public void DoYourThing()
{
var collection = new ObservableCollection <ObserverThing>();
SelectedCollection = new ObservableCollection <ObserverThing>();
collection.CollectionChanged += Collection_CollectionChanged;
SelectedCollection.CollectionChanged += SelectedCollection_CollectionChanged;
{
var first = new ObserverThing("First");
var second = new ObserverThing("Second");
var third = new ObserverThing("Third");
collection.Add(first);
collection.Add(second);
collection.Add(third);
first.IsSelected = true;
second.IsSelected = true;
third.IsSelected = true;
first.IsSelected = false;
//second.IsSelected = false;
third.IsSelected = false;
Console.WriteLine("Removing 'second' from the global list ...");
collection.Remove(second);
}
}
private void Thing_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == nameof(ObserverThing.IsSelected))
{
ObserverThing thing = (ObserverThing)sender;
if (thing.IsSelected == true)
{
SelectedCollection.Add(thing);
}
else
{
SelectedCollection.Remove(thing);
}
}
}
private void Collection_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
ObserverThing newThing = (ObserverThing)e.NewItems[0];
newThing.PropertyChanged += Thing_PropertyChanged;
break;
case NotifyCollectionChangedAction.Remove:
var oldThing = (ObserverThing)e.OldItems[0];
oldThing.IsSelected = false;
oldThing.PropertyChanged -= Thing_PropertyChanged;
break;
case NotifyCollectionChangedAction.Move:
case NotifyCollectionChangedAction.Replace:
case NotifyCollectionChangedAction.Reset:
throw new NotImplementedException($"Collection_CollectionChanged, Action:{e.Action}");
}
}
