Making changes from #2446 review

-Adding validation for size, channels and colorspace
-Refactoring to throw general exceptions
-Creating tests
-Using other better data types

Author: LuisAlfredo92

src/ImageSharp/Configuration.cs

@@ -8,6 +8,7 @@
 using SixLabors.ImageSharp.Formats.Jpeg;
 using SixLabors.ImageSharp.Formats.Pbm;
 using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.Formats.Qoi;
 using SixLabors.ImageSharp.Formats.Tga;
 using SixLabors.ImageSharp.Formats.Tiff;
 using SixLabors.ImageSharp.Formats.Webp;
@@ -212,6 +213,7 @@ public void Configure(IImageFormatConfigurationModule configuration)
     /// <see cref="TgaConfigurationModule"/>.
     /// <see cref="TiffConfigurationModule"/>.
     /// <see cref="WebpConfigurationModule"/>.
+    /// <see cref="QoiConfigurationModule"/>.
     /// </summary>
     /// <returns>The default configuration of <see cref="Configuration"/>.</returns>
     internal static Configuration CreateDefaultInstance() => new(
@@ -222,5 +224,6 @@ public void Configure(IImageFormatConfigurationModule configuration)
             new PbmConfigurationModule(),
             new TgaConfigurationModule(),
             new TiffConfigurationModule(),
-            new WebpConfigurationModule());
+            new WebpConfigurationModule(),
+            new QoiConfigurationModule());
 }

src/ImageSharp/Formats/Qoi/QoiConfigurationModule.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Qoi;
+
+/// <summary>
+/// Registers the image encoders, decoders and mime type detectors for the qoi format.
+/// </summary>
+public sealed class QoiConfigurationModule : IImageFormatConfigurationModule
+{
+    /// <inheritdoc/>
+    public void Configure(Configuration configuration)
+    {
+        configuration.ImageFormatsManager.SetDecoder(QoiFormat.Instance, QoiDecoder.Instance);
+        //configuration.ImageFormatsManager.SetEncoder(QoiFormat.Instance, new QoiEncoder());
+        configuration.ImageFormatsManager.AddImageFormatDetector(new QoiImageFormatDetector());
+    }
+}

src/ImageSharp/Formats/Qoi/QoiConstants.cs

@@ -7,19 +7,21 @@ namespace SixLabors.ImageSharp.Formats.Qoi;
 
 internal static class QoiConstants
 {
+    private static readonly byte[] SMagic = Encoding.UTF8.GetBytes("qoif");
+
     /// <summary>
     /// Gets the bytes that indicates the image is QOI
     /// </summary>
-    public static ReadOnlySpan<byte> Magic => Encoding.UTF8.GetBytes("qoif");
+    public static ReadOnlySpan<byte> Magic => SMagic;
 
     /// <summary>
     /// The list of mimetypes that equate to a QOI.
     /// See https://github.com/phoboslab/qoi/issues/167
     /// </summary>
-    public static readonly IEnumerable<string> MimeTypes = new[] { "image/qoi", "image/x-qoi", "image/vnd.qoi" };
+    public static readonly string[] MimeTypes = { "image/qoi", "image/x-qoi", "image/vnd.qoi" };
 
     /// <summary>
     /// The list of file extensions that equate to a QOI.
     /// </summary>
-    public static readonly IEnumerable<string> FileExtensions = new[] { "qoi" };
+    public static readonly string[] FileExtensions = { "qoi" };
 }

src/ImageSharp/Formats/Qoi/QoiDecoderCore.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Buffers.Binary;
+using System.Diagnostics.CodeAnalysis;
 using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.Metadata;
@@ -48,47 +50,67 @@ public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken
     public ImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken)
     {
         ImageMetadata metadata = new();
+        QoiMetadata qoiMetadata = metadata.GetQoiMetadata();
 
-        byte[] magicBytes = new byte[4], widthBytes = new byte[4], heightBytes = new byte[4];
+        Span<byte> magicBytes = stackalloc byte[4];
+        Span<byte> widthBytes = stackalloc byte[4];
+        Span<byte> heightBytes = stackalloc byte[4];
 
         // Read magic bytes
         int read = stream.Read(magicBytes);
         if (read != 4 || !magicBytes.SequenceEqual(QoiConstants.Magic.ToArray()))
         {
-            throw new InvalidImageContentException("The image is not a QOI image");
+            ThrowInvalidImageContentException();
         }
 
         // If it's a qoi image, read the rest of properties
         read = stream.Read(widthBytes);
         if (read != 4)
         {
-            throw new InvalidImageContentException("The image is not a QOI image");
+            ThrowInvalidImageContentException();
         }
 
         read = stream.Read(heightBytes);
         if (read != 4)
         {
-            throw new InvalidImageContentException("The image is not a QOI image");
+            ThrowInvalidImageContentException();
         }
 
