void OnItemsDropped(DragEventArgs e, int index)
{
ModelItemHelper.TryCreateImmediateEditingScopeAndExecute(this.Items.GetEditingContext(), System.Activities.Presentation.SR.CollectionAddEditingScopeDescription, (es) =>
{
DragDropHelper.SetDragDropCompletedEffects(e, DragDropEffects.None);
List <object> droppedObjects = new List <object>(DragDropHelper.GetDroppedObjects(this, e, Context));
List <WorkflowViewElement> movedViewElements = new List <WorkflowViewElement>();
List <object> externalMoveList = new List <object>();
List <ModelItem> internalMoveList = new List <ModelItem>();
// Step 1: Sort the list
List <object> sortedDroppingList = DragDropHelper.SortSelectedObjects(droppedObjects);
// Step 2: Categorize dropped objects by their source container.
foreach (object droppedObject in sortedDroppingList)
{
ModelItem modelItem = droppedObject as ModelItem;
WorkflowViewElement view = (modelItem == null) ? null : (modelItem.View as WorkflowViewElement);
if (view == null)
{
externalMoveList.Add(droppedObject);
continue;
}
UIElement container = DragDropHelper.GetCompositeView(view);
if (container == this)
{
internalMoveList.Add(modelItem);
continue;
}
movedViewElements.Add(view);
externalMoveList.Add(droppedObject);
}
// Step 3: Internal movement
if (this.ShouldMoveItems(internalMoveList, index))
{
foreach (ModelItem modelItem in internalMoveList)
{
int oldIndex = this.Items.IndexOf(modelItem);
this.Items.Remove(modelItem);
//if element is placed ahead of old location, decrement the index not to include moved object
if (oldIndex < index)
{
this.InsertItem(index - 1, modelItem);
}
else
{
this.InsertItem(index, modelItem);
index++;
}
}
}
// Step 4: External move and drop from toolbox
foreach (object droppedObject in externalMoveList)
{
if (!this.IsDropAllowed(droppedObject))
{
continue;
}
this.InsertItem(index++, droppedObject);
DragDropHelper.SetDragDropCompletedEffects(e, DragDropEffects.Move);
}
DragDropHelper.SetDragDropMovedViewElements(e, movedViewElements);
e.Handled = true;
if (es != null)
{
es.Complete();
}
});
}
List <object> GetSortedObjectList(DragEventArgs args)
{
IEnumerable <object> droppedObjects = DragDropHelper.GetDroppedObjects(this, args, this.context);
return(DragDropHelper.SortSelectedObjects(droppedObjects));
}
