Ensure frame metadata is a deep copy.

src/ImageSharp/Formats/Gif/GifFrameMetaData.cs

@@ -6,8 +6,26 @@ namespace SixLabors.ImageSharp.Formats.Gif
     /// <summary>
     /// Provides Gif specific metadata information for the image frame.
     /// </summary>
-    public class GifFrameMetaData
+    public class GifFrameMetaData : IDeepCloneable
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GifFrameMetaData"/> class.
+        /// </summary>
+        public GifFrameMetaData()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GifFrameMetaData"/> class.
+        /// </summary>
+        /// <param name="other">The metadata to create an instance from.</param>
+        internal GifFrameMetaData(GifFrameMetaData other)
+        {
+            this.ColorTableLength = other.ColorTableLength;
+            this.FrameDelay = other.FrameDelay;
+            this.DisposalMethod = other.DisposalMethod;
+        }
+
         /// <summary>
         /// Gets or sets the length of the color table for paletted images.
         /// If not 0, then this field indicates the maximum number of colors to use when quantizing the
@@ -29,5 +47,8 @@ namespace SixLabors.ImageSharp.Formats.Gif
         /// be treated after being displayed.
         /// </summary>
         public GifDisposalMethod DisposalMethod { get; set; }
+
+        /// <inheritdoc/>
+        public IDeepCloneable DeepClone() => new GifFrameMetaData(this);
     }
 }

src/ImageSharp/IDeepCloneable.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// A generic interface for a deeply cloneable type.
+    /// </summary>
+    /// <typeparam name="T">The type of object to clone.</typeparam>
+    public interface IDeepCloneable<T>
+        where T : class, IDeepCloneable<T>
+    {
+        /// <summary>
+        /// Creates a new <typeparamref name="T"/> that is a deep copy of the current instance.
+        /// </summary>
+        /// <returns>The <typeparamref name="T"/>.</returns>
+        T DeepClone();
+    }
+
+    /// <summary>
+    /// An interface for objects that can be cloned. This creates a deep copy of the object.
+    /// </summary>
+    public interface IDeepCloneable
+    {
+        /// <summary>
+        /// Creates a new object that is a deep copy of the current instance.
+        /// </summary>
+        /// <returns>The <see cref="IDeepCloneable"/>.</returns>
+        IDeepCloneable DeepClone();
+    }
+}

src/ImageSharp/ImageFrame{TPixel}.cs

@@ -135,7 +135,7 @@ namespace SixLabors.ImageSharp
             this.MemoryAllocator = configuration.MemoryAllocator;
             this.PixelBuffer = this.MemoryAllocator.Allocate2D<TPixel>(source.PixelBuffer.Width, source.PixelBuffer.Height);
             source.PixelBuffer.GetSpan().CopyTo(this.PixelBuffer.GetSpan());
-            this.MetaData = source.MetaData.Clone();
+            this.MetaData = source.MetaData.DeepClone();
         }
 
         /// <summary>
@@ -260,7 +260,7 @@ namespace SixLabors.ImageSharp
                 return this.Clone() as ImageFrame<TPixel2>;
             }
 
-            var target = new ImageFrame<TPixel2>(this.configuration, this.Width, this.Height, this.MetaData.Clone());
+            var target = new ImageFrame<TPixel2>(this.configuration, this.Width, this.Height, this.MetaData.DeepClone());
 
             ParallelFor.WithTemporaryBuffer(
                 0,

src/ImageSharp/MetaData/ImageFrameMetaData.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System;
 using System.Collections.Generic;
 using SixLabors.ImageSharp.Formats;
 
@@ -10,9 +9,9 @@ namespace SixLabors.ImageSharp.MetaData
     /// <summary>
     /// Encapsulates the metadata of an image frame.
     /// </summary>
-    public sealed class ImageFrameMetaData
+    public sealed class ImageFrameMetaData : IDeepCloneable<ImageFrameMetaData>
     {
-        private readonly Dictionary<IImageFormat, object> formatMetaData = new Dictionary<IImageFormat, object>();
+        private readonly Dictionary<IImageFormat, IDeepCloneable> formatMetaData = new Dictionary<IImageFormat, IDeepCloneable>();
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageFrameMetaData"/> class.
@@ -32,17 +31,14 @@ namespace SixLabors.ImageSharp.MetaData
         {
             DebugGuard.NotNull(other, nameof(other));
 
