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add some nullable ref types for image detection #2275

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3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/Bmp/BmpImageFormatDetector.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
using System.Buffers.Binary;

namespace SixLabors.ImageSharp.Formats.Bmp;
Expand All @@ -14,7 +15,7 @@ public sealed class BmpImageFormatDetector : IImageFormatDetector
public int HeaderSize => 2;

/// <inheritdoc/>
public IImageFormat DetectFormat(ReadOnlySpan<byte> header)
public IImageFormat? DetectFormat(ReadOnlySpan<byte> header)
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@JimBobSquarePants JimBobSquarePants Oct 25, 2022

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I cannot decide what the best pattern for nullable return types should be. I feel like anything that returns a nullable type should probably use a TryXX(in, out..) pattern (though I still haven't found a nice async pattern for that)

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@SimonCropp SimonCropp Oct 25, 2022

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I feel like anything that returns a nullable type should probably use a TryXX(in, out..)

yeah. i was trying to do this in the least intrusive way

though I still haven't found a nice async pattern for that

neither have I

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@SimonCropp SimonCropp Oct 25, 2022

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happy to add some TryXX overloads. but i would prefer to do those in a new PR

{
return this.IsSupportedFileFormat(header) ? BmpFormat.Instance : null;
}
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3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/Gif/GifImageFormatDetector.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
namespace SixLabors.ImageSharp.Formats.Gif;

/// <summary>
Expand All @@ -12,7 +13,7 @@ public sealed class GifImageFormatDetector : IImageFormatDetector
public int HeaderSize => 6;

/// <inheritdoc/>
public IImageFormat DetectFormat(ReadOnlySpan<byte> header)
public IImageFormat? DetectFormat(ReadOnlySpan<byte> header)
{
return this.IsSupportedFileFormat(header) ? GifFormat.Instance : null;
}
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3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/IImageFormatDetector.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
namespace SixLabors.ImageSharp.Formats;

/// <summary>
Expand All @@ -19,5 +20,5 @@ public interface IImageFormatDetector
/// </summary>
/// <param name="header">The <see cref="T:byte[]"/> containing the file header.</param>
/// <returns>returns the mime type of detected otherwise returns null</returns>
IImageFormat DetectFormat(ReadOnlySpan<byte> header);
IImageFormat? DetectFormat(ReadOnlySpan<byte> header);
}
13 changes: 7 additions & 6 deletions src/ImageSharp/Formats/ImageFormatManager.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
using System.Collections.Concurrent;

namespace SixLabors.ImageSharp.Formats;
Expand Down Expand Up @@ -92,7 +93,7 @@ public void AddImageFormat(IImageFormat format)
/// </summary>
/// <param name="extension">The extension to discover</param>
/// <returns>The <see cref="IImageFormat"/> if found otherwise null</returns>
public IImageFormat FindFormatByFileExtension(string extension)
public IImageFormat? FindFormatByFileExtension(string extension)
{
Guard.NotNullOrWhiteSpace(extension, nameof(extension));

Expand All @@ -109,7 +110,7 @@ public IImageFormat FindFormatByFileExtension(string extension)
/// </summary>
/// <param name="mimeType">The mime-type to discover</param>
/// <returns>The <see cref="IImageFormat"/> if found; otherwise null</returns>
public IImageFormat FindFormatByMimeType(string mimeType)
public IImageFormat? FindFormatByMimeType(string mimeType)
=> this.imageFormats.FirstOrDefault(x => x.MimeTypes.Contains(mimeType, StringComparer.OrdinalIgnoreCase));

/// <summary>
Expand Down Expand Up @@ -159,11 +160,11 @@ public void AddImageFormatDetector(IImageFormatDetector detector)
/// </summary>
/// <param name="format">The format to discover</param>
/// <returns>The <see cref="IImageDecoder"/> if found otherwise null</returns>
public IImageDecoder FindDecoder(IImageFormat format)
public IImageDecoder? FindDecoder(IImageFormat format)
{
Guard.NotNull(format, nameof(format));

return this.mimeTypeDecoders.TryGetValue(format, out IImageDecoder decoder)
return this.mimeTypeDecoders.TryGetValue(format, out IImageDecoder? decoder)
? decoder
: null;
}
Expand All @@ -173,11 +174,11 @@ public IImageDecoder FindDecoder(IImageFormat format)
/// </summary>
/// <param name="format">The format to discover</param>
/// <returns>The <see cref="IImageEncoder"/> if found otherwise null</returns>
public IImageEncoder FindEncoder(IImageFormat format)
public IImageEncoder? FindEncoder(IImageFormat format)
{
Guard.NotNull(format, nameof(format));

return this.mimeTypeEncoders.TryGetValue(format, out IImageEncoder encoder)
return this.mimeTypeEncoders.TryGetValue(format, out IImageEncoder? encoder)
? encoder
: null;
}
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3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/Jpeg/JpegImageFormatDetector.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
namespace SixLabors.ImageSharp.Formats.Jpeg;

