C# 处理通过ContentPresenter加载的UserControl

我的主视图（窗口）上有以下代码

这是我的另一个代码：

public class MyListBox : ListBox
{
    public MyListBox() { Debug.WriteLine("Created instance of MyListBox:" + this.GetHashCode()); }
    ~MyListBox() { Debug.WriteLine("destroyed instance of MyListBox:" + this.GetHashCode()); }
}

public class ViewModelBase : INotifyPropertyChanged
{
    private PropertyChangedEventHandler _propertyChanged;

    public event PropertyChangedEventHandler PropertyChanged
    {
        add
        {
            _propertyChanged += value;
        }
        remove
        {
            _propertyChanged -= value;
        }
    }

    protected virtual void OnPropertyChanged(string property)
    {
        if (_propertyChanged != null)
        {
            _propertyChanged(this, new PropertyChangedEventArgs(property));
        }
    }
}

public class MainViewModel : ViewModelBase
{
    private ChildViewModel _ChildViewModel;
    public ChildViewModel ChildViewModel
    {
        get { return _ChildViewModel; }
        set
        {
            if (_ChildViewModel != value)
            {
                _ChildViewModel = value;
                OnPropertyChanged(nameof(ChildViewModel));
            }
        }
    }
}

public class ChildViewModel : ViewModelBase
{
    public ChildViewModel()
    {
        Debug.WriteLine("Created instance of ChildViewModel:" + this.GetHashCode());
        this.Items = new List<string>(new string[] { "ABC", "DEF" });
    }

    ~ChildViewModel()
    {
        this.Items = null;
        Debug.WriteLine("destroyed instance of ChildViewModel:" + this.GetHashCode());
    }

    private IEnumerable<string> _Items;
    public IEnumerable<string> Items
    {
        get { return _Items; }
        set
        {
            if (_Items != value)
            {
                _Items = value;
                OnPropertyChanged(nameof(Items));
            }
        }
    }
}

当我将ChildView的XAML更改为：

   <StackPanel>
        <local:MyListBox>
        </local:MyListBox>
    </StackPanel>

---

所以，似乎我真的无法摆脱WPF的NotifyPropertyChangedEventHandler，所以我的列表框和视图将无法处理。我怎样才能做到这一点？因为我认为它正在清除，所以删除绑定不是一个选项。

好的，我结束这个，因为实际上清除是以正确的方式构建的，但是垃圾收集器似乎真的花了一些时间来考虑清理win8.1机器上的东西。在“卸载”按钮上单击大约10-15次后，将进行清理。在win7机器上，清理总是在第二次单击时进行。

您能显示

ViewModelBase

类代码吗？这是Galasoft.MvvmLight名称空间中的代码。很抱歉，我没有那种

Galasoft

东西（不管是什么）。为了实现您的目标，您需要访问定义PropertyChanged事件的类。我将其更改为使用自己的ViewModelBase，正如预期的那样，它不会更改任何内容。很抱歉，我被误导，认为问题是由NotifyPropertyChangedEventHandler引起的，但事实并非如此。执行卸载代码时，

ContentPresenter.Content

属性将被清除，但

ContentPresenter.DataContext

不会被清除（至少不会立即清除-稍后在用户代码之外发生）

public MainView()
{
    InitializeComponent();

    MainViewModel vm = new MainViewModel();
    this.DataContext = vm;
}

public MainViewModel Model { get { return this.DataContext as MainViewModel; } }

private void OnLoadChildView(object sender, System.Windows.RoutedEventArgs e)
{
    this.Model.ChildViewModel = new ChildViewModel();
}

private void OnUnloadChildView(object sender, System.Windows.RoutedEventArgs e)
{
    this.Model.ChildViewModel = null;
    GC.Collect();
    GC.WaitForPendingFinalizers();
    GC.Collect();
}

public class MyListBox : ListBox
{
    public MyListBox() { Debug.WriteLine("Created instance of MyListBox:" + this.GetHashCode()); }
    ~MyListBox() { Debug.WriteLine("destroyed instance of MyListBox:" + this.GetHashCode()); }
}

public class ViewModelBase : INotifyPropertyChanged
{
    private PropertyChangedEventHandler _propertyChanged;

    public event PropertyChangedEventHandler PropertyChanged
    {
        add
        {
            _propertyChanged += value;
        }
        remove
        {
            _propertyChanged -= value;
        }
    }

    protected virtual void OnPropertyChanged(string property)
    {
        if (_propertyChanged != null)
        {
            _propertyChanged(this, new PropertyChangedEventArgs(property));
        }
    }
}

public class MainViewModel : ViewModelBase
{
    private ChildViewModel _ChildViewModel;
    public ChildViewModel ChildViewModel
    {
        get { return _ChildViewModel; }
        set
        {
            if (_ChildViewModel != value)
            {
                _ChildViewModel = value;
                OnPropertyChanged(nameof(ChildViewModel));
            }
        }
    }
}

public class ChildViewModel : ViewModelBase
{
    public ChildViewModel()
    {
        Debug.WriteLine("Created instance of ChildViewModel:" + this.GetHashCode());
        this.Items = new List<string>(new string[] { "ABC", "DEF" });
    }

    ~ChildViewModel()
    {
        this.Items = null;
        Debug.WriteLine("destroyed instance of ChildViewModel:" + this.GetHashCode());
    }

    private IEnumerable<string> _Items;
    public IEnumerable<string> Items
    {
        get { return _Items; }
        set
        {
            if (_Items != value)
            {
                _Items = value;
                OnPropertyChanged(nameof(Items));
            }
        }
    }
}

 <Application.Resources>
        <DataTemplate DataType="{x:Type vm:ChildViewModel}">
            <vw:ChildView/>
        </DataTemplate>
    </Application.Resources>

Created instance of ChildViewModel:2670961
Created instance of ChildView:2080614
Created instance of MyListBox:33397791
destroyed instance of ChildViewModel:2670961

   <StackPanel>
        <local:MyListBox>
        </local:MyListBox>
    </StackPanel>

Created instance of ChildViewModel:30767036
Created instance of ChildView:50297887
Created instance of MyListBox:5453341
destroyed instance of MyListBox:5453341
destroyed instance of ChildViewModel:30767036
Destroyed instance of ChildView:50297887