// Copyright © Clinton Ingram and Contributors // SPDX-License-Identifier: MIT using System; using System.IO; using System.Linq; using System.Numerics; using System.Reflection; using System.Collections; using System.Collections.Generic; using System.Runtime.InteropServices; using System.Runtime.CompilerServices; using System.Diagnostics.CodeAnalysis; #if HWINTRINSICS using System.Runtime.Intrinsics; using System.Runtime.Intrinsics.X86; #endif namespace PhotoSauce.MagicScaler; ///

Well-known MIME types for image formats.

public static class ImageMimeTypes { #pragma warning disable CS1591 // Missing XML comments public const string Avif = "image/avif"; public const string Bmp = "image/bmp"; public const string Dds = "image/vnd.ms-dds"; public const string Gif = "image/gif"; public const string Heic = "image/heic"; public const string Jpeg = "image/jpeg"; public const string Jxl = "image/jxl"; public const string Jxr = "image/vnd.ms-photo"; // actual IANA assignment is image/jxr, but WIC reports otherwise public const string Png = "image/png"; public const string Tiff = "image/tiff"; public const string Webp = "image/webp"; #pragma warning restore CS1591 internal static FileFormat ToFileFormat(string? mime, bool indexed = false) => mime switch { Bmp => FileFormat.Bmp, Gif => FileFormat.Gif, Png => indexed ? FileFormat.Png8 : FileFormat.Png, Jpeg => FileFormat.Jpeg, Tiff => FileFormat.Tiff, _ => default }; } ///

Well-known file extensions for image formats.

public static class ImageFileExtensions { #pragma warning disable CS1591 // Missing XML comments public const string Avif = ".avif"; public const string Bmp = ".bmp"; public const string Dds = ".dds"; public const string Gif = ".gif"; public const string Heic = ".heic"; public const string Jpeg = ".jpeg"; public const string Jxl = ".jxl"; public const string Jxr = ".jxr"; public const string Png = ".png"; public const string Tiff = ".tiff"; public const string Webp = ".webp"; #pragma warning restore CS1591 internal static string[] All = typeof(ImageFileExtensions) .GetFields(BindingFlags.Public | BindingFlags.Static) .Where(static f => f.FieldType == typeof(string)) .Select(static f => (string)f.GetValue(null)!) .ToArray(); } ///

A pattern used to match magic bytes in an image file header.

/// Number of bytes to skip from the start of the file before attempting pattern match. /// A byte pattern to match at the given . /// A mask to apply to image bytes (using binary ) before matching against the . /// The total length described by ( + .Length) should not be more than 16 bytes. public readonly record struct ContainerPattern(int Offset, byte[] Pattern, byte[] Mask); /// /// /// /// public abstract record class CodecInfo( string Name, IEnumerable MimeTypes, IEnumerable FileExtensions ) : IImageCodecInfo; /// /// /// /// public sealed record class DecoderInfo( string Name, IEnumerable MimeTypes, IEnumerable FileExtensions, IEnumerable Patterns, IDecoderOptions? DefaultOptions, Func Factory ) : CodecInfo(Name, MimeTypes, FileExtensions), IImageDecoderInfo; /// /// /// /// /// /// /// public record class EncoderInfo( string Name, IEnumerable MimeTypes, IEnumerable FileExtensions, IEnumerable PixelFormats, IEncoderOptions? DefaultOptions, Func Factory, bool SupportsMultiFrame, bool SupportsAnimation, bool SupportsColorProfile ) : CodecInfo(Name, MimeTypes, FileExtensions), IImageEncoderInfo; /// /// A list of s supported by the encoder. /// The sampling position used by the encoder for subsampled chroma. /// The default color matrix to use for RGB->YCbCr conversion. /// True if the encoder supports custom RGB->YCbCr matrices, otherwise false. public sealed record class PlanarEncoderInfo( string Name, IEnumerable MimeTypes, IEnumerable FileExtensions, IEnumerable PixelFormats, IEncoderOptions? DefaultOptions, Func Factory, bool SupportsMultiFrame, bool SupportsAnimation, bool SupportsColorProfile, ChromaSubsampleMode[] SubsampleModes, ChromaPosition ChromaPosition, Matrix4x4 DefaultMatrix, bool SupportsCustomMatrix ) : EncoderInfo(Name, MimeTypes, FileExtensions, PixelFormats, DefaultOptions, Factory, SupportsMultiFrame, SupportsAnimation, SupportsColorProfile), IPlanarImageEncoderInfo; ///

Represents the set of configured codecs for the processing pipeline.

