将属性与用户控件拥有的另一个属性绑定

Question

我想实现几个属性之间的绑定。有可能吗？

我有一个名为“MainWindow”的主窗口类，它拥有一个属性“InputText”。此类包含一个名为 MyUserControl 的用户控件。 MyUserControl 有一个文本框绑定到依赖属性“MyTextProperty”

我想将我的主窗口的属性“InputText”与我的用户控件的依赖属性“MyTextProperty”绑定。所以，如果用户写了一个文本，我希望属性“InputText”、“MyTextProperty”、“MyText”被更新。

用户控制代码：

using System;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.ComponentModel;

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MyUserControl.xaml
    /// </summary>
    public partial class MyUserControl : UserControl
    {

        public string MyText
        {
            get { return (string)GetValue(MyTextProperty); }
            set { SetValue(MyTextProperty, value); }
        }

        public static readonly DependencyProperty MyTextProperty =
            DependencyProperty.Register("MyText", typeof(string), typeof(MyUserControl), new PropertyMetadata(0));



        public MyUserControl()
        {
            this.DataContext = this;
            InitializeComponent();
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected void NotifyPropertyChanged(string property)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs(property));
            }
        }

    }
}

WPF 用户控制代码：

<UserControl x:Class="WpfApplication1.MyUserControl"
             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="25 " d:DesignWidth="100"
             Background="Black">
    <Grid>
        <TextBox Height="20" Width="100" Text="{Binding MyText}"></TextBox>
    </Grid>
</UserControl>

主窗口代码：

using System;
using System.Linq;
using System.Windows;
using System.ComponentModel;

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private string inputText;

        public string InputText
        {
            get { return inputText; }
            set 
            { 
                inputText = value;
                NotifyPropertyChanged("InputText");
            }
        }

        public MainWindow()
        {
            this.DataContext = this;

            InitializeComponent();

        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected void NotifyPropertyChanged(String property)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs(property));
            }
        }
    }
}

WPF主窗口代码：

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:myNS="clr-namespace:WpfApplication1"
        Title="MainWindow" Height="80" Width="300">
    <Grid>
        <StackPanel Orientation="Vertical">
            <myNS:MyUserControl x:Name="test" MyText="{Binding InputText}"></myNS:MyUserControl>
            <Button Name="cmdValidation" Content="Validation" Height="20"></Button>
        </StackPanel>
    </Grid>
</Window>

谢谢！

Answer 1

如果您希望您发布的代码以尽可能少的更改工作，那么：

在 MainWindow.xaml 中，更改

MyText="{Binding InputText}"

到

MyText="{Binding RelativeSource={RelativeSource AncestorType=Window}, Path=DataContext.InputText, Mode=TwoWay}"

如果你想让 UC 更新 InputText，你需要 TwoWay。

此外，在 MyUserControl.xaml.cs 中，在 DependencyProperty.Register 语句中，您将字符串的 PropertyMetadata 默认值设置为 0 - 将其更改为适合字符串的值 - 例如 null 或 string.empty。

public static readonly DependencyProperty MyTextProperty =
    DependencyProperty.Register("MyText", typeof(string), typeof(MyUserControl), new PropertyMetadata(null));

如果你想稍微修改一下代码，你可以在用户控件中让它更复杂，但在使用时更简单：

使依赖属性 MyText 默认绑定两种方式

停止在用户控件中设置 DataContext

更改 UC xaml 文本绑定以使用 UC 的相对源

我总是觉得代码更容易理解，所以这里是您的文件的修改版本： 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:myNS="clr-namespace:WpfApplication1"
        Title="MainWindow" Height="180" Width="300">
    <Grid>
        <StackPanel Orientation="Vertical">
            <TextBlock>
                <Run Text="MainWindow.InputText: " />
                <Run Text="{Binding InputText}" />
            </TextBlock>
            <TextBlock>
                <Run Text="MyUserControl.MyText: " />
                <Run Text="{Binding ElementName=test, Path=MyText}" />
            </TextBlock>
            <myNS:MyUserControl x:Name="test" MyText="{Binding InputText}"></myNS:MyUserControl>
            <Button Name="cmdValidation" Content="Validation" Height="20"></Button>
        </StackPanel>
    </Grid>
</Window>

MainWindow.xaml.cs

using System;
using System.Windows;
using System.ComponentModel;

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private string inputText = "Initial Value";

        public string InputText
        {
            get { return inputText; }
            set
            {
                inputText = value;
                NotifyPropertyChanged("InputText");
            }
        }

        public MainWindow()
        {
            this.DataContext = this;

            InitializeComponent();

        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected void NotifyPropertyChanged(String property)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs(property));
            }
        }
    }
}

MyUserControl.xaml

<UserControl x:Class="WpfApplication1.MyUserControl"
             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="25 " d:DesignWidth="100"
             Background="Black">
    <Grid>
        <TextBox Height="20" Width="100" Text="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path=MyText, UpdateSourceTrigger=PropertyChanged}"></TextBox>
    </Grid>
</UserControl>

MyUserControl.xaml.cs

using System.Windows;
using System.Windows.Controls;

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MyUserControl.xaml
    /// </summary>
    public partial class MyUserControl : UserControl
    {

        public string MyText
        {
            get { return (string)GetValue(MyTextProperty); }
            set { SetValue(MyTextProperty, value); }
        }

        public static readonly DependencyProperty MyTextProperty =
            DependencyProperty.Register("MyText", typeof(string), typeof(MyUserControl), new FrameworkPropertyMetadata(null) { BindsTwoWayByDefault = true });

        public MyUserControl()
        {
            InitializeComponent();
        }
    }
}

Answer 2

首先，

this.DataContext = this;

没有。就是不行。您正在覆盖由其父窗口设置的UserControl 中的DataContext。

对于你的UserControl，给它一个x:Name，并直接绑定到依赖属性。

<UserControl
    ...
    x:Name="usr">

    <TextBox Text="{Binding MyText, ElementName=usr}" ... />

完成后，您可以简单地将您的MyText 属性绑定到MainWindow 的DataContext。

<myNS:MyUserControl x:Name="test" MyText="{Binding InputText}" />