Catalog/imagecatalog/ViewModelBase.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ImageCatalog_2
{
    public class ViewModelBase : INotifyPropertyChanged
    {
        private readonly SynchronizationContext? _synchronizationContext;

        protected ViewModelBase()
        {
            // Capture the synchronization context (UI thread context)
            _synchronizationContext = SynchronizationContext.Current;
        }

        public event PropertyChangedEventHandler? PropertyChanged;

        // This method is called by the Set accessor of each property.
        // The CallerMemberName attribute that is applied to the optional propertyName
        // parameter causes the property name of the caller to be substituted as an argument.
        protected void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
        {
            if (PropertyChanged == null)
                return;

            if (_synchronizationContext != null && SynchronizationContext.Current != _synchronizationContext)
            {
                // We're on a different thread, marshal to the UI thread
                _synchronizationContext.Send(_ =>
                {
                    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
                }, null);
            }
            else
            {
                // We're already on the UI thread or no sync context available
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }

    }
}