/// <summary>
/// Invokes an action for each item in a collection and subsequently each item added or
/// removed from the collection.
/// </summary>
/// <typeparam name="T">The type of the collection items.</typeparam>
/// <param name="collection">The collection.</param>
/// <param name="added">
/// An action called initially for each item in the collection and subsequently for each
/// item added to the collection. The parameters passed are the index in the collection and
/// the item.
/// </param>
/// <param name="removed">
/// An action called for each item removed from the collection. The parameters passed are
/// the index in the collection and the item.
/// </param>
/// <param name="reset">
/// An action called when the collection is reset.
/// </param>
/// <returns>A disposable used to terminate the subscription.</returns>
public static IDisposable ForEachItem <T>(
this IPerspexReadOnlyList <T> collection,
Action <T> added,
Action <T> removed,
Action reset)
{
return(collection.ForEachItem((_, i) => added(i), (_, i) => removed(i), reset));
}
/// <summary>
/// Invokes an action for each item in a collection and subsequently each item added or
/// removed from the collection.
/// </summary>
/// <typeparam name="T">The type of the collection items.</typeparam>
/// <param name="collection">The collection.</param>
/// <param name="added">
/// An action called initially for each item in the collection and subsequently for each
/// item added to the collection.
/// </param>
/// <param name="removed">
/// An action called for each item removed from the collection.
/// </param>
/// <returns>A disposable used to terminate the subscription.</returns>
public static IDisposable ForEachItem <T>(
this IPerspexReadOnlyList <T> collection,
Action <T> added,
Action <T> removed)
{
NotifyCollectionChangedEventHandler handler = (_, e) =>
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
foreach (T i in e.NewItems)
{
added(i);
}
break;
case NotifyCollectionChangedAction.Replace:
foreach (T i in e.OldItems)
{
removed(i);
}
foreach (T i in e.NewItems)
{
added(i);
}
break;
case NotifyCollectionChangedAction.Remove:
foreach (T i in e.OldItems)
{
removed(i);
}
break;
}
};
foreach (T i in collection)
{
added(i);
}
collection.CollectionChanged += handler;
return(Disposable.Create(() => collection.CollectionChanged -= handler));
}
/// <summary>
/// Listens for property changed events from all items in a collection.
/// </summary>
/// <typeparam name="T">The type of the collection items.</typeparam>
/// <param name="collection">The collection.</param>
/// <param name="callback">A callback to call for each property changed event.</param>
/// <returns>A disposable used to terminate the subscription.</returns>
public static IDisposable TrackItemPropertyChanged <T>(
this IPerspexReadOnlyList <T> collection,
Action <Tuple <object, PropertyChangedEventArgs> > callback)
{
List <INotifyPropertyChanged> tracked = new List <INotifyPropertyChanged>();
PropertyChangedEventHandler handler = (s, e) =>
{
callback(Tuple.Create(s, e));
};
collection.ForEachItem(
x =>
{
var inpc = x as INotifyPropertyChanged;
if (inpc != null)
{
inpc.PropertyChanged += handler;
tracked.Add(inpc);
}
},
x =>
{
var inpc = x as INotifyPropertyChanged;
if (inpc != null)
{
inpc.PropertyChanged -= handler;
tracked.Remove(inpc);
}
},
null);
return(Disposable.Create(() =>
{
foreach (var i in tracked)
{
i.PropertyChanged -= handler;
}
}));
}
/// <summary>
/// Invokes an action for each item in a collection and subsequently each item added or
/// removed from the collection.
/// </summary>
/// <typeparam name="T">The type of the collection items.</typeparam>
/// <param name="collection">The collection.</param>
/// <param name="added">
/// An action called initially with all items in the collection and subsequently with a
/// list of items added to the collection. The parameters passed are the index of the
/// first item added to the collection and the items added.
/// </param>
/// <param name="removed">
/// An action called with all items removed from the collection. The parameters passed
/// are the index of the first item removed from the collection and the items removed.
/// </param>
/// <param name="reset">
/// An action called when the collection is reset.
/// </param>
/// <returns>A disposable used to terminate the subscription.</returns>
public static IDisposable ForEachItem <T>(
this IPerspexReadOnlyList <T> collection,
Action <int, IEnumerable <T> > added,
Action <int, IEnumerable <T> > removed,
Action reset)
{
NotifyCollectionChangedEventHandler handler = (_, e) =>
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
added(e.NewStartingIndex, e.NewItems.Cast <T>());
break;
case NotifyCollectionChangedAction.Replace:
removed(e.OldStartingIndex, e.OldItems.Cast <T>());
added(e.NewStartingIndex, e.NewItems.Cast <T>());
break;
case NotifyCollectionChangedAction.Remove:
removed(e.OldStartingIndex, e.OldItems.Cast <T>());
break;
case NotifyCollectionChangedAction.Reset:
if (reset == null)
{
throw new InvalidOperationException(
"Reset called on collection without reset handler.");
}
reset();
break;
}
};
added(0, collection);
collection.CollectionChanged += handler;
return(Disposable.Create(() => collection.CollectionChanged -= handler));
}
/// <summary>
/// Invokes an action for each item in a collection and subsequently each item added or
/// removed from the collection.
/// </summary>
/// <typeparam name="T">The type of the collection items.</typeparam>
/// <param name="collection">The collection.</param>
/// <param name="added">
/// An action called initially for each item in the collection and subsequently for each
/// item added to the collection. The parameters passed are the index in the collection and
/// the item.
/// </param>
/// <param name="removed">
/// An action called for each item removed from the collection. The parameters passed are
/// the index in the collection and the item.
/// </param>
/// <param name="reset">
/// An action called when the collection is reset.
/// </param>
/// <returns>A disposable used to terminate the subscription.</returns>
public static IDisposable ForEachItem <T>(
this IPerspexReadOnlyList <T> collection,
Action <int, T> added,
Action <int, T> removed,
Action reset)
{
int index;
NotifyCollectionChangedEventHandler handler = (_, e) =>
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
index = e.NewStartingIndex;
foreach (T item in e.NewItems)
{
added(index++, item);
}
break;
case NotifyCollectionChangedAction.Replace:
index = e.OldStartingIndex;
foreach (T item in e.OldItems)
{
removed(index++, item);
}
index = e.NewStartingIndex;
foreach (T item in e.NewItems)
{
added(index++, item);
}
break;
case NotifyCollectionChangedAction.Remove:
index = e.OldStartingIndex;
foreach (T item in e.OldItems)
{
removed(index++, item);
}
break;
case NotifyCollectionChangedAction.Reset:
if (reset == null)
{
throw new InvalidOperationException(
"Reset called on collection without reset handler.");
}
reset();
break;
}
};
index = 0;
foreach (T i in collection)
{
added(index++, i);
}
collection.CollectionChanged += handler;
return(Disposable.Create(() => collection.CollectionChanged -= handler));
}
