wpf 如何在多绑定中为 1 绑定传递常量值？
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How can I pass a constant value for 1 binding in multi-binding?
提问by Nam G VU
I have a multi-binding like
我有一个多重绑定
<TextBlock>
<TextBlock.Text>
<MultiBinding Converter="{StaticResource myConverter}">
<Binding Path="myFirst.Value" />
<Binding Path="mySecond.Value" />
</MultiBinding>
</TextBlock.Text>
</TextBlock>
And I want to pass a fixed value e.g. "123" to one of the two bindings above. How can I do that using XAML?
我想将一个固定值（例如“123”）传递给上述两个绑定之一。我如何使用 XAML 做到这一点？
回答by Noldorin
If your value is simply a string, you can specify it as a constant in the Sourceproperty of a binding. If it is any other primitive data type, you need to define a static resource and reference this.
如果您的值只是 a string，您可以在Source绑定的属性中将其指定为常量。如果是任何其他原始数据类型，则需要定义一个静态资源并引用它。
Define the sysnamespace in the root of the XAML to point to Systemin mscorlib, and the following should work:
sys在 XAML 的根中定义命名空间以System在 mscorlib 中指向，并且以下内容应该起作用：
<TextBlock>
<TextBlock.Resources>
<sys:Int32 x:Key="fixedValue">123</sys:Int32>
</TextBlock.Resources>
<TextBlock.Text>
<MultiBinding Converter="{StaticResource myConverter}">
<Binding Path="myFirst.Value" />
<Binding Source="{StaticResource fixedValue}" />
</MultiBinding>
</TextBlock.Text>
</TextBlock>
回答by Anders Kaplan
Or, combining the two answers above:
或者，结合上面的两个答案：
<MultiBinding Converter="{StaticResource ScalingConverter}">
<Binding>
<Binding.Source>
<sys:Double>0.5</sys:Double>
</Binding.Source>
</Binding>
<Binding ElementName="TC" Path="ActualWidth" />
</MultiBinding>
Which provides the right type without the Resources kludge.
它提供了正确的类型而没有资源杂乱。
回答by benPearce
I don't quite follow the question but there are two options:
我不太了解这个问题，但有两种选择：
Put the line <Binding Source="123" />in your multibinding will pass 123 as a bound value to your converter.
将该行<Binding Source="123" />放入您的多重绑定中，会将 123 作为绑定值传递给您的转换器。
Put ConverterParameter="123"in your MultiBinding:
放入ConverterParameter="123"你的多重绑定：
<MultiBinding Converter="{StaticResource conv}" ConverterParameter="123">
<MultiBinding Converter="{StaticResource conv}" ConverterParameter="123">
回答by David Hollinshead
I'm not saying this an especially good answer but here is another approach:
我并不是说这是一个特别好的答案，但这是另一种方法：
<Binding Path="DoesNotExist" FallbackValue="123" />
