Deleting folders with custom icons no longer triggers system file warning

Source/LibationUiBase/IcoEncoder.cs

@@ -0,0 +1,52 @@
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp;
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using SixLabors.ImageSharp.Formats;
+
+namespace LibationUiBase
+{
+	public class IcoEncoder : IImageEncoder
+	{
+		public bool SkipMetadata { get; init; } = true;
+
+		public void Encode<TPixel>(Image<TPixel> image, Stream stream) where TPixel : unmanaged, IPixel<TPixel>
+		{
+			// https://stackoverflow.com/a/21389253
+
+			using var ms = new MemoryStream();
+			//Knowing the image size ahead of time removes the
+			//requirement of the output stream to support seeking.
+			image.SaveAsPng(ms);
+
+			//Disposing of the BinaryWriter disposes the soutput stream. Let the caller clean up.
+			var bw = new BinaryWriter(stream);
+
+			// Header
+			bw.Write((short)0);   // 0-1 : reserved
+			bw.Write((short)1);   // 2-3 : 1=ico, 2=cur
+			bw.Write((short)1);   // 4-5 : number of images
+
+			// Image directory
+			var w = image.Width;
+			if (w >= 256) w = 0;
+			bw.Write((byte)w);                      // 0 : width of image
+			var h = image.Height;
+			if (h >= 256) h = 0;
+			bw.Write((byte)h);                      // 1 : height of image
+			bw.Write((byte)0);                      // 2 : number of colors in palette
+			bw.Write((byte)0);                      // 3 : reserved
+			bw.Write((short)0);                     // 4 : number of color planes
+			bw.Write((short)0);                     // 6 : bits per pixel
+			bw.Write((int)ms.Position);             // 8 : image size
+			bw.Write((int)stream.Position + 4);     // 12: offset of image data
+			ms.Position = 0;
+			ms.CopyTo(stream);                      // Image data
+		}
+
+		public Task EncodeAsync<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken) where TPixel : unmanaged, IPixel<TPixel>
+			=> throw new NotImplementedException();
+	}
+}