/// Instances should not be retained or used outside of . public sealed class CodecCollection : ICollection, IReadOnlyCollection { private readonly List codecs = [ ]; private readonly Dictionary encoderMimeMap = new(StringComparer.OrdinalIgnoreCase); private readonly Dictionary encoderExtensionMap = new(StringComparer.OrdinalIgnoreCase); private DecoderPattern[] decoderPatterns = [ ]; /// public int Count => codecs.Count; /// public bool Contains(IImageCodecInfo item) => codecs.Contains(item); /// public void Add(IImageCodecInfo item) => codecs.Add(item); /// public bool Remove(IImageCodecInfo item) => codecs.Remove(item); /// public void Clear() => codecs.Clear(); /// public IEnumerator GetEnumerator() => codecs.GetEnumerator(); bool ICollection.IsReadOnly => false; void ICollection.CopyTo(IImageCodecInfo[] array, int arrayIndex) => codecs.CopyTo(array, arrayIndex); IEnumerator IEnumerable.GetEnumerator() => codecs.GetEnumerator(); internal void AddRange(IEnumerable items) => codecs.AddRange(items); internal IImageContainer GetDecoderForStream(Stream stm, IDecoderOptions? options = null) { const int siglen = sizeof(ulong) * 2; if ((stm.Length - stm.Position) < siglen) throw new InvalidDataException("The input is too small to be a valid image."); var patBuffer = (Span)stackalloc byte[siglen]; stm.FillBuffer(patBuffer); stm.Seek(-siglen, SeekOrigin.Current); ref byte testval = ref MemoryMarshal.GetReference(patBuffer); #if HWINTRINSICS if (Sse2.IsSupported) { var vtv = Unsafe.ReadUnaligned>(ref testval); foreach (ref readonly var pat in decoderPatterns.AsSpan()) { var vcv = Unsafe.ReadUnaligned>(ref Unsafe.As(ref Unsafe.AsRef(in pat.p1))); var vcm = Unsafe.ReadUnaligned>(ref Unsafe.As(ref Unsafe.AsRef(in pat.m1))); if (HWIntrinsics.IsMaskedZero(Sse2.Xor(vtv, vcv), vcm)) { var dec = pat.dec.Factory(stm, options ?? pat.dec.DefaultOptions); if (dec is not null) return dec; } } } else #endif { ulong tv0 = Unsafe.ReadUnaligned(ref testval); ulong tv1 = Unsafe.ReadUnaligned(ref Unsafe.Add(ref testval, sizeof(ulong))); foreach (ref readonly var pat in decoderPatterns.AsSpan()) { if ((((tv0 ^ pat.p1) & pat.m1) | ((tv1 ^ pat.p2) & pat.m2)) == 0) { var dec = pat.dec.Factory(stm, options ?? pat.dec.DefaultOptions); if (dec is not null) return dec; } } } throw new InvalidDataException("Image format not supported. Please ensure the input file is an image and that a codec capable of reading the image is registered."); } internal bool TryGetEncoderForFileExtension(string extension, [NotNullWhen(true)] out IImageEncoderInfo? info) => (info = encoderExtensionMap.GetValueOrDefault(extension)) is not null; internal bool TryGetEncoderForMimeType(string mimeType, [NotNullWhen(true)] out IImageEncoderInfo? info) => (info = encoderMimeMap.GetValueOrDefault(mimeType)) is not null; internal void ResetCaches() { decoderPatterns = codecs.OfType().SelectMany(static i => i.Patterns.Select(s => (Info: i, Pattern: s))).Select(static dec => { var pat = new DecoderPattern { dec = dec.Info }; int offset = dec.Pattern.Offset.Clamp(0, sizeof(ulong) * 2); Unsafe.CopyBlockUnaligned(ref Unsafe.Add(ref Unsafe.As(ref pat.m1), offset), ref MemoryMarshal.GetReference(dec.Pattern.Mask.AsSpan()), (uint)(dec.Pattern.Mask?.Length ?? 0).Clamp(0, sizeof(ulong) * 2 - offset)); Unsafe.CopyBlockUnaligned(ref Unsafe.Add(ref Unsafe.As(ref pat.p1), offset), ref MemoryMarshal.GetReference(dec.Pattern.Pattern.AsSpan()), (uint)(dec.Pattern.Pattern?.Length ?? 0).Clamp(0, sizeof(ulong) * 2 - offset)); return pat; }).ToArray(); encoderMimeMap.Clear(); foreach (var enc in codecs.OfType().SelectMany(static i => i.MimeTypes.Select(s => (Info: i, MimeType: s)))) encoderMimeMap.TryAdd(enc.MimeType, enc.Info); encoderExtensionMap.Clear(); foreach (var enc in codecs.OfType().SelectMany(static i => i.FileExtensions.Select(s => (Info: i, Extension: s)))) { string ext = enc.Extension; if (string.IsNullOrEmpty(ext)) continue; if (ext[0] != '.') ext = string.Concat(".", ext); encoderExtensionMap.TryAdd(ext, enc.Info); } } [StructLayout(LayoutKind.Sequential)] private struct DecoderPattern { public ulong m1; public ulong m2; public ulong p1; public ulong p2; public IImageDecoderInfo dec; } } ///

