WPF：DependencyProperty.UnsetValue上的触发器 [英] WPF: Trigger on DependencyProperty.UnsetValue

问题描述

在此问题的答案中，提出了以下声明

in an answer to this question the following statement was made

理论上来说，可能会触发{x：Static DependencyProperty.UnsetValue}，这将会更清晰，但这并不会出现在实践中工作。

"In theory it might be possible to .... trigger on {x:Static DependencyProperty.UnsetValue}, which would be much cleaner, but this doesn't appear to work in practice."

有没有人有这样的运气？

Has anybody had any luck in doing this?

推荐答案

失败的Binding将返回null（或fallbackvalue），这与UnsetValue不同。

A failing Binding will return null (or the fallbackvalue), which is different from an UnsetValue.

itowlson给你的答案可能是你最好的得到。在这种具体情况下，您可能可以使用：

the answer itowlson gave you is probably the best you will get. In this specific case, you might be able to use:

<DataTrigger Binding="{Binding Hibble, FallbackValue={x:Static DependencyProperty.UnsetValue}}" Value="{x:Static DependencyProperty.UnsetValue}">
  <Setter Property="Background" Value="Red" />
</DataTrigger>

这几乎是一样的。

（您可能需要查看此）

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