LISTVIEW WITH RE-ORDERING THROUGH DRAG AND DROP

1. using System.Drawing;
2. using System.Windows.Forms;
4. namespace System.Windows.Forms // May need to set to something else
5. {
6. ///
7. /// A ListView with DragDrop reordering.
8. ///
9. ///
10. public class ListViewWithReordering : ListView
11. {
12. protected override void OnItemDrag(ItemDragEventArgs e)
13. {
14. base.OnItemDrag(e);
15. //Begins a drag-and-drop operation in the ListView control.
16. this.DoDragDrop(this.SelectedItems, DragDropEffects.Move);
17. }
19. protected override void OnDragEnter(DragEventArgs drgevent)
20. {
21. base.OnDragEnter(drgevent);
22. int len = drgevent.Data.GetFormats().Length - 1;
23. int i;
24. for (i = 0; i <= len; i++)
25. {
26. if (drgevent.Data.GetFormats()[i].Equals("System.Windows.Forms.ListView+SelectedListViewItemCollection"))
27. {
28. //The data from the drag source is moved to the target.
29. drgevent.Effect = DragDropEffects.Move;
30. }
31. }
33. }
35. protected override void OnDragDrop(DragEventArgs drgevent)
36. {
37. base.OnDragDrop(drgevent);
38. //Return if the items are not selected in the ListView control.
39. if (this.SelectedItems.Count == 0)
40. {
41. return;
42. }
43. //Returns the location of the mouse pointer in the ListView control.
44. Point cp = this.PointToClient(new Point(drgevent.X, drgevent.Y));
45. //Obtain the item that is located at the specified location of the mouse pointer.
46. ListViewItem dragToItem = this.GetItemAt(cp.X, cp.Y);
47. if (dragToItem == null)
48. {
49. return;
50. }
51. //Obtain the index of the item at the mouse pointer.
52. int dragIndex = dragToItem.Index;
53. ListViewItem[] sel = new ListViewItem[this.SelectedItems.Count];
54. for (int i = 0; i <= this.SelectedItems.Count - 1; i++)
55. {
56. sel[i] = this.SelectedItems[i];
57. }
58. for (int i = 0; i < sel.GetLength(0); i++)
59. {
60. //Obtain the ListViewItem to be dragged to the target location.
61. ListViewItem dragItem = sel[i];
62. int itemIndex = dragIndex;
63. if (itemIndex == dragItem.Index)
64. {
65. return;
66. }
67. if (dragItem.Index < itemIndex)
68. itemIndex++;
69. else
70. itemIndex = dragIndex + i;
71. //Insert the item at the mouse pointer.
72. ListViewItem insertItem = (ListViewItem)dragItem.Clone();
73. this.Items.Insert(itemIndex, insertItem);
74. //Removes the item from the initial location while
75. //the item is moved to the new location.
76. this.Items.Remove(dragItem);
77. }
78. }
79. }
80. }