/// <summary>
/// Is called when a drag-and-drop operation is completed in order to raise the Dropped event.
/// </summary>
/// <param name="e">Event arguments which hold information on the completed operation.</param>
/// <remarks>Is called for the target as well as for the source.
/// The role a control plays (source or target) can be determined from e.Operation.</remarks>
public virtual void OnDropped(DroppedEventArgs e)
{
var dropEvent = Dropped;
if (dropEvent != null)
{
dropEvent(this, e);
}
}
protected override void OnDragDrop(DragEventArgs drgevent)
{
base.OnDragDrop(drgevent);
_visualCue.Clear();
// Retrieve the drag item data.
// Conditions have been testet in OnDragEnter and OnDragOver, so everything should be ok here.
IDragDropSource src = drgevent.Data.GetData("IDragDropSource") as IDragDropSource;
object[] srcItems = src.GetSelectedItems();
// If the list box is sorted, we don't know where the items will be inserted
// and we will have troubles selecting the inserted items. So let's disable sorting here.
bool sortedSave = Sorted;
Sorted = false;
// Insert at the currently hovered row.
int row = DropIndex(drgevent.Y);
int insertPoint = row;
if (row >= Items.Count) // Append items to the end.
{
Items.AddRange(srcItems);
}
else // Insert items before row.
{
foreach (object item in srcItems)
{
Items.Insert(row++, item);
}
}
// Remove all the selected items from the source, if moving.
DropOperation operation; // Remembers the operation for the event we'll raise.
if (drgevent.Effect == DragDropEffects.Move)
{
int adjustedInsertPoint = insertPoint;
src.RemoveSelectedItems(ref adjustedInsertPoint);
if (src == this) // Items are being reordered.
{
insertPoint = adjustedInsertPoint;
operation = DropOperation.Reorder;
}
else
{
operation = DropOperation.MoveToHere;
}
}
else
{
operation = DropOperation.CopyToHere;
}
// Adjust the selected items in the target.
ClearSelected();
if (SelectionMode == SelectionMode.One) // Select the first item inserted.
{
SelectedIndex = insertPoint;
}
else if (SelectionMode != SelectionMode.None) // Select the inserted items.
{
for (int i = insertPoint; i < insertPoint + srcItems.Length; i++)
{
SetSelected(i, true);
}
}
// Now that we've selected the inserted items, restore the "Sorted" property.
Sorted = sortedSave;
// Notify the target (this control).
DroppedEventArgs e = new DroppedEventArgs()
{
Operation = operation,
Source = src,
Target = this,
DroppedItems = srcItems
};
OnDropped(e);
// Notify the source (the other control).
if (operation != DropOperation.Reorder)
{
e = new DroppedEventArgs()
{
Operation = operation == DropOperation.MoveToHere ? DropOperation.MoveFromHere : DropOperation.CopyFromHere,
Source = src,
Target = this,
DroppedItems = srcItems
};
src.OnDropped(e);
}
}
