Clearer – A Gesture-Driven Windows 8 To-Do Application

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


namespace ClearStyle.ViewModel
{
  /// <summary>
  /// An ObservableCollection which exposes a Reset method, which raises a CollectionChanged
  /// eventy of type 'NotifyCollectionChangedAction.Reset'.
  /// </summary>
  public class ObservableCollectionEx<T> : ObservableCollection<T>
  {
    public ObservableCollectionEx()
    {
    }

    public ObservableCollectionEx(IEnumerable<T> list)
      : base(list)
    {
    }

    public void Reset()
    {
      OnCollectionChanged(new NotifyCollectionChangedEventArgs(
        NotifyCollectionChangedAction.Reset));
    }

    #region property changed relay

    protected override void InsertItem(int index, T item)
    {
      var propertyChangedItem = item as INotifyPropertyChanged;
      if (propertyChangedItem != null)
      {
        propertyChangedItem.PropertyChanged += Item_PropertyChanged;
      }

      base.InsertItem(index, item);
    }

    protected override void RemoveItem(int index)
    {
      T item = this[index];

      var propertyChangedItem = item as INotifyPropertyChanged;
      if (propertyChangedItem != null)
      {
        propertyChangedItem.PropertyChanged -= Item_PropertyChanged;
      }

      base.RemoveItem(index);
    }

    private void Item_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
      RelayedPropertyChanged(sender, e);
    }

    public event PropertyChangedEventHandler RelayedPropertyChanged = delegate { };

    #endregion
  }
}