ImageSharp/tests/ImageSharp.Tests/TestUtilities/ReferenceCodecs/MagickReferenceDecoder.cs

// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.

using System;
using System.IO;
using System.Runtime.InteropServices;

using ImageMagick;

using SixLabors.ImageSharp.Advanced;
using SixLabors.ImageSharp.Formats;
using SixLabors.ImageSharp.PixelFormats;

namespace SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs
{
    public class MagickReferenceDecoder : IImageDecoder
    {
        public static MagickReferenceDecoder Instance { get; } = new MagickReferenceDecoder();

        public Image<TPixel> Decode<TPixel>(Configuration configuration, Stream stream)
            where TPixel : struct, IPixel<TPixel>
        {
            using var magickImage = new MagickImage(stream);
            var result = new Image<TPixel>(configuration, magickImage.Width, magickImage.Height);
            Span<TPixel> resultPixels = result.GetPixelSpan();

            using IPixelCollection pixels = magickImage.GetPixelsUnsafe();
            if (magickImage.Depth == 8)
            {
                byte[] data = pixels.ToByteArray(PixelMapping.RGBA);

                PixelOperations<TPixel>.Instance.FromRgba32Bytes(
                    configuration,
                    data,
                    resultPixels,
                    resultPixels.Length);
            }
            else if (magickImage.Depth == 16)
            {
                ushort[] data = pixels.ToShortArray(PixelMapping.RGBA);
                Span<byte> bytes = MemoryMarshal.Cast<ushort, byte>(data.AsSpan());

                PixelOperations<TPixel>.Instance.FromRgba64Bytes(
                    configuration,
                    bytes,
                    resultPixels,
                    resultPixels.Length);
            }
            else
            {
                throw new InvalidOperationException();
            }

            return result;
        }

        public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
    }
}