Added metadata class for image frames.

src/ImageSharp.Formats.Gif/GifDecoderCore.cs

@@ -321,12 +321,14 @@ namespace ImageSharp.Formats
 
             if (this.previousFrame == null)
             {
-                image = this.decodedImage;
-
                 this.decodedImage.MetaData.Quality = colorTableLength / 3;
 
                 // This initializes the image to become fully transparent because the alpha channel is zero.
-                image.InitPixels(imageWidth, imageHeight);
+                this.decodedImage.InitPixels(imageWidth, imageHeight);
+
+                this.SetFrameDelay(this.decodedImage.MetaData);
+
+                image = this.decodedImage;
             }
             else
             {
@@ -338,6 +340,8 @@ namespace ImageSharp.Formats
 
                 currentFrame = this.previousFrame.Clone();
 
+                this.SetFrameDelay(currentFrame.MetaData);
+
                 image = currentFrame;
 
                 this.RestoreToBackground(image);
@@ -345,11 +349,6 @@ namespace ImageSharp.Formats
                 this.decodedImage.Frames.Add(currentFrame);
             }
 
-            if (this.graphicsControlExtension != null && this.graphicsControlExtension.DelayTime > 0)
-            {
-                image.FrameDelay = this.graphicsControlExtension.DelayTime;
-            }
-
             int i = 0;
             int interlacePass = 0; // The interlace pass
             int interlaceIncrement = 8; // The interlacing line increment
@@ -465,5 +464,17 @@ namespace ImageSharp.Formats
 
             this.restoreArea = null;
         }
+
+        /// <summary>
+        /// Sets the frame delay in the metadata.
+        /// </summary>
+        /// <param name="metaData">The meta data.</param>
+        private void SetFrameDelay(IMetaData metaData)
+        {
+            if (this.graphicsControlExtension != null && this.graphicsControlExtension.DelayTime > 0)
+            {
+                metaData.FrameDelay = this.graphicsControlExtension.DelayTime;
+            }
+        }
     }
 }

src/ImageSharp.Formats.Gif/GifEncoderCore.cs

@@ -229,14 +229,41 @@ namespace ImageSharp.Formats
             }
         }
 
+        /// <summary>
+        /// Writes the graphics control extension to the stream.
+        /// </summary>
+        /// <typeparam name="TColor">The pixel format.</typeparam>
+        /// <param name="image">The <see cref="Image{TColor}"/> to encode.</param>
+        /// <param name="writer">The stream to write to.</param>
+        /// <param name="transparencyIndex">The index of the color in the color palette to make transparent.</param>
+        private void WriteGraphicalControlExtension<TColor>(Image<TColor> image, EndianBinaryWriter writer, int transparencyIndex)
+            where TColor : struct, IPackedPixel, IEquatable<TColor>
+        {
+            this.WriteGraphicalControlExtension(image, image.MetaData, writer, transparencyIndex);
+        }
+
+        /// <summary>
+        /// Writes the graphics control extension to the stream.
+        /// </summary>
+        /// <typeparam name="TColor">The pixel format.</typeparam>
+        /// <param name="imageFrame">The <see cref="ImageFrame{TColor}"/> to encode.</param>
+        /// <param name="writer">The stream to write to.</param>
+        /// <param name="transparencyIndex">The index of the color in the color palette to make transparent.</param>
+        private void WriteGraphicalControlExtension<TColor>(ImageFrame<TColor> imageFrame, EndianBinaryWriter writer, int transparencyIndex)
+            where TColor : struct, IPackedPixel, IEquatable<TColor>
+        {
+            this.WriteGraphicalControlExtension(imageFrame, imageFrame.MetaData, writer, transparencyIndex);
+        }
+
         /// <summary>
         /// Writes the graphics control extension to the stream.
         /// </summary>
         /// <typeparam name="TColor">The pixel format.</typeparam>
         /// <param name="image">The <see cref="ImageBase{TColor}"/> to encode.</param>
+        /// <param name="metaData">The metadata of the image or frame.</param>
         /// <param name="writer">The stream to write to.</param>
         /// <param name="transparencyIndex">The index of the color in the color palette to make transparent.</param>
-        private void WriteGraphicalControlExtension<TColor>(ImageBase<TColor> image, EndianBinaryWriter writer, int transparencyIndex)
+        private void WriteGraphicalControlExtension<TColor>(ImageBase<TColor> image, IMetaData metaData, EndianBinaryWriter writer, int transparencyIndex)
             where TColor : struct, IPackedPixel, IEquatable<TColor>
         {
             // TODO: Check transparency logic.
@@ -250,7 +277,7 @@ namespace ImageSharp.Formats
                 DisposalMethod = disposalMethod,
                 TransparencyFlag = hasTransparent,
                 TransparencyIndex = transparencyIndex,
-                DelayTime = image.FrameDelay
+                DelayTime = metaData.FrameDelay
             };
 