/// <summary>
Expand All @@ -12,7 +13,7 @@ public sealed class JpegImageFormatDetector : IImageFormatDetector
public int HeaderSize => 11;

/// <inheritdoc/>
public IImageFormat DetectFormat(ReadOnlySpan<byte> header)
public IImageFormat? DetectFormat(ReadOnlySpan<byte> header)
=> this.IsSupportedFileFormat(header) ? JpegFormat.Instance : null;

private bool IsSupportedFileFormat(ReadOnlySpan<byte> header)
Expand Down
3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/Pbm/PbmImageFormatDetector.cs
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// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
namespace SixLabors.ImageSharp.Formats.Pbm;

/// <summary>
Expand All @@ -16,7 +17,7 @@ public sealed class PbmImageFormatDetector : IImageFormatDetector
public int HeaderSize => 2;

/// <inheritdoc/>
public IImageFormat DetectFormat(ReadOnlySpan<byte> header) => IsSupportedFileFormat(header) ? PbmFormat.Instance : null;
public IImageFormat? DetectFormat(ReadOnlySpan<byte> header) => IsSupportedFileFormat(header) ? PbmFormat.Instance : null;

private static bool IsSupportedFileFormat(ReadOnlySpan<byte> header)
{
Expand Down
3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/Png/PngImageFormatDetector.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
using System.Buffers.Binary;

namespace SixLabors.ImageSharp.Formats.Png;
Expand All @@ -14,7 +15,7 @@ public sealed class PngImageFormatDetector : IImageFormatDetector
public int HeaderSize => 8;

/// <inheritdoc/>
public IImageFormat DetectFormat(ReadOnlySpan<byte> header)
public IImageFormat? DetectFormat(ReadOnlySpan<byte> header)
{
return this.IsSupportedFileFormat(header) ? PngFormat.Instance : null;
}
Expand Down
3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/Tga/TgaImageFormatDetector.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
namespace SixLabors.ImageSharp.Formats.Tga;

/// <summary>
Expand All @@ -12,7 +13,7 @@ public sealed class TgaImageFormatDetector : IImageFormatDetector
public int HeaderSize => 16;

/// <inheritdoc/>
public IImageFormat DetectFormat(ReadOnlySpan<byte> header)
public IImageFormat? DetectFormat(ReadOnlySpan<byte> header)
{
return this.IsSupportedFileFormat(header) ? TgaFormat.Instance : null;
}
Expand Down
3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/Tiff/TiffImageFormatDetector.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
namespace SixLabors.ImageSharp.Formats.Tiff;

/// <summary>
Expand All @@ -12,7 +13,7 @@ public sealed class TiffImageFormatDetector : IImageFormatDetector
public int HeaderSize => 8;

/// <inheritdoc/>
public IImageFormat DetectFormat(ReadOnlySpan<byte> header)
public IImageFormat? DetectFormat(ReadOnlySpan<byte> header)
{
if (this.IsSupportedFileFormat(header))
{
Expand Down
3 changes: 2 additions & 1 deletion src/ImageSharp/Formats/Webp/WebpImageFormatDetector.cs
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// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
namespace SixLabors.ImageSharp.Formats.Webp;

/// <summary>
Expand All @@ -12,7 +13,7 @@ public sealed class WebpImageFormatDetector : IImageFormatDetector
public int HeaderSize => 12;

/// <inheritdoc />
public IImageFormat DetectFormat(ReadOnlySpan<byte> header)
public IImageFormat? DetectFormat(ReadOnlySpan<byte> header)
=> this.IsSupportedFileFormat(header) ? WebpFormat.Instance : null;

