From 1d45fe8d3c7a66098b0769a7c22b9baa17d6dd25 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Wed, 28 Feb 2018 23:18:11 +1100
Subject: [PATCH 1/5] Introducing ReadOrigin. Fix #477

---
 src/ImageSharp/Image/Image.FromStream.cs | 152 +++++++++++++++++------
 src/ImageSharp/Image/ReadOrigin.cs       |  21 ++++
 2 files changed, 138 insertions(+), 35 deletions(-)
 create mode 100644 src/ImageSharp/Image/ReadOrigin.cs

diff --git a/src/ImageSharp/Image/Image.FromStream.cs b/src/ImageSharp/Image/Image.FromStream.cs
index 62668dd02..30d801423 100644
--- a/src/ImageSharp/Image/Image.FromStream.cs
+++ b/src/ImageSharp/Image/Image.FromStream.cs
@@ -20,10 +20,15 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="stream">The image stream to read the header from.</param>
         /// <returns>The mime type or null if none found.</returns>
-        public static IImageFormat DetectFormat(Stream stream)
-        {
-            return DetectFormat(null, stream);
-        }
+        public static IImageFormat DetectFormat(Stream stream) => DetectFormat(null, stream);
+
+        /// <summary>
+        /// By reading the header on the provided stream this calculates the images mime type.
+        /// </summary>
+        /// <param name="stream">The image stream to read the header from.</param>
+        /// <param name="origin">The position in the stream to use for reading.</param>
+        /// <returns>The mime type or null if none found.</returns>
+        public static IImageFormat DetectFormat(Stream stream, ReadOrigin origin) => DetectFormat(null, stream, origin);
 
         /// <summary>
         /// By reading the header on the provided stream this calculates the images mime type.
@@ -31,10 +36,17 @@ namespace SixLabors.ImageSharp
         /// <param name="config">The configuration.</param>
         /// <param name="stream">The image stream to read the header from.</param>
         /// <returns>The mime type or null if none found.</returns>
-        public static IImageFormat DetectFormat(Configuration config, Stream stream)
-        {
-            return WithSeekableStream(stream, s => InternalDetectFormat(s, config ?? Configuration.Default));
-        }
+        public static IImageFormat DetectFormat(Configuration config, Stream stream) => DetectFormat(config, stream, ReadOrigin.Begin);
+
+        /// <summary>
+        /// By reading the header on the provided stream this calculates the images mime type.
+        /// </summary>
+        /// <param name="config">The configuration.</param>
+        /// <param name="stream">The image stream to read the header from.</param>
+        /// <param name="origin">The position in the stream to use for reading.</param>
+        /// <returns>The mime type or null if none found.</returns>
+        public static IImageFormat DetectFormat(Configuration config, Stream stream, ReadOrigin origin)
+            => WithSeekableStream(stream, origin, s => InternalDetectFormat(s, config ?? Configuration.Default));
 
         /// <summary>
         /// By reading the header on the provided stream this reads the raw image information.
@@ -46,10 +58,7 @@ namespace SixLabors.ImageSharp
         /// <returns>
         /// The <see cref="IImageInfo"/> or null if suitable info detector not found.
         /// </returns>
-        public static IImageInfo Identify(Stream stream)
-        {
-            return Identify(null, stream);
-        }
+        public static IImageInfo Identify(Stream stream) => Identify(null, stream);
 
