Exposed used compression method in metadata

src/ImageSharp/Formats/Heic/HeicCompressionMethod.cs

@@ -0,0 +1,45 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Heic;
+
+/// <summary>
+/// Compression algorithms possible inside an HEIF (High Efficiency File Format) based file.
+/// </summary>
+public enum HeicCompressionMethod
+{
+    /// <summary>
+    /// High Efficiency Video Coding
+    /// </summary>
+    Hevc,
+
+    /// <summary>
+    /// Legact JPEG
+    /// </summary>
+    LegacyJpeg,
+
+    /// <summary>
+    /// JPEG 2000
+    /// </summary>
+    Jpeg2000,
+
+    /// <summary>
+    /// JPEG-XR
+    /// </summary>
+    JpegXR,
+
+    /// <summary>
+    /// JPEG-XS
+    /// </summary>
+    JpegXS,
+
+    /// <summary>
+    /// AOMedia's Video 1 coding
+    /// </summary>
+    Av1,
+
+    /// <summary>
+    /// Advanced Video Coding
+    /// </summary>
+    Avc,
+}

src/ImageSharp/Formats/Heic/HeicDecoderCore.cs

@@ -25,7 +25,7 @@ internal sealed class HeicDecoderCore : IImageDecoderInternals
     /// <summary>
     /// The <see cref="ImageMetadata"/> decoded by this decoder instance.
     /// </summary>
-    private ImageMetadata? metadata;
+    private readonly ImageMetadata metadata;
 
     private uint primaryItem;
 
@@ -130,6 +130,12 @@ internal sealed class HeicDecoderCore : IImageDecoderInternals
             throw new ImageFormatException("No primary item found");
         }
 
+        HeicMetadata meta = this.metadata.GetHeicMetadata();
+        if (this.itemLinks.Any(link => link.Type == Heic4CharCode.thmb))
+        {
+            meta.CompressionMethod = HeicCompressionMethod.LegacyJpeg;
+        }
+
         return new ImageInfo(new PixelTypeInfo(item.BitsPerPixel), new(item.Extent.Width, item.Extent.Height), this.metadata);
     }
 
@@ -432,6 +438,7 @@ internal sealed class HeicDecoderCore : IImageDecoderInternals
                 case Heic4CharCode.rloc:
                 case Heic4CharCode.udes:
                     // TODO: Implement
+                    properties.Add(new KeyValuePair<Heic4CharCode, object>(itemType, new object()));
                     break;
                 default:
                     throw new ImageFormatException($"Unknown item type in property box of '{PrettyPrint(itemType)}'");
@@ -594,6 +601,9 @@ internal sealed class HeicDecoderCore : IImageDecoderInternals
         Span<byte> thumbSpan = thumbMemory.GetSpan();
         stream.Read(thumbSpan);
 
+        HeicMetadata meta = this.metadata.GetHeicMetadata();
+        meta.CompressionMethod = HeicCompressionMethod.LegacyJpeg;
+
         return Image.Load<TPixel>(thumbSpan);
     }
 

src/ImageSharp/Formats/Heic/HeicMetadata.cs

@@ -20,8 +20,12 @@ public class HeicMetadata : IDeepCloneable
     /// </summary>
     /// <param name="other">The metadata to create an instance from.</param>
     private HeicMetadata(HeicMetadata other)
-    {
-    }
+        => this.CompressionMethod = other.CompressionMethod;
+
+    /// <summary>
+    /// Gets or sets the compression method used for the primary frame.
+    /// </summary>
+    public HeicCompressionMethod CompressionMethod { get; set; }
 
     /// <inheritdoc/>
     public IDeepCloneable DeepClone() => new HeicMetadata(this);

tests/ImageSharp.Tests/Formats/Heic/HeicDecoderTests.cs

@@ -11,10 +11,10 @@ namespace SixLabors.ImageSharp.Tests.Formats.Heic;
 public class HeicDecoderTests
 {
     [Theory]
-    [InlineData(TestImages.Heic.Image1)]
-    [InlineData(TestImages.Heic.Sample640x427)]
-    [InlineData(TestImages.Heic.FujiFilmHif)]
-    public void Identify(string imagePath)
+    [InlineData(TestImages.Heic.Image1, HeicCompressionMethod.Hevc)]
+    [InlineData(TestImages.Heic.Sample640x427, HeicCompressionMethod.Hevc)]
+    [InlineData(TestImages.Heic.FujiFilmHif, HeicCompressionMethod.LegacyJpeg)]
+    public void Identify(string imagePath, HeicCompressionMethod compressionMethod)
     {
         TestFile testFile = TestFile.Create(imagePath);
         using MemoryStream stream = new(testFile.Bytes, false);
@@ -23,8 +23,8 @@ public class HeicDecoderTests
         HeicMetadata heicMetadata = imageInfo.Metadata.GetHeicMetadata();
 
         Assert.NotNull(imageInfo);
-        Assert.Equal(imageInfo.Metadata.DecodedImageFormat, HeicFormat.Instance);
-        //Assert.Equal(heicMetadata.Channels, channels);
+        Assert.Equal(HeicFormat.Instance, imageInfo.Metadata.DecodedImageFormat);
+        Assert.Equal(compressionMethod, heicMetadata.CompressionMethod);
     }
 
     [Theory]
@@ -33,10 +33,10 @@ public class HeicDecoderTests
         where TPixel : unmanaged, IPixel<TPixel>
     {
         using Image<TPixel> image = provider.GetImage();
-        HeicMetadata qoiMetadata = image.Metadata.GetHeicMetadata();
+        HeicMetadata heicMetadata = image.Metadata.GetHeicMetadata();
         image.DebugSave(provider);
 
         image.CompareToReferenceOutput(provider);
-        //Assert.Equal(heicMetadata.Channels, channels);
+        Assert.Equal(HeicCompressionMethod.LegacyJpeg, heicMetadata.CompressionMethod);
     }
 }

tests/ImageSharp.Tests/TestImages.cs

@@ -1112,6 +1112,7 @@ public static class TestImages
         public const string Image3 = "Heic/image3.heic";
         public const string Image4 = "Heic/image4.heic";
         public const string Sample640x427 = "Heic/dwsample-heic-640.heic";
+        // Downloaded from: https://github.com/draktable-org/darktable/issues/14473
         public const string FujiFilmHif = "Heic/IMG-20230508-0053.hif";
     }
 }