Improve Decoder/Encoder symmetry

src/ImageSharp/Advanced/AotCompilerTools.cs

@@ -288,7 +288,7 @@ private static void AotCompileImageEncoder<TPixel, TEncoder>()
     private static void AotCompileImageDecoder<TPixel, TDecoder>()
        where TPixel : unmanaged, IPixel<TPixel>
        where TDecoder : class, IImageDecoder
-        => default(TDecoder).Decode<TPixel>(default, default, default);
+        => default(TDecoder).Decode<TPixel>(default, default);
 
     /// <summary>
     /// This method pre-seeds the all <see cref="IImageProcessor" /> in the AoT compiler.

src/ImageSharp/Configuration.cs

@@ -42,11 +42,11 @@ public Configuration()
     /// Initializes a new instance of the <see cref="Configuration" /> class.
     /// </summary>
     /// <param name="configurationModules">A collection of configuration modules to register.</param>
-    public Configuration(params IConfigurationModule[] configurationModules)
+    public Configuration(params IImageFormatConfigurationModule[] configurationModules)
     {
         if (configurationModules != null)
         {
-            foreach (IConfigurationModule p in configurationModules)
+            foreach (IImageFormatConfigurationModule p in configurationModules)
             {
                 p.Configure(this);
             }
@@ -180,7 +180,7 @@ public MemoryAllocator MemoryAllocator
     /// Registers a new format provider.
     /// </summary>
     /// <param name="configuration">The configuration provider to call configure on.</param>
-    public void Configure(IConfigurationModule configuration)
+    public void Configure(IImageFormatConfigurationModule configuration)
     {
         Guard.NotNull(configuration, nameof(configuration));
         configuration.Configure(this);
@@ -203,7 +203,7 @@ public void Configure(IConfigurationModule configuration)
     };
 
     /// <summary>
-    /// Creates the default instance with the following <see cref="IConfigurationModule"/>s preregistered:
+    /// Creates the default instance with the following <see cref="IImageFormatConfigurationModule"/>s preregistered:
     /// <see cref="PngConfigurationModule"/>
     /// <see cref="JpegConfigurationModule"/>
     /// <see cref="GifConfigurationModule"/>

src/ImageSharp/Formats/Bmp/BmpConfigurationModule.cs

@@ -1,18 +1,18 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
 namespace SixLabors.ImageSharp.Formats.Bmp;
 
 /// <summary>
 /// Registers the image encoders, decoders and mime type detectors for the bmp format.
 /// </summary>
-public sealed class BmpConfigurationModule : IConfigurationModule
+public sealed class BmpConfigurationModule : IImageFormatConfigurationModule
 {
     /// <inheritdoc/>
     public void Configure(Configuration configuration)
     {
         configuration.ImageFormatsManager.SetEncoder(BmpFormat.Instance, new BmpEncoder());
-        configuration.ImageFormatsManager.SetDecoder(BmpFormat.Instance, new BmpDecoder());
+        configuration.ImageFormatsManager.SetDecoder(BmpFormat.Instance, BmpDecoder.Instance);
         configuration.ImageFormatsManager.AddImageFormatDetector(new BmpImageFormatDetector());
     }
 }

src/ImageSharp/Formats/Bmp/BmpDecoder.cs

@@ -8,10 +8,19 @@ namespace SixLabors.ImageSharp.Formats.Bmp;
 /// <summary>
 /// Image decoder for generating an image out of a Windows bitmap stream.
 /// </summary>
-public class BmpDecoder : IImageDecoderSpecialized<BmpDecoderOptions>
+public sealed class BmpDecoder : SpecializedImageDecoder<BmpDecoderOptions>
 {
+    private BmpDecoder()
+    {
+    }
+
+    /// <summary>
+    /// Gets the shared instance.
+    /// </summary>
+    public static BmpDecoder Instance { get; } = new();
+
     /// <inheritdoc/>
-    IImageInfo IImageInfoDetector.Identify(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    protected override IImageInfo Identify(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
     {
         Guard.NotNull(options, nameof(options));
         Guard.NotNull(stream, nameof(stream));
@@ -20,27 +29,23 @@ IImageInfo IImageInfoDetector.Identify(DecoderOptions options, Stream stream, Ca
     }
 
