protected override void HandleLongPressGesture()
{
switch (LongPressGestureRecognizer.State)
{
case UIGestureRecognizerState.Began:
{
// we try to grab the current seelected item and draw a floating copy of it on the Drag Surface
// the copy is just an image of it using RasterizedImage
var currentIndexPath = CollectionView.IndexPathForItemAtPoint(LongPressGestureRecognizer.LocationInView(CollectionView));
SelectedItemIndexPath = currentIndexPath;
if (SelectedItemIndexPath == null)
{
return;
}
if (!DataSource.CanMoveItemAtIndexPath(SelectedItemIndexPath))
{
return;
}
var collectionViewCell = CollectionView.CellForItem(SelectedItemIndexPath);
var tpoint = DragSurface.ConvertPointFromView(collectionViewCell.Frame.Location, CollectionView);
RectangleF frame = new RectangleF(tpoint.X, tpoint.Y, collectionViewCell.Frame.Size.Width, collectionViewCell.Frame.Size.Height);
CurrentView = new UIView(frame);
collectionViewCell.Highlighted = true;
var highlightedImageView = new UIImageView(RastertizedImage(collectionViewCell));
highlightedImageView.AutoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight;
highlightedImageView.Alpha = 1.0f;
collectionViewCell.Highlighted = false;
var imageView = new UIImageView(RastertizedImage(collectionViewCell));
imageView.AutoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight;
imageView.Alpha = 0.0f;
CurrentView.AddSubview(imageView);
CurrentView.AddSubview(highlightedImageView);
DragSurface.AddSubview(CurrentView); // add this to the top level view so that we can drag outside
CurrentViewCenter = CurrentView.Center;
OnWillBeginDraggingItem(SelectedItemIndexPath);
// we animate the drawing out of the floating copy
UIView.Animate(0.3, 0.0, UIViewAnimationOptions.BeginFromCurrentState,
() =>
{
CurrentView.Transform = CGAffineTransform.MakeScale(1.1f, 1.1f);
highlightedImageView.Alpha = 0.0f;
imageView.Alpha = 1.0f;
},
() =>
{
highlightedImageView.RemoveFromSuperview();
OnDidBegingDraggingItem(SelectedItemIndexPath);
});
InvalidateLayout();
}
break;
case UIGestureRecognizerState.Cancelled:
case UIGestureRecognizerState.Ended:
{
var currentIndexPath = SelectedItemIndexPath;
if (currentIndexPath == null || CurrentView == null)
{
return;
}
SelectedItemIndexPath = null;
CurrentViewCenter = PointF.Empty;
OnWillEndDraggingItem(currentIndexPath);
UIView.Animate(0.3, 0.0, UIViewAnimationOptions.BeginFromCurrentState,
() =>
{
var layoutAttributes = this.LayoutAttributesForItem(currentIndexPath);
CurrentView.Transform = CGAffineTransform.MakeScale(1.0f, 1.0f);
CurrentView.Center = CollectionView.ConvertPointToView(layoutAttributes.Center, DragSurface);
},
() =>
{
CurrentView.RemoveFromSuperview();
CurrentView = null;
InvalidateLayout();
OnDidEndDraggingItem(currentIndexPath);
});
}
break;
}
}