Question

I have a winform with a listbox and a treeview.

Once my listbox is filled with items, I want to drag them (multiple or single) from the listbox and drop them in a node in the treeview.

If somebody has a good example in C# that would be great.

Answer 1

It’s been a while since I’ve messed with Drag/Drop so I figured I’ll write a quick sample.

Basically, I have a form, with a listbox on the left, and a treeview on the right. Then I put a button on top. When the button is clicked, it just puts the date of the next ten days into the list box. It also populates the TreeView with 2 parents nodes and two child nodes. Then, you just have to handle all the subsequent drag/drop events to make it work.

 public partial class Form1 : Form     {         public Form1()         {             InitializeComponent();             this.treeView1.AllowDrop = true;             this.listBox1.AllowDrop = true;             this.listBox1.MouseDown += new MouseEventHandler(listBox1_MouseDown);             this.listBox1.DragOver += new DragEventHandler(listBox1_DragOver);              this.treeView1.DragEnter += new DragEventHandler(treeView1_DragEnter);             this.treeView1.DragDrop += new DragEventHandler(treeView1_DragDrop);          }          private void button1_Click(object sender, EventArgs e)         {             this.PopulateListBox();             this.PopulateTreeView();         }          private void PopulateListBox()         {             for (int i = 0; i <= 10; i++)             {                 this.listBox1.Items.Add(DateTime.Now.AddDays(i));             }         }          private void PopulateTreeView()         {             for (int i = 1; i <= 2; i++)             {                 TreeNode node = new TreeNode('Node' + i);                 for (int j = 1; j <= 2; j++)                 {                     node.Nodes.Add('SubNode' + j);                 }                 this.treeView1.Nodes.Add(node);             }         }          private void treeView1_DragDrop(object sender, DragEventArgs e)         {              TreeNode nodeToDropIn = this.treeView1.GetNodeAt(this.treeView1.PointToClient(new Point(e.X, e.Y)));             if (nodeToDropIn == null) { return; }             if(nodeToDropIn.Level > 0)             {                 nodeToDropIn = nodeToDropIn.Parent;             }              object data = e.Data.GetData(typeof(DateTime));             if (data == null) { return; }             nodeToDropIn.Nodes.Add(data.ToString());             this.listBox1.Items.Remove(data);         }          private void listBox1_DragOver(object sender, DragEventArgs e)         {             e.Effect = DragDropEffects.Move;         }          private void treeView1_DragEnter(object sender, DragEventArgs e)         {             e.Effect = DragDropEffects.Move;         }          private void listBox1_MouseDown(object sender, MouseEventArgs e)         {             this.listBox1.DoDragDrop(this.listBox1.SelectedItem, DragDropEffects.Move);         }       }