wpf 绑定到自定义依赖属性 - 再次
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Binding to custom dependency property - again
提问by Martin Booka Weser
OK, i know. This has been asked literally one million times, but i still don't get it. Sorry for that.
好的，我知道。这实际上已经被问了一百万次，但我仍然不明白。对不起。
The task: implement the simplest Dependency Property ever, which can be used in xaml like that:
任务：实现有史以来最简单的依赖属性，可以像这样在 xaml 中使用：
<uc:MyUserControl1 MyTextProperty="{Binding Text}"/>
I think that thisanswer is quite close. For better readability i copy all my code here (mostly from that answer above).
我认为这个答案非常接近。为了更好的可读性，我在这里复制了我所有的代码（主要来自上面的答案）。
<UserControl x:Class="Test.UserControls.MyUserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<Grid>
<!-- Text is being bound to outward representative property;
Note the DataContext of the UserControl -->
<TextBox Text="{Binding MyTextProperty}"/>
</Grid>
</UserControl>
and
和
public partial class MyUserControl1 : UserControl
{
// The dependency property which will be accessible on the UserControl
public static readonly DependencyProperty MyTextPropertyProperty =
DependencyProperty.Register("MyTextProperty", typeof(string), typeof(MyUserControl1), new UIPropertyMetadata(String.Empty));
public string MyTextProperty
{
get { return (string)GetValue(MyTextPropertyProperty); }
set { SetValue(MyTextPropertyProperty, value); }
}
public MyUserControl1()
{
InitializeComponent();
}
}
And this is my MainWindow.xaml
这是我的 MainWindow.xaml
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:uc="clr-namespace:WpfApplication1"
Title="MainWindow" Height="350" Width="525">
<StackPanel Orientation="Vertical">
<uc:MyUserControl1 MyTextProperty="my text goes here"/>
<Button Click="ButtonBase_OnClick" Content="click"/>
</StackPanel>
</Window>
So far, everything works. However, i find this quite not usefull. What i'd need is
到目前为止，一切正常。但是，我发现这非常没有用。我需要的是
<uc:MyUserControl1 MyTextProperty="{Binding Text}"/>
and being able to change this by setting a DataContext(as you usually do in MVVM)
并且能够通过设置 a 来改变它DataContext（就像你通常在 MVVM 中所做的那样）
So i replace the line as above and add my code behind as follows:
所以我替换上面的行并添加我的代码如下：
public partial class MainWindow : Window, INotifyPropertyChanged
{
public MainWindow()
{
InitializeComponent();
Text = "Initial Text";
DataContext = this;
}
private string _Text;
public string Text
{
get { return _Text; }
set
{
if (value != _Text)
{
_Text = value;
NotifyPropertyChanged("Text");
}
}
}
private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
Text = "clicked";
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
Neither the "initial Text" nor the "clicked" is displayed... ever. So my question is how to implement a dept. property correctly to be used with
“初始文本”和“点击”都没有显示......永远。所以我的问题是如何实现一个部门。正确使用的属性
<uc:MyUserControl1 MyTextProperty="{Binding Text}"/>
? Thanks for helping me out.
? 谢谢你的协助。
回答by Blachshma
The Textproperty is located on the DataContextof the MainWindownot of the UserControl.
该Text物业位于DataContext中的主窗口不是用户控件的。
So change this line <uc:MyUserControl1 MyTextProperty="{Binding Text}"/>into this:
所以把这一行<uc:MyUserControl1 MyTextProperty="{Binding Text}"/>改成这样：
<uc:MyUserControl1 MyTextProperty="{Binding Text, ElementName=MyMainWindow}"/>
Which will tell the Binding that you're talking about the Text element located in you MainWindow. Of course, since in this example I used ElementName, you're going to want to nameyour window MyMainWindow...
这将告诉 Binding 您正在谈论位于 MainWindow 中的 Text 元素。当然，因为在这个例子中，我使用的ElementName，你会想命名你的窗口MyMainWindow ...
So add this to your MainWindow:
因此，将其添加到您的 MainWindow：
<Window Name="MyMainWindow" ..... />
If you rather not name your window, you can use the RelativeSource FindAncestor binding like this:
如果您不想为您的窗口命名，您可以像这样使用 RelativeSource FindAncestor 绑定：
<wpfApplication6:MyUserControl1 MyTextProperty="{Binding Text, RelativeSource={RelativeSource FindAncestor, AncestorType=Window}}"/>
In both ways, you are asking to find the property named 'Text' in the DataContext of the window.
在这两种方式中，您都要求在窗口的 DataContext 中查找名为“Text”的属性。