private bool IsSupportedFileFormat(ReadOnlySpan<byte> header)
Expand Down
23 changes: 12 additions & 11 deletions src/ImageSharp/Image.Decode.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
using SixLabors.ImageSharp.Formats;
using SixLabors.ImageSharp.Memory;
using SixLabors.ImageSharp.Metadata;
Expand Down Expand Up @@ -44,7 +45,7 @@ internal static Image<TPixel> CreateUninitialized<TPixel>(
/// <param name="configuration">The general configuration.</param>
/// <param name="stream">The image stream to read the header from.</param>
/// <returns>The mime type or null if none found.</returns>
private static IImageFormat InternalDetectFormat(Configuration configuration, Stream stream)
private static IImageFormat? InternalDetectFormat(Configuration configuration, Stream stream)
{
// We take a minimum of the stream length vs the max header size and always check below
// to ensure that only formats that headers fit within the given buffer length are tested.
Expand Down Expand Up @@ -76,12 +77,12 @@ private static IImageFormat InternalDetectFormat(Configuration configuration, St
// Does the given stream contain enough data to fit in the header for the format
// and does that data match the format specification?
// Individual formats should still check since they are public.
IImageFormat format = null;
IImageFormat? format = null;
foreach (IImageFormatDetector formatDetector in configuration.ImageFormatsManager.FormatDetectors)
{
if (formatDetector.HeaderSize <= headerSize)
{
IImageFormat attemptFormat = formatDetector.DetectFormat(headersBuffer);
IImageFormat? attemptFormat = formatDetector.DetectFormat(headersBuffer);
if (attemptFormat != null)
{
format = attemptFormat;
Expand All @@ -99,7 +100,7 @@ private static IImageFormat InternalDetectFormat(Configuration configuration, St
/// <param name="stream">The image stream to read the header from.</param>
/// <param name="format">The IImageFormat.</param>
/// <returns>The image format or null if none found.</returns>
private static IImageDecoder DiscoverDecoder(DecoderOptions options, Stream stream, out IImageFormat format)
private static IImageDecoder? DiscoverDecoder(DecoderOptions options, Stream stream, out IImageFormat? format)
{
format = InternalDetectFormat(options.Configuration, stream);

Expand All @@ -118,10 +119,10 @@ private static IImageDecoder DiscoverDecoder(DecoderOptions options, Stream stre
/// <returns>
/// A new <see cref="Image{TPixel}"/>.
/// </returns>
private static (Image<TPixel> Image, IImageFormat Format) Decode<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default)
private static (Image<TPixel>? Image, IImageFormat? Format) Decode<TPixel>(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default)
where TPixel : unmanaged, IPixel<TPixel>
{
IImageDecoder decoder = DiscoverDecoder(options, stream, out IImageFormat format);
IImageDecoder? decoder = DiscoverDecoder(options, stream, out IImageFormat? format);
if (decoder is null)
{
return (null, null);
Expand All @@ -131,9 +132,9 @@ private static (Image<TPixel> Image, IImageFormat Format) Decode<TPixel>(Decoder
return (img, format);
}

private static (Image Image, IImageFormat Format) Decode(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default)
private static (Image? Image, IImageFormat? Format) Decode(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default)
{
IImageDecoder decoder = DiscoverDecoder(options, stream, out IImageFormat format);
IImageDecoder? decoder = DiscoverDecoder(options, stream, out IImageFormat? format);
if (decoder is null)
{
return (null, null);
Expand All @@ -152,16 +153,16 @@ private static (Image Image, IImageFormat Format) Decode(DecoderOptions options,
/// <returns>
/// The <see cref="IImageInfo"/> or null if a suitable info detector is not found.
/// </returns>
private static (IImageInfo ImageInfo, IImageFormat Format) InternalIdentity(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default)
private static (IImageInfo? ImageInfo, IImageFormat? Format) InternalIdentity(DecoderOptions options, Stream stream, CancellationToken cancellationToken = default)
{
IImageDecoder decoder = DiscoverDecoder(options, stream, out IImageFormat format);
IImageDecoder? decoder = DiscoverDecoder(options, stream, out IImageFormat? format);

if (decoder is not IImageInfoDetector detector)
{
return (null, null);
}

IImageInfo info = detector?.Identify(options, stream, cancellationToken);
IImageInfo? info = detector.Identify(options, stream, cancellationToken);
return (info, format);
}
}
21 changes: 11 additions & 10 deletions src/ImageSharp/Image.FromBytes.cs
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@@ -1,6 +1,7 @@
// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

#nullable enable
using SixLabors.ImageSharp.Formats;
using SixLabors.ImageSharp.PixelFormats;

Expand All @@ -16,7 +17,7 @@ public abstract partial class Image
/// </summary>
/// <param name="data">The byte span containing encoded image data to read the header from.</param>
/// <returns>The format or null if none found.</returns>
public static IImageFormat DetectFormat(ReadOnlySpan<byte> data)
public static IImageFormat? DetectFormat(ReadOnlySpan<byte> data)
=> DetectFormat(DecoderOptions.Default, data);

