//
// Item Drag event handler
//
protected override void OnItemDrag(ItemDragEventArgs e)
{
base.OnItemDrag(e);
base.OnItemDrag(e);
_draggedItems = new List <ListViewItem>();
foreach (ListViewItem item in SelectedItems)
{
_draggedItems.Add(item);
}
ListViewItemDragEventArgs evArgs = new ListViewItemDragEventArgs(ListViewItemDragEventType.DragStart, ListViewItemDragEventBehavior.PlaceBeforeOrAfterAuto, _draggedItems, null);
if (DragOperation != null)
{
DragOperation(evArgs);
// Cancel the operation if the user specified so
if (evArgs.Cancel)
{
return;
}
}
DoDragDrop(_draggedItems, DragDropEffects.Move);
InsertionMark.Index = 0;
}
//
// OnDragOver event handler. Updates the dragged node's ghost image's position
//
protected override void OnDragOver(DragEventArgs drgevent)
{
base.OnDragOver(drgevent);
// Cancel if no node is being dragged
if (_draggedItems == null)
{
return;
}
// Get actual drop item
Point controlP = PointToClient(new Point(drgevent.X, drgevent.Y));
int index = InsertionMark.NearestIndex(controlP);
if (index == -1)
{
return;
}
InsertionMark.Index = index;
ListViewItem dropItem = Items[index];//GetItemAt(controlP.X, controlP.Y);
if (dropItem != _tempDropItem)
{
ListViewItemDragEventArgs evArgs = new ListViewItemDragEventArgs(ListViewItemDragEventType.DragOver, ListViewItemDragEventBehavior.PlaceBeforeOrAfterAuto, _draggedItems, dropItem);
if (DragOperation != null)
{
DragOperation(evArgs);
// Cancel the operation if the user specified so
if (evArgs.Cancel)
{
drgevent.Effect = DragDropEffects.None;
OnDragDrop(drgevent);
return;
}
if (!evArgs.Allow)
{
return;
}
}
drgevent.Effect = DragDropEffects.Move;
// Dissalow the drag here
if (!evArgs.Allow)
{
drgevent.Effect = DragDropEffects.None;
}
_tempDropItem = dropItem;
}
}
//
// OnDragDrop event handler. Ends a node dragging
//
protected override void OnDragDrop(DragEventArgs drgevent)
{
base.OnDragDrop(drgevent);
// Cancel if no node is being dragged
if (_draggedItems == null)
{
_timer.Start();
return;
}
if (drgevent.Effect == DragDropEffects.None)
{
// Set drag node and temp drop node to null
_draggedItems = null;
_tempDropItem = null;
// Disable scroll timer
_timer.Enabled = false;
_timer.Start();
return;
}
if (InsertionMark.Index == -1)
{
_timer.Start();
return;
}
// Get drop item
ListViewItem dropItem = Items[InsertionMark.Index];
// Launch the feedback for the drag operation
ListViewItemDragEventArgs evArgs = new ListViewItemDragEventArgs(ListViewItemDragEventType.DragEnd, ListViewItemDragEventBehavior.PlaceBeforeOrAfterAuto, _draggedItems, dropItem);
if (DragOperation != null)
{
DragOperation(evArgs);
// Cancel the operation if the user specified so
if (evArgs.Cancel)
{
_timer.Start();
return;
}
}
// If drop node isn't equal to drag node, add drag node as child of drop node
if (_draggedItems[0] != dropItem)
{
int index = InsertionMark.Index;
SelectedItems.Clear();
foreach (ListViewItem item in _draggedItems)
{
Items.Remove(item);
Items.Add(item);
item.Selected = true;
}
// Deal with a bug from the framework that adds all items to the end even though you insert
// them at other indexes by also pushing all items after the current selection to the end
for (int i = index; i < Items.Count - SelectedItems.Count; i++)
{
ListViewItem item = Items[index];
Items.Remove(item);
Items.Add(item);
}
// Launch the feedback for the drag operation
evArgs = new ListViewItemDragEventArgs(ListViewItemDragEventType.AfterDragEnd, evArgs.EventBehavior, _draggedItems, dropItem);
DragOperation?.Invoke(evArgs);
// Set drag node and temp drop node to null
_draggedItems = null;
_tempDropItem = null;
// Disable scroll timer
_timer.Enabled = false;
}
_timer.Start();
}
