你如何绑定到用户控件的属性？ [英] How do you bind to the property of a User Control?

问题描述

在Windows应用商店的应用程序，您可以创建一个用户控件封装和重用代码隐藏和布局XAML。一个简单的用户控件可能是这样的：

In Windows Store Apps, you create a user control to encapsulate and reuse code-behind and layout XAML. A simple user control might look like this:

<UserControl>
    <StackPanel>
        <TextBlock Text="First Name" />
        <TextBox x:Name="MyTextBox" />
    </StackPanel>
</UserControl>

现在，我想设置绑定。所以我创建的代码隐藏与暴露UI控件的Text属性的属性。事情是这样的：

Now, I want to setup binding. So I create code-behind with properties that expose the Text properties of the UI controls. Something like this:

public string TextBoxText
{
    get { return MyTextBoxText.Text; }
    set { MyTextBoxText.Text = value; }
}

不过，这是行不通的。这似乎是数据绑定到用户控件是一个XAML UI中有价值的一部分。但它是如何实现的？

However, this does not work. It seems like data binding to a user control is a valuable part of a XAML UI. But how is it accomplished?

推荐答案

有只有一个用户控件实现一个属性，它支持在方页面绑定。这是一个依赖项属性。实现是很简单的，但你也必须包括更改事件直接与UI交互，因为一个依赖属性是一个控制的静态属性。像这样的：

There is only one implementation of a property in a user control that supports binding in the consuming page. That is a dependency property. The implementation is simple enough, but you must also include the changed event to interact directly with the UI, since a dependency property is a static property on a control. Like this:

public string TextBoxText
{
    get { return (string)GetValue(TextBoxTextProperty); }
    set { SetValue(TextBoxTextProperty, value); }
}

public static readonly DependencyProperty TextBoxTextProperty =
    DependencyProperty.Register("TextBoxText", typeof(string), typeof(MyUserControl),
    new PropertyMetadata(string.Empty, OnTextBoxTextPropertyChanged));

private static void OnTextBoxTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    (d as MyUserControl).MyTextBox.Text = e.NewValue.ToString();
}

我承认，这不是超级明显。但希望现在你知道，这将节省您在搜索，并试图弄清楚小时。同样，你只能绑定到用户控件的依赖属性。而且，您可以只设置UI值的时候使用更改事件的静态线程。

I admit, this is not super obvious. But hopefully now that you know, it will save you hours of searching and trying to figure out. Again, you can only bind to a dependency property of a user control. And, you can only set the UI values off the static thread using the changed event.

祝你好运！

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