public void Drop(IDropInfo dropInfo)
{
var targetIndex = dropInfo.InsertIndex;
var selectedItems = this.GetItemsBlock(dropInfo.Data);
if (!selectedItems.Any())
{
return;
}
var sourceIndices = selectedItems.Select(c => FootballClubs.IndexOf(c)).ToArray();
var sourceMinIndex = sourceIndices.Min();
if (targetIndex < sourceMinIndex || targetIndex > sourceMinIndex + 1)
{
if (targetIndex < sourceMinIndex)
{
for (int i = 0; i < sourceMinIndex - targetIndex; i++)
{
sourceIndices = MoveAllLeft(FootballClubs, sourceIndices);
}
}
else if (targetIndex > sourceMinIndex + 1)
{
for (int i = 0; i < targetIndex - sourceMinIndex - 1; i++)
{
sourceIndices = MoveAllRight(FootballClubs, sourceIndices);
}
}
}
}
public void DragOver(IDropInfo dropInfo)
{
var selectedIndices = this.GetItemsBlock(dropInfo.Data).Select(c => FootballClubs.IndexOf(c)).ToList();
//important: InsertIndex is the index of the item right AFTER the position we are inserting into
//consequently the range is within (both included) 0 and Items.Count
if (selectedIndices.Any() && !selectedIndices.Contains(dropInfo.InsertIndex))
{
dropInfo.DropTargetAdorner = DropTargetAdorners.Insert;
dropInfo.Effects = DragDropEffects.Copy;
}
}
//drag and drop only allows insertion of contiguous blocks...
private IEnumerable <IFootballClub> GetItemsBlock(object data)
{
if (data is IFootballClub)
{
return(new[] { (IFootballClub)data });
}
else if (data is IEnumerable <IFootballClub> )
{
var block = ((IEnumerable <IFootballClub>)data).ToArray();
var sortedIndices = block.Select(c => FootballClubs.IndexOf(c)).OrderBy(i => i).ToArray();
if (IsANonDiscontiguousInterval(sortedIndices))
{
return((IEnumerable <IFootballClub>)data);
}
return(Enumerable.Empty <IFootballClub>());
}
else
{
return(Enumerable.Empty <IFootballClub>());
}
}