pixel-agnostic decoder API

src/ImageSharp/Advanced/AdvancedImageExtensions.cs

@@ -21,8 +21,7 @@ namespace SixLabors.ImageSharp.Advanced
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
         /// <param name="source">The source image.</param>
         /// <returns>Returns the configuration.</returns>
-        public static Configuration GetConfiguration<TPixel>(this Image<TPixel> source)
-            where TPixel : struct, IPixel<TPixel>
+        public static Configuration GetConfiguration(this Image source)
             => GetConfiguration((IConfigurable)source);
 
         /// <summary>

src/ImageSharp/Formats/Bmp/BmpDecoder.cs

@@ -30,6 +30,8 @@ namespace SixLabors.ImageSharp.Formats.Bmp
             return new BmpDecoderCore(configuration, this).Decode<TPixel>(stream);
         }
 
+        public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
+
         /// <inheritdoc/>
         public IImageInfo Identify(Configuration configuration, Stream stream)
         {

src/ImageSharp/Formats/Gif/GifDecoder.cs

@@ -44,5 +44,7 @@ namespace SixLabors.ImageSharp.Formats.Gif
             var decoder = new GifDecoderCore(configuration, this);
             return decoder.Identify(stream);
         }
+        
+        public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
     }
 }

src/ImageSharp/Formats/IImageDecoder.cs

@@ -20,5 +20,7 @@ namespace SixLabors.ImageSharp.Formats
         /// <returns>The decoded image</returns>
         Image<TPixel> Decode<TPixel>(Configuration configuration, Stream stream)
             where TPixel : struct, IPixel<TPixel>;
+
+        Image Decode(Configuration configuration, Stream stream);
     }
 }

src/ImageSharp/Formats/Jpeg/JpegDecoder.cs

@@ -38,5 +38,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
                 return decoder.Identify(stream);
             }
         }
+        
+        public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
     }
 }

src/ImageSharp/Formats/Png/PngDecoder.cs

@@ -59,5 +59,7 @@ namespace SixLabors.ImageSharp.Formats.Png
             var decoder = new PngDecoderCore(configuration, this);
             return decoder.Identify(stream);
         }
+        
+        public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
     }
 }

src/ImageSharp/Image.Decode.cs

@@ -102,6 +102,18 @@ namespace SixLabors.ImageSharp
             Image<TPixel> img = decoder.Decode<TPixel>(config, stream);
             return (img, format);
         }
+        
+        private static (Image img, IImageFormat format) Decode(Stream stream, Configuration config)
+        {
+            IImageDecoder decoder = DiscoverDecoder(stream, config, out IImageFormat format);
+            if (decoder is null)
+            {
+                return (null, null);
+            }
+
+            Image img = decoder.Decode(config, stream);
+            return (img, format);
+        }
 
         /// <summary>
         /// Reads the raw image information from the specified stream.

src/ImageSharp/Image.FromFile.cs

@@ -46,7 +46,7 @@ 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(string path) => Load<Rgba32>(path);
+        public static Image Load(string path) => Load(path);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given file.
@@ -57,7 +57,7 @@ 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(string path, out IImageFormat format) => Load<Rgba32>(path, out format);
+        public static Image Load(string path, out IImageFormat format) => Load(path, out format);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given file.
@@ -68,19 +68,7 @@ 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, string path) => Load<Rgba32>(config, path);
-
-        /// <summary>
-        /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given file.
-        /// </summary>
-        /// <param name="config">The config for the decoder.</param>
-        /// <param name="path">The file path to the image.</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>
-        /// <returns>A new <see cref="Image{Rgba32}"/>.</returns>
-        public static Image<Rgba32> Load(Configuration config, string path, out IImageFormat format) => Load<Rgba32>(config, path, out format);
+        public static Image Load(Configuration config, string path) => Load(config, path);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given file.
@@ -92,7 +80,7 @@ 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, string path, IImageDecoder decoder) => Load<Rgba32>(config, path, decoder);
+        public static Image Load(Configuration config, string path, IImageDecoder decoder) => Load(config, path, decoder);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given file.
@@ -103,7 +91,7 @@ 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(string path, IImageDecoder decoder) => Load<Rgba32>(path, decoder);
+        public static Image Load(string path, IImageDecoder decoder) => Load(path, decoder);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given file.
@@ -174,6 +162,14 @@ namespace SixLabors.ImageSharp
                 return Load<TPixel>(config, stream, out format);
             }
         }
+        
+        public static Image Load(Configuration config, string path, out IImageFormat format)
+        {
+            using (Stream stream = config.FileSystem.OpenRead(path))
+            {
+                return Load(config, stream, out format);
+            }
+        }
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given file.

