取消订阅来自Protected Override Void的事件处理程序

Question

是否可以从受保护的override override void取消订阅事件处理程序？

protected override void OnViewLoaded(object sender, ViewLoadedEventArg e) 
    { 
     base.OnViewLoaded(sender, e); 
     list = VisualTreeUtil.FindFirstInTree<ListView>(Application.Current.MainWindow, "ListView"); 
     ConfigureAndSuperviseInputControls(this.list); 
     ScrollViewer scroll = VisualTreeUtil.FindFirstInTree<ScrollViewer>(this.list); 
     scroll.ScrollChanged+=new ScrollChangedEventHandler(scroll_ScrollChanged);  
    } 

    void scroll_ScrollChanged(object sender, ScrollChangedEventArgs e) 
    { 
     ConfigureAndSuperviseInputControls(this.list); 
     ScrollViewer sb = e.OriginalSource as ScrollViewer; 
     if (sb.ContentVerticalOffset==sb.ScrollableHeight) 
     { 
      scroll.ScrollChanged-=new ScrollChangedEventHandler(scroll_ScrollChanged); 
     } 
    } 

我的问题是，我没有得到访问scroll_ScrollChanged方法中的滚动obejct。

Answer 1

此代码未经测试，但你不能简单的铸件发送对象到ScrollViewer中，并从这样的事件退订：

protected override void OnViewLoaded(object sender, ViewLoadedEventArg e) 
    { 
     base.OnViewLoaded(sender, e); 
     list = VisualTreeUtil.FindFirstInTree<ListView>(Application.Current.MainWindow, "ListView"); 
     ConfigureAndSuperviseInputControls(this.list); 
     ScrollViewer scroll = VisualTreeUtil.FindFirstInTree<ScrollViewer>(this.list); 
     scroll.ScrollChanged+=new ScrollChangedEventHandler(scroll_ScrollChanged);  
    } 

    void scroll_ScrollChanged(object sender, ScrollChangedEventArgs e) 
    { 
     ConfigureAndSuperviseInputControls(this.list); 
     ScrollViewer scroll = (ScrollViewer)sender; 
     if (scroll.ContentVerticalOffset==scroll.ScrollableHeight) 
     { 
      scroll.ScrollChanged-=new ScrollChangedEventHandler(scroll_ScrollChanged); 
     } 
    } 

Answer 2

发件人应该是您需要的对象的引用。

protected override void OnViewLoaded(object sender, ViewLoadedEventArg e) 
    { 
     base.OnViewLoaded(sender, e); 
     list = VisualTreeUtil.FindFirstInTree<ListView>(Application.Current.MainWindow, "ListView"); 
     ConfigureAndSuperviseInputControls(this.list); 
     ScrollViewer scroll = VisualTreeUtil.FindFirstInTree<ScrollViewer>(this.list); 
     scroll.ScrollChanged+=new ScrollChangedEventHandler(scroll_ScrollChanged);  
    } 

    void scroll_ScrollChanged(object sender, ScrollChangedEventArgs e) 
    { 
     ConfigureAndSuperviseInputControls(this.list); 
     ScrollViewer sb = sender as ScrollViewer; 
     if (sb.ContentVerticalOffset==sb.ScrollableHeight) 
     { 
      scroll.ScrollChanged-=new ScrollChangedEventHandler(scroll_ScrollChanged); 
     } 
    }