         /// <summary>
         /// Reads the raw image information from the specified stream without fully decoding it.
@@ -62,10 +71,20 @@ namespace SixLabors.ImageSharp
         /// <returns>
         /// The <see cref="IImageInfo"/> or null if suitable info detector is not found.
         /// </returns>
-        public static IImageInfo Identify(Configuration config, Stream stream)
-        {
-            return WithSeekableStream(stream, s => InternalIdentity(s, config ?? Configuration.Default));
-        }
+        public static IImageInfo Identify(Configuration config, Stream stream) => Identify(config, stream, ReadOrigin.Begin);
+
+        /// <summary>
+        /// Reads the raw image information from the specified stream without fully decoding it.
+        /// </summary>
+        /// <param name="config">The configuration.</param>
+        /// <param name="stream">The image stream to read the information from.</param>
+        /// <param name="origin">The position in the stream to use for reading.</param>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
+        /// <returns>
+        /// The <see cref="IImageInfo"/> or null if suitable info detector is not found.
+        /// </returns>
+        public static IImageInfo Identify(Configuration config, Stream stream, ReadOrigin origin)
+            => WithSeekableStream(stream, origin, s => InternalIdentity(s, config ?? Configuration.Default));
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given stream.
@@ -120,7 +139,8 @@ namespace SixLabors.ImageSharp
         /// Thrown if the stream is not readable nor seekable.
         /// </exception>
         /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>>
-        public static Image<Rgba32> Load(Configuration config, Stream stream, out IImageFormat format) => Load<Rgba32>(config, stream, out format);
+        public static Image<Rgba32> Load(Configuration config, Stream stream, out IImageFormat format)
+            => Load<Rgba32>(config, stream, out format);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -133,9 +153,7 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Stream stream)
             where TPixel : struct, IPixel<TPixel>
-        {
-            return Load<TPixel>(null, stream);
-        }
+            => Load<TPixel>(null, stream);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -149,9 +167,7 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Stream stream, out IImageFormat format)
             where TPixel : struct, IPixel<TPixel>
-        {
-            return Load<TPixel>(null, stream, out format);
-        }
+            => Load<TPixel>(null, stream, out format);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -165,9 +181,22 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Stream stream, IImageDecoder decoder)
             where TPixel : struct, IPixel<TPixel>
-        {
-            return WithSeekableStream(stream, s => decoder.Decode<TPixel>(Configuration.Default, s));
-        }
+        => Load<TPixel>(stream, ReadOrigin.Begin, decoder);
+
+        /// <summary>
+        /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
+        /// </summary>
+        /// <param name="stream">The stream containing image information.</param>
+        /// <param name="origin">The position in the stream to use for reading.</param>
+        /// <param name="decoder">The decoder.</param>
+        /// <exception cref="NotSupportedException">
+        /// Thrown if the stream is not readable nor seekable.
+        /// </exception>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
+        public static Image<TPixel> Load<TPixel>(Stream stream, ReadOrigin origin, IImageDecoder decoder)
+            where TPixel : struct, IPixel<TPixel>
+            => WithSeekableStream(stream, origin, s => decoder.Decode<TPixel>(Configuration.Default, s));
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -182,9 +211,23 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, IImageDecoder decoder)
             where TPixel : struct, IPixel<TPixel>
-        {
-            return WithSeekableStream(stream, s => decoder.Decode<TPixel>(config, s));
-        }
+            => Load<TPixel>(config, stream, ReadOrigin.Begin, decoder);
+
+        /// <summary>
+        /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
+        /// </summary>
+        /// <param name="config">The Configuration.</param>
+        /// <param name="stream">The stream containing image information.</param>
+        /// <param name="origin">The position in the stream to use for reading.</param>
+        /// <param name="decoder">The decoder.</param>
+        /// <exception cref="NotSupportedException">
+        /// Thrown if the stream is not readable nor seekable.
+        /// </exception>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
+        public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, ReadOrigin origin, IImageDecoder decoder)
+            where TPixel : struct, IPixel<TPixel>
+            => WithSeekableStream(stream, origin, s => decoder.Decode<TPixel>(config, s));
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -198,9 +241,22 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream)
             where TPixel : struct, IPixel<TPixel>
-        {
-            return Load<TPixel>(config, stream, out var _);
-        }
+            => Load<TPixel>(config, stream, out IImageFormat _);
+
+        /// <summary>
+        /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
+        /// </summary>
+        /// <param name="config">The configuration options.</param>
+        /// <param name="stream">The stream containing image information.</param>
+        /// <param name="origin">The position in the stream to use for reading.</param>
+        /// <exception cref="NotSupportedException">
+        /// Thrown if the stream is not readable nor seekable.
+        /// </exception>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
+        public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, ReadOrigin origin)
+            where TPixel : struct, IPixel<TPixel>
+            => Load<TPixel>(config, stream, origin, out IImageFormat _);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -214,10 +270,26 @@ namespace SixLabors.ImageSharp
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, out IImageFormat format)
-        where TPixel : struct, IPixel<TPixel>
+            where TPixel : struct, IPixel<TPixel>
+            => Load<TPixel>(config, stream, ReadOrigin.Begin, out format);
+
+        /// <summary>
+        /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
+        /// </summary>
+        /// <param name="config">The configuration options.</param>
+        /// <param name="stream">The stream containing image information.</param>
+        /// <param name="origin">The position in the stream to use for reading.</param>
+        /// <param name="format">the mime type of the decoded image.</param>
+        /// <exception cref="NotSupportedException">
+        /// Thrown if the stream is not readable nor seekable.
+        /// </exception>
+        /// <typeparam name="TPixel">The pixel format.</typeparam>
+        /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
+        public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, ReadOrigin origin, out IImageFormat format)
+            where TPixel : struct, IPixel<TPixel>
         {
             config = config ?? Configuration.Default;
-            (Image<TPixel> img, IImageFormat format) data = WithSeekableStream(stream, s => Decode<TPixel>(s, config));
+            (Image<TPixel> img, IImageFormat format) data = WithSeekableStream(stream, origin, s => Decode<TPixel>(s, config));
 
             format = data.format;
 
