以编程方式绑定 WPF 中的附加属性

问题描述

我正在使用

Jason 的代码以编程方式创建一个 ContentPresenter，将其内容设置为 CueBanner.Content，将 ContentPresenter 添加到 Adorner 子类，并在适当的时候显示它.

他的代码从装饰控件的填充和边距推断 ContentPresenter，但我添加了 hpext:CueBanner.Padding 代替，所以我可以将它显式设置为我的值比较喜欢.

contentPresenter.Margin = CueBanner.GetPadding(adornedElement);

到目前为止一切顺利.

麻烦来了:它可以工作，但我想改为绑定它.

var binding = new Binding("hpext:CueBanner.Padding") { Source = adornedElement };BindingOperations.SetBinding(contentPresenter, ContentPresenter.MarginProperty, binding);

但是我用什么作为源属性的路径? "hpext:CueBanner.Padding" 不起作用，也不应该起作用；该命名空间在那里不存在."CueBanner.Padding" 和 "(CueBanner.Padding)" 没有乐趣."MyProject.Extensions.CueBanner.Padding" 也不起作用，我不明白为什么应该这样做.

我在 PropertyPath，但是当我读到它时，我的头脑开始变得有点空白.

我应该只是在 XAML 中这样做，不是吗?

解决方案

你可以像这样直接从附加的属性创建一个 PropertyPath:

var 绑定 = 新绑定{Path = new PropertyPath(CueBanner.PaddingProperty),//这里来源 = 装饰元素};

I'm using Jason Kemp's cool CueBanner class for "watermarking" text boxes in WPF:

<TextBox
    hpext:CueBanner.Content="Find Text"
    hpext:CueBanner.Padding="2,6,0,0"
    />

Jason's code creates a ContentPresenter programmatically, sets its content to the CueBanner.Content, adds the ContentPresenter to an Adorner subclass, and displays it when appropriate.

His code infers the ContentPresenter from padding and margin of the adorned control, but I added hpext:CueBanner.Padding instead so I could set it explicitly to a value I like better.

contentPresenter.Margin = CueBanner.GetPadding(adornedElement);

So far so good.

Here's the trouble: It works but I'd like to bind it instead.

var binding = new Binding("hpext:CueBanner.Padding") { Source = adornedElement };

BindingOperations.SetBinding(contentPresenter, ContentPresenter.MarginProperty, binding);

But what do I use for a path for the source property? "hpext:CueBanner.Padding" doesn't work and it shouldn't work; that namespace doesn't exist there. No joy with "CueBanner.Padding" and "(CueBanner.Padding)". "MyProject.Extensions.CueBanner.Padding" doesn't work either and I can't see why it ought to.

I can't see anything that looks helpful in PropertyPath, but when I read that my mind starts to go a little blank.

I should be just doing this in XAML, shouldn't I?

解决方案

You may directly create a PropertyPath from the attached property like this:

var binding = new Binding
{
    Path = new PropertyPath(CueBanner.PaddingProperty), // here
    Source = adornedElement
};

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