UWP用戶控件：綁定依賴項屬性的集合更改事件

Question

當我調用Generate() ，不會觸發與ObservableCollection（ X ）相關的事件。

我究竟做錯了什么？

編碼：

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隨機頁面：

 <local:MyControl
            Title="Test"
            X="{Binding TestX, Mode=TwoWay}"
            />

該頁面的.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));
            }
        }
   ....
 }

請注意，我在輸出窗口中沒有看到任何BindingExpression錯誤。

更新

我注意到，如果在頁面中這樣做，它會起作用：

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

Answer 1

您在這里缺少兩件事：

第一：
確保在構造函數中設置DataContext ：

public MainPage()
{
    this.InitializeComponent();

    DataContext = this; // Important, but you should use a seperated ViewModel instead

    TestX = new ObservableCollection<double>();
} 

第二：
您的類缺少INotifyPropertyChanged實現，以及TestX屬性的PropertyChanged調用：

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！