/// <summary>
/// Raises the <see cref="ItemDrag" /> event.
/// </summary>
/// <param name="e">The <see cref="ListBoxItemDragEventArgs" /> instance containing the event data.</param>
protected virtual void OnItemDrag(ListBoxItemDragEventArgs e)
{
EventHandler <ListBoxItemDragEventArgs> handler;
handler = this.ItemDrag;
handler?.Invoke(this, e);
}
/// <summary>
/// Raises the <see cref="E:System.Windows.Forms.Control.DragDrop"/> event.
/// </summary>
/// <param name="drgevent">A <see cref="T:System.Windows.Forms.DragEventArgs"/> that contains the event data. </param>
protected override void OnDragDrop(DragEventArgs drgevent)
{
if (this.IsDragging)
{
try
{
InsertionIndex = CheckInsertionIndex(InsertionIndex);
if (this.InsertionIndex != InvalidIndex)
{
int dragIndex;
int dropIndex;
dragIndex = (int)drgevent.Data.GetData(typeof(int));
dropIndex = this.InsertionIndex;
if (dragIndex < dropIndex)
{
dropIndex--;
}
if (this.InsertionMode == InsertionMode.After && dragIndex < this.Items.Count - 1)
{
dropIndex++;
}
if (dropIndex != dragIndex)
{
ListBoxItemDragEventArgs args;
Point clientPoint;
clientPoint = this.PointToClient(new Point(drgevent.X, drgevent.Y));
args = new ListBoxItemDragEventArgs(dragIndex, dropIndex, this.InsertionMode, clientPoint.X, clientPoint.Y);
this.OnItemDrag(args);
if (!args.Cancel)
{
object dragItem;
try
{
dragItem = this.Items[dragIndex];
this.Items.Remove(dragItem);
this.Items.Insert(dropIndex, dragItem);
this.SelectedItem = dragItem;
}
catch (Exception) { }
}
}
}
}
finally
{
//this.Invalidate(this.InsertionIndex);
Invalidate();
this.InsertionIndex = InvalidIndex;
this.InsertionMode = InsertionMode.None;
this.IsDragging = false;
}
}
Invalidate();
base.OnDragDrop(drgevent);
}