XAML-Map-Control/MapControl/Avalonia/Tile.Avalonia.cs

using Avalonia;
using Avalonia.Animation;
using Avalonia.Media;
using Avalonia.Styling;
using Avalonia.Threading;
using System;
using System.Threading.Tasks;

namespace MapControl
{
    public partial class Tile
    {
        public async Task LoadImageAsync(Func<Task<IImage>> loadImageFunc)
        {
            var image = await loadImageFunc().ConfigureAwait(false);

            void SetImageSource()
            {
                Image.Source = image;

                if (image != null && MapBase.ImageFadeDuration > TimeSpan.Zero)
                {
                    var fadeInAnimation = new Animation
                    {
                        Duration = MapBase.ImageFadeDuration,
                        Children =
                            {
                                new KeyFrame
                                {
                                    KeyTime = TimeSpan.Zero,
                                    Setters = { new Setter(Visual.OpacityProperty, 0d) }
                                },
                                new KeyFrame
                                {
                                    KeyTime = MapBase.ImageFadeDuration,
                                    Setters = { new Setter(Visual.OpacityProperty, 1d) }
                                }
                            }
                    };

                    _ = fadeInAnimation.RunAsync(Image);
                }
            }

            await Dispatcher.UIThread.InvokeAsync(SetImageSource);
        }
    }
}