feat: extend bimg with support for autorotate

[haf]

http://www.vips.ecs.soton.ac.uk/supported/7.42/doc/html/libvips/libvips-conversion.html#vips-autorot

[haf]

Ref #180

[greut]

What's wrong with NoAutoRotate? As it doesn't have any tests, it's behaviour could be wrong.

[haf]

It's the negation of what I want? And the rotate call requires an angle?

[greut]

By default, it reads the EXIF data and autorotates the picture. At least, it should do that.

[haf]

I haven't tested this lib stand-alone, but calling rotate with a zero angle fails in imaginary, even after removing the input validation that the angle is not zero.

How do I invoke this library's auto-rotate via imaginary to have it only auto-rotate?

[greut]

Does norotation changes anything? In any case, bimg could have a test case for that.

https://github.com/h2non/imaginary/blob/a1bef74cc15b78a08085a0859c51c9372a0ee593/README.md#params

[greut]

Some resources for the tests cases:

• https://www.daveperrett.com/articles/2012/07/28/exif-orientation-handling-is-a-ghetto/
• https://github.com/recurser/exif-orientation-examples

[haf]

I just spent 14 hours straight (minus lunch) implementing this feature in the browser with FileReader and ArrayBuffer and Canvas, so I'm pretty into the different rotation modes right now ;)

All the code you find online when googling is wrong.

[haf]

All cases handled: https://codepen.io/haf/pen/OjEBao

[greut]

@haf the sole fact that bimg EXIF interpretation doesn't do a flop means it's wrong.

https://github.com/h2non/bimg/blob/master/resize.go#L290-L296

I'm onto some test cases.

[h2non]

Thanks for the help, @greut. I can't invest time on this right now, but feel free to send a PR with the required fixes, if needed. There might be something wrong in the implementation.

[h2non]

After seeing this for a bit, I think it would be more convenient relying on libvips built-in implementation = vips_autorot() and optionally allow the user overwrite that behavior by a specific rotation angle. @haf implementation looks good for this, but resize.go logic requires some (non-breaking) changes. Opinions?

[h2non]

Apparently, libvips API provides vips_autorot() since v7.42+, which is the minimum version currently supported by bimg.

[greut]

@h2non libvips can even perform the autorotate when loading the file. Once we have some test cases #183, we can proceed with the refactoring.

[greut]

Regarding the refactoring using autorotate, it works.

 int
-vips_init_image (void *buf, size_t len, int imageType, VipsImage **out) {
+vips_init_image (void *buf, size_t len, int imageType, int autorotate, VipsImage **out) {
        int code = 1;
 
        if (imageType == JPEG) {
-               code = vips_jpegload_buffer(buf, len, out, "access", VIPS_ACCESS_RANDOM, NULL);
+               code = vips_jpegload_buffer(buf, len, out,
+                       "access", VIPS_ACCESS_RANDOM,
+                       "autorotate", with_interlace(autorotate),
+                       NULL
+               );

But libvips doesn't handle all the EXIF cases 😭, so it's not usable as is.

https://github.com/jcupitt/libvips/blob/e241d1333926180c5258dbf6650d0c1af7538f7a/libvips/conversion/autorot.c#L62-L109

[h2non]

Right, dammit!

[haf]

Just convert my four lines of code + sin ± check into a transformation matrix? http://www.vips.ecs.soton.ac.uk/supported/8.3/doc/html/libvips/libvips-resample.html

[h2non]

Can you check now that the default bimg automatic rotation implemtnation doesn't work for you as expected? @greut improvements are now available in latest bimg version. Try it again upgrading it:

go get -u gopkg.in/h2non/bimg.v1

[haf]

Have you changed libvips to support all cases?

[greut]

@haf since #183 got merged in, all cases should be handled.

[haf]

Can you give me a sample command line to run to test it, please?

[greut]

@haf bimg != libvips, afaik there are no command-line tools with bimg.