How can I implement drag-and-drop to allow rearranging items in a ListView?

Question

I would like to enable support for drag-and-drop in a ListView so that the user can rearrange the items, similar to what they can do in Windows Explorer.

Specifically, how do I enable the Drag event handler when I double-click on the ListView?

This is what I get after double-clicking on the ListView:

private void listView1(object sender, EventArgs e)

However, I want it to be:

private void listView(object sender, DragEventArgs e)

How can I do this?

I have tried many ways, such as:

  private void Form_Load(object sender, EventArgs e)
  {
      // Enable drag and drop for this form
      // (this can also be applied to any controls)
      this.AllowDrop = true;

      // Add event handlers for the drag & drop functionality
      this.DragEnter += new DragEventHandler(Form_DragEnter);
      this.DragDrop += new DragEventHandler(Form_DragDrop);
 }

But none of these seem to work.

Answer 1

You need to implement the DragEnter event and set the Effect property of the DragEventArgs. The DragEnter event is what allows things to be dropped into a control. After that the DragDrop event will fire when the mouse button is released.

Here is a version that will allow objects to be dropped into the a ListView:

    private void Form1_Load(object sender, EventArgs e)
    {
        listView1.AllowDrop = true;
        listView1.DragDrop += new DragEventHandler(listView1_DragDrop);
        listView1.DragEnter += new DragEventHandler(listView1_DragEnter);
    }

    void listView1_DragEnter(object sender, DragEventArgs e)
    {
        e.Effect = DragDropEffects.Copy;
    }

    void listView1_DragDrop(object sender, DragEventArgs e)
    {
        listView1.Items.Add(e.Data.ToString());
    }

No doubt your sample code was taken from : http://msdn.microsoft.com/en-us/library/system.windows.forms.control.allowdrop(v=vs.71).aspx

Answer 2

To answer your question: There is no built in functionality for dragging and dropping items within a ListView control. Even the MSDN documentation instructs you to implement your own code-behind for the various events in order to achieve this functionality (see the ListViewInsertionMark Class )

Answer 3

ObjectListView (an open source wrapper around .NET WinForms ListView) provides this ability without further work (plus lots of other nice features ). Have a look at the "Drag and Drop" tab of the demo.

_{(source: codeproject.com )}