src/ImageSharp/Image.FromStream.cs

@@ -62,7 +62,7 @@ namespace SixLabors.ImageSharp
         /// <param name="format">the mime type of the decoded image.</param>
         /// <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);
+        public static Image Load(Stream stream, out IImageFormat format) => Load(stream, out format);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given stream.
@@ -70,7 +70,7 @@ namespace SixLabors.ImageSharp
         /// <param name="stream">The stream containing image information.</param>
         /// <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);
+        public static Image Load(Stream stream) => Load(stream);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given stream.
@@ -79,7 +79,7 @@ namespace SixLabors.ImageSharp
         /// <param name="decoder">The decoder.</param>
         /// <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);
+        public static Image Load(Stream stream, IImageDecoder decoder) => Load(stream, decoder);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given stream.
@@ -88,18 +88,7 @@ namespace SixLabors.ImageSharp
         /// <param name="stream">The stream containing image information.</param>
         /// <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);
-
-        /// <summary>
-        /// Create a new instance of the <see cref="Image{Rgba32}"/> class from the given stream.
-        /// </summary>
-        /// <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.</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 Load(Configuration config, Stream stream) => Load(config, stream);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given stream.
@@ -193,6 +182,28 @@ namespace SixLabors.ImageSharp
 
             throw new NotSupportedException(sb.ToString());
         }
+        private static Image Load(Configuration config, Stream stream, out IImageFormat format)
+        {
+            config = config ?? Configuration.Default;
+            (Image img, IImageFormat format) data = WithSeekableStream(config, stream, s => Decode(s, config));
+
+            format = data.format;
+
+            if (data.img != null)
+            {
+                return data.img;
+            }
+
+            var sb = new StringBuilder();
+            sb.AppendLine("Image cannot be loaded. Available decoders:");
+
+            foreach (KeyValuePair<IImageFormat, IImageDecoder> val in config.ImageFormatsManager.ImageDecoders)
+            {
+                sb.AppendLine($" - {val.Key.Name} : {val.Value.GetType().Name}");
+            }
+
+            throw new NotSupportedException(sb.ToString());
+        }
 
         private static T WithSeekableStream<T>(Configuration config, Stream stream, Func<Stream, T> action)
         {

src/ImageSharp/Image.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System.IO;
+
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Metadata;
@@ -45,5 +47,39 @@ namespace SixLabors.ImageSharp
         public abstract void Dispose();
 
         internal abstract void AcceptVisitor(IImageVisitor visitor);
+
+        /// <summary>
+        /// Saves the image to the given stream using the given image encoder.
+        /// </summary>
+        /// <param name="stream">The stream to save the image to.</param>
+        /// <param name="encoder">The encoder to save the image with.</param>
+        /// <exception cref="System.ArgumentNullException">Thrown if the stream or encoder is null.</exception>
+        public void Save(Stream stream, IImageEncoder encoder)
+        {
+            Guard.NotNull(stream, nameof(stream));
+            Guard.NotNull(encoder, nameof(encoder));
+
+            EncodeVisitor visitor = new EncodeVisitor(encoder, stream);
+            this.AcceptVisitor(visitor);
+        }
+
+        class EncodeVisitor : IImageVisitor
+        {
+            private readonly IImageEncoder encoder;
+
+            private readonly Stream stream;
+
+            public EncodeVisitor(IImageEncoder encoder, Stream stream)
+            {
+                this.encoder = encoder;
+                this.stream = stream;
+            }
+
+            public void Visit<TPixel>(Image<TPixel> image)
+                where TPixel : struct, IPixel<TPixel>
+            {
+                this.encoder.Encode(image, this.stream);
+            }
+        }
     }
 }

src/ImageSharp/ImageExtensions.cs

@@ -23,8 +23,7 @@ namespace SixLabors.ImageSharp
         /// <param name="source">The source image.</param>
         /// <param name="filePath">The file path to save the image to.</param>
         /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
-        public static void Save<TPixel>(this Image<TPixel> source, string filePath)
-            where TPixel : struct, IPixel<TPixel>
+        public static void Save(this Image source, string filePath)
         {
             Guard.NotNullOrWhiteSpace(filePath, nameof(filePath));
 
