如何正確使用Data.GetData（）父類

Question

我目前試圖實現拖放我的列表框。我需要處理被拖動的元素。

每個拖動對象中的一個繼承卡利科技的屏幕和我的BaseViewModel

例如

BaseViewModel : Screen 

ListBoxItem1 DataContext = PersonViewModel : BaseViewModel 
ListBoxItem2 DataContext = BusinessViewModel : BaseViewModel 

private void ListBoxItem_DropEvent(object sender, DragEventArgs e) 
{ 
    if (sender is ListBoxItem) 
    { 
     var source = e.Data.GetData(typeof(PersonViewModel)) as PersonViewModel ; 
     var target = ((ListBoxItem)(sender)).DataContext as BusinessViewModel; 

     int sourceIndex = Items.Items.IndexOf(source); 
     int targetIndex = Items.Items.IndexOf(target); 

     Move(source, sourceIndex, targetIndex); 
    } 
} 

所以，我目前所面對的問題是，我不希望指定PersonViewModel/BusinessViewModel我試圖通過typeof使用繼承值希望BaseViewModel或屏幕。我可以得到一些提示或建議

我試過下面的解決方案，但他們返回空。

var test = e.Data.GetData(typeof(BaseViewModel)) as BaseViewModel; 
var test1 = e.Data.GetData(typeof(Screen)) as Screen; 

上鼠標事件

private void PreviewMouseMove(object sender, MouseEventArgs e) 
{ 
    Point point = e.GetPosition(null); 
    Vector diff = _dragStartPoint - point; 
    if (e.LeftButton == MouseButtonState.Pressed && 
     (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance || 
      Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance)) 
    { 
     var lb = sender as ListBox; 
     var lbi = FindVisualParent<ListBoxItem>(((DependencyObject)e.OriginalSource)); 
     if (lbi != null) 
     { 
      DragDrop.DoDragDrop(lbi, lbi.DataContext, DragDropEffects.Move); 
     } 
    } 
} 

Answer 1

試試這個：

var test = e.Data.GetData(e.Data.GetFormats()[0]) as BaseViewModel;