Manages registration of encoders, decoders, and image type mappings.

public static class CodecManager { private static volatile CodecCollection? codecs; internal static readonly EncoderInfo FallbackEncoder = new( nameof(FallbackEncoder), [ ], [ ], [ ], null, (s, o) => throw new InvalidOperationException("No encoders are registered."), false, false, false ); private static CodecCollection getCodecs() { if (codecs is null) Configure(default); return codecs; } ///

Configure codecs for the application lifetime.

/// A callback that allows manipulation of the codec collection before it is registered with the pipeline. /// [MemberNotNull(nameof(codecs))] public static void Configure(Action? configure) { var cc = new CodecCollection(); if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) cc.UseWicCodecs(WicCodecPolicy.BuiltIn); if (configure is not null) configure(cc); if (cc.Count == 0) throw new InvalidOperationException($"No codecs are configured. You must add some codecs in a call to {nameof(CodecManager)}.{nameof(Configure)}."); cc.ResetCaches(); codecs = cc; } internal static IImageContainer GetDecoderForStream(Stream stm, IDecoderOptions? opt = null) => getCodecs().GetDecoderForStream(stm, opt); internal static bool TryGetEncoderForFileExtension(string extension, [NotNullWhen(true)] out IImageEncoderInfo? info) => getCodecs().TryGetEncoderForFileExtension(extension, out info); internal static bool TryGetEncoderForMimeType(string mimeType, [NotNullWhen(true)] out IImageEncoderInfo? info) => getCodecs().TryGetEncoderForMimeType(mimeType, out info); internal static bool SupportsMimeType(this IImageEncoderInfo enc, string mime) => enc.MimeTypes.ContainsInsensitive(mime); internal static bool SupportsPixelFormat(this IImageEncoderInfo enc, Guid fmt) => enc.PixelFormats.Contains(fmt); internal static ChromaSubsampleMode GetClosestSubsampling(this IPlanarImageEncoderInfo enc, ChromaSubsampleMode sub) { var modes = enc.SubsampleModes; for (int i = 0; i < modes.Length; i++) if (modes[i] >= sub) return modes[i]; for (int i = modes.Length - 1; i >= 0; i--) if (modes[i] < sub) return modes[i]; return default; } internal static PixelFormat GetClosestPixelFormat(this IImageEncoderInfo enc, PixelFormat fmt) { if (enc.SupportsPixelFormat(fmt.FormatGuid)) return fmt; if (fmt.AlphaRepresentation != PixelAlphaRepresentation.None) { if (enc.SupportsPixelFormat(PixelFormat.Bgra32.FormatGuid)) return PixelFormat.Bgra32; else if (enc.SupportsPixelFormat(PixelFormat.Rgba32.FormatGuid)) return PixelFormat.Rgba32; } if (fmt.ColorRepresentation == PixelColorRepresentation.Bgr || fmt == PixelFormat.Grey8) { if (enc.SupportsPixelFormat(PixelFormat.Bgr24.FormatGuid)) return PixelFormat.Bgr24; else if (enc.SupportsPixelFormat(PixelFormat.Rgb24.FormatGuid)) return PixelFormat.Rgb24; else if (enc.SupportsPixelFormat(PixelFormat.Bgra32.FormatGuid)) return PixelFormat.Bgra32; else if (enc.SupportsPixelFormat(PixelFormat.Rgba32.FormatGuid)) return PixelFormat.Rgba32; } else if (fmt == PixelFormat.Y8 || fmt == PixelFormat.Y8Video) { if (enc.SupportsPixelFormat(PixelFormat.Y8.FormatGuid)) return PixelFormat.Y8; else if (enc.SupportsPixelFormat(PixelFormat.Y8Video.FormatGuid)) return PixelFormat.Y8Video; } else if (fmt == PixelFormat.Cb8 || fmt == PixelFormat.Cb8Video) { if (enc.SupportsPixelFormat(PixelFormat.Cb8.FormatGuid)) return PixelFormat.Cb8; else if (enc.SupportsPixelFormat(PixelFormat.Cb8Video.FormatGuid)) return PixelFormat.Cb8Video; } else if (fmt == PixelFormat.Cr8 || fmt == PixelFormat.Cr8Video) { if (enc.SupportsPixelFormat(PixelFormat.Cr8.FormatGuid)) return PixelFormat.Cr8; else if (enc.SupportsPixelFormat(PixelFormat.Cr8Video.FormatGuid)) return PixelFormat.Cr8Video; } return fmt; } }

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