WPF UserControl如何在CheckBox状态变更时更新自身属性控制TextBox启停

我在WPF应用中开发了一个由CheckBox和TextBox组成的UserControl，希望TextBox的启用/禁用状态跟随CheckBox选中状态动态变化，且状态支持数据绑定。

初始代码 #

UserControl XAML代码 #

<UserControl x:Class="WpfApp.Views.Elements.TextCheckBox"
             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="450" d:DesignWidth="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="Auto"/>
        </Grid.ColumnDefinitions>

        <CheckBox Content="Disabled"
              IsChecked="{Binding CheckBoxChecked,
                          Mode=OneWayToSource,
                          UpdateSourceTrigger=PropertyChanged,
                          RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}"
              HorizontalAlignment="Center"
              VerticalAlignment="Center"
              Grid.Row="1"
              Grid.Column="1"
              Margin="5,5,8,5"/>

        <TextBox Text="{Binding TextBoxText,
                        Mode=OneWayToSource,
                        UpdateSourceTrigger=PropertyChanged,
                        RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}"
                IsEnabled="{Binding TextBoxEnabled,
                             Mode=OneWay,
                             RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}"
                 Grid.Row="1"
                 Grid.Column="0"
                 Height="20"/>
    </Grid>
</UserControl>

UserControl后台代码 #

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

namespace WpfApp.Views.Elements
{
    /// <summary>
    /// Interaction logic for TextCheckBox.xaml
    /// </summary>
    public partial class TextCheckBox : UserControl
    {
        public bool TextBoxEnabled => !CheckBoxChecked;

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

        public bool CheckBoxChecked
        {
            get => (bool)GetValue(CheckBoxCheckedProperty);
            set => SetValue(CheckBoxCheckedProperty, value);
        }

        public event DependencyPropertyChangedEventHandler TextPropertyChanged;

        public static readonly DependencyProperty TextBoxTextProperty =
            DependencyProperty.Register(nameof(TextBoxText), typeof(string), typeof(TextCheckBox), new PropertyMetadata(OnAnyPropertyChanged));

        public static readonly DependencyProperty CheckBoxCheckedProperty =
            DependencyProperty.Register(nameof(CheckBoxChecked), typeof(bool), typeof(CheckBoxInput), new PropertyMetadata(OnAnyPropertyChanged));

        public TextCheckBox()
            => InitializeComponent();

        static void OnAnyPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
            => (obj as TextCheckBox).OnAnyPropertyChanged(args);

        void OnAnyPropertyChanged(DependencyPropertyChangedEventArgs args)
            => TextPropertyChanged?.Invoke(this, args);
    }
}

引用UserControl的页面代码 #

<UserControl x:Class="WpfApp.Views.MyView"
             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" 
             xmlns:other="clr-namespace:WpfApp.Other" xmlns:elements="clr-namespace:WpfApp.Views.Elements"
             mc:Ignorable="d" 
             other:ViewModelLocator.AutoWireViewModel="True"
             d:DesignHeight="450" d:DesignWidth="800">
    <Grid>
        <elements:TextCheckBox
                            CheckBoxChecked="{Binding IsChecked,
                                              Mode=OneWayToSource}"
                                              
                            TextBoxText="{Binding TextContent,
                                          Mode=OneWayToSource,
                                          UpdateSourceTrigger=PropertyChanged}"/>
    </Grid>
</UserControl>

已尝试方案及问题 #

1. 尝试将TextBoxEnabled定义为依赖属性，在CheckBoxChecked的setter中更新它的值，出现两个问题：点击CheckBox时TextBox状态无变化，且CheckBoxChecked的setter中断点不会被命中。
2. 尝试给TextBox加样式触发器绑定CheckBox的IsChecked属性，依然没有效果。

你代码里存在3个核心错误导致所有方案失效：

• 依赖属性注册的所有者类型错误：注册CheckBoxCheckedProperty和TextBoxEnabledProperty时，OwnerType参数填的是typeof(CheckBoxInput)，但你的控件类是TextCheckBox，直接导致依赖属性系统找不到对应属性，绑定完全失效。
• 依赖属性CLR包装器逻辑不生效：WPF依赖属性系统更新属性值时会直接调用SetValue方法，不会走你定义的CLR属性setter，所以你在setter里写的更新逻辑永远不会执行，这也是断点不命中的原因。
• 初始版本的TextBoxEnabled不是依赖属性，没有属性变更通知，就算值变化了界面也收不到更新通知。

