// Performs custom drop logic for the top ListView.
void dragMgr_ProcessDrop(object sender, ProcessDropEventArgs <Path> e)
{
// This shows how to customize the behavior of a drop.
// Here we perform a swap, instead of just moving the dropped item.
int higherIdx = Math.Max(e.OldIndex, e.NewIndex);
int lowerIdx = Math.Min(e.OldIndex, e.NewIndex);
if (lowerIdx < 0)
{
// The item came from the lower ListView
// so just insert it.
e.ItemsSource.Insert(higherIdx, e.DataItem);
}
else
{
// null values will cause an error when calling Move.
// It looks like a bug in ObservableCollection to me.
if (e.ItemsSource[lowerIdx] == null ||
e.ItemsSource[higherIdx] == null)
{
return;
}
// The item came from the ListView into which
// it was dropped, so swap it with the item
// at the target index.
e.ItemsSource.Move(lowerIdx, higherIdx);
e.ItemsSource.Move(higherIdx - 1, lowerIdx);
}
// Set this to 'Move' so that the OnListViewDrop knows to
// remove the item from the other ListView.
e.Effects = DragDropEffects.Move;
var obsCollection = (IEnumerable <Path>) this.listViewFavorites.ItemsSource;
FavoritePaths.Instance.SetFavorites(new List <Path>(obsCollection));
}
void listView_Drop(object sender, DragEventArgs e)
{
if (this.ItemUnderDragCursor != null)
{
this.ItemUnderDragCursor = null;
}
e.Effects = DragDropEffects.None;
if (!e.Data.GetDataPresent(typeof(ItemType)))
{
return;
}
// Get the data object which was dropped.
ItemType data = e.Data.GetData(typeof(ItemType)) as ItemType;
if (data == null)
{
return;
}
// Get the ObservableCollection<ItemType> which contains the dropped data object.
ObservableCollection <ItemType> itemsSource = this.listView.ItemsSource as ObservableCollection <ItemType>;
if (itemsSource == null)
{
throw new Exception(
"A ListView managed by ListViewDragManager must have its ItemsSource set to an ObservableCollection<ItemType>.");
}
int oldIndex = itemsSource.IndexOf(data);
int newIndex = this.IndexUnderDragCursor;
if (newIndex < 0)
{
// The drag started somewhere else, and our ListView is empty
// so make the new item the first in the list.
if (itemsSource.Count == 0)
{
newIndex = 0;
}
// The drag started somewhere else, but our ListView has items
// so make the new item the last in the list.
else if (oldIndex < 0)
{
newIndex = itemsSource.Count;
}
// The user is trying to drop an item from our ListView into
// our ListView, but the mouse is not over an item, so don't
// let them drop it.
else
{
return;
}
}
// Dropping an item back onto itself is not considered an actual 'drop'.
if (oldIndex == newIndex)
{
return;
}
if (this.ProcessDrop != null)
{
// Let the client code process the drop.
ProcessDropEventArgs <ItemType> args = new ProcessDropEventArgs <ItemType>(itemsSource, data, oldIndex, newIndex, e.AllowedEffects);
this.ProcessDrop(this, args);
e.Effects = args.Effects;
}
else
{
// Move the dragged data object from it's original index to the
// new index (according to where the mouse cursor is). If it was
// not previously in the ListBox, then insert the item.
if (oldIndex > -1)
{
itemsSource.Move(oldIndex, newIndex);
}
else
{
itemsSource.Insert(newIndex, data);
}
// Set the Effects property so that the call to DoDragDrop will return 'Move'.
e.Effects = DragDropEffects.Move;
}
}