-        widthBytes = widthBytes.Reverse().ToArray();
-        heightBytes = heightBytes.Reverse().ToArray();
-        Size size = new((int)BitConverter.ToUInt32(widthBytes), (int)BitConverter.ToUInt32(heightBytes));
+        // These numbers are in Big Endian so we have to reverse them to get the real number
+        uint width = BinaryPrimitives.ReadUInt32BigEndian(widthBytes),
+            height = BinaryPrimitives.ReadUInt32BigEndian(heightBytes);
+        if (width == 0 || height == 0)
+        {
+            throw new InvalidImageContentException(
+                $"The image has an invalid size: width = {width}, height = {height}");
+        }
+
+        qoiMetadata.Width = width;
+        qoiMetadata.Height = height;
+
+        Size size = new((int)width, (int)height);
 
         int channels = stream.ReadByte();
-        if (channels == -1)
+        if (channels is -1 or (not 3 and not 4))
         {
-            throw new InvalidImageContentException("The image is not a QOI image");
+            ThrowInvalidImageContentException();
         }
 
         PixelTypeInfo pixelType = new(8 * channels);
+        qoiMetadata.Channels = (QoiChannels)channels;
 
         int colorSpace = stream.ReadByte();
-        if (colorSpace == -1)
+        if (colorSpace is -1 or (not 0 and not 1))
         {
-            throw new InvalidImageContentException("The image is not a QOI image");
+            ThrowInvalidImageContentException();
         }
 
+        qoiMetadata.ColorSpace = (QoiColorSpace)colorSpace;
+
         return new ImageInfo(pixelType, size, metadata);
     }
+
+    [DoesNotReturn]
+    private static void ThrowInvalidImageContentException()
+        => throw new InvalidImageContentException("The image is not a valid QOI image.");
 }

src/ImageSharp/Formats/Qoi/QoiImageFormatDetector.cs

@@ -0,0 +1,27 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Buffers.Binary;
+using System.Diagnostics.CodeAnalysis;
+using SixLabors.ImageSharp.Formats.Png;
+
+namespace SixLabors.ImageSharp.Formats.Qoi;
+
+/// <summary>
+/// Detects qoi file headers
+/// </summary>
+public class QoiImageFormatDetector : IImageFormatDetector
+{
+    /// <inheritdoc/>
+    public int HeaderSize => 14;
+
+    /// <inheritdoc/>
+    public bool TryDetectFormat(ReadOnlySpan<byte> header, [NotNullWhen(true)] out IImageFormat? format)
+    {
+        format = this.IsSupportedFileFormat(header) ? QoiFormat.Instance : null;
+        return format != null;
+    }
+
+    private bool IsSupportedFileFormat(ReadOnlySpan<byte> header)
+        => header.Length == this.HeaderSize && header[..4] == QoiConstants.Magic;
+}

tests/ImageSharp.Benchmarks/Program.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using BenchmarkDotNet.Configs;
 using BenchmarkDotNet.Running;
 
 namespace SixLabors.ImageSharp.Benchmarks;
@@ -16,5 +15,5 @@ public class Program
     /// </param>
     public static void Main(string[] args) => BenchmarkSwitcher
         .FromAssembly(typeof(Program).Assembly)
-        .Run(args, new DebugInProcessConfig());
+        .Run(args);
 }

tests/ImageSharp.Tests/Formats/Qoi/QoiDecoderTests.cs

@@ -0,0 +1,28 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Tests.Formats.Qoi;
+
+[Trait("Format", "Qoi")]
+[ValidateDisposedMemoryAllocations]
+public class QoiDecoderTests
+{
+    [Theory]
+    [InlineData(TestImages.Qoi.Dice)]
+    [InlineData(TestImages.Qoi.EdgeCase)]
+    [InlineData(TestImages.Qoi.Kodim10)]
+    [InlineData(TestImages.Qoi.Kodim23)]
+    [InlineData(TestImages.Qoi.QoiLogo)]
+    [InlineData(TestImages.Qoi.TestCard)]
+    [InlineData(TestImages.Qoi.TestCardRGBA)]
+    [InlineData(TestImages.Qoi.Wikipedia008)]
+    public void Identify(string imagePath)
+    {
+        TestFile testFile = TestFile.Create(imagePath);
+        using MemoryStream stream = new(testFile.Bytes, false);
+
+        ImageInfo imageInfo = Image.Identify(stream);
+
+        Assert.NotNull(imageInfo);
+    }
+}

tests/ImageSharp.Tests/ImageSharp.Tests.csproj

@@ -73,5 +73,9 @@
     <Service Include="{508349b6-6b84-4df5-91f0-309beebad82d}" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Folder Include="Formats\Qoi\" />
+  </ItemGroup>
+
 </Project>