c# - 滚动时防止拖放

Question

我正在处理一个 Wpf 项目，但现在我遇到了 ListView 问题。

原来我在 ListView 上实现了一个Drag&Drop 功能，效果很好。当我尝试向下或向上滚动时出现问题。通过这样做，拖放 功能被激活，阻止我继续滚动。

我找到了 this solution这表明我们需要将控件附加到 ScrollChanged 事件。

<ListView ScrollViewer.ScrollChanged="listView1_ScrollChanged"...

但我真的不知道在该处理程序中该做什么。 如何禁用该事件的拖放功能？我怎样才能再次启用它？或者，有没有更好的方法来解决这个问题？？

这是我的拖放代码:

 private void listView1_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        // Store the mouse position
        startPoint = e.GetPosition(null);
    }

    private void listView1_MouseMove(object sender, MouseEventArgs e)
    {
        // Get the current mouse position
        Point mousePos = e.GetPosition(null);
        Vector diff = startPoint - mousePos;

        if (e.LeftButton == MouseButtonState.Pressed &&
            (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
            Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance))
        {
            // Get the dragged ListViewItem
            ListView listView = sender as ListView;

            // Get items to drag
            var a = listView.SelectedItems;

            // Initialize the drag & drop operation
            DataObject dragData = new DataObject("myFormat", a);
            DragDrop.DoDragDrop(listView, dragData, DragDropEffects.Move);
        } 
    }

提前致谢。

Answer 1

如果您不在 MouseDown 事件中，您可以阻止 MouseMove 事件:

bool stopDrag = true;
     private void listView1_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            // Store the mouse position
            startPoint = e.GetPosition(null);
stopDrag = false;
        }

        private void listView1_MouseMove(object sender, MouseEventArgs e)
        {
if(stopDrag)
   return;

            // Get the current mouse position
            Point mousePos = e.GetPosition(null);
            Vector diff = startPoint - mousePos;

            if (e.LeftButton == MouseButtonState.Pressed &&
                (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
                Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance))
            {
                // Get the dragged ListViewItem
                ListView listView = sender as ListView;

                // Get items to drag
                var a = listView.SelectedItems;

                // Initialize the drag & drop operation
                DataObject dragData = new DataObject("myFormat", a);
                DragDrop.DoDragDrop(listView, dragData, DragDropEffects.Move);
            } 
        }

private void listView1_MouseUp(...)
{
stopDrag = true;
}

这应该可行，我是在浏览器中编写的，所以如果我做错了什么请原谅，关于格式，我希望你明白了。