两种方案任选其一即可：

方案1：通过依赖属性关联状态（适合需要向外暴露TextBoxEnabled属性的场景） #

仅修改后台代码即可：

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

namespace WpfApp.Views.Elements
{
    public partial class TextCheckBox : UserControl
    {
        public bool TextBoxEnabled
        {
            get => (bool)GetValue(TextBoxEnabledProperty);
            set => SetValue(TextBoxEnabledProperty, value);
        }

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

        public bool CheckBoxChecked
        {
            get => (bool)GetValue(CheckBoxCheckedProperty);
            set => SetValue(CheckBoxCheckedProperty, value);
        }

        public event DependencyPropertyChangedEventHandler TextPropertyChanged;

        public static readonly DependencyProperty TextBoxEnabledProperty =
            DependencyProperty.Register(nameof(TextBoxEnabled), typeof(bool), typeof(TextCheckBox), new PropertyMetadata(OnAnyPropertyChanged));

        public static readonly DependencyProperty TextBoxTextProperty =
            DependencyProperty.Register(nameof(TextBoxText), typeof(string), typeof(TextCheckBox), new PropertyMetadata(OnAnyPropertyChanged));

        public static readonly DependencyProperty CheckBoxCheckedProperty =
            DependencyProperty.Register(nameof(CheckBoxChecked), typeof(bool), typeof(TextCheckBox), new PropertyMetadata(OnCheckBoxCheckedChanged));

        public TextCheckBox()
            => InitializeComponent();

        private static void OnCheckBoxCheckedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var control = (TextCheckBox)d;
            control.TextBoxEnabled = !(bool)e.NewValue;
            OnAnyPropertyChanged(d, e);
        }

        static void OnAnyPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
            => (obj as TextCheckBox)?.OnAnyPropertyChanged(args);

        void OnAnyPropertyChanged(DependencyPropertyChangedEventArgs args)
            => TextPropertyChanged?.Invoke(this, args);
    }
}

方案2：直接在XAML绑定（逻辑最简单，不需要额外依赖属性） #

先修复后台代码的依赖属性所有者类型错误，去掉TextBoxEnabled相关逻辑：

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

namespace WpfApp.Views.Elements
{
    public partial class TextCheckBox : UserControl
    {
        public string TextBoxText
        {
            get => (string)GetValue(TextBoxTextProperty);
            set => SetValue(TextBoxTextProperty, value);
        }

        public bool CheckBoxChecked
        {
            get => (bool)GetValue(CheckBoxCheckedProperty);
            set => SetValue(CheckBoxCheckedProperty, value);
        }

        public event DependencyPropertyChangedEventHandler TextPropertyChanged;

        public static readonly DependencyProperty TextBoxTextProperty =
            DependencyProperty.Register(nameof(TextBoxText), typeof(string), typeof(TextCheckBox), new PropertyMetadata(OnAnyPropertyChanged));

        public static readonly DependencyProperty CheckBoxCheckedProperty =
            DependencyProperty.Register(nameof(CheckBoxChecked), typeof(bool), typeof(TextCheckBox), new PropertyMetadata(OnAnyPropertyChanged));

        public TextCheckBox()
            => InitializeComponent();

        static void OnAnyPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
            => (obj as TextCheckBox)?.OnAnyPropertyChanged(args);

        void OnAnyPropertyChanged(DependencyPropertyChangedEventArgs args)
            => TextPropertyChanged?.Invoke(this, args);
    }
}

修改XAML代码，直接用触发器关联状态：

<UserControl x:Class="WpfApp.Views.Elements.TextCheckBox"
             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="450" d:DesignWidth="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="Auto"/>
        </Grid.ColumnDefinitions>

        <CheckBox x:Name="checkBox"
              Content="Disabled"
              IsChecked="{Binding CheckBoxChecked,
                          Mode=OneWayToSource,
                          UpdateSourceTrigger=PropertyChanged,
                          RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}"
              HorizontalAlignment="Center"
              VerticalAlignment="Center"
              Grid.Row="1"
              Grid.Column="1"
              Margin="5,5,8,5"/>

        <TextBox Text="{Binding TextBoxText,
                        Mode=OneWayToSource,
                        UpdateSourceTrigger=PropertyChanged,
                        RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}"
                 Grid.Row="1"
                 Grid.Column="0"
                 Height="20">
            <TextBox.Style>
                <Style TargetType="TextBox">
                    <Setter Property="IsEnabled" Value="True"/>
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding IsChecked, ElementName=checkBox}" Value="True">
                            <Setter Property="IsEnabled" Value="False"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </TextBox.Style>
        </TextBox>
    </Grid>
</UserControl>

内容的提问来源于stack exchange，提问作者K-RUSHer