Question

As the title really – I have some code for reordering some thumbnails in a ListView (‘LargeIcon’ view format), and it works great when dragging an image to the right (i.e. a greater index). But when dragging to the left it doesn’t work at all.

Any ideas?

  private void lstImages_ItemDrag(object sender, ItemDragEventArgs e)
    {
        lstImages.DoDragDrop(lstImages.SelectedItems, DragDropEffects.Move);
    }

    private void lstImages_DragEnter(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(typeof(ListView.SelectedListViewItemCollection)))
        {
            e.Effect = DragDropEffects.Move;
        }
    }

    private void lstImages_DragDrop(object sender, DragEventArgs e)
    {
        if (lstImages.SelectedItems.Count == 0) return;

        Point p = lstImages.PointToClient(new Point(e.X, e.Y));
        ListViewItem dragToItem = lstImages.GetItemAt(p.X, p.Y);

        if (dragToItem == null) return;

        int dragIndex = dragToItem.Index;

        ListViewItem dataItem = (e.Data.GetData(typeof(ListView.SelectedListViewItemCollection)) as ListView.SelectedListViewItemCollection)[0];
        int itemIndex = dragIndex;
        if (itemIndex == dataItem.Index) return;

        itemIndex = itemIndex + 1;

        ListViewItem insertItem = (ListViewItem)dataItem.Clone();
        lstImages.Items.Insert(itemIndex, insertItem);
        lstImages.Items.Remove(dataItem);
    }

Answer 1

I modified your code a little bit and it works now. (Just the _DragDrop part). There seems to be a bug and it can be fixed by changing the alignment during Drag & Drop.

  listView1.Alignment = ListViewAlignment.Default;
  if (listView1.SelectedItems.Count == 0)
    return;
  Point p = listView1.PointToClient(new Point(e.X, e.Y));
  ListViewItem MovetoNewPosition = listView1.GetItemAt(p.X, p.Y);
  if (MovetoNewPosition == null) return;
  ListViewItem DropToNewPosition = (e.Data.GetData(typeof(ListView.SelectedListViewItemCollection)) as ListView.SelectedListViewItemCollection)[0];
  ListViewItem CloneToNew = (ListViewItem)DropToNewPosition.Clone();
  int index = MovetoNewPosition.Index;
  listView1.Items.Remove(DropToNewPosition);
  listView1.Items.Insert(index, CloneToNew);
  listView1.Alignment = ListViewAlignment.SnapToGrid;