStream(mypath, FileMode.Open, FileAccess.Read);

                ThreadPool.QueueUserWorkItem((WaitCallback)delegate
                {
                    image.Dispatcher.Invoke(DispatcherPriority.Normal,
                        (ThreadStart)delegate
                        {
                            BI= new BitmapImage();
                            BI.BeginInit();
                            BI.StreamSource = fileStream;
                            BI.EndInit();
                            image.Source = BI;
                        });
                });
        return BI;
    }

    public object[] ConvertBack(object value, Type[] targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new Exception("The method or operation is not implemented.");
    }
}

我明白了：

  

未处理的类型异常   'System.Windows.Markup.XamlParseException'发生在   PresentationFramework.dll

     

附加信息：无法在'来源'上设置'绑定'   '绑定'类型的属性。 '绑定'只能在a上设置   DependencyObject的DependencyProperty。

你能告诉我我做错了什么吗？