@@ -237,7 +309,7 @@ namespace SixLabors.ImageSharp
             throw new NotSupportedException(stringBuilder.ToString());
         }
 
-        private static T WithSeekableStream<T>(Stream stream, Func<Stream, T> action)
+        private static T WithSeekableStream<T>(Stream stream, ReadOrigin origin, Func<Stream, T> action)
         {
             if (!stream.CanRead)
             {
@@ -246,9 +318,19 @@ namespace SixLabors.ImageSharp
 
             if (stream.CanSeek)
             {
+                if (origin == ReadOrigin.Begin)
+                {
+                    stream.Position = 0;
+                }
+
                 return action(stream);
             }
 
+            if (origin == ReadOrigin.Current)
+            {
+                throw new NotSupportedException("Cannot seek within the stream.");
+            }
+
             // We want to be able to load images from things like HttpContext.Request.Body
             using (var memoryStream = new MemoryStream())
             {
diff --git a/src/ImageSharp/Image/ReadOrigin.cs b/src/ImageSharp/Image/ReadOrigin.cs
new file mode 100644
index 000000000..f17bc82f1
--- /dev/null
+++ b/src/ImageSharp/Image/ReadOrigin.cs
@@ -0,0 +1,21 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// Specifies the position in a stream to use for reading.
+    /// </summary>
+    public enum ReadOrigin
+    {
+        /// <summary>
+        /// Specifies the beginning of a stream.
+        /// </summary>
+        Begin,
+
+        /// <summary>
+        /// Specifies the current position within a stream.
+        /// </summary>
+        Current
+    }
+}

From c5f7f27e19b5ebfe73d54aba65b90b962fe2801b Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 1 Mar 2018 00:29:55 +1100
Subject: [PATCH 2/5] Use configuration to set ReadOrigin

---
 src/ImageSharp/Configuration.cs              |   5 +
 src/ImageSharp/Image/Image.FromStream.cs     | 101 +++----------------
 tests/ImageSharp.Tests/ConfigurationTests.cs |  11 +-
 3 files changed, 27 insertions(+), 90 deletions(-)

diff --git a/src/ImageSharp/Configuration.cs b/src/ImageSharp/Configuration.cs
index 9a627eeb7..7b02f21c4 100644
--- a/src/ImageSharp/Configuration.cs
+++ b/src/ImageSharp/Configuration.cs
@@ -83,6 +83,11 @@ namespace SixLabors.ImageSharp
         /// </summary>
         public IEnumerable<IImageFormat> ImageFormats => this.imageFormats;
 
+        /// <summary>
+        /// Gets or sets the position in a stream to use for reading.
+        /// </summary>
+        public ReadOrigin ReadOrigin { get; set; } = ReadOrigin.Begin;
+
         /// <summary>
         /// Gets or sets the <see cref="MemoryManager"/> that is currently in use.
         /// </summary>
diff --git a/src/ImageSharp/Image/Image.FromStream.cs b/src/ImageSharp/Image/Image.FromStream.cs
index 30d801423..a0c71133c 100644
--- a/src/ImageSharp/Image/Image.FromStream.cs
+++ b/src/ImageSharp/Image/Image.FromStream.cs
@@ -20,15 +20,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="stream">The image stream to read the header from.</param>
         /// <returns>The mime type or null if none found.</returns>
-        public static IImageFormat DetectFormat(Stream stream) => DetectFormat(null, stream);
-
-        /// <summary>
-        /// By reading the header on the provided stream this calculates the images mime type.
-        /// </summary>
-        /// <param name="stream">The image stream to read the header from.</param>
-        /// <param name="origin">The position in the stream to use for reading.</param>
-        /// <returns>The mime type or null if none found.</returns>
-        public static IImageFormat DetectFormat(Stream stream, ReadOrigin origin) => DetectFormat(null, stream, origin);
+        public static IImageFormat DetectFormat(Stream stream) => DetectFormat(Configuration.Default, stream);
 