@@ -67,8 +66,7 @@ namespace SixLabors.ImageSharp
         /// <param name="filePath">The file path to save the image to.</param>
         /// <param name="encoder">The encoder to save the image with.</param>
         /// <exception cref="ArgumentNullException">Thrown if the encoder is null.</exception>
-        public static void Save<TPixel>(this Image<TPixel> source, string filePath, IImageEncoder encoder)
-            where TPixel : struct, IPixel<TPixel>
+        public static void Save(this Image source, string filePath, IImageEncoder encoder)
         {
             Guard.NotNull(encoder, nameof(encoder));
             using (Stream fs = source.GetConfiguration().FileSystem.Create(filePath))
@@ -85,8 +83,7 @@ namespace SixLabors.ImageSharp
         /// <param name="stream">The stream to save the image to.</param>
         /// <param name="format">The format to save the image in.</param>
         /// <exception cref="ArgumentNullException">Thrown if the stream is null.</exception>
-        public static void Save<TPixel>(this Image<TPixel> source, Stream stream, IImageFormat format)
-            where TPixel : struct, IPixel<TPixel>
+        public static void Save(this Image source, Stream stream, IImageFormat format)
         {
             Guard.NotNull(format, nameof(format));
             IImageEncoder encoder = source.GetConfiguration().ImageFormatsManager.FindEncoder(format);

src/ImageSharp/Image{TPixel}.cs

@@ -158,20 +158,6 @@ namespace SixLabors.ImageSharp
             set => this.PixelSource.PixelBuffer[x, y] = value;
         }
 
-        /// <summary>
-        /// Saves the image to the given stream using the given image encoder.
-        /// </summary>
-        /// <param name="stream">The stream to save the image to.</param>
-        /// <param name="encoder">The encoder to save the image with.</param>
-        /// <exception cref="System.ArgumentNullException">Thrown if the stream or encoder is null.</exception>
-        public void Save(Stream stream, IImageEncoder encoder)
-        {
-            Guard.NotNull(stream, nameof(stream));
-            Guard.NotNull(encoder, nameof(encoder));
-
-            encoder.Encode(this, stream);
-        }
-
         /// <summary>
         /// Clones the current image
         /// </summary>

tests/ImageSharp.Tests/Processing/Processors/Transforms/ResizeTests.cs

@@ -42,6 +42,22 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
 
         private static readonly ImageComparer ValidatorComparer = ImageComparer.TolerantPercentage(0.07F);
 
+        [Fact]
+        public void Resize_PixelAgnostic()
+        {
+            var filePath = TestFile.GetInputFileFullPath(TestImages.Jpeg.Baseline.Calliphora);
+            
+            using (Image image = Image.Load(filePath))
+            {
+                image.Mutate(x => x.Resize(image.Size() / 2));
+                string path = System.IO.Path.Combine(
+                    TestEnvironment.CreateOutputDirectory(nameof(ResizeTests)),
+                    nameof(this.Resize_PixelAgnostic) + ".png");
+                
+                image.Save(path);
+            }
+        }
+        
         [Theory(
             Skip = "Debug only, enable manually"
             )]

tests/ImageSharp.Tests/TestFormat.cs

@@ -199,6 +199,8 @@ namespace SixLabors.ImageSharp.Tests
             }
 
             public bool IsSupportedFileFormat(Span<byte> header) => testFormat.IsSupportedFileFormat(header);
+            
+            public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
         }
 
         public class TestEncoder : ImageSharp.Formats.IImageEncoder

tests/ImageSharp.Tests/TestUtilities/ReferenceCodecs/MagickReferenceDecoder.cs

@@ -57,5 +57,7 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs
                 return result;
             }
         }
+        
+        public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
     }
 }

tests/ImageSharp.Tests/TestUtilities/ReferenceCodecs/SystemDrawingReferenceDecoder.cs

@@ -51,5 +51,7 @@ namespace SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs
                 return new ImageInfo(pixelType, sourceBitmap.Width, sourceBitmap.Height, new ImageMetadata());
             }
         }
+        
+        public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
     }
 }

tests/ImageSharp.Tests/TestUtilities/Tests/TestImageProviderTests.cs

@@ -379,6 +379,8 @@ namespace SixLabors.ImageSharp.Tests
                 this.callerName = name;
                 invocationCounts[name] = 0;
             }
+            
+            public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
         }
 
         private class TestDecoderWithParameters : IImageDecoder
@@ -416,6 +418,8 @@ namespace SixLabors.ImageSharp.Tests
                 this.callerName = name;
                 invocationCounts[name] = 0;
             }
+            
+            public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
         }
     }
 }