WPF 用户控件双向绑定依赖属性
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WPF usercontrol Twoway binding Dependency Property
提问by Spen D
I created a Dependency Property in the usercontrol, but however changes in the usercontrol was NOT notified to the Viewmodel
我在用户控件中创建了一个依赖属性，但是没有将用户控件中的更改通知给 Viewmodel
Usercontrol
用户控件
<UserControl x:Class="DPsample.UserControl1"
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"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<TextBox x:Name="txtName"></TextBox>
</Grid>
UserControl.cs
用户控件.cs
/// <summary>
/// Interaction logic for UserControl1.xaml
/// </summary>
public partial class UserControl1 : UserControl
{
public UserControl1()
{
InitializeComponent();
}
#region SampleProperty
public static readonly DependencyProperty SamplePropertyProperty
= DependencyProperty.Register("SampleProperty",
typeof(string),
typeof(UserControl1),
new PropertyMetadata(OnSamplePropertyChanged));
public string SampleProperty
{
get { return (string)GetValue(SamplePropertyProperty); }
set { SetValue(SamplePropertyProperty, value); }
}
static void OnSamplePropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
(obj as UserControl1).OnSamplePropertyChanged(e);
}
private void OnSamplePropertyChanged(DependencyPropertyChangedEventArgs e)
{
string SamplePropertyNewValue = (string)e.NewValue;
txtName.Text = SamplePropertyNewValue;
}
#endregion
}
MainWindow
主窗口
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:DPsample" x:Class="DPsample.MainWindow"
Title="MainWindow" Height="350" Width="525">
<Grid>
<local:UserControl1 SampleProperty="{Binding SampleText,Mode=TwoWay}" HorizontalAlignment="Left" Margin="76,89,0,0" VerticalAlignment="Top" Width="99"/>
<Button Content="Show" HorizontalAlignment="Left" Margin="76,125,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>
</Grid>
MainWindow.cs
主窗口.cs
public MainWindow()
{
InitializeComponent();
this.DataContext = new MainViewModel();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
var item = this.DataContext as MainViewModel;
MessageBox.Show(item.SampleText.ToString());
}
MainViewModel.cs
主视图模型.cs
public class MainViewModel : NotifyViewModelBase
{
public MainViewModel()
{
this.SampleText = "test";
}
private string _sampleText;
public string SampleText
{
get { return _sampleText; }
set { _sampleText = value; OnPropertyChanged("SampleText"); }
}
}
回答by Clemens
Bind the TextBox.Textproperty in the UserControl to its SamplePropertylike this:
像这样TextBox.Text将 UserControl 中的属性绑定到它SampleProperty：
<TextBox Text="{Binding SampleProperty,
RelativeSource={RelativeSource AncestorType=UserControl}}"/>
Now you could simply remove your OnSamplePropertyChangedcallback.
现在您可以简单地删除您的OnSamplePropertyChanged回调。
You might also register SamplePropertyto bind two-way by default like this:
您也可以SampleProperty像这样默认注册为双向绑定：
public static readonly DependencyProperty
SamplePropertyProperty = DependencyProperty.Register(
"SampleProperty", typeof(string), typeof(UserControl1),
new FrameworkPropertyMetadata(
null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
回答by Dabbas
An alternative way to do this is an ElementName Binding. First assign the x:Nameattribute to the UserControl (for example x:Name="MyUC"), then change the binding to:
执行此操作的另一种方法是 ElementName 绑定。首先将x:Name属性分配给UserControl（例如x:Name="MyUC"），然后将绑定更改为：
<TextBox Text="{Binding ElementName=MyUC, Path=SampleProperty}"/>
