Crash when running in AOT-only mode (Release mode) in SixLabors.ImageSharp.PixelAccessor #383

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1. Lapinou42 commented on Nov 20, 2017

   

   Lapinou42

   on Nov 20, 2017

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   It seems to be a runtime error when reflection is used.
   I got an error of this kind with EF Core. I wrote a linker.xml file for this. Maybe I could solve this issue by using this linker file, but a don't know of to write this.

   I tried something like :

   <?xml version="1.0" encoding="utf-8"?>
   <linker>
   	<assembly fullname="SixLabors.ImageSharp">
   		<type fullname="SixLabors.ImageSharp.PixelAccessor`1">
   		</type>
   	</assembly>
   </linker>
   

   But it does nothing.
2. JimBobSquarePants commented on Nov 20, 2017

   

   JimBobSquarePants

   on Nov 20, 2017

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   Hi @Lapinou42

   We're not using actually reflection in that method.

   Could you please attempt to narrow down the issue by creating a simple application that calls only Unsafe.Add(ref byte, int)

   If that throws then you will need to raise an issue with Xamarin.

   Cheers

   James
3. Lapinou42 commented on Nov 20, 2017

   

   Lapinou42

   on Nov 20, 2017

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   Hi @JimBobSquarePants ,

   Thank you for your reply.
   I tried to call this method but it doesn't crash and I have no exception.

   Chris.
4. JimBobSquarePants commented on Nov 20, 2017

   

   JimBobSquarePants

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   Thanks. Can you post the code you used to narrow it down please?
5. Lapinou42 commented on Nov 20, 2017

   

   Lapinou42

   on Nov 20, 2017

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   Hmmm... Finally, It seems the crash comes from this method :

   public static UIImage ToUIImage(this IImage image)
           {
               using (var stream = new MemoryStream())
               {
                   var rgba32image = image.ToRgba32Image();
   
                   rgba32image.Save(stream, ImageFormats.Jpeg);
   
                   var bytes = stream.ToArray();
   
                   var imageData = NSData.FromArray(bytes);
   
                   return UIImage.LoadFromData(imageData);
               }
           }
   

   IImage interface :

   public interface IImage
       {
           Image<Rgba32> ToRgba32Image();
       }
   
       public class Rgba32Image : IImage
       {
           private readonly Image<Rgba32> _innerImage;
   
           public Rgba32Image(Image<Rgba32> innerImage)
           {
               _innerImage = innerImage;
           }
   
           public Image<Rgba32> ToRgba32Image()
           {
               return _innerImage;
           }
       }
   

   I'm investigating to understand what's going wrong.
6. antonfirsov commented on Nov 20, 2017

   

   antonfirsov

   on Nov 20, 2017

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   @Lapinou42 @JimBobSquarePants
   I think the AOT compiler somehow fails to discover, that on this execution path it has to compile Unsafe.Add<T>(ref T, int) with byte as a generic argument.

   It's definitely an issue with the Xamarin/mono AOT compiler. I will try to find out where is the official place to post issues for them.

   Meanwhile an amateurish workaround idea:
   Try doing a dummy Unsafe.Add<byte>(ref byte, int) call somewhere around the entry point of your application. I hope, it will make it to AOT compile the method for the whole app. I'm not familiar with Xamarin, but you probably can achive the same with linker.xml.

   👍React with 👍2Reacted by James Jackson-South and Christophe Chantraine
7. Lapinou42 commented on Nov 20, 2017

   

   Lapinou42

   on Nov 20, 2017

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   @antonfirsov
   I think you are right.
   Thank you for your investigation. It helped me to understand what's wrong ;)
8. JimBobSquarePants commented on Nov 20, 2017

   

   JimBobSquarePants

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   Thanks @antonfirsov I was thinking the same after a bit of reading.
9. Lapinou42 commented on Nov 20, 2017

   

   Lapinou42

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   @antonfirsov

   I tried your workaround but it doesn't work.

   Sorry for this post that actually doesn't related to ImageSharp.

   Btw, do you have post the issue on Xamarin Bugzilla or must I do ?

   EDIT: I opened an issue on Xamarin Bugzilla ;)

   Kind regards,
   Chris.
10. antonfirsov commented on Nov 20, 2017

    

    antonfirsov

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    @Lapinou42 thanks for opening the issue on Xamarin Bugzilla! I also posted a comment, hope it helps.

    I suppose, the workaround does not work, because the Unsafe.Add method is AggressiveInlined.
11. antonfirsov commented on Nov 21, 2017

    

    antonfirsov

    on Nov 21, 2017

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    @Lapinou42 I've noticed your latest comment on Bugzilla. Regarding this comment:

    We noticed it's very slow on both side (iOS / Android) when we need to convert from Image to native image object.

    I'm being curious about your native image pixel format, and how do you implement conversion from Image<Rgba32> to native image objects? :)
12. Lapinou42 commented on Nov 21, 2017

    

    Lapinou42

    on Nov 21, 2017

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    @antonfirsov

    This is the code I mean :

    {
            byte[] bytes = image.AsJPEG(1.0f).ToArray();
            var rgba32image = SixLabors.ImageSharp.Image.Load(bytes); // This lines takes around 10-11 sec.
            return new Rgba32Image(rgba32image);
     }
    

    But, the peace of code is really fast:

    public static UIImage ToUIImage(this IImage image)
            {
                using (var stream = new MemoryStream())
                {
                    var rgba32image = image.ToRgba32Image();
    
                    rgba32image.Save(stream, ImageFormats.Jpeg);
    
                    var bytes = stream.ToArray();
    
                    var imageData = NSData.FromArray(bytes);
    
                    return UIImage.LoadFromData(imageData);
                }
            }
    
13. antonfirsov commented on Nov 21, 2017

    

    antonfirsov

    on Nov 21, 2017

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    @Lapinou42 the NSImage.AsJpeg() -> ImageSharp jpeg decoding step seems unnecessary.

    If you are familiar with the underlying UIImage + CGImage + CGContext... API-s, you can try extracting the pixel data into a byte[] array of Rgba32 format or into an Rgba32[] array directly. Then you can use our Image.LoadPixelData<Rgba32>(data) to construct an ImageSharp image in a more efficient way.

    Using .AsPNG() should be also faster. Jpeg is a super expensive stuff if your .NET runtime doesnt support SIMD.
14. tocsoft commented on Nov 21, 2017

    

    tocsoft

    on Nov 21, 2017

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    you want to access the raw byte array from the UIImage directly instead of converting back and fourth in jpeg format.

    This looks like some sample code that can help you access image data https://forums.xamarin.com/discussion/comment/60985/#Comment_60985
    disclaimer: not been tested, not an IOS developer.

    Then as @antonfirsov suggests call var img = Image.LoadPixelData<Rgba32>(rawData, width, height);

    That will prevent new overhead of any encoding/decoding and will be the fastest way of gettign data from UIImage->Image

    👍React with 👍1Reacted by Anton Firszov
15. JimBobSquarePants

    closed this as completedon Jul 18, 2018