private static IDisposable CreateSubscription<TModel, TViewModel>(
INotifyCollectionChanged source, Func<TModel, TViewModel> converter,
DispatcherCollectionRx<TViewModel> target)
{
return source.ListenCollectionChanged(e =>
DispatcherHelper.UIDispatcher.InvokeAsync(() =>
{
if (e.NewItems != null && e.NewItems.Count >= 2)
{
throw new ArgumentException("Too many new items.");
}
try
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
if (e.NewItems == null)
{
throw new ArgumentException("New item is null.");
}
target.Insert(e.NewStartingIndex, converter((TModel)e.NewItems[0]));
break;
case NotifyCollectionChangedAction.Move:
target.Move(e.OldStartingIndex, e.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Remove:
if (typeof(IDisposable).IsAssignableFrom(typeof(TViewModel)))
{
((IDisposable)target[e.OldStartingIndex]).Dispose();
}
target.RemoveAt(e.OldStartingIndex);
break;
case NotifyCollectionChangedAction.Replace:
if (typeof(IDisposable).IsAssignableFrom(typeof(TViewModel)))
{
((IDisposable)target[e.NewStartingIndex]).Dispose();
}
if (e.NewItems == null)
{
throw new ArgumentException("New item is null.");
}
target[e.NewStartingIndex] = converter((TModel)e.NewItems[0]);
break;
case NotifyCollectionChangedAction.Reset:
if (typeof(IDisposable).IsAssignableFrom(typeof(TViewModel)))
{
// ReSharper disable once PossibleInvalidCastExceptionInForeachLoop
foreach (IDisposable item in target)
{
item.Dispose();
}
}
target.Clear();
break;
default:
throw new ArgumentException();
}
}
catch (ArgumentOutOfRangeException aoex)
{
// collection inconsistent state
throw new InvalidOperationException(
"Collection state is invalid." + Environment.NewLine +
"INDEX OUT OF RANGE - " + e.Action + "[" + typeof(TModel).Name + " -> " +
typeof(TViewModel).Name + "]" + Environment.NewLine +
"new start: " + e.NewStartingIndex + ", count: " +
(e.NewItems == null
? "null"
: e.NewItems.Count.ToString(CultureInfo.InvariantCulture)) +
Environment.NewLine +
"source length: " + ((IList<TModel>)source).Count + ", target length: " + target.Count +
".",
aoex);
}
}));
}
private static IDisposable CreateSubscription <TModel, TViewModel>(
INotifyCollectionChanged source, Func <TModel, TViewModel> converter,
DispatcherCollectionRx <TViewModel> target)
{
bool resetOccured = false;
return(source
.ListenCollectionChanged()
.ObserveOn(DispatcherHolder.Dispatcher)
.Subscribe(e =>
{
if (e.NewItems != null && e.NewItems.Count >= 2)
{
throw new ArgumentException("Too many new items.");
}
try
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
target.Insert(e.NewStartingIndex, converter((TModel)e.NewItems[0]));
break;
case NotifyCollectionChangedAction.Move:
target.Move(e.OldStartingIndex, e.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Remove:
if (typeof(IDisposable).IsAssignableFrom(typeof(TViewModel)))
{
((IDisposable)target[e.OldStartingIndex]).Dispose();
}
target.RemoveAt(e.OldStartingIndex);
break;
case NotifyCollectionChangedAction.Replace:
if (typeof(IDisposable).IsAssignableFrom(typeof(TViewModel)))
{
((IDisposable)target[e.NewStartingIndex]).Dispose();
}
target[e.NewStartingIndex] = converter((TModel)e.NewItems[0]);
break;
case NotifyCollectionChangedAction.Reset:
if (typeof(IDisposable).IsAssignableFrom(typeof(TViewModel)))
{
foreach (IDisposable item in target)
{
item.Dispose();
}
resetOccured = true;
}
target.Clear();
break;
default:
throw new ArgumentException();
}
}
catch (ArgumentOutOfRangeException aoex)
{
throw new InvalidOperationException(
"Collection state is invalid." + Environment.NewLine +
"INDEX OUT OF RANGE - " + e.Action + "[" + typeof(TModel).Name + " -> " +
typeof(TViewModel).Name + ", reset: " + resetOccured + " ]" + Environment.NewLine +
"new start: " + e.NewStartingIndex + ", count: " +
(e.NewItems == null ? "null" : e.NewItems.Count.ToString()) + Environment.NewLine +
"source length: " + ((IList <TModel>)source).Count + ", target length: " + target.Count +
".",
aoex);
}
}));
}