         /// <summary>
         /// By reading the header on the provided stream this calculates the images mime type.
@@ -36,17 +28,8 @@ namespace SixLabors.ImageSharp
         /// <param name="config">The configuration.</param>
         /// <param name="stream">The image stream to read the header from.</param>
         /// <returns>The mime type or null if none found.</returns>
-        public static IImageFormat DetectFormat(Configuration config, Stream stream) => DetectFormat(config, stream, ReadOrigin.Begin);
-
-        /// <summary>
-        /// By reading the header on the provided stream this calculates the images mime type.
-        /// </summary>
-        /// <param name="config">The configuration.</param>
-        /// <param name="stream">The image stream to read the header from.</param>
-        /// <param name="origin">The position in the stream to use for reading.</param>
-        /// <returns>The mime type or null if none found.</returns>
-        public static IImageFormat DetectFormat(Configuration config, Stream stream, ReadOrigin origin)
-            => WithSeekableStream(stream, origin, s => InternalDetectFormat(s, config ?? Configuration.Default));
+        public static IImageFormat DetectFormat(Configuration config, Stream stream)
+            => WithSeekableStream(config, stream, s => InternalDetectFormat(s, config));
 
         /// <summary>
         /// By reading the header on the provided stream this reads the raw image information.
@@ -58,33 +41,19 @@ namespace SixLabors.ImageSharp
         /// <returns>
         /// The <see cref="IImageInfo"/> or null if suitable info detector not found.
         /// </returns>
-        public static IImageInfo Identify(Stream stream) => Identify(null, stream);
-
-        /// <summary>
-        /// Reads the raw image information from the specified stream without fully decoding it.
-        /// </summary>
-        /// <param name="config">The configuration.</param>
-        /// <param name="stream">The image stream to read the information from.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
-        /// <returns>
-        /// The <see cref="IImageInfo"/> or null if suitable info detector is not found.
-        /// </returns>
-        public static IImageInfo Identify(Configuration config, Stream stream) => Identify(config, stream, ReadOrigin.Begin);
+        public static IImageInfo Identify(Stream stream) => Identify(Configuration.Default, stream);
 
         /// <summary>
         /// Reads the raw image information from the specified stream without fully decoding it.
         /// </summary>
         /// <param name="config">The configuration.</param>
         /// <param name="stream">The image stream to read the information from.</param>
-        /// <param name="origin">The position in the stream to use for reading.</param>
         /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>
         /// The <see cref="IImageInfo"/> or null if suitable info detector is not found.
         /// </returns>
-        public static IImageInfo Identify(Configuration config, Stream stream, ReadOrigin origin)
-            => WithSeekableStream(stream, origin, s => InternalIdentity(s, config ?? Configuration.Default));
+        public static IImageInfo Identify(Configuration config, Stream stream)
+            => WithSeekableStream(config, stream, s => InternalIdentity(s, config ?? Configuration.Default));
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given stream.
@@ -181,22 +150,7 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Stream stream, IImageDecoder decoder)
             where TPixel : struct, IPixel<TPixel>
-        => Load<TPixel>(stream, ReadOrigin.Begin, decoder);
-
-        /// <summary>
-        /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
-        /// </summary>
-        /// <param name="stream">The stream containing image information.</param>
-        /// <param name="origin">The position in the stream to use for reading.</param>
-        /// <param name="decoder">The decoder.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
-        /// <typeparam name="TPixel">The pixel format.</typeparam>
-        /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
-        public static Image<TPixel> Load<TPixel>(Stream stream, ReadOrigin origin, IImageDecoder decoder)
-            where TPixel : struct, IPixel<TPixel>
-            => WithSeekableStream(stream, origin, s => decoder.Decode<TPixel>(Configuration.Default, s));
+            => WithSeekableStream(Configuration.Default, stream, s => decoder.Decode<TPixel>(Configuration.Default, s));
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -211,23 +165,7 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, IImageDecoder decoder)
             where TPixel : struct, IPixel<TPixel>
-            => Load<TPixel>(config, stream, ReadOrigin.Begin, decoder);
-
-        /// <summary>
-        /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
-        /// </summary>
-        /// <param name="config">The Configuration.</param>
-        /// <param name="stream">The stream containing image information.</param>
-        /// <param name="origin">The position in the stream to use for reading.</param>
-        /// <param name="decoder">The decoder.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
-        /// <typeparam name="TPixel">The pixel format.</typeparam>
-        /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
-        public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, ReadOrigin origin, IImageDecoder decoder)
-            where TPixel : struct, IPixel<TPixel>
-            => WithSeekableStream(stream, origin, s => decoder.Decode<TPixel>(config, s));
+            => WithSeekableStream(config, stream, s => decoder.Decode<TPixel>(config, s));
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -243,21 +181,6 @@ namespace SixLabors.ImageSharp
             where TPixel : struct, IPixel<TPixel>
             => Load<TPixel>(config, stream, out IImageFormat _);
 