             // Write the intro.

src/ImageSharp/Image/IImageBase.cs

@@ -15,14 +15,6 @@ namespace ImageSharp
         /// </summary>
         Rectangle Bounds { get; }
 
-        /// <summary>
-        /// Gets or sets the frame delay for animated images.
-        /// If not 0, this field specifies the number of hundredths (1/100) of a second to
-        /// wait before continuing with the processing of the Data Stream.
-        /// The clock starts ticking immediately after the graphic is rendered.
-        /// </summary>
-        int FrameDelay { get; set; }
-
         /// <summary>
         /// Gets or sets the maximum allowable width in pixels.
         /// </summary>

src/ImageSharp/Image/IImageFrame.cs

@@ -0,0 +1,18 @@
+// <copyright file="IImageFrame.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp
+{
+    /// <summary>
+    /// Encapsulates the basic properties and methods required to manipulate images.
+    /// </summary>
+    internal interface IImageFrame : IImageBase
+    {
+        /// <summary>
+        /// Gets the meta data of the image.
+        /// </summary>
+        ImageFrameMetaData MetaData { get; }
+    }
+}

src/ImageSharp/Image/ImageBase{TColor}.cs

@@ -110,9 +110,6 @@ namespace ImageSharp
         /// <inheritdoc/>
         public Rectangle Bounds => new Rectangle(0, 0, this.Width, this.Height);
 
-        /// <inheritdoc/>
-        public int FrameDelay { get; set; }
-
         /// <summary>
         /// Gets the configuration providing initialization code which allows extending the library.
         /// </summary>
@@ -187,7 +184,6 @@ namespace ImageSharp
         {
             Debug.Assert(other != null);
 
-            this.FrameDelay = other.FrameDelay;
             this.Configuration = other.Configuration;
         }
 

src/ImageSharp/Image/ImageFrame{TColor}.cs

@@ -13,7 +13,7 @@ namespace ImageSharp
     /// Represents a single frame in a animation.
     /// </summary>
     /// <typeparam name="TColor">The pixel format.</typeparam>
-    public class ImageFrame<TColor> : ImageBase<TColor>
+    public class ImageFrame<TColor> : ImageBase<TColor>, IImageFrame
         where TColor : struct, IPackedPixel, IEquatable<TColor>
     {
         /// <summary>
@@ -38,6 +38,11 @@ namespace ImageSharp
         {
         }
 
+        /// <summary>
+        /// Gets the meta data of the frame.
+        /// </summary>
+        public ImageFrameMetaData MetaData { get; private set; } = new ImageFrameMetaData();
+
         /// <inheritdoc/>
         public override string ToString()
         {
@@ -87,5 +92,18 @@ namespace ImageSharp
         {
             return new ImageFrame<TColor>(this);
         }
+
+        /// <summary>
+        /// Copies the properties from the other <see cref="IImageFrame"/>.
+        /// </summary>
+        /// <param name="other">
+        /// The other <see cref="IImageFrame"/> to copy the properties from.
+        /// </param>
+        private void CopyProperties(IImageFrame other)
+        {
+            base.CopyProperties(other);
+
+            this.MetaData = new ImageFrameMetaData(other.MetaData);
+        }
     }
 }

src/ImageSharp/Metadata/IMetaData.cs

@@ -0,0 +1,21 @@
+// <copyright file="IMetaData.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp
+{
+    /// <summary>
+    /// Encapsulates the metadata of an image frame.
+    /// </summary>
+    internal interface IMetaData
+    {
+        /// <summary>
+        /// Gets or sets the frame delay for animated images.
+        /// If not 0, this field specifies the number of hundredths (1/100) of a second to
+        /// wait before continuing with the processing of the Data Stream.
+        /// The clock starts ticking immediately after the graphic is rendered.
+        /// </summary>
+        int FrameDelay { get; set; }
+    }
+}

