設置經由ContentPresenter

加載的用戶控件

我在我的MAINVIEW以下代碼（窗口）設置經由ContentPresenter

<StackPanel> 
    <Button Click="OnLoadChildView">Load</Button> 
    <Button Click="OnUnloadChildView">UnLoad</Button> 
    <ContentPresenter Content="{Binding ChildViewModel}"/> 
</StackPanel>

和這個代碼在我ChildView（用戶控件）

<StackPanel> 
    <local:MyListBox ItemsSource="{Binding Items}"> 
    </local:MyListBox> 
</StackPanel>

這是的MainView的代碼

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(); 
}

，在這裏我的其他代碼：

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)); 
      } 
     } 
    } 
}

我使用的應用程序資源ADRESS的觀點：

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

當我啓動應用程序，然後單擊Load按鈕，然後卸載按鈕幾次我得到這樣的輸出：

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

當我改變ChildView的XAML到：

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

所以祛瘀荷蘭國際集團的結合，重新開始我的了的應用程式上，單擊Load按鈕，然後卸載按鈕幾次我得到這個：

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

這樣看來，我不能真的無法擺脫WPF的NotifyPropertyChangedEventHandler，所以我的列表框和我的視圖不會被丟棄。我怎樣才能做到這一點？因爲我認爲它已經清除，所以刪除綁定不是一種選擇。

來源

2015-08-28 Tobias Krasinger

你可以顯示'ViewModelBase'類代碼嗎？ –

多數民衆贊成Galasoft.MvvmLight命名空間 –

嗯，恐怕我沒有那個'Galasoft'的東西（不管它是什麼）。爲了實現您的目標，您需要訪問PropertyChanged事件定義的類。 –

好的我正在關閉它，因爲實際上清理是以正確的方式構建的，但似乎GarbageCollector真的花了一些時間來考慮清理win8.1機器上的事情。在卸載按鈕上單擊10-15次後，將進行清理。在win7機器上，清理總是在第二次點擊時發生。

來源

2015-08-31 07:30:17

設置經由ContentPresenter

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