Introduce JpegComData.cs

Author: RobertMut

src/ImageSharp/Formats/Jpeg/JpegComData.cs

@@ -0,0 +1,32 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Formats.Jpeg;
+
+/// <summary>
+/// Contains JPEG comment
+/// </summary>
+public readonly struct JpegComData
+{
+    /// <summary>
+    /// Converts string to <see cref="JpegComData"/>
+    /// </summary>
+    /// <param name="value">The comment string.</param>
+    /// <returns>The <see cref="JpegComData"/></returns>
+    public static JpegComData FromString(string value) => new(value.AsMemory());
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="JpegComData"/> struct.
+    /// </summary>
+    /// <param name="value">The comment ReadOnlyMemory of chars.</param>
+    public JpegComData(ReadOnlyMemory<char> value)
+        => this.Value = value;
+
+    public ReadOnlyMemory<char> Value { get; }
+
+    /// <summary>
+    /// Converts Value to string
+    /// </summary>
+    /// <returns>The comment string.</returns>
+    public override string ToString() => this.Value.ToString();
+}

src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs

@@ -529,7 +529,7 @@ private void ProcessComMarker(BufferedReadStream stream, int markerContentByteSi
         stream.Read(temp);
         string comment = Encoding.ASCII.GetString(temp);
 
-        metadata.Comments.Add(comment);
+        metadata.Comments.Add(JpegComData.FromString(comment));
     }
 
     /// <summary>

src/ImageSharp/Formats/Jpeg/JpegEncoderCore.cs

@@ -186,12 +186,12 @@ private void WriteComment(JpegMetadata metadata)
 
         for (int i = 0; i < metadata.Comments.Count; i++)
         {
-            string comment = metadata.Comments[i];
+            string comment = metadata.Comments[i].ToString();
 
             if (comment.Length > maxCommentLength)
             {
                 string splitComment = comment.Substring(maxCommentLength, comment.Length - maxCommentLength);
-                metadata.Comments.Insert(i + 1, splitComment);
+                metadata.Comments.Insert(i + 1, JpegComData.FromString(splitComment));
 
                 // We don't want to keep the extra bytes
                 comment = comment.Substring(0, maxCommentLength);

src/ImageSharp/Formats/Jpeg/JpegMetadata.cs

@@ -15,7 +15,7 @@ public class JpegMetadata : IDeepCloneable
     /// </summary>
     public JpegMetadata()
     {
-        this.Comments = new List<string>();
+        this.Comments = new List<JpegComData>();
     }
 
     /// <summary>
@@ -106,7 +106,7 @@ public int Quality
     /// <summary>
     /// Gets the comments.
     /// </summary>
-    public IList<string> Comments { get; }
+    public IList<JpegComData> Comments { get; }
 
     /// <inheritdoc/>
     public IDeepCloneable DeepClone() => new JpegMetadata(this);

tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Metadata.cs

@@ -435,7 +435,7 @@ public void JpegDecoder_DecodeMetadataComment<TPixel>(TestImageProvider<TPixel>
         JpegMetadata metadata = image.Metadata.GetJpegMetadata();
 
         Assert.Equal(1, metadata.Comments.Count);
-        Assert.Equal(expectedComment, metadata.Comments.ElementAtOrDefault(0));
+        Assert.Equal(expectedComment, metadata.Comments.ElementAtOrDefault(0).ToString());
         image.DebugSave(provider);
         image.CompareToOriginal(provider);
     }

tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.Metadata.cs

@@ -172,7 +172,7 @@ public void Encode_PreservesComments<TPixel>(TestImageProvider<TPixel> provider)
         JpegMetadata actual = output.Metadata.GetJpegMetadata();
         Assert.NotEmpty(actual.Comments);
         Assert.Equal(1, actual.Comments.Count);
-        Assert.Equal("TEST COMMENT", actual.Comments.ElementAtOrDefault(0));
+        Assert.Equal("TEST COMMENT", actual.Comments.ElementAtOrDefault(0).ToString());
     }
 
     [Fact]
@@ -184,8 +184,8 @@ public void Encode_SavesMultipleComments()
         using var memStream = new MemoryStream();
 
         // act
-        meta.Comments.Add("First comment");
-        meta.Comments.Add("Second Comment");
+        meta.Comments.Add(JpegComData.FromString("First comment"));
+        meta.Comments.Add(JpegComData.FromString("Second Comment"));
         input.Save(memStream, JpegEncoder);
 
         // assert
@@ -194,8 +194,8 @@ public void Encode_SavesMultipleComments()
         JpegMetadata actual = output.Metadata.GetJpegMetadata();
         Assert.NotEmpty(actual.Comments);
         Assert.Equal(2, actual.Comments.Count);
-        Assert.Equal(meta.Comments.ElementAtOrDefault(0), actual.Comments.ElementAtOrDefault(0));
-        Assert.Equal(meta.Comments.ElementAtOrDefault(1), actual.Comments.ElementAtOrDefault(1));
+        Assert.Equal(meta.Comments.ElementAtOrDefault(0).ToString(), actual.Comments.ElementAtOrDefault(0).ToString());
+        Assert.Equal(meta.Comments.ElementAtOrDefault(1).ToString(), actual.Comments.ElementAtOrDefault(1).ToString());
     }
 
     [Theory]

tests/ImageSharp.Tests/Formats/Jpg/JpegMetadataTests.cs

@@ -64,7 +64,7 @@ public void Comment_EmptyComment()
     {
         var meta = new JpegMetadata();
 
-        Assert.True(Array.Empty<string>().SequenceEqual(meta.Comments));
+        Assert.True(Array.Empty<JpegComData>().SequenceEqual(meta.Comments));
     }
 
     [Fact]
@@ -74,9 +74,9 @@ public void Comment_OnlyComment()
         var expectedCollection = new Collection<string> { comment };
 
         var meta = new JpegMetadata();
-        meta.Comments.Add(comment);
+        meta.Comments.Add(JpegComData.FromString(comment));
 
         Assert.Equal(1, meta.Comments.Count);
-        Assert.True(expectedCollection.FirstOrDefault() == meta.Comments.FirstOrDefault());
+        Assert.True(expectedCollection.FirstOrDefault() == meta.Comments.FirstOrDefault().ToString());
     }
 }