     /// <inheritdoc/>
-    Image<TPixel> IImageDecoder.Decode<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
-        => ((IImageDecoderSpecialized<BmpDecoderOptions>)this).Decode<TPixel>(new() { GeneralOptions = options }, stream, cancellationToken);
-
-    /// <inheritdoc/>
-    Image IImageDecoder.Decode(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
-      => ((IImageDecoderSpecialized<BmpDecoderOptions>)this).Decode(new() { GeneralOptions = options }, stream, cancellationToken);
-
-    /// <inheritdoc/>
-    Image<TPixel> IImageDecoderSpecialized<BmpDecoderOptions>.Decode<TPixel>(BmpDecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    protected override Image<TPixel> Decode<TPixel>(BmpDecoderOptions options, Stream stream, CancellationToken cancellationToken)
     {
         Guard.NotNull(options, nameof(options));
         Guard.NotNull(stream, nameof(stream));
 
         Image<TPixel> image = new BmpDecoderCore(options).Decode<TPixel>(options.GeneralOptions.Configuration, stream, cancellationToken);
 
-        ImageDecoderUtilities.Resize(options.GeneralOptions, image);
+        ScaleToTargetSize(options.GeneralOptions, image);
 
         return image;
     }
 
     /// <inheritdoc/>
-    Image IImageDecoderSpecialized<BmpDecoderOptions>.Decode(BmpDecoderOptions options, Stream stream, CancellationToken cancellationToken)
-        => ((IImageDecoderSpecialized<BmpDecoderOptions>)this).Decode<Rgba32>(options, stream, cancellationToken);
+    protected override Image Decode(BmpDecoderOptions options, Stream stream, CancellationToken cancellationToken)
+        => this.Decode<Rgba32>(options, stream, cancellationToken);
+
+    /// <inheritdoc/>
+    protected override BmpDecoderOptions CreateDefaultSpecializedOptions(DecoderOptions options)
+        => new() { GeneralOptions = options };
 }

src/ImageSharp/Formats/Bmp/BmpDecoderOptions.cs

@@ -9,11 +9,11 @@ namespace SixLabors.ImageSharp.Formats.Bmp;
 public sealed class BmpDecoderOptions : ISpecializedDecoderOptions
 {
     /// <inheritdoc/>
-    public DecoderOptions GeneralOptions { get; set; } = new();
+    public DecoderOptions GeneralOptions { get; init; } = new();
 
     /// <summary>
-    /// Gets or sets the value indicating how to deal with skipped pixels,
+    /// Gets the value indicating how to deal with skipped pixels,
     /// which can occur during decoding run length encoded bitmaps.
     /// </summary>
-    public RleSkippedPixelHandling RleSkippedPixelHandling { get; set; }
+    public RleSkippedPixelHandling RleSkippedPixelHandling { get; init; }
 }

src/ImageSharp/Formats/Bmp/BmpEncoder.cs

@@ -24,16 +24,9 @@ public sealed class BmpEncoder : QuantizingImageEncoder
     public bool SupportTransparency { get; init; }
 
     /// <inheritdoc/>
-    public override void Encode<TPixel>(Image<TPixel> image, Stream stream)
+    protected override void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
     {
         BmpEncoderCore encoder = new(this, image.GetMemoryAllocator());
-        encoder.Encode(image, stream);
-    }
-
-    /// <inheritdoc/>
-    public override Task EncodeAsync<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
-    {
-        BmpEncoderCore encoder = new(this, image.GetMemoryAllocator());
-        return encoder.EncodeAsync(image, stream, cancellationToken);
+        encoder.Encode(image, stream, cancellationToken);
     }
 }

src/ImageSharp/Formats/Bmp/BmpFormat.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
 namespace SixLabors.ImageSharp.Formats.Bmp;
@@ -13,7 +13,7 @@ private BmpFormat()
     }
 
     /// <summary>
-    /// Gets the current instance.
+    /// Gets the shared instance.
     /// </summary>
     public static BmpFormat Instance { get; } = new BmpFormat();
 
@@ -30,5 +30,5 @@ private BmpFormat()
     public IEnumerable<string> FileExtensions => BmpConstants.FileExtensions;
 
     /// <inheritdoc/>
-    public BmpMetadata CreateDefaultFormatMetadata() => new BmpMetadata();
+    public BmpMetadata CreateDefaultFormatMetadata() => new();
 }

src/ImageSharp/Formats/DecoderOptions.cs

@@ -21,27 +21,27 @@ public sealed class DecoderOptions
     internal static DecoderOptions Default { get; } = LazyOptions.Value;
 
     /// <summary>
-    /// Gets or sets a custom Configuration instance to be used by the image processing pipeline.
+    /// Gets a custom configuration instance to be used by the image processing pipeline.
     /// </summary>
-    public Configuration Configuration { get; set; } = Configuration.Default;
+    public Configuration Configuration { get; internal set; } = Configuration.Default;
 
