用户控件依赖项列表视图中的属性绑定

本文关键字：属性 绑定 视图 列表 控件 依赖 用户 | 更新日期: 2023-09-27 18:33:07

当我尝试在列表视图中使用自定义用户控件时，它失败并且仅显示空块（以下文本块有效）。虽然列表视图之外的自定义控件运行良好。怎么了？

MainWindow.xaml

<Grid>
    <StackPanel>
        <controls:CustomControl x:Name="customControl" CustomText="Test"/>
        <ListView x:Name="listView">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <StackPanel>
                        <controls:CustomControl CustomObject="{Binding}"/>
                        <TextBlock Text="{Binding Text}"/>
                    </StackPanel>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    </StackPanel>
</Grid>

主窗口.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        InitializeMyComponent();
    }
    public System.Collections.ObjectModel.ObservableCollection<CustomClass> CustomCollection { get; set; }
    private void InitializeMyComponent()
    {
        this.CustomCollection = new System.Collections.ObjectModel.ObservableCollection<CustomClass>();
        this.CustomCollection.Add(new CustomClass() { Number = 1, Text = "a" });
        this.CustomCollection.Add(new CustomClass() { Number = 2, Text = "b" });
        this.CustomCollection.Add(new CustomClass() { Number = 3, Text = "c" });
        this.listView.ItemsSource = this.CustomCollection;
        this.customControl.Custom = new CustomClass() { Number = 0, Text = "customControl" };
    }
}

CustomControl.xaml

<Grid>
    <StackPanel>
        <TextBlock>
            <Run x:Name="numberRun" Text="{Binding CustomObject.Number}"/>
            <Run x:Name="textRun" Text="{Binding CustomObject.Text}"/>
            <Run Text="{Binding CustomText}"/>
        </TextBlock>
    </StackPanel>
</Grid>

自定义控制.cs

public partial class CustomControl : UserControl
{
    public static readonly DependencyProperty CustomObjectProperty;
    public static readonly DependencyProperty CustomTextProperty;
    static CustomControl()
    {
        CustomObjectProperty = DependencyProperty.Register("CustomObject", typeof(CustomClass), typeof(CustomControl), new PropertyMetadata(default(CustomClass), OnCustomObjectPropertyChanged));
        CustomTextProperty = DependencyProperty.Register("CustomText", typeof(string), typeof(CustomControl), new PropertyMetadata(string.Empty, OnCustomTextPropertyChanged));
    }
    public CustomControl()
    {
        InitializeComponent();
        this.DataContext = this;
    }
    public CustomClass CustomObject
    {
        get
        {
            return (CustomClass)(this.GetValue(CustomObjectProperty));
        }
        set
        {
            this.SetValue(CustomObjectProperty, value);
        }
    }
    public string CustomText
    {
        get
        {
            return (string)(this.GetValue(CustomTextProperty));
        }
        set
        {
            this.SetValue(CustomTextProperty, value);
        }
    }
    private static void OnCustomObjectPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { }
    private static void OnCustomTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { }
}

自定义类.cs

public class CustomClass : INotifyPropertyChanged
{
    private int number;
    private string text;
    public CustomClass()
    {
        this.number = new int();
        this.text = string.Empty;
    }
    public int Number
    {
        get
        {
            return this.number;
        }
        set
        {
            this.number = value;
            this.OnPropertyChanged();
        }
    }
    public string Text
    {
        get
        {
            return this.text;
        }
        set
        {
            this.text = value;
            this.OnPropertyChanged();
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged([System.Runtime.CompilerServices.CallerMemberName] string name = null)
    {
        PropertyChangedEventHandler handler = this.PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(name));
        }
    }
}

用户控件依赖项列表视图中的属性绑定

设置用户控件对用户控件实例的DataContext，如下所示

this.DataContext = this;

有效防止绑定到"外部"、继承的数据上下文，如预期的那样

<controls:CustomControl CustomObject="{Binding}"/>

作为一般规则，切勿显式设置用户控件的数据上下文。从用户控件的构造函数中删除上述行，并使用 RelativeSource 在用户控件的 XAML 中编写绑定：

<Run x:Name="numberRun" Text="{Binding CustomObject.Number,
    RelativeSource={RelativeSource AncestorType=UserControl}}"/>
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