-            foreach (KeyValuePair<IImageFormat, object> meta in other.formatMetaData)
+            foreach (KeyValuePair<IImageFormat, IDeepCloneable> meta in other.formatMetaData)
             {
-                this.formatMetaData.Add(meta.Key, meta.Value);
+                this.formatMetaData.Add(meta.Key, meta.Value.DeepClone());
             }
         }
 
-        /// <summary>
-        /// Clones this ImageFrameMetaData.
-        /// </summary>
-        /// <returns>The cloned instance.</returns>
-        public ImageFrameMetaData Clone() => new ImageFrameMetaData(this);
+        /// <inheritdoc/>
+        public ImageFrameMetaData DeepClone() => new ImageFrameMetaData(this);
 
         /// <summary>
         /// Gets the metadata value associated with the specified key.
@@ -55,9 +51,9 @@ namespace SixLabors.ImageSharp.MetaData
         /// </returns>
         public TFormatFrameMetaData GetFormatMetaData<TFormatMetaData, TFormatFrameMetaData>(IImageFormat<TFormatMetaData, TFormatFrameMetaData> key)
             where TFormatMetaData : class
-            where TFormatFrameMetaData : class
+            where TFormatFrameMetaData : class, IDeepCloneable
         {
-            if (this.formatMetaData.TryGetValue(key, out object meta))
+            if (this.formatMetaData.TryGetValue(key, out IDeepCloneable meta))
             {
                 return (TFormatFrameMetaData)meta;
             }

src/ImageSharp/Processing/Processors/Transforms/AffineTransformProcessor.cs

@@ -51,7 +51,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         {
             // We will always be creating the clone even for mutate because we may need to resize the canvas
             IEnumerable<ImageFrame<TPixel>> frames =
-                source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.TargetDimensions, x.MetaData.Clone()));
+                source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.TargetDimensions, x.MetaData.DeepClone()));
 
             // Use the overload to prevent an extra frame being added
             return new Image<TPixel>(source.GetConfiguration(), source.MetaData.Clone(), frames);

src/ImageSharp/Processing/Processors/Transforms/CropProcessor.cs

@@ -36,7 +36,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         protected override Image<TPixel> CreateDestination(Image<TPixel> source, Rectangle sourceRectangle)
         {
             // We will always be creating the clone even for mutate because we may need to resize the canvas
-            IEnumerable<ImageFrame<TPixel>> frames = source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.CropRectangle.Width, this.CropRectangle.Height, x.MetaData.Clone()));
+            IEnumerable<ImageFrame<TPixel>> frames = source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.CropRectangle.Width, this.CropRectangle.Height, x.MetaData.DeepClone()));
 
             // Use the overload to prevent an extra frame being added
             return new Image<TPixel>(source.GetConfiguration(), source.MetaData.Clone(), frames);

src/ImageSharp/Processing/Processors/Transforms/ProjectiveTransformProcessor.cs

@@ -51,7 +51,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         {
             // We will always be creating the clone even for mutate because we may need to resize the canvas
             IEnumerable<ImageFrame<TPixel>> frames =
-                source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.TargetDimensions.Width, this.TargetDimensions.Height, x.MetaData.Clone()));
+                source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.TargetDimensions.Width, this.TargetDimensions.Height, x.MetaData.DeepClone()));
 
             // Use the overload to prevent an extra frame being added
             return new Image<TPixel>(source.GetConfiguration(), source.MetaData.Clone(), frames);

src/ImageSharp/Processing/Processors/Transforms/ResizeProcessor.cs

@@ -215,7 +215,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         protected override Image<TPixel> CreateDestination(Image<TPixel> source, Rectangle sourceRectangle)
         {
             // We will always be creating the clone even for mutate because we may need to resize the canvas
-            IEnumerable<ImageFrame<TPixel>> frames = source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.Width, this.Height, x.MetaData.Clone()));
+            IEnumerable<ImageFrame<TPixel>> frames = source.Frames.Select(x => new ImageFrame<TPixel>(source.GetConfiguration(), this.Width, this.Height, x.MetaData.DeepClone()));
 
             // Use the overload to prevent an extra frame being added
             return new Image<TPixel>(source.GetConfiguration(), source.MetaData.Clone(), frames);