-        /// <summary>
-        /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
-        /// </summary>
-        /// <param name="config">The configuration options.</param>
-        /// <param name="stream">The stream containing image information.</param>
-        /// <param name="origin">The position in the stream to use for reading.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
-        /// <typeparam name="TPixel">The pixel format.</typeparam>
-        /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
-        public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, ReadOrigin origin)
-            where TPixel : struct, IPixel<TPixel>
-            => Load<TPixel>(config, stream, origin, out IImageFormat _);
-
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
         /// </summary>
@@ -289,7 +212,7 @@ namespace SixLabors.ImageSharp
             where TPixel : struct, IPixel<TPixel>
         {
             config = config ?? Configuration.Default;
-            (Image<TPixel> img, IImageFormat format) data = WithSeekableStream(stream, origin, s => Decode<TPixel>(s, config));
+            (Image<TPixel> img, IImageFormat format) data = WithSeekableStream(config, stream, s => Decode<TPixel>(s, config));
 
             format = data.format;
 
@@ -309,7 +232,7 @@ namespace SixLabors.ImageSharp
             throw new NotSupportedException(stringBuilder.ToString());
         }
 
-        private static T WithSeekableStream<T>(Stream stream, ReadOrigin origin, Func<Stream, T> action)
+        private static T WithSeekableStream<T>(Configuration config, Stream stream, Func<Stream, T> action)
         {
             if (!stream.CanRead)
             {
@@ -318,7 +241,7 @@ namespace SixLabors.ImageSharp
 
             if (stream.CanSeek)
             {
-                if (origin == ReadOrigin.Begin)
+                if (config.ReadOrigin == ReadOrigin.Begin)
                 {
                     stream.Position = 0;
                 }
@@ -326,7 +249,7 @@ namespace SixLabors.ImageSharp
                 return action(stream);
             }
 
-            if (origin == ReadOrigin.Current)
+            if (config.ReadOrigin == ReadOrigin.Current)
             {
                 throw new NotSupportedException("Cannot seek within the stream.");
             }
diff --git a/tests/ImageSharp.Tests/ConfigurationTests.cs b/tests/ImageSharp.Tests/ConfigurationTests.cs
index 18d4abdd1..fc97b2209 100644
--- a/tests/ImageSharp.Tests/ConfigurationTests.cs
+++ b/tests/ImageSharp.Tests/ConfigurationTests.cs
@@ -59,6 +59,15 @@ namespace SixLabors.ImageSharp.Tests
             Assert.True(Configuration.Default.ParallelOptions != null);
         }
 
+        /// <summary>
+        /// Test that the default configuration read origin options is set to begin.
+        /// </summary>
+        [Fact]
+        public void TestDefultConfigurationReadOriginIsBegin()
+        {
+            Assert.True(Configuration.Default.ReadOrigin == ReadOrigin.Begin);
+        }
+
         /// <summary>
         /// Test that the default configuration parallel options max degrees of parallelism matches the
         /// environment processor count.
@@ -83,7 +92,7 @@ namespace SixLabors.ImageSharp.Tests
         {
             Assert.Throws<ArgumentNullException>(() =>
             {
-               this.DefaultConfiguration.SetEncoder(null, new Mock<IImageEncoder>().Object);
+                this.DefaultConfiguration.SetEncoder(null, new Mock<IImageEncoder>().Object);
             });
             Assert.Throws<ArgumentNullException>(() =>
             {

From 24b42172969e8d8c392c927aa8809c7307c4687b Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 1 Mar 2018 00:49:43 +1100
Subject: [PATCH 3/5] So many nulls!