     /// <summary>
-    /// Gets or sets the target size to decode the image into.
+    /// Gets the target size to decode the image into. Scaling should use an operation equivalent to <see cref="ResizeMode.Max"/>.
     /// </summary>
-    public Size? TargetSize { get; set; }
+    public Size? TargetSize { get; init; }
 
     /// <summary>
-    /// Gets or sets the sampler to use when resizing during decoding.
+    /// Gets the sampler to use when resizing during decoding.
     /// </summary>
-    public IResampler Sampler { get; set; } = KnownResamplers.Box;
+    public IResampler Sampler { get; init; } = KnownResamplers.Box;
 
     /// <summary>
-    /// Gets or sets a value indicating whether to ignore encoded metadata when decoding.
+    /// Gets a value indicating whether to ignore encoded metadata when decoding.
     /// </summary>
-    public bool SkipMetadata { get; set; }
+    public bool SkipMetadata { get; init; }
 
     /// <summary>
-    /// Gets or sets the maximum number of image frames to decode, inclusive.
+    /// Gets the maximum number of image frames to decode, inclusive.
     /// </summary>
-    public uint MaxFrames { get => this.maxFrames; set => this.maxFrames = Math.Clamp(value, 1, int.MaxValue); }
+    public uint MaxFrames { get => this.maxFrames; init => this.maxFrames = Math.Clamp(value, 1, int.MaxValue); }
 }

src/ImageSharp/Formats/Gif/GifConfigurationModule.cs

@@ -1,18 +1,18 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
 namespace SixLabors.ImageSharp.Formats.Gif;
 
 /// <summary>
 /// Registers the image encoders, decoders and mime type detectors for the gif format.
 /// </summary>
-public sealed class GifConfigurationModule : IConfigurationModule
+public sealed class GifConfigurationModule : IImageFormatConfigurationModule
 {
     /// <inheritdoc/>
     public void Configure(Configuration configuration)
     {
         configuration.ImageFormatsManager.SetEncoder(GifFormat.Instance, new GifEncoder());
-        configuration.ImageFormatsManager.SetDecoder(GifFormat.Instance, new GifDecoder());
+        configuration.ImageFormatsManager.SetDecoder(GifFormat.Instance, GifDecoder.Instance);
         configuration.ImageFormatsManager.AddImageFormatDetector(new GifImageFormatDetector());
     }
 }

src/ImageSharp/Formats/Gif/GifDecoder.cs

@@ -8,10 +8,19 @@ namespace SixLabors.ImageSharp.Formats.Gif;
 /// <summary>
 /// Decoder for generating an image out of a gif encoded stream.
 /// </summary>
-public sealed class GifDecoder : IImageDecoder
+public sealed class GifDecoder : ImageDecoder
 {
+    private GifDecoder()
+    {
+    }
+
+    /// <summary>
+    /// Gets the shared instance.
+    /// </summary>
+    public static GifDecoder Instance { get; } = new();
+
     /// <inheritdoc/>
-    IImageInfo IImageInfoDetector.Identify(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    protected override IImageInfo Identify(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
     {
         Guard.NotNull(options, nameof(options));
         Guard.NotNull(stream, nameof(stream));
@@ -20,20 +29,20 @@ IImageInfo IImageInfoDetector.Identify(DecoderOptions options, Stream stream, Ca
     }
 
     /// <inheritdoc/>
-    Image<TPixel> IImageDecoder.Decode<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    protected override Image<TPixel> Decode<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
     {
         Guard.NotNull(options, nameof(options));
         Guard.NotNull(stream, nameof(stream));
 
         GifDecoderCore decoder = new(options);
         Image<TPixel> image = decoder.Decode<TPixel>(options.Configuration, stream, cancellationToken);
 
-        ImageDecoderUtilities.Resize(options, image);
+        ScaleToTargetSize(options, image);
 
         return image;
     }
 
     /// <inheritdoc/>
-    Image IImageDecoder.Decode(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
-        => ((IImageDecoder)this).Decode<Rgba32>(options, stream, cancellationToken);
+    protected override Image Decode(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+        => this.Decode<Rgba32>(options, stream, cancellationToken);
 }

src/ImageSharp/Formats/Gif/GifEncoder.cs

@@ -16,16 +16,9 @@ public sealed class GifEncoder : QuantizingImageEncoder
     public GifColorTableMode? ColorTableMode { get; init; }
 
