public SampleViewModel()
{
Items = new ReactiveList <SampleObject> ();
var rand = new Random();
Observable.Interval(TimeSpan.FromMilliseconds(300))
.ObserveOn(RxApp.MainThreadScheduler)
.Subscribe(num =>
{
var idx = rand.Next(Items.Count);
var act = rand.NextDouble();
if (act < 0.4 || idx >= Items.Count)
{
Items.Insert(
idx,
new SampleObject()
{
Name = "Hallo Number " + num
});
Debug.WriteLine("Inserted " + idx);
}
else if (act < 0.8)
{
Items [idx].Name = "Now I'm Number " + num;
Debug.WriteLine("Renamed " + idx);
}
else
{
Items.RemoveAt(idx);
Debug.WriteLine("Removed " + idx);
}
});
}
/// <summary>
/// Takes each list produced by this observable and mirrors its contents in the target list.
/// The target list is modified, not replaced.
/// The type of the target list property is IReadOnlyReactiveList because it doesn't make sense to have a mutible list
/// if this binding keeps changing the contents of the list, but the type of the actual object should be ReactiveList
/// so the list can be modified by this binding.
/// </summary>
/// <typeparam name="TObj">The type of viewmodel</typeparam>
/// <typeparam name="TListItem">The type of object contained in the list</typeparam>
/// <param name="data">The observable to take lists from.</param>
/// <param name="target">The viewmodel that is used as a base for finding the target list property</param>
/// <param name="property">The IReactiveList property that will be modified.</param>
/// <returns>A disposable to break the binding</returns>
public static IDisposable BindListContents <TObj, TListItem>(this IObservable <IList <TListItem> > data,
TObj target, Expression <Func <TObj, IReadOnlyReactiveList <TListItem> > > property) where TObj : class
{
IObservable <IReadOnlyReactiveList <TListItem> > targetListObservable = target.WhenAnyValue(property);
return(Observable.CombineLatest(targetListObservable, data, (a, b) => (TargetList: a, SourceList: b))
.Subscribe(t =>
{
IReactiveList <TListItem> latestTargetList = t.TargetList as IReactiveList <TListItem>;
IList <TListItem> latestData = t.SourceList;
if (latestTargetList == null)
{
return;
}
if (latestData == null)
{
latestTargetList.Clear();
return;
}
var changes = LongestCommonSubsequence.GetChanges(latestTargetList, latestData).ToArray();
if (changes.Length == 0)
{
return;
}
using (changes.Length > 1 ? latestTargetList.SuppressChangeNotifications() : Disposable.Empty)
{
foreach (var(index, item, changeType) in changes)
{
if (changeType == LongestCommonSubsequence.ChangeType.Removed)
{
latestTargetList.RemoveAt(index);
}
else if (changeType == LongestCommonSubsequence.ChangeType.Added)
{
latestTargetList.Insert(index, item);
}
}
}
}));
}
