对于完全加载后新设置的 ContentControl 内容，不会触发 Loaded 事件

问：

我希望能够将 的属性绑定到 ViewModel 属性，以便当 ViewModel 更改其属性的值时，将根据 确定 ，并为新呈现的 View 触发事件（即根据 选择）。下面的代码示例演示了该问题，即更改时不会触发事件。ContentContentPresenterContentContentPresenterDataTemplateLoadedDataTemplateLoadedContent

据我了解，更改时不会触发事件，我对此感到满意。问题是新加载的上下文的事件不会被触发，但它仍然会被呈现出来。有什么方法可以实现这种行为吗？LoadedContentContentPresenterLoaded

主窗口

<Window x:Class="WpfLoadProblem.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfLoadProblem"
        Height="450"
        Title="MainWindow"
        Width="800">
    <Window.Resources>
        <DataTemplate DataType="{x:Type local:ContentViewModel}">
            <local:ContentUserControl/>
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="5"/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Button Command="{Binding Path=ChangeContentCommand}" Grid.Row="0">Change Content</Button>
        <ContentPresenter Content="{Binding Path=Content}" Grid.Row="2"/>
    </Grid>
</Window>

MainWindowView模型

internal sealed class MainWindowViewModel : INotifyPropertyChanged
{
    private object content;

    public MainWindowViewModel()
    {
        ChangeContentCommand = new DelegateCommand(ChangeContent);
    }

    public ICommand ChangeContentCommand { get; }

    public object Content
    {
        get => content;
        private set
        {
            if (content != value)
            {
                content = value;
                OnPropertyChanged(new PropertyChangedEventArgs(nameof(Content)));
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void ChangeContent()
    {
        // After setting this property Loaded event is not fired for the 2nd and consecutive times.
        Content = new ContentViewModel();
    }

    private void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        PropertyChanged?.Invoke(this, e);
    }
}

ContentUserControl

<UserControl x:Class="WpfLoadProblem.ContentUserControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:i="clr-namespace:Microsoft.Xaml.Behaviors;assembly=Microsoft.Xaml.Behaviors">
    <i:Interaction.Triggers>
        <i:EventTrigger x:Name="Loaded">
            <i:InvokeCommandAction Command="{Binding Path=LoadedCommand}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
    <ListBox ItemsSource="{Binding Path=Numbers}"/>
</UserControl>

ContentView模型

internal sealed class ContentViewModel
{
    private readonly ICollection<int> numbers = new ObservableCollection<int>();

    public ContentViewModel()
    {
        LoadedCommand = new DelegateCommand(Load);
    }

    public ICommand LoadedCommand { get; }

    public IEnumerable<int> Numbers => numbers;

    private void Load()
    {
        int start = numbers.Count == 0 ? 0 : numbers.Max();

        numbers.Clear();

        for (int number = start; number < start + 5; ++number)
        {
            numbers.Add(number);
        }
    }
}