/// <summary>
///
/// </summary>
/// <typeparam name="TItem"></typeparam>
/// <typeparam name="TValue"></typeparam>
/// <param name="source"></param>
/// <param name="selector"></param>
/// <param name="whenEmpty"></param>
/// <param name="trackItemChanges">If true we subscribe to property changes for each item. This is much slower.</param>
/// <returns>A tracker with Value synced with source.Max()</returns>
public static MaxTracker <TValue> TrackMax <TItem, TValue>(this ReadOnlyObservableCollection <TItem> source, Expression <Func <TItem, TValue> > selector, TValue?whenEmpty, bool trackItemChanges)
where TItem : class, INotifyPropertyChanged
where TValue : struct, IComparable <TValue>
{
var onItemChanged = trackItemChanges
? source.ObserveItemPropertyChanged(selector, false)
: null;
var mapped = source.AsMappingView(selector.Compile(), onItemChanged);
return(new MaxTracker <TValue>(mapped, mapped.ObserveCollectionChangedSlim(false), whenEmpty));
}
