MultiBinding的特殊行为VS指定的ImageSource当绑定

我绑定到图像的来源属性时，碰到了一个特殊的行为，使用转换器。

I ran into a special behavior when binding to the Source property of an Image, using a converter.

看来，如果我用一个简单的绑定与的IValueConverter 返回字符串correpsonding为相对路径到图像，一切正常，并显示图像。

It appears that if I use a simple Binding with a IValueConverter that returns a string correpsonding to a relative path to the image, everything is OK and the image is displayed.

在另一方面，如果我用一个 MultiBinding 与 IMultiValueConverter 返回相同的字符串，绑定不工作，并显示在VS2010输出窗口此错误消息：

On the other hand, if I use a MultiBinding with a IMultiValueConverter that returns the same string, the binding doesn't work and this error message is displayed in VS2010 output window :

System.Windows.Data错误：5：BindingEx pression生产值是不是有效的目标属性;值=''MultiBindingEx pression：目标元素是'图像'（名称=''）;目标属性是源（类型'的ImageSource'）

System.Windows.Data Error: 5 : Value produced by BindingExpression is not valid for target property.; Value='' MultiBindingExpression:target element is 'Image' (Name=''); target property is 'Source' (type 'ImageSource')

我发现这个工作，我不能返回一个简单的字符串（而不是连乌里）。我不是在我的转换器来创建一个ImageSource的（A 的BitmapImage ，其实）并返回。

I found out that for this to work, I can't return a simple string (and not even a Uri). I instead have to create a ImageSource in my converter (a BitmapImage, in fact) and return it.

你知道为什么这种奇怪的行为发生？这是之间的已知差异绑定和 MultiBinding ，或者是一个错误吗？

Do you know why this strange behavior happens? Is this a known difference between Binding and MultiBinding, or is it a bug?

我发现可能会涉及到这个计算器的另一个话题，其中阿尔文贴当绑定都解决了时间评论：

I found another * topic that may relate to this, where Alvin posted a comment about the time when the binding are resolved :

我觉得MultiBinding作出后TextBlock的渲染，以及（单）绑定之前TextBlok渲染 - Avlin

I think that MultiBinding is made AFTER TextBlock rendering, and (single)Binding BEFORE TextBlok rendering – Avlin

要说明这个问题，我写了一个小的项目，你可以下载和测试一>

To Illustrate this problem, I wrote a small project that you can download and test.

感谢您的任何见解！