---
 src/ImageSharp/Image/Image.FromBytes.cs | 14 +++++---------
 src/ImageSharp/Image/Image.FromFile.cs  | 11 ++++-------
 2 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/src/ImageSharp/Image/Image.FromBytes.cs b/src/ImageSharp/Image/Image.FromBytes.cs
index 9da9c5e43..44c53d776 100644
--- a/src/ImageSharp/Image/Image.FromBytes.cs
+++ b/src/ImageSharp/Image/Image.FromBytes.cs
@@ -19,7 +19,7 @@ namespace SixLabors.ImageSharp
         /// <returns>The format or null if none found.</returns>
         public static IImageFormat DetectFormat(byte[] data)
         {
-            return DetectFormat(null, data);
+            return DetectFormat(Configuration.Default, data);
         }
 
         /// <summary>
@@ -41,7 +41,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="data">The byte array containing image data.</param>
         /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>
-        public static Image<Rgba32> Load(byte[] data) => Load<Rgba32>(null, data);
+        public static Image<Rgba32> Load(byte[] data) => Load<Rgba32>(Configuration.Default, data);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given byte array.
@@ -49,7 +49,7 @@ namespace SixLabors.ImageSharp
         /// <param name="data">The byte array containing image data.</param>
         /// <param name="format">The mime type of the decoded image.</param>
         /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>
-        public static Image<Rgba32> Load(byte[] data, out IImageFormat format) => Load<Rgba32>(null, data, out format);
+        public static Image<Rgba32> Load(byte[] data, out IImageFormat format) => Load<Rgba32>(Configuration.Default, data, out format);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given byte array.
@@ -93,9 +93,7 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
         public static Image<TPixel> Load<TPixel>(byte[] data)
             where TPixel : struct, IPixel<TPixel>
-        {
-            return Load<TPixel>(null, data);
-        }
+            => Load<TPixel>(Configuration.Default, data);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given byte array.
@@ -106,9 +104,7 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
         public static Image<TPixel> Load<TPixel>(byte[] data, out IImageFormat format)
             where TPixel : struct, IPixel<TPixel>
-        {
-            return Load<TPixel>(null, data, out format);
-        }
+            => Load<TPixel>(Configuration.Default, data, out format);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given byte array.
diff --git a/src/ImageSharp/Image/Image.FromFile.cs b/src/ImageSharp/Image/Image.FromFile.cs
index 0474a6d47..ad8f3426f 100644
--- a/src/ImageSharp/Image/Image.FromFile.cs
+++ b/src/ImageSharp/Image/Image.FromFile.cs
@@ -21,7 +21,7 @@ namespace SixLabors.ImageSharp
         /// <returns>The mime type or null if none found.</returns>
         public static IImageFormat DetectFormat(string filePath)
         {
-            return DetectFormat(null, filePath);
+            return DetectFormat(Configuration.Default, filePath);
         }
 
         /// <summary>
@@ -118,7 +118,7 @@ namespace SixLabors.ImageSharp
         public static Image<TPixel> Load<TPixel>(string path)
             where TPixel : struct, IPixel<TPixel>
         {
-            return Load<TPixel>(null, path);
+            return Load<TPixel>(Configuration.Default, path);
         }
 
         /// <summary>
@@ -134,7 +134,7 @@ namespace SixLabors.ImageSharp
         public static Image<TPixel> Load<TPixel>(string path, out IImageFormat format)
             where TPixel : struct, IPixel<TPixel>
         {
-            return Load<TPixel>(null, path, out format);
+            return Load<TPixel>(Configuration.Default, path, out format);
         }
 
         /// <summary>
@@ -150,7 +150,6 @@ namespace SixLabors.ImageSharp
         public static Image<TPixel> Load<TPixel>(Configuration config, string path)
             where TPixel : struct, IPixel<TPixel>
         {
-            config = config ?? Configuration.Default;
             using (Stream stream = config.FileSystem.OpenRead(path))
             {
                 return Load<TPixel>(config, stream);
@@ -171,7 +170,6 @@ namespace SixLabors.ImageSharp
         public static Image<TPixel> Load<TPixel>(Configuration config, string path, out IImageFormat format)
             where TPixel : struct, IPixel<TPixel>
         {
-            config = config ?? Configuration.Default;
             using (Stream stream = config.FileSystem.OpenRead(path))
             {
                 return Load<TPixel>(config, stream, out format);
@@ -191,7 +189,7 @@ namespace SixLabors.ImageSharp
         public static Image<TPixel> Load<TPixel>(string path, IImageDecoder decoder)
             where TPixel : struct, IPixel<TPixel>
         {
-            return Load<TPixel>(null, path, decoder);
+            return Load<TPixel>(Configuration.Default, path, decoder);
         }
 
         /// <summary>
@@ -208,7 +206,6 @@ namespace SixLabors.ImageSharp
         public static Image<TPixel> Load<TPixel>(Configuration config, string path, IImageDecoder decoder)
             where TPixel : struct, IPixel<TPixel>
         {
-            config = config ?? Configuration.Default;
             using (Stream stream = config.FileSystem.OpenRead(path))
             {
                 return Load<TPixel>(config, stream, decoder);

