Inverted thumbnail ratