列表框拖放项目以移动到同一列表框中的不同位置 [英] Listbox drag and drop items to move to different locations in the same listbox

问题描述

我试图弄清楚如何使用拖放事件来切换列表框项目的顺序。每当我尝试使用我的代码时，它会不断给我一个圆圈，并在其中划一条线。无论我做什么，我都无法让他们移动。

I am trying to figure out how to use the drag and drop event to switch the order of the listbox items. every time I try to use my code it keeps giving me a circle with a line through it. no matter what I do I cant get them to move.

Private Sub ListBox1_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles ListBox1.MouseDown

       Dim index As Integer = ListBox1.IndexFromPoint(e.X, e.Y)
       Dim s As String = ListBox1.Items(index).ToString()
       Dim dde1 As DragDropEffects = DoDragDrop(s, DragDropEffects.Move)

       If dde1 = DragDropEffects.All Then
           ListBox1.Items.RemoveAt(ListBox1.IndexFromPoint(e.X, e.Y))
       End If


   End Sub
   Private Sub ListBox1_DragOver(sender As Object, e As System.Windows.Forms.DragEventArgs) Handles ListBox1.DragEnter

       e.Effect = DragDropEffects.All
   End Sub

   Private Sub ListBox1_DragDrop(sender As Object, e As System.Windows.Forms.DragEventArgs) Handles ListBox1.DragDrop


       If e.Data.GetDataPresent(DataFormats.Text) Then
           e.Effect = DragDropEffects.Move
           ListBox1.SelectedIndex = ListBox1.IndexFromPoint(ListBox1.PointToClient(New Point(e.X, e.Y)))
       End If
       Dim str As String = DirectCast(e.Data.GetData(DataFormats.StringFormat), String)
       ListBox1.Items.Insert(ListBox1.SelectedIndex, str)


   End Sub

< br $> b $ b

我尝试了什么：



已更改。移至.copy但是我仍然通过它获得相同的圆圈。

What I have tried:

changed .move to .copy but I still get the same circle with the line through it.

推荐答案

我建​​议阅读：在Visual Basic .NET中实现拖放 [ ^ ]



至于你的代码...

在 ListBox1_DragDrop 程序中你必须添加这一行：

I'd suggest to read this: Implementing Drag and Drop in Visual Basic .NET[^]

As to your code...
Inside ListBox1_DragDrop procedure you have to add this line:

Dim myitem = DataFormats.Text
ListBox1.Items.Add(mtitem)

上面的代码可让你复制项目。现在，您必须提供代码来移除已移动的项目。

Above code enable you to copy item. Now, you have to provide code to remove item, which have ben moved.

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