From c483cb5a53025cc801fe3e949537987ed01cf7c6 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 1 Mar 2018 15:03:28 +1100
Subject: [PATCH 4/5] Use Current as Default, Don't additionally throw

---
 src/ImageSharp/Configuration.cs              |  4 +-
 src/ImageSharp/Image/Image.FromStream.cs     | 59 +++++---------------
 tests/ImageSharp.Tests/ConfigurationTests.cs |  4 +-
 3 files changed, 19 insertions(+), 48 deletions(-)

diff --git a/src/ImageSharp/Configuration.cs b/src/ImageSharp/Configuration.cs
index 7b02f21c4..34bbb61e0 100644
--- a/src/ImageSharp/Configuration.cs
+++ b/src/ImageSharp/Configuration.cs
@@ -84,9 +84,9 @@ namespace SixLabors.ImageSharp
         public IEnumerable<IImageFormat> ImageFormats => this.imageFormats;
 
         /// <summary>
-        /// Gets or sets the position in a stream to use for reading.
+        /// Gets or sets the position in a stream to use for reading when using a seekable stream as an image data source.
         /// </summary>
-        public ReadOrigin ReadOrigin { get; set; } = ReadOrigin.Begin;
+        public ReadOrigin ReadOrigin { get; set; } = ReadOrigin.Current;
 
         /// <summary>
         /// Gets or sets the <see cref="MemoryManager"/> that is currently in use.
diff --git a/src/ImageSharp/Image/Image.FromStream.cs b/src/ImageSharp/Image/Image.FromStream.cs
index a0c71133c..c3f4a714f 100644
--- a/src/ImageSharp/Image/Image.FromStream.cs
+++ b/src/ImageSharp/Image/Image.FromStream.cs
@@ -19,6 +19,7 @@ namespace SixLabors.ImageSharp
         /// By reading the header on the provided stream this calculates the images mime type.
         /// </summary>
         /// <param name="stream">The image stream to read the header from.</param>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>The mime type or null if none found.</returns>
         public static IImageFormat DetectFormat(Stream stream) => DetectFormat(Configuration.Default, stream);
 
@@ -27,6 +28,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="config">The configuration.</param>
         /// <param name="stream">The image stream to read the header from.</param>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>The mime type or null if none found.</returns>
         public static IImageFormat DetectFormat(Configuration config, Stream stream)
             => WithSeekableStream(config, stream, s => InternalDetectFormat(s, config));
@@ -35,9 +37,7 @@ namespace SixLabors.ImageSharp
         /// By reading the header on the provided stream this reads the raw image information.
         /// </summary>
         /// <param name="stream">The image stream to read the header from.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>
         /// The <see cref="IImageInfo"/> or null if suitable info detector not found.
         /// </returns>
@@ -60,9 +60,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="stream">The stream containing image information.</param>
         /// <param name="format">the mime type of the decoded image.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>>
         public static Image<Rgba32> Load(Stream stream, out IImageFormat format) => Load<Rgba32>(stream, out format);
 
@@ -70,9 +68,7 @@ namespace SixLabors.ImageSharp
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given stream.
         /// </summary>
         /// <param name="stream">The stream containing image information.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>>
         public static Image<Rgba32> Load(Stream stream) => Load<Rgba32>(stream);
 
@@ -81,9 +77,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="stream">The stream containing image information.</param>
         /// <param name="decoder">The decoder.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>>
         public static Image<Rgba32> Load(Stream stream, IImageDecoder decoder) => Load<Rgba32>(stream, decoder);
 
@@ -92,9 +86,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="config">The config for the decoder.</param>
         /// <param name="stream">The stream containing image information.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>>
         public static Image<Rgba32> Load(Configuration config, Stream stream) => Load<Rgba32>(config, stream);
 
