MagickImage cannot detect correct image format with ReadAsync

[d2phap]

Magick.NET version

11.1.0 - Magick.NET-Q16-OpenMP-x64

Environment (Operating system, version and so on)

Windows 10 21H2

Description

• Probably similar to Load image from Stream #422 but happens to both
  <MagickImage>.ReadAsync() and <MagickImageCollection>.ReadAsync() function.
• I'm using ReadAsync because it supports CancellationToken, and it's convenient to do some quick check before loading entire image file which is time-consuming.
• Error:

  TIFF directory is missing required "ImageLength" field. `MissingRequired' @ error/tiff.c/TIFFErrors/656
  

• Sample file: icon256.zip
• See Step to Reproduce for more details.

Steps to Reproduce

Code produces error:

var filename = @"D:\icon256.ico";

// Some settings
var settings = new MagickReadSettings();

using var imgM = new MagickImage();
// Check something here
// ...
// ...

// read image file async
await imgM.ReadAsync(filename, settings, cancelToken);

// ❌ Error:
// TIFF directory is missing required "ImageLength" field.
// `MissingRequired' @ error/tiff.c/TIFFErrors/656

Code without error:

Solution 1: Directly pass filename to constructor

using var imgM = new MagickImage(filename, settings);

// no error!

Solution 2: Tell what the format is

// Some settings
var settings = new MagickReadSettings() {
    Format = MagickFormat.Ico,
};

using var imgM = new MagickImage();
// Check something here
// ...
// ...

// read image file async
await imgM.ReadAsync(filename, settings, cancelToken);

// no error!

You can access full source code at:
https://github.com/d2phap/ImageGlass/blob/v9/v9/IgCodecs/ImageMagickIgCodec/Main.cs#L493

[dlemstra]

Thanks for reporting this I just pushed a fix for this issue that will be resolved in the next release.

[d2phap]

I hope this fix can be released some time this week, or else I will miss it for ImageGlass 9.0 beta 1 🕊

[d2phap]

Hi @dlemstra,

The bug still persists when using MagickImageCollection.ReadAsync() 😅
Sample file: icon256.zip

using var imgColl = new MagickImageCollection();

// ❌ CANNOT detect format
settings.Format = MagickFormat.Ico;
await imgColl.ReadAsync(filename, settings, cancelToken);

// ✅ CAN detect format
await imgColl.ReadAsync(filename, settings, cancelToken);

// ✅ CAN detect format
imgColl.Read(filename, settings);

I checked the MagickImageCollection source code a bit, and found this:
filename is not passed to the AddImages()

Magick.NET/src/Magick.NET/Netstandard21/MagickImageCollection.cs

Lines 292 to 301 in 8a4f9de

	public async Task ReadAsync(string fileName, IMagickReadSettings<QuantumType>? readSettings, CancellationToken cancellationToken)
	{
	Throw.IfNullOrEmpty(nameof(fileName), fileName);
	var bytes = await File.ReadAllBytesAsync(fileName, cancellationToken).ConfigureAwait(false);
	cancellationToken.ThrowIfCancellationRequested();
	Clear();
	AddImages(bytes, 0, bytes.Length, readSettings, false);
	}

settings.FileName = null;

Magick.NET/src/Magick.NET/Netstandard21/MagickImageCollection.cs

Lines 582 to 601 in 8a4f9de

	private void AddImages(ReadOnlySequence<byte> data, IMagickReadSettings<QuantumType>? readSettings, bool ping)
	{
	if (data.IsSingleSegment)
	{
	AddImages(data.FirstSpan, readSettings, ping);
	return;
	}
	var settings = CreateSettings(readSettings);
	settings.Ping = ping;
	settings.FileName = null;
	var wrapper = new ReadOnlySequenceWrapper(data);
	var reader = new ReadWriteStreamDelegate(wrapper.Read);
	var seeker = new SeekStreamDelegate(wrapper.Seek);
	var teller = new TellStreamDelegate(wrapper.Tell);
	var result = _nativeInstance.ReadStream(settings, reader, seeker, teller);
	AddImages(result, settings);
	}

[dlemstra]

Seems that I only fixed this in the MagickImage class and not in the MagickImageCollection. Just pushed a patch for this and I will publish a new release this weekend for you.