/// <summary>
Expand All @@ -26,7 +27,7 @@ public static IImageFormat DetectFormat(ReadOnlySpan<byte> data)
/// <param name="data">The byte span containing encoded image data to read the header from.</param>
/// <exception cref="ArgumentNullException">The options are null.</exception>
/// <returns>The mime type or null if none found.</returns>
public static IImageFormat DetectFormat(DecoderOptions options, ReadOnlySpan<byte> data)
public static IImageFormat? DetectFormat(DecoderOptions options, ReadOnlySpan<byte> data)
{
Guard.NotNull(options, nameof(options.Configuration));

Expand All @@ -39,7 +40,7 @@ public static IImageFormat DetectFormat(DecoderOptions options, ReadOnlySpan<byt

foreach (IImageFormatDetector detector in configuration.ImageFormatsManager.FormatDetectors)
{
IImageFormat f = detector.DetectFormat(data);
IImageFormat? f = detector.DetectFormat(data);

if (f != null)
{
Expand All @@ -59,7 +60,7 @@ public static IImageFormat DetectFormat(DecoderOptions options, ReadOnlySpan<byt
/// <returns>
/// The <see cref="IImageInfo"/> or null if suitable info detector not found.
/// </returns>
public static IImageInfo Identify(ReadOnlySpan<byte> data) => Identify(data, out IImageFormat _);
public static IImageInfo? Identify(ReadOnlySpan<byte> data) => Identify(data, out IImageFormat? _);

/// <summary>
/// Reads the raw image information from the specified stream without fully decoding it.
Expand All @@ -71,7 +72,7 @@ public static IImageFormat DetectFormat(DecoderOptions options, ReadOnlySpan<byt
/// <returns>
/// The <see cref="IImageInfo"/> or null if suitable info detector not found.
/// </returns>
public static IImageInfo Identify(ReadOnlySpan<byte> data, out IImageFormat format)
public static IImageInfo? Identify(ReadOnlySpan<byte> data, out IImageFormat? format)
=> Identify(DecoderOptions.Default, data, out format);

/// <summary>
Expand All @@ -86,7 +87,7 @@ public static IImageInfo Identify(ReadOnlySpan<byte> data, out IImageFormat form
/// <returns>
/// The <see cref="IImageInfo"/> or null if suitable info detector is not found.
/// </returns>
public static unsafe IImageInfo Identify(DecoderOptions options, ReadOnlySpan<byte> data, out IImageFormat format)
public static unsafe IImageInfo? Identify(DecoderOptions options, ReadOnlySpan<byte> data, out IImageFormat? format)
{
fixed (byte* ptr = data)
{
Expand Down Expand Up @@ -118,7 +119,7 @@ public static Image<TPixel> Load<TPixel>(ReadOnlySpan<byte> data)
/// <exception cref="InvalidImageContentException">Image contains invalid content.</exception>
/// <exception cref="NotSupportedException">Image format is not supported.</exception>
/// <returns>A new <see cref="Image{TPixel}"/>.</returns>
public static Image<TPixel> Load<TPixel>(ReadOnlySpan<byte> data, out IImageFormat format)
public static Image<TPixel> Load<TPixel>(ReadOnlySpan<byte> data, out IImageFormat? format)
where TPixel : unmanaged, IPixel<TPixel>
=> Load<TPixel>(DecoderOptions.Default, data, out format);

Expand Down Expand Up @@ -158,7 +159,7 @@ public static unsafe Image<TPixel> Load<TPixel>(DecoderOptions options, ReadOnly
public static unsafe Image<TPixel> Load<TPixel>(
DecoderOptions options,
ReadOnlySpan<byte> data,
out IImageFormat format)
out IImageFormat? format)
where TPixel : unmanaged, IPixel<TPixel>
{
fixed (byte* ptr = data)
Expand Down Expand Up @@ -189,7 +190,7 @@ public static Image Load(ReadOnlySpan<byte> data)
/// <exception cref="InvalidImageContentException">Image contains invalid content.</exception>
/// <exception cref="NotSupportedException">Image format is not supported.</exception>
/// <returns>The <see cref="Image"/>.</returns>
public static Image Load(ReadOnlySpan<byte> data, out IImageFormat format)
public static Image Load(ReadOnlySpan<byte> data, out IImageFormat? format)
=> Load(DecoderOptions.Default, data, out format);

/// <summary>
Expand All @@ -215,7 +216,7 @@ public static Image Load(DecoderOptions options, ReadOnlySpan<byte> data)
public static unsafe Image Load(
DecoderOptions options,
ReadOnlySpan<byte> data,
out IImageFormat format)
out IImageFormat? format)
{
fixed (byte* ptr = data)
{
Expand Down
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