June 9, 2014 by Nitesh

How To Perform Drag-Drop Operations on TreeView Control in Windows Forms

Friends,

Drag/Drop functionality is a ease to end user in each and every technology and almost every user is comfortable using the drag-drop feature. In this post we will see how to perform drag and drop operation of nodes in a single TreeView control. There are few events that we will be working with. They are – ItemDrag(), DragEnter() and DragDrop(). Apart from these, we will also use some inbuilt functions that facilitate drag/drop operations on Windows forms. So, Let’s get started. To create a draggable/drop-ableĀ  Treeview control on windows forms, we will use the steps mentioned below –

  • Set the AllowDrop property of TreeView control to True.
  • Populate the TreeView with some nodes. I am here filling the nodes with some sample data.
         private function LoadData()
         {
                for (int i = 0; i < 5; i++)
                {
                    TreeNode node = new TreeNode("Node " + i);
                    for (int j = 0; j < 3; j++)
                    {
                        TreeNode n1 = new TreeNode("Sub-node :" + i + " - " + j);
                        node.Nodes.Add(n1);
                    }
                    treeView1.Nodes.Add(node);
                }
         }
    
  • Handle the ItemDrag() event handler of the TreeView and write the code below-
         private void treeView1_ItemDrag(object sender, ItemDragEventArgs e)
         {
               DoDragDrop(e.Item, DragDropEffects.Move);
         }
    
  • Handle the DragEnter() event handler of the TreeView and write the code below-
         private void treeView1_DragEnter(object sender, ItemDragEventArgs e)
         {
               e.Effect = DragDropEffects.Move;
         }
    
  • Handle the DragDrop() event handler of the TreeView and write the code below-
         private void treeView1_DragDrop(object sender, ItemDragEventArgs e)
         {
                TreeNode NewNode;
    
                if (e.Data.GetDataPresent("System.Windows.Forms.TreeNode", false))
                {
                    Point pt = ((TreeView)sender).PointToClient(new Point(e.X, e.Y));
                    TreeNode DestinationNode = ((TreeView)sender).GetNodeAt(pt);
                    NewNode = (TreeNode)e.Data.GetData("System.Windows.Forms.TreeNode");
                    DestinationNode.Nodes.Add((TreeNode)NewNode.Clone());
                    DestinationNode.Expand();
                    //Remove Original Node
                    NewNode.Remove();
                }
         }
    
  • You’re done.
  • Execute the application and try dragging/dropping the nodes on the TreeView control.

Keep learning and sharing! Cheers!

#.Net#C##TreeView#Winforms

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