从代码中设置自定义的MarkupExtension [英] Set custom MarkupExtension from code
问题描述
您设置代码的自定义的MarkupExtension 怎么办？
How do you set a custom MarkupExtension from code?
您可以轻松地设置如果XAML的。这同样适用于绑定和 DynamicResource 。
You can easily set if from Xaml. The same goes for Binding and DynamicResource.
<TextBox FontSize="{Binding MyFontSize}"
Style="{DynamicResource MyStyle}"
Text="{markup:CustomMarkup}"/>
设置通过代码相同的价值观背后需要一点点不同的方法
Setting the same values through code behind requires a little different approach
-
绑定：使用textBox.SetBinding或BindingOperations.SetBinding
Binding: Use textBox.SetBinding or BindingOperations.SetBinding
Binding binding = new Binding("MyFontSize");
BindingOperations.SetBinding(textBox, TextBox.FontSizeProperty, binding);
DynamicResource：使用SetResourceReference
DynamicResource: Use SetResourceReference
textBox.SetResourceReference(TextBox.StyleProperty, "MyStyle");
CustomMarkup：如何设置自定义的的MarkupExtension ？我应该叫 ProvideValue ，它那种情况下，我怎么得到一个保持的的IServiceProvider *？
CustomMarkup: How do I set a custom MarkupExtension from code? Should I call ProvideValue and it that case, how do I get a hold of a IServiceProvider?*
CustomMarkupExtension customExtension = new CustomMarkupExtension();
textBox.Text = customExtension.ProvideValue(??);
我发现令人惊讶的一点关于这个问题的话，能不能做到？
I found surprisingly little on the subject so, can it be done?
HB 已经回答了这个问题。只是增加了一些细节在这里我为什么要这么做。我试图创建下列问题的方法。
H.B. has answered the question. Just adding some details here to why I wanted to do this. I tried to create a workaround for the following problem.
的问题是，你不能从导出绑定并覆盖 ProvideValue ，因为它是密封的。你必须做这样的事情，而不是：基类自定义WPF绑定标记扩展。但随后的问题是，当你返回绑定到二传手你会得到一个异常，而是在<外code>风格它工作正常。
The problem is that you can't derive from Binding and override ProvideValue since it is sealed. You'll have to do something like this instead: A base class for custom WPF binding markup extensions. But then the problem is that when you return a Binding to a Setter you get an exception, but outside of the Style it works fine.
我在几个地方看，你应该返回的MarkupExtension 本身如果 TargetObject 是二传手允许它reeavaluate一旦它被应用于实际 FrameworkElement的，这是有道理的。
I've read in several places that you should return the MarkupExtension itself if the TargetObject is a Setter to allow it to reeavaluate once it is being applied to an actual FrameworkElement and this makes sense.
- 的WPF：标记扩展数据触发
- 的一的MarkupExtension
- 的基类为自定义WPF绑定标记扩展（在评论）
的巨大的限制
- WPF: Markup Extension in Data Trigger
- Huge limitation of a MarkupExtension
- A base class for custom WPF binding markup extensions (in the comments)
不过，这只能当 TargetProperty 的类型为对象，否则异常又回来了。如果你看一下源代码 BindingBase 你可以看到，这不正是这一点，但它出现在框架有一些秘密的成分，使得它的工作。
However, that only works when the TargetProperty is of type object, otherwise the exception is back. If you look at the source code for BindingBase you can see that it does exactly this but it appears the framework has some secret ingredient that makes it work.
推荐答案
我觉得没有代码相同，则该服务只能通过XAML。从 MSDN ：
I think there is no code-equivalent, the services are only available via XAML. From MSDN:
的MarkupExtension只有一个虚方法，ProvideValue。输入的ServiceProvider参数是怎样的服务传达给当标记扩展是通过XAML处理器称为实现。
MarkupExtension has only one virtual method, ProvideValue. The input serviceProvider parameter is how the services are communicated to implementations when the markup extension is called by a XAML processor.
这篇关于从代码中设置自定义的MarkupExtension的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
