ImageSharp/tests/ImageSharp.Tests/TestUtilities/ImageComparison/ImageComparingUtils.cs

// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

using System;
using System.IO;
using ImageMagick;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
using Xunit;

namespace SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison
{
    public static class ImageComparingUtils
    {
        public static void CompareWithReferenceDecoder<TPixel>(
            TestImageProvider<TPixel> provider,
            Image<TPixel> image,
            bool useExactComparer = true,
            float compareTolerance = 0.01f)
            where TPixel : unmanaged, ImageSharp.PixelFormats.IPixel<TPixel>
        {
            string path = TestImageProvider<TPixel>.GetFilePathOrNull(provider);
            if (path == null)
            {
                throw new InvalidOperationException("CompareToOriginal() works only with file providers!");
            }

            var testFile = TestFile.Create(path);
            using Image<Rgba32> magickImage = DecodeWithMagick<Rgba32>(new FileInfo(testFile.FullPath));
            if (useExactComparer)
            {
                ImageComparer.Exact.VerifySimilarity(magickImage, image);
            }
            else
            {
                ImageComparer.Tolerant(compareTolerance).VerifySimilarity(magickImage, image);
            }
        }

        public static Image<TPixel> DecodeWithMagick<TPixel>(FileInfo fileInfo)
            where TPixel : unmanaged, ImageSharp.PixelFormats.IPixel<TPixel>
        {
            Configuration configuration = Configuration.Default.Clone();
            configuration.PreferContiguousImageBuffers = true;
            using (var magickImage = new MagickImage(fileInfo))
            {
                magickImage.AutoOrient();
                var result = new Image<TPixel>(configuration, magickImage.Width, magickImage.Height);

                Assert.True(result.DangerousTryGetSinglePixelMemory(out Memory<TPixel> resultPixels));

                using (IUnsafePixelCollection<ushort> pixels = magickImage.GetPixelsUnsafe())
                {
                    byte[] data = pixels.ToByteArray(PixelMapping.RGBA);

                    PixelOperations<TPixel>.Instance.FromRgba32Bytes(
                        configuration,
                        data,
                        resultPixels.Span,
                        resultPixels.Length);
                }

                return result;
            }
        }
    }
}