Also allow specification of the text encoding inside the gif decoder.

src/ImageSharp.Formats.Gif/GifDecoder.cs

@@ -17,7 +17,9 @@ namespace ImageSharp.Formats
         public void Decode<TColor>(Image<TColor> image, Stream stream, IDecoderOptions options)
             where TColor : struct, IPixel<TColor>
         {
-            new GifDecoderCore<TColor>(options).Decode(image, stream);
+            IGifDecoderOptions gifOptions = GifDecoderOptions.Create(options);
+
+            new GifDecoderCore<TColor>(gifOptions).Decode(image, stream);
         }
     }
 }

src/ImageSharp.Formats.Gif/GifDecoderCore.cs

@@ -25,7 +25,7 @@ namespace ImageSharp.Formats
         /// <summary>
         /// The decoder options.
         /// </summary>
-        private readonly IDecoderOptions options;
+        private readonly IGifDecoderOptions options;
 
         /// <summary>
         /// The image to decode the information to.
@@ -71,9 +71,9 @@ namespace ImageSharp.Formats
         /// Initializes a new instance of the <see cref="GifDecoderCore{TColor}"/> class.
         /// </summary>
         /// <param name="options">The decoder options.</param>
-        public GifDecoderCore(IDecoderOptions options)
+        public GifDecoderCore(IGifDecoderOptions options)
         {
-            this.options = options ?? new DecoderOptions();
+            this.options = options ?? new GifDecoderOptions();
         }
 
         /// <summary>
@@ -260,7 +260,7 @@ namespace ImageSharp.Formats
                 try
                 {
                     this.currentStream.Read(commentsBuffer, 0, length);
-                    string comments = Encoding.GetEncoding("ASCII").GetString(commentsBuffer, 0, length);
+                    string comments = this.options.TextEncoding.GetString(commentsBuffer, 0, length);
                     this.decodedImage.MetaData.Properties.Add(new ImageProperty("Comments", comments));
                 }
                 finally

src/ImageSharp.Formats.Gif/GifDecoderOptions.cs

@@ -0,0 +1,62 @@
+// <copyright file="GifDecoderOptions.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Formats
+{
+    using System.Text;
+
+    /// <summary>
+    /// Encapsulates the gif decoder options.
+    /// </summary>
+    public sealed class GifDecoderOptions : DecoderOptions, IGifDecoderOptions
+    {
+        private static readonly Encoding DefaultEncoding = Encoding.GetEncoding("ASCII");
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GifDecoderOptions"/> class.
+        /// </summary>
+        public GifDecoderOptions()
+        {
+            this.InitializeWithDefaults();
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GifDecoderOptions"/> class.
+        /// </summary>
+        /// <param name="options">The options for the decoder.</param>
+        private GifDecoderOptions(IDecoderOptions options)
+            : base(options)
+        {
+            this.InitializeWithDefaults();
+        }
+
+        /// <summary>
+        /// Gets the encoding that should be used when reading comments.
+        /// </summary>
+        public Encoding TextEncoding { get; set; }
+
+        /// <summary>
+        /// Converts the options to a <see cref="GifDecoderOptions"/> instance with a cast
+        /// or by creating a new instance with the specfied options.
+        /// </summary>
+        /// <param name="options">The options for the decoder.</param>
+        /// <returns>The options for the png decoder.</returns>
+        internal static IGifDecoderOptions Create(IDecoderOptions options)
+        {
+            IGifDecoderOptions gifOptions = options as IGifDecoderOptions;
+            if (gifOptions != null)
+            {
+                return gifOptions;
+            }
+
+            return new GifDecoderOptions(options);
+        }
+
+        private void InitializeWithDefaults()
+        {
+            this.TextEncoding = DefaultEncoding;
+        }
+    }
+}

src/ImageSharp.Formats.Gif/IGifDecoderOptions.cs

@@ -0,0 +1,20 @@
+// <copyright file="IGifDecoderOptions.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Formats
+{
+    using System.Text;
+
+    /// <summary>
+    /// Encapsulates the gif decoder options.
+    /// </summary>
+    public interface IGifDecoderOptions : IDecoderOptions
+    {
+        /// <summary>
+        /// Gets the encoding that should be used when reading comments.
+        /// </summary>
+        Encoding TextEncoding { get; }
+    }
+}

tests/ImageSharp.Tests/Formats/Gif/GifDecoderCoreTests.cs

@@ -5,8 +5,11 @@
 
 namespace ImageSharp.Tests
 {
+    using System.Text;
     using Xunit;
 
+    using ImageSharp.Formats;
+
     public class GifDecoderCoreTests
     {
         [Fact]
@@ -42,5 +45,22 @@ namespace ImageSharp.Tests
                 Assert.Equal(0, image.MetaData.Properties.Count);
             }
         }
+
+        [Fact]
+        public void Decode_TextEncodingSetToUnicode_TextIsReadWithCorrectEncoding()
+        {
+            var options = new GifDecoderOptions()
+            {
+                TextEncoding = Encoding.Unicode
+            };
+
+            TestFile testFile = TestFile.Create(TestImages.Gif.Rings);
+
+            using (Image image = new Image(testFile.FilePath, options))
+            {
+                Assert.Equal(1, image.MetaData.Properties.Count);
+                Assert.Equal("浉条卥慨灲", image.MetaData.Properties[0].Value);
+            }
+        }
     }
 }