protected override void OnElementChanged(ElementChangedEventArgs <ListView> e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
Control.Adapter?.Dispose();
Control.Adapter = null;
Control.SetOnDragListener(null);
Control.OnItemLongClickListener = null;
}
if (e.NewElement != null)
{
_dragAndDropListViewAdapter = new DragAndDropListViewAdapter(Control, Element);
Control.Adapter = _dragAndDropListViewAdapter;
Control.SetOnDragListener(_dragAndDropListViewAdapter);
Control.OnItemLongClickListener = _dragAndDropListViewAdapter;
}
}
//public override bool HasStableIds => WrappedAdapter.HasStableIds;
//public override bool IsEmpty => WrappedAdapter.IsEmpty;
//public override int ViewTypeCount => WrappedAdapter.ViewTypeCount;
//public override bool AreAllItemsEnabled() => WrappedAdapter.AreAllItemsEnabled();
public bool OnDrag(View v, DragEvent e)
{
var dragItem = (DragItem)e.LocalState;
switch (e.Action)
{
case DragAction.Started:
break;
case DragAction.Entered:
System.Diagnostics.Debug.WriteLine($"DragAction.Entered from {v.GetType()}");
if (!(v is ListView))
{
//var dragItem = (DragItem)e.LocalState;
var targetPosition = InsertOntoView(v, dragItem);
dragItem.Index = targetPosition;
// Keep a list of items that has translation so we can reset
// them once the drag'n'drop is finished.
_translatedItems.Add(v);
_listView.Invalidate();
}
break;
case DragAction.Location:
var currentPosition = (int)e.GetX();
var point = GetTouchPositionFromDragEvent(v, e);
System.Diagnostics.Debug.WriteLine($"DragAction.Location from {v.GetType()} => {currentPosition}");
System.Diagnostics.Debug.WriteLine($"DragAction.GLOBAL from {v.GetType()} => {point.X}");
int y = Java.Lang.Math.Round(e.GetY());
int translatedY = y - 50;
int threshold = 50;
// make a scrolling up due the y has passed the threshold
if (translatedY < threshold)
{
// make a scroll up by 30 px
_hostScrollView.ScrollBy(0, -30);
}
// make a autoscrolling down due y has passed the 500 px border
if (translatedY + threshold > 500)
{
// make a scroll down by 30 px
_hostScrollView.ScrollBy(0, 30);
}
//if (point.X > App.AppScreenWidth - 50)
//{
// //_hostScrollView.ScrollToAsync(_hostScrollView.ScrollX + 30, 0, true);
// _hostScrollView.StartScroll(50);
//}
//if (point.X < 50)
//{
// //_hostScrollView.ScrollToAsync(_hostScrollView.ScrollX - 30, 0, true);
// _hostScrollView.StartScroll(-50);
//}
//if (currentPosition > _element.Width - 40)
//{
// _hostScrollView.ScrollToAsync(_hostScrollView.ScrollX + 30, 0, true);
//}
//else if (currentPosition < 40)
//{
// _hostScrollView.ScrollToAsync(_hostScrollView.ScrollX - 30, 0, true);
//}
//if (v.Right < (_hostScrollView.ScrollX + _hostScrollView.Width - 100))
//{
// _hostScrollView.ScrollToAsync(_hostScrollView.ScrollX + 30, 0, true);
//}
//if (v.Left > (_hostScrollView.ScrollX + _hostScrollView.Width - 100))
//{
// _hostScrollView.ScrollToAsync(_hostScrollView.ScrollX - 30, 0, true);
//}
break;
case DragAction.Exited:
System.Diagnostics.Debug.WriteLine($"DragAction.Entered from {v.GetType()}");
_lastPosition = _listView.GetPositionForView(v);
if (!(v is ListView))
{
var positionEntered = GetListPositionForView(v);
//var item1 = _listAdapter.GetItem(positionEntered);
System.Diagnostics.Debug.WriteLine($"DragAction.Exited index {positionEntered}");
}
break;
case DragAction.Drop:
System.Diagnostics.Debug.WriteLine($"DragAction.Drop from {v.GetType()}");
if (v is ListView)
{
bool isDropped = true;
int positionSource = -1;
int insertLocation = -1;
var dropItem = (DragItem)e.LocalState;
Android.Views.View view = dropItem.View;
object passedItem = dropItem.Item;
Android.Widget.ListView oldParent = (Android.Widget.ListView)view.Parent;
//DragListAdapter oldParentAdapter = (DragListAdapter)oldParent.;
BaseAdapter sourceAdapter = (oldParent.Adapter is IWrapperListAdapter)
? ((IWrapperListAdapter)oldParent.Adapter).WrappedAdapter as BaseAdapter
: ((BaseAdapter)oldParent.Adapter);
DragAndDropListViewAdapter sourceDragListAdaptor = sourceAdapter as DragAndDropListViewAdapter;
//positionSource = (int)view.Tag;
Console.WriteLine(v.Parent.Parent);
Android.Widget.ListView newParent = _listView;
//Person customList = (Person)sourceAdapter.Collection[positionSource];
ObservableListCollection <Item> sourceList = sourceDragListAdaptor.Collection;
//customListSource.RemoveAt(positionSource);
//Android.Widget.ListView target = this.Element.
//DragListAdapter adapterTarget = (DragListAdapter)_listView.Adapter;
BaseAdapter destinationAdapter = (oldParent.Adapter is IWrapperListAdapter)
? ((IWrapperListAdapter)newParent.Adapter).WrappedAdapter as BaseAdapter
: ((BaseAdapter)oldParent.Adapter);
DragAndDropListViewAdapter destinationDragListAdaptor = destinationAdapter as DragAndDropListViewAdapter;
ObservableListCollection <Item> targetList = destinationDragListAdaptor.Collection;
int removeLocation = oldParent.GetPositionForView(view);
insertLocation = newParent.GetPositionForView(dropItem.View);
var item = dropItem.Item as Item;
//if (sourceList.Contains(dropItem.Item as Item) && sourceList != targetList)
if (sourceList != targetList)
{
if (insertLocation >= 0)
{
targetList.Insert(insertLocation, item);
targetList.ItemAdded(item);
}
else
{
targetList.Add(dropItem.Item as Item);
targetList.ItemAdded(item);
}
sourceList.Remove(item);
sourceAdapter.NotifyDataSetChanged();
destinationAdapter.NotifyDataSetChanged();
v.Visibility = ViewStates.Visible; //(View.VISIBLE);
}
else
{
if (_element.ItemsSource is IOrderable orderable)
{
if (((IList)_element.ItemsSource).Contains(dropItem.Item))
{
orderable.ChangeOrdinal(dropItem.OriginalIndex, dropItem.Index);
}
}
}
//foreach (var viewTrans in _translatedItems)
//{
// viewTrans.TranslationY = 0;
//}
//_translatedItems.Clear();
}
break;
case DragAction.Ended:
if (!(v is ListView))
{
return(false);
}
//System.Diagnostics.Debug.WriteLine($"DragAction.Ended from {v.GetType()}");
var mobileItem = (DragItem)e.LocalState;
mobileItem.View.Visibility = ViewStates.Visible;
foreach (var view in _translatedItems)
{
view.TranslationY = 0;
}
_translatedItems.Clear();
//if (_element.ItemsSource is IOrderable orderable)
//{
// if (((IList)_element.ItemsSource).Contains(mobileItem.Item))
// {
// orderable.ChangeOrdinal(mobileItem.OriginalIndex, mobileItem.Index);
// }
// else
// {
// orderable.ItemAdded(mobileItem.Item);
// }
//}
break;
}
return(true);
}