SwitchableObservableCollection AddRange

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;

namespace Utilz
{
    // LOLLO http://blog.stephencleary.com/2009/07/interpreting-notifycollectionchangedeve.html
    public class SwitchableObservableCollection<T> : ObservableCollection<T>
    {
        protected volatile bool _isObserving = true;
        public bool IsObserving { get { return _isObserving; } set { _isObserving = value; } }

        public static readonly int MAX_CAPACITY = int.MaxValue - 1; // MS limit
        private readonly int _capacity = MAX_CAPACITY;
        public int Capacity { get { return _capacity; } }

        public SwitchableObservableCollection() : base() { }
        public SwitchableObservableCollection(IEnumerable<T> collection) : base(collection) { }
        public SwitchableObservableCollection(int capacity) : base() { _capacity = capacity; }
        public SwitchableObservableCollection(bool isObserving) : base() { _isObserving = isObserving; }
        public SwitchableObservableCollection(bool isObserving, IEnumerable<T> collection) : base(collection) { _isObserving = isObserving; }
        public SwitchableObservableCollection(bool isObserving, int capacity) : base() { _isObserving = isObserving; _capacity = capacity; }

        public void AddRange(IEnumerable<T> range)
        {
            // get out if no new items
            if (range == null || !range.Any()) return;

            // prepare data for firing the events
            int newStartingIndex = Count;
            var newItems = new List<T>();
            newItems.AddRange(range);

            // add the items, making sure no events are fired
            _isObserving = false;
            foreach (var item in range)
            {
                Add(item);
            }
            _isObserving = true;

            // fire the events
            OnPropertyChanged(new PropertyChangedEventArgs("Count"));
            OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
            // this is tricky: call Reset first to make sure the controls will respond properly and not only add one item
            // LOLLO NOTE I took out the following so the list viewers don't lose the position.
            //OnCollectionChanged(new NotifyCollectionChangedEventArgs(action: NotifyCollectionChangedAction.Reset));
            OnCollectionChanged(new NotifyCollectionChangedEventArgs(action: NotifyCollectionChangedAction.Add, changedItems: newItems, startingIndex: newStartingIndex));
        }

        public void ReplaceAll(IEnumerable<T> range)
        {
            // get out if no new items
            if (range == null || !range.Any())
            {
                Clear();
            }
            else
            {
                // prepare data for firing the events
                var newItems = new List<T>();
                newItems.AddRange(range);

                // add the items, making sure no events are fired
                _isObserving = false;
                ClearItems();
                foreach (var item in range)
                {
                    Add(item);
                }
                _isObserving = true;

                // fire the events
                OnPropertyChanged(new PropertyChangedEventArgs("Count"));
                OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
                // this is tricky: call Reset first to make sure the controls will respond properly and not only add one item
                // when clearing a collection, only .Reset is thrown!
                OnCollectionChanged(new NotifyCollectionChangedEventArgs(action: NotifyCollectionChangedAction.Reset));
                OnCollectionChanged(new NotifyCollectionChangedEventArgs(action: NotifyCollectionChangedAction.Add, changedItems: newItems, startingIndex: 0));
            }
        }

        protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
        {
            if (_isObserving) base.OnCollectionChanged(e);
        }
        protected override void OnPropertyChanged(PropertyChangedEventArgs e)
        {
            if (_isObserving) base.OnPropertyChanged(e);
        }
        protected override void InsertItem(int index, T item)
        {
            if (Count < _capacity) base.InsertItem(index, item);
            else throw new IndexOutOfRangeException("SwitchableObservableCollection has reached max capacity = " + Capacity + " items");
        }
    }
}