/// <summary>
/// constructor
/// </summary>
/// <param name="source">source collection</param>
/// <param name="filter">filter function</param>
public FilteredReadOnlyObservableCollection(TCollection source, Func <TElement, bool> filter)
{
Source = source;
Filter = filter;
Initialize();
{
// propertychanged
CollectionUtilities.ObserveElementPropertyChanged <TCollection, TElement>(source)
.Subscribe(x =>
{
var index = source.IndexOf(x.Sender);
var filteredIndex = IndexList[index];
var isTarget = Filter(x.Sender);
if (isTarget && filteredIndex == null)
{
// add
AppearNewItem(index);
}
else if (!isTarget && filteredIndex.HasValue)
{
// remove
DisappearItem(index);
IndexList[index] = null;
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, x.Sender, filteredIndex.Value));
}
})
.AddTo(Subscription);
}
{
// collection changed(support single changed only)
source.CollectionChangedAsObservable()
.Subscribe(x =>
{
switch (x.Action)
{
case NotifyCollectionChangedAction.Add:
// appear
IndexList.Insert(x.NewStartingIndex, null);
if (Filter(x.NewItems.Cast <TElement>().Single()))
{
AppearNewItem(x.NewStartingIndex);
}
break;
case NotifyCollectionChangedAction.Move:
throw new NotSupportedException("Move is not supported");
case NotifyCollectionChangedAction.Remove:
var removedIndex = IndexList[x.OldStartingIndex];
if (removedIndex.HasValue)
{
DisappearItem(x.OldStartingIndex);
IndexList.RemoveAt(x.OldStartingIndex);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove,
x.OldItems.Cast <TElement>().Single(), removedIndex.Value));
}
else
{
IndexList.RemoveAt(x.OldStartingIndex);
}
break;
case NotifyCollectionChangedAction.Replace:
var index = IndexList[x.NewStartingIndex];
var isTarget = Filter(x.NewItems.Cast <TElement>().Single());
if (index == null && isTarget)
{
// add
AppearNewItem(x.NewStartingIndex);
}
else if (index.HasValue && isTarget)
{
// replace
InnerCollection[index.Value] = x.NewItems.Cast <TElement>().Single();
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace,
x.NewItems.Cast <TElement>().Single(), x.OldItems.Cast <TElement>().Single(), index.Value));
}
else if (index.HasValue && !isTarget)
{
// remove
DisappearItem(x.NewStartingIndex);
IndexList[x.NewStartingIndex] = null;
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove,
x.OldItems.Cast <TElement>().Single(), index.Value));
}
break;
case NotifyCollectionChangedAction.Reset:
Initialize();
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
break;
default:
throw new InvalidOperationException();
}
})
.AddTo(Subscription);
}
}
/// <summary>
/// Observe collection element's IObservable sequence.
/// </summary>
/// <typeparam name="TElement">Collection element type</typeparam>
/// <typeparam name="TProperty">Type of observable property element</typeparam>
/// <param name="source">Source collection</param>
/// <param name="propertySelector">IObservable selection expression</param>
/// <returns>IObservable sequence sequence</returns>
public static IObservable <PropertyPack <TElement, TProperty> > ObserveElementObservableProperty <TElement, TProperty>(this IFilteredReadOnlyObservableCollection <TElement> source, Expression <Func <TElement, IObservable <TProperty> > > propertySelector)
where TElement : class, INotifyPropertyChanged =>
CollectionUtilities.ObserveElementObservableProperty(source, propertySelector);
/// <summary>
/// Observe collection element's PropertyChanged event.
/// </summary>
/// <typeparam name="TElement">Type of Element</typeparam>
/// <param name="source">source collection</param>
/// <returns>PropertyChanged event stream.</returns>
public static IObservable <SenderEventArgsPair <TElement, PropertyChangedEventArgs> > ObserveElementPropertyChanged <TElement>(this IFilteredReadOnlyObservableCollection <TElement> source)
where TElement : class, INotifyPropertyChanged =>
CollectionUtilities.ObserveElementPropertyChanged <IFilteredReadOnlyObservableCollection <TElement>, TElement>(source);
/// <summary>
/// Observe collection element's property.
/// </summary>
/// <typeparam name="TElement">Type of element</typeparam>
/// <typeparam name="TProperty">Type of property</typeparam>
/// <param name="source">Data source</param>
/// <param name="propertySelector">Property selection expression</param>
/// <param name="isPushCurrentValueAtFirst">Push current value on first subscribe</param>
/// <returns>Property sequence</returns>
public static IObservable <PropertyPack <TElement, TProperty> > ObserveElementProperty <TElement, TProperty>(this IFilteredReadOnlyObservableCollection <TElement> source, Expression <Func <TElement, TProperty> > propertySelector, bool isPushCurrentValueAtFirst = true)
where TElement : class, INotifyPropertyChanged =>
CollectionUtilities.ObserveElementProperty(source, propertySelector, isPushCurrentValueAtFirst);