In this tutorial, I will show you how to drag/drop and copy in a Treeview by using Visual Basic 2008. I made this to show you not only a PictureBox or a TextBox can be drag and drop but also a treeview.

Let’s begin:

Open Visual Basic 2008, create a new Windows Application and drag the two Treeview in the Form. Name it “trview_left” and “trview_right”.



After that, click the two Treeviews and go to the properties. In the properties, click the events that look like a lightning symbol and double click the Drag/Drop

event handler. And do this following code.

Declare this constant variable above the sub procedure.

1. 
   
2. 'DECLARE A CONSTANT VARIABLE
   
3. 'IT IS USED FOR DETECTING THE CTRL KEY WHETHER THE CTRL KEY WAS PRESSED OR NOT DURING THE DRAG OPERATION
   
4. Const
   
   mask_ctrl As
   
   Int32 =
   
   8
   

1. Private
   
   Sub
   
   TreeView_DragDrop(
   
   ByVal
   
   sender As
   
   System.
   
   Object
   
   , ByVal
   
   e As
   
   System.
   
   Windows
   
   .
   
   Forms
   
   .
   
   DragEventArgs
   
   )
   
   Handles
   
   trview_left.
   
   DragDrop
   
   , trview_right.
   
   DragDrop
   
2. 
   
3. 'SET A VARIABLE TO HOLDS THE NODE TO BE DRAGGED
   
4. Dim
   
   nodeorigination As
   
   TreeNode =
   
   CType
   
   (
   
   e.
   
   Data
   
   .
   
   GetData
   
   (
   
   "System.Windows.Forms.TreeNode"
   
   )
   
   , TreeNode)
   
5. 
   
6. 'GETDATAPRESENT IS A BIT DIFFERENT FROM A TREEVIEW AND PICTUREBOX CONTROL.
   
7. 'THE TREENODE IS NOT INCLUDED IN THE DATAFORMATS CLASS. THAT'S WHY IT'S NOT A PREDEFINED TYPE
   
8. 'ONE OF THE GETDATAPRESENT CONTAINS A STRING THAT SPECIFY THE TYPE.
   
9. If
   
   e.
   
   Data
   
   .
   
   GetDataPresent
   
   (
   
   "System.Windows.Forms.TreeNode"
   
   , False
   
   )
   
   Then
   
10. Dim
    
    pnt As
    
    Point
    
11. Dim
    
    distination_node As
    
    TreeNode
    
12. 
    
13. 'POINTTOCLIENT IS USED TO COMPUTE THE LOCATION OF THE MOUSE OVER THE DESTINATION TREEVIEW
    
14. pnt =
    
    CType
    
    (
    
    sender, TreeView)
    
    .
    
    PointToClient
    
    (
    
    New
    
    Point(
    
    e.
    
    X
    
    , e.
    
    Y
    
    )
    
    )
    
15. 'POINT IS USED TO GET THE CLOSEST NODE IN THE DESTINATION TREEVIEW
    
16. distination_node =
    
    CType
    
    (
    
    sender, TreeView)
    
    .
    
    GetNodeAt
    
    (
    
    pnt)
    
17. 
    
18. 'IF THE NEW NODE WAS NOT DROPPED DIRECTLY AT THE TOP OF THE NODE,
    
19. 'THEN THE RESULT OF THE DESTINATIONNODE WILL BE NOTHING
    
20. If
    
    distination_node IsNot
    
    Nothing
    
    Then
    
21. 'IF THE ORIGINAL NODE AND DISTINATION NODE ARE THE SAME, THE THE NODE WOULD DISAPPEAR.
    
22. 'THIS CODE INSURES THAT IT WILL NOT HAPPEN.
    
23. If
    
    Not
    
    distination_node.
    
    TreeView
    
    Is
    
    nodeorigination.
    
    TreeView
    
    Then
    
24. distination_node.
    
    Nodes
    
    .
    
    Add
    
    (
    
    CType
    
    (
    
    nodeorigination.
    
    Clone
    
    , TreeNode)
    
    )
    
25. 'EMPHASIZE PARENT NOT WHEN ADDING THE NEW NODE, WITHOUT THIS , ONLY THE a+ SYMBOL WILL APPEAR.
    
26. distination_node.
    
    Expand
    
    (
    
    )
    
27. 
    
28. If
    
    (
    
    e.
    
    KeyState
    
    And
    
    maskctrl)
    
    <>
    
    maskctrl Then
    
    'CHECKING THE CTRL KEY WAS NOT PRESSED
    
29. nodeorigination.
    
    Remove
    
    (
    
    )
    
    'REMOVE THE NODE
    
30. End
    
    If
    
31. End
    
    If
    
32. End
    
    If
    
33. End
    
    If
    
34. End
    
    Sub
    

Then, click the method name and choose the Drag/Enter

events handler, and do this following code.

1. Private
   
   Sub
   
   TreeView_DragEnter(
   
   ByVal
   
   sender As
   
   System.
   
   Object
   
   , ByVal
   
   e As
   
   System.
   
   Windows
   
   .
   
   Forms
   
   .
   
   DragEventArgs
   
   )
   
   Handles
   
   trview_left.
   
   DragEnter
   
   , trview_right.
   
   DragEnter
   
2. 
   
3. If
   
   (
   
   e.
   
   Data
   
   .
   
   GetDataPresent
   
   (
   
   "System.Windows.Forms.TreeNode"
   
   )
   
   )
   
   Then
   
   'CHECKING THE DRAG CONTENT TO BE SURE THAT IT IS THE CORRECT TYPE.
   
4. 
   
5. If
   
   (
   
   e.
   
   KeyState
   
   And
   
   maskctrl)
   
   =
   
   maskctrl Then
   
   'CHECKINKG IF THE CTRL KEY WAS PRESSED.
   
6. 'IF IT WAS PRESSED
   
7. e.
   
   Effect
   
   =
   
   DragDropEffects.
   
   Copy
   
   'PERFORM COPY
   
8. Else
   
9. 'IF IT WAS NOT PRESSED
   
10. e.
    
    Effect
    
    =
    
    DragDropEffects.
    
    Move
    
    'PERFORM A MOVE
    
11. End
    
    If
    
12. Else
    
13. 'REJECT THE DROP
    
14. e.
    
    Effect
    
    =
    
    DragDropEffects.
    
    None
    
15. End
    
    If
    
16. End
    
    Sub
    

Go back to the method name again and choose the Item/Drag

event handler and do this following code.

1. Private
   
   Sub
   
   TreeView_ItemDrag(
   
   ByVal
   
   sender As
   
   System.
   
   Object
   
   , ByVal
   
   e As
   
   System.
   
   Windows
   
   .
   
   Forms
   
   .
   
   ItemDragEventArgs
   
   )
   
   Handles
   
   trview_left.
   
   ItemDrag
   
   , trview_right.
   
   ItemDrag
   
2. If
   
   e.
   
   Button
   
   =
   
   Windows.
   
   Forms
   
   .
   
   MouseButtons
   
   .
   
   Left
   
   Then
   
3. 'PERFORM THE DRAG AND DROP OPERATION.
   
4. DoDragDrop(
   
   e.
   
   Item
   
   , DragDropEffects.
   
   Move
   
   Or
   
   DragDropEffects.
   
   Copy
   
   )
   
5. End
   
   If
   
6. End
   
   Sub
   

You can download the complete source code.

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