@@ -104,9 +96,7 @@ namespace SixLabors.ImageSharp
         /// <param name="config">The config for the decoder.</param>
         /// <param name="stream">The stream containing image information.</param>
         /// <param name="format">the mime type of the decoded image.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>>
         public static Image<Rgba32> Load(Configuration config, Stream stream, out IImageFormat format)
             => Load<Rgba32>(config, stream, out format);
@@ -115,9 +105,7 @@ namespace SixLabors.ImageSharp
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
         /// </summary>
         /// <param name="stream">The stream containing image information.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Stream stream)
@@ -129,9 +117,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="stream">The stream containing image information.</param>
         /// <param name="format">the mime type of the decoded image.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Stream stream, out IImageFormat format)
@@ -143,9 +129,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="stream">The stream containing image information.</param>
         /// <param name="decoder">The decoder.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Stream stream, IImageDecoder decoder)
@@ -158,9 +142,7 @@ namespace SixLabors.ImageSharp
         /// <param name="config">The Configuration.</param>
         /// <param name="stream">The stream containing image information.</param>
         /// <param name="decoder">The decoder.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, IImageDecoder decoder)
@@ -172,9 +154,7 @@ namespace SixLabors.ImageSharp
         /// </summary>
         /// <param name="config">The configuration options.</param>
         /// <param name="stream">The stream containing image information.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream)
@@ -187,9 +167,7 @@ namespace SixLabors.ImageSharp
         /// <param name="config">The configuration options.</param>
         /// <param name="stream">The stream containing image information.</param>
         /// <param name="format">the mime type of the decoded image.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, out IImageFormat format)
@@ -203,9 +181,7 @@ namespace SixLabors.ImageSharp
         /// <param name="stream">The stream containing image information.</param>
         /// <param name="origin">The position in the stream to use for reading.</param>
         /// <param name="format">the mime type of the decoded image.</param>
-        /// <exception cref="NotSupportedException">
-        /// Thrown if the stream is not readable nor seekable.
-        /// </exception>
+        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, ReadOrigin origin, out IImageFormat format)
@@ -249,11 +225,6 @@ namespace SixLabors.ImageSharp
                 return action(stream);
             }
 
-            if (config.ReadOrigin == ReadOrigin.Current)
-            {
-                throw new NotSupportedException("Cannot seek within the stream.");
-            }
-
             // We want to be able to load images from things like HttpContext.Request.Body
             using (var memoryStream = new MemoryStream())
             {
diff --git a/tests/ImageSharp.Tests/ConfigurationTests.cs b/tests/ImageSharp.Tests/ConfigurationTests.cs
index fc97b2209..06f02fcf1 100644
--- a/tests/ImageSharp.Tests/ConfigurationTests.cs
+++ b/tests/ImageSharp.Tests/ConfigurationTests.cs
@@ -63,9 +63,9 @@ namespace SixLabors.ImageSharp.Tests
         /// Test that the default configuration read origin options is set to begin.
         /// </summary>
         [Fact]
-        public void TestDefultConfigurationReadOriginIsBegin()
+        public void TestDefultConfigurationReadOriginIsCurrent()
         {
-            Assert.True(Configuration.Default.ReadOrigin == ReadOrigin.Begin);
+            Assert.True(Configuration.Default.ReadOrigin == ReadOrigin.Current);
         }
 
         /// <summary>

From 450a85387c305291bff136ff8d20854939d4bc1f Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 1 Mar 2018 20:33:03 +1100
Subject: [PATCH 5/5] Remove unneeded overload.

---
 src/ImageSharp/Image/Image.FromStream.cs | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/src/ImageSharp/Image/Image.FromStream.cs b/src/ImageSharp/Image/Image.FromStream.cs
index c3f4a714f..4e294260a 100644
--- a/src/ImageSharp/Image/Image.FromStream.cs
+++ b/src/ImageSharp/Image/Image.FromStream.cs
@@ -172,20 +172,6 @@ namespace SixLabors.ImageSharp
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
         public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, out IImageFormat format)
             where TPixel : struct, IPixel<TPixel>
-            => Load<TPixel>(config, stream, ReadOrigin.Begin, out format);
-
-        /// <summary>
-        /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
-        /// </summary>
-        /// <param name="config">The configuration options.</param>
-        /// <param name="stream">The stream containing image information.</param>
-        /// <param name="origin">The position in the stream to use for reading.</param>
-        /// <param name="format">the mime type of the decoded image.</param>
-        /// <exception cref="NotSupportedException">Thrown if the stream is not readable.</exception>
-        /// <typeparam name="TPixel">The pixel format.</typeparam>
-        /// <returns>A new <see cref="Image{TPixel}"/>.</returns>>
-        public static Image<TPixel> Load<TPixel>(Configuration config, Stream stream, ReadOrigin origin, out IImageFormat format)
-            where TPixel : struct, IPixel<TPixel>
         {
             config = config ?? Configuration.Default;
             (Image<TPixel> img, IImageFormat format) data = WithSeekableStream(config, stream, s => Decode<TPixel>(s, config));