private void MyScrollViewer_PreviewMouseWheel(object sender, System.Windows.Input.MouseWheelEventArgs e)
        {
            ScrollViewer scrollViewer = sender as ScrollViewer;
            if (e.Delta > 0)
            {                
                    scrollViewer.LineUp();
                    if (scrollViewer.VerticalOffset == 0)
                        // Top end reached                
            }
            else
            {
                    scrollViewer.LineDown();
                    if (scrollViewer.VerticalOffset == scrollViewer.ScrollableHeight)
                        // Bottom end reached                
            }
        }

创建一个Behavior或Attached Property来侦听ScrollViewer：：ScrollChanged事件、检查VerticalOffset并调用ViewModel上的方法/命令，怎么样？例如ScrollViewerHelper。ScrolledToTopCommand="{Binding ScrolledToTop}”