src/ImageSharp/Metadata/ImageFrameMetaData.cs

@@ -0,0 +1,44 @@
+// <copyright file="ImageFrameMetaData.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp
+{
+    using System.Diagnostics;
+
+    /// <summary>
+    /// Encapsulates the metadata of an image frame.
+    /// </summary>
+    public sealed class ImageFrameMetaData : IMetaData
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ImageFrameMetaData"/> class.
+        /// </summary>
+        internal ImageFrameMetaData()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ImageFrameMetaData"/> class
+        /// by making a copy from other metadata.
+        /// </summary>
+        /// <param name="other">
+        /// The other <see cref="ImageFrameMetaData"/> to create this instance from.
+        /// </param>
+        internal ImageFrameMetaData(ImageFrameMetaData other)
+        {
+            Debug.Assert(other != null);
+
+            this.FrameDelay = other.FrameDelay;
+        }
+
+        /// <summary>
+        /// Gets or sets the frame delay for animated images.
+        /// If not 0, this field specifies the number of hundredths (1/100) of a second to
+        /// wait before continuing with the processing of the Data Stream.
+        /// The clock starts ticking immediately after the graphic is rendered.
+        /// </summary>
+        public int FrameDelay { get; set; }
+    }
+}

src/ImageSharp/Metadata/ImageMetaData.cs

@@ -11,7 +11,7 @@ namespace ImageSharp
     /// <summary>
     /// Encapsulates the metadata of an image.
     /// </summary>
-    public sealed class ImageMetaData
+    public sealed class ImageMetaData : IMetaData
     {
         /// <summary>
         /// The default horizontal resolution value (dots per inch) in x direction.
@@ -51,6 +51,8 @@ namespace ImageSharp
             this.HorizontalResolution = other.HorizontalResolution;
             this.VerticalResolution = other.VerticalResolution;
             this.Quality = other.Quality;
+            this.FrameDelay = other.FrameDelay;
+            this.RepeatCount = other.RepeatCount;
 
             foreach (ImageProperty property in other.Properties)
             {
@@ -110,6 +112,14 @@ namespace ImageSharp
         /// </summary>
         public ExifProfile ExifProfile { get; set; }
 
+        /// <summary>
+        /// Gets or sets the frame delay for animated images.
+        /// If not 0, this field specifies the number of hundredths (1/100) of a second to
+        /// wait before continuing with the processing of the Data Stream.
+        /// The clock starts ticking immediately after the graphic is rendered.
+        /// </summary>
+        public int FrameDelay { get; set; }
+
         /// <summary>
         /// Gets the list of properties for storing meta information about this image.
         /// </summary>

tests/ImageSharp.Tests/Metadata/ImageFrameMetaDataTests.cs

@@ -0,0 +1,26 @@
+// <copyright file="ImageFrameMetaDataTests.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Tests
+{
+    using Xunit;
+
+    /// <summary>
+    /// Tests the <see cref="ImageFrameMetaDataTests"/> class.
+    /// </summary>
+    public class ImageFrameMetaDataTests
+    {
+        [Fact]
+        public void ConstructorImageFrameMetaData()
+        {
+            ImageFrameMetaData metaData = new ImageFrameMetaData();
+            metaData.FrameDelay = 42;
+
+            ImageFrameMetaData clone = new ImageFrameMetaData(metaData);
+
+            Assert.Equal(42, clone.FrameDelay);
+        }
+    }
+}

tests/ImageSharp.Tests/Metadata/ImageMetaDataTests.cs

@@ -0,0 +1,42 @@
+// <copyright file="ImageMetaDataTests.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Tests
+{
+    using Xunit;
+
+    /// <summary>
+    /// Tests the <see cref="ImageMetaData"/> class.
+    /// </summary>
+    public class ImageMetaDataTests
+    {
+        [Fact]
+        public void ConstructorImageMetaData()
+        {
+            ImageMetaData metaData = new ImageMetaData();
+
+            ExifProfile exifProfile = new ExifProfile();
+            ImageProperty imageProperty = new ImageProperty("name", "value");
+
+            metaData.ExifProfile = exifProfile;
+            metaData.FrameDelay = 42;
+            metaData.HorizontalResolution = 4;
+            metaData.VerticalResolution = 2;
+            metaData.Properties.Add(imageProperty);
+            metaData.Quality = 24;
+            metaData.RepeatCount = 1;
+
+            ImageMetaData clone = new ImageMetaData(metaData);
+
+            Assert.Equal(exifProfile.ToByteArray(), clone.ExifProfile.ToByteArray());
+            Assert.Equal(42, clone.FrameDelay);
+            Assert.Equal(4, clone.HorizontalResolution);
+            Assert.Equal(2, clone.VerticalResolution);
+            Assert.Equal(imageProperty, clone.Properties[0]);
+            Assert.Equal(24, clone.Quality);
+            Assert.Equal(1, clone.RepeatCount);
+        }
+    }
+}