     /// <inheritdoc/>
-    public override void Encode<TPixel>(Image<TPixel> image, Stream stream)
+    protected override void Encode<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
     {
         GifEncoderCore encoder = new(image.GetConfiguration(), this);
-        encoder.Encode(image, stream);
-    }
-
-    /// <inheritdoc/>
-    public override Task EncodeAsync<TPixel>(Image<TPixel> image, Stream stream, CancellationToken cancellationToken)
-    {
-        GifEncoderCore encoder = new(image.GetConfiguration(), this);
-        return encoder.EncodeAsync(image, stream, cancellationToken);
+        encoder.Encode(image, stream, cancellationToken);
     }
 }

src/ImageSharp/Formats/Gif/GifFormat.cs

@@ -13,7 +13,7 @@ private GifFormat()
     }
 
     /// <summary>
-    /// Gets the current instance.
+    /// Gets the shared instance.
     /// </summary>
     public static GifFormat Instance { get; } = new();
 

src/ImageSharp/Formats/IImageDecoder.cs

@@ -6,35 +6,68 @@
 namespace SixLabors.ImageSharp.Formats;
 
 /// <summary>
-/// Encapsulates properties and methods required for decoding an image from a stream.
+/// Defines the contract for all image decoders.
 /// </summary>
-public interface IImageDecoder : IImageInfoDetector
+public interface IImageDecoder
 {
+    /// <summary>
+    /// Reads the raw image information from the specified stream.
+    /// </summary>
+    /// <param name="options">The general decoder options.</param>
+    /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
+    /// <returns>The <see cref="IImageInfo"/> object.</returns>
+    /// <exception cref="ImageFormatException">Thrown if the encoded image contains errors.</exception>
+    public IImageInfo Identify(DecoderOptions options, Stream stream);
+
+    /// <summary>
+    /// Reads the raw image information from the specified stream.
+    /// </summary>
+    /// <param name="options">The general decoder options.</param>
+    /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
+    /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
+    /// <returns>The <see cref="Task{IImageInfo}"/> object.</returns>
+    /// <exception cref="ImageFormatException">Thrown if the encoded image contains errors.</exception>
+    public Task<IImageInfo> IdentifyAsync(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default);
+
     /// <summary>
     /// Decodes the image from the specified stream to an <see cref="Image{TPixel}"/> of a specific pixel type.
     /// </summary>
-    /// <remarks>
-    /// This method is designed to support the ImageSharp internal infrastructure and is not recommended for direct use.
-    /// </remarks>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
     /// <param name="options">The general decoder options.</param>
     /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
-    /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
     /// <returns>The <see cref="Image{TPixel}"/>.</returns>
     /// <exception cref="ImageFormatException">Thrown if the encoded image contains errors.</exception>
-    Image<TPixel> Decode<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken)
+    public Image<TPixel> Decode<TPixel>(DecoderOptions options, Stream stream)
+        where TPixel : unmanaged, IPixel<TPixel>;
+
+    /// <summary>
+    /// Decodes the image from the specified stream to an <see cref="Image"/> of a specific pixel type.
+    /// </summary>
+    /// <param name="options">The general decoder options.</param>
+    /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
+    /// <returns>The <see cref="Image{TPixel}"/>.</returns>
+    /// <exception cref="ImageFormatException">Thrown if the encoded image contains errors.</exception>
+    public Image Decode(DecoderOptions options, Stream stream);
+
+    /// <summary>
+    /// Decodes the image from the specified stream to an <see cref="Image{TPixel}"/> of a specific pixel type.
+    /// </summary>
+    /// <typeparam name="TPixel">The pixel format.</typeparam>
+    /// <param name="options">The general decoder options.</param>
+    /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
+    /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
+    /// <returns>A <see cref="Task{Image}"/> representing the asynchronous operation.</returns>
+    /// <exception cref="ImageFormatException">Thrown if the encoded image contains errors.</exception>
+    public Task<Image<TPixel>> DecodeAsync<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default)
         where TPixel : unmanaged, IPixel<TPixel>;
 
     /// <summary>
-    /// Decodes the image from the specified stream to an <see cref="Image"/>.
+    /// Decodes the image from the specified stream to an <see cref="Image"/> of a specific pixel type.
     /// </summary>
-    /// <remarks>
-    /// This method is designed to support the ImageSharp internal infrastructure and is not recommended for direct use.
-    /// </remarks>
     /// <param name="options">The general decoder options.</param>
     /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
     /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
-    /// <returns>The <see cref="Image"/>.</returns>
+    /// <returns>A <see cref="Task{Image}"/> representing the asynchronous operation.</returns>
     /// <exception cref="ImageFormatException">Thrown if the encoded image contains errors.</exception>
-    Image Decode(DecoderOptions options, Stream stream, CancellationToken cancellationToken);
+    public Task<Image> DecodeAsync(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default);
 }