private void Update(Chunk <NotifyCollectionChangedEventArgs> changes)
{
if (changes == null || changes.Count == 0)
{
return;
}
using (changes.ClearTransaction())
{
if (changes.Count > 1)
{
this.Refresh(changes);
return;
}
var e = changes[0];
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
{
if (!e.TryGetSingleNewItem(out TSource newSource))
{
goto case NotifyCollectionChangedAction.Reset;
}
var index = e.NewStartingIndex;
var value = this.GetOrCreate(newSource, index);
this.Tracker.Insert(index, value);
var args = this.UpdateRange(index + 1, this.Count - 1);
args.Add(Diff.CreateAddEventArgs(value, index));
this.Notify(args);
break;
}
case NotifyCollectionChangedAction.Remove:
{
if (!e.TryGetSingleOldItem(out TSource oldSource))
{
goto case NotifyCollectionChangedAction.Reset;
}
var index = e.OldStartingIndex;
var value = this.Tracker[index];
this.Tracker.RemoveAt(index);
var argses = this.UpdateRange(index, this.Count - 1);
argses.Add(Diff.CreateRemoveEventArgs(value, index));
this.Notify(argses);
this.factory.Remove(oldSource, value);
break;
}
case NotifyCollectionChangedAction.Replace:
{
if (!e.TryGetSingleNewItem(out TSource newSource) ||
!e.TryGetSingleOldItem(out TSource oldSource))
{
goto case NotifyCollectionChangedAction.Reset;
}
var index = e.NewStartingIndex;
var value = this.GetOrCreate(newSource, index);
var oldValue = this.Tracker[e.OldStartingIndex];
this.Tracker[index] = value;
var arg = Diff.CreateReplaceEventArgs(value, oldValue, index);
this.Notify(arg);
this.factory.Remove(oldSource, oldValue);
break;
}
case NotifyCollectionChangedAction.Move:
{
var value = this.Tracker[e.OldStartingIndex];
this.Tracker.RemoveAt(e.OldStartingIndex);
this.Tracker.Insert(e.NewStartingIndex, value);
var args = this.UpdateRange(Math.Min(e.OldStartingIndex, e.NewStartingIndex), Math.Max(e.OldStartingIndex, e.NewStartingIndex));
args.Add(Diff.CreateMoveEventArgs(value, e.NewStartingIndex, e.OldStartingIndex));
this.Notify(args);
break;
}
case NotifyCollectionChangedAction.Reset:
using (this.factory.RefreshTransaction())
{
this.Refresh(changes);
}
break;
default:
throw new ArgumentOutOfRangeException(nameof(changes));
}
}
}
protected virtual void OnSourceCollectionChanged(IReadOnlyList <NotifyCollectionChangedEventArgs> changeCollection)
{
if (changeCollection == null || changeCollection.Count == 0)
{
return;
}
if (changeCollection.Count > 1)
{
this.Refresh();
return;
}
var singleChange = changeCollection[0];
try
{
switch (singleChange.Action)
{
case NotifyCollectionChangedAction.Add:
{
var index = singleChange.NewStartingIndex;
var value = this.GetOrCreateValue(this.source.ElementAt(index), index);
this.mapped.Insert(index, value);
var changes = this.UpdateIndicesFrom(index + 1);
var change = Diff.CreateAddEventArgs(value, index);
changes.Add(change);
base.Refresh(changes);
break;
}
case NotifyCollectionChangedAction.Remove:
{
var index = singleChange.OldStartingIndex;
var value = this.mapped[index];
this.mapped.RemoveAt(index);
var changes = this.UpdateIndicesFrom(index);
var change = Diff.CreateRemoveEventArgs(value, index);
changes.Add(change);
base.Refresh(changes);
break;
}
case NotifyCollectionChangedAction.Replace:
{
var index = singleChange.NewStartingIndex;
var value = this.GetOrCreateValue(this.source.ElementAt(index), index);
var oldValue = this.mapped[singleChange.OldStartingIndex];
this.mapped[index] = value;
var change = Diff.CreateReplaceEventArgs(value, oldValue, index);
base.Refresh(new[] { change });
break;
}
case NotifyCollectionChangedAction.Move:
{
var value = this.mapped[singleChange.OldStartingIndex];
this.mapped.RemoveAt(singleChange.OldStartingIndex);
this.mapped.Insert(singleChange.NewStartingIndex, value);
this.UpdateIndex(singleChange.OldStartingIndex);
this.UpdateIndex(singleChange.NewStartingIndex);
var change = Diff.CreateMoveEventArgs(this.mapped[singleChange.NewStartingIndex], singleChange.NewStartingIndex, singleChange.OldStartingIndex);
base.Refresh(new[] { change });
break;
}
case NotifyCollectionChangedAction.Reset:
this.Refresh();
break;
default:
throw new ArgumentOutOfRangeException();
}
}
catch (Exception)
{
this.Refresh(); // Resetting
}
}