UWP用户控件:绑定依赖项属性的集合更改事件

本文关键字：集合 事件 属性 控件 用户 绑定 依赖 UWP | 更新日期: 2023-09-27 18:12:01

当我调用Generate()时，与ObservableCollection (X)相关的事件没有被触发。

我做错了什么?

代码:

MyControl.xaml.cs 

 public ObservableCollection<double> X
    {
        get { return (ObservableCollection<double>)GetValue(XProperty); }
        set { SetValue(XProperty, value); }
    }
    public static readonly DependencyProperty XProperty =
        DependencyProperty.Register(
            "X", typeof(ObservableCollection<double>),
            typeof(MyControl), 
            new PropertyMetadata(
                new ObservableCollection<double>(),
                new PropertyChangedCallback(OnXChanged)));
   private static void OnXChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            var control = sender as MyControl;
            // DoSomething
        }

使用MyControl:

的XAML随机页面
 <local:MyControl
            Title="Test"
            X="{Binding TestX, Mode=TwoWay}"
            />

那页是。cs

   public sealed partial class MainPage : Page
    {
    public ObservableCollection<double> TestX { get; set; }
    private static Random rand_ = new Random();
    public MainPage()
    {
        this.InitializeComponent();
        TestX = new ObservableCollection<double>();
    }
    private void Generate()
        {
            TestX.Clear();
            for (int i = 0; i < 100; ++i)
            {
                TestX.Add(rand_.Next(1, 100));
            }
        }
   ....
 }

请注意，我在输出窗口中没有看到任何BindingExpression错误。

我注意到，如果在页面中这样做，它会工作:

TestX = new ObservableCollection<double>();
this.MyUserControlInstance.X = TestX;

UWP用户控件:绑定依赖项属性的集合更改事件

你错过了两件事:

:
确保在构造函数中设置了DataContext:

public MainPage()
{
    this.InitializeComponent();
    DataContext = this; // Important, but you should use a seperated ViewModel instead
    TestX = new ObservableCollection<double>();
}
第二:


您的类缺少INotifyPropertyChanged实现，以及TestX属性的PropertyChanged调用:

private ObservableCollection<double> _testX;
public ObservableCollection<double> TestX
{
    get { return _testX; }
    set
    {
        if (value == _testX) return;
        _testX = value;
        OnPropertyChanged();
    }
}
private void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
    var handler = PropertyChanged;
    if (handler != null)
        handler(this, new PropertyChangedEventArgs(propertyName));
}

旁注:做MVVM!

相关文章：