自定義具有通知功能的字典-ObservableDictionary

public class ObservableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, INotifyCollectionChanged, INotifyPropertyChanged where TKey : notnull
{
    private int _index;
    public event NotifyCollectionChangedEventHandler? CollectionChanged;
    public event PropertyChangedEventHandler? PropertyChanged;

    public new KeyCollection Keys
    {
        get { return base.Keys; }
    }

    public new ValueCollection Values
    {
        get { return base.Values; }
    }

    public new int Count
    {
        get { return base.Count; }
    }

    public new TValue this[TKey key]
    {
        get { return this.GetValue(key); }
        set { this.SetValue(key, value); }
    }

    public TValue this[int index]
    {
        get { return this.GetIndexValue(index); }
        set { this.SetIndexValue(index, value); }
    }

    public new void Add(TKey key, TValue value)
    {
        base.Add(key, value);
        this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, this.FindPair(key), _index));
        OnPropertyChanged(nameof(Keys));
        OnPropertyChanged(nameof(Values));
        OnPropertyChanged(nameof(Count));
    }

    public new void Clear()
    {
        base.Clear();
        this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
        OnPropertyChanged(nameof(Keys));
        OnPropertyChanged(nameof(Values));
        OnPropertyChanged(nameof(Count));
    }

    public new bool Remove(TKey key)
    {
        var pair = this.FindPair(key);
        if (base.Remove(key))
        {
            this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, pair, _index));
            OnPropertyChanged(nameof(Keys));
            OnPropertyChanged(nameof(Values));
            OnPropertyChanged(nameof(Count));
            return true;
        }
        return false;
    }

    protected void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
    {
        if (this.CollectionChanged != null)
        {
            this.CollectionChanged(this, e);
        }
    }

    protected void OnPropertyChanged(string propertyName)
    {
        if (this.PropertyChanged != null)
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    private TValue GetIndexValue(int index)
    {
        for (int i = 0; i < this.Count; i++)
        {
            if (i == index)
            {
                var pair = this.ElementAt(i);
                return pair.Value;
            }
        }

        return default;
    }

    private void SetIndexValue(int index, TValue value)
    {
        try
        {
            var pair = this.ElementAtOrDefault(index);
            SetValue(pair.Key, value);
        }
        catch (Exception)
        {

        }
    }

    private TValue GetValue(TKey key)
    {
        if (base.ContainsKey(key))
        {
            return base[key];
        }
        else
        {
            return default;
        }
    }

    private void SetValue(TKey key, TValue value)
    {
        if (base.ContainsKey(key))
        {
            var pair = this.FindPair(key);
            int index = _index;
            base[key] = value;
            var newpair = this.FindPair(key);
            this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, newpair, pair, index));
            OnPropertyChanged(nameof(Values));
            OnPropertyChanged("Item[]");
        }
        else
        {
            this.Add(key, value);
        }
    }

    private KeyValuePair<TKey, TValue> FindPair(TKey key)
    {
        _index = 0;
        foreach (var item in this)
        {
            if (item.Key.Equals(key))
            {
                return item;
            }
            _index++;
        }
        return default;
    }

    private int IndexOf(TKey key)
    {
        int index = 0;
        foreach (var item in this)
        {
            if (item.Key.Equals(key))
            {
                return index;
            }
            index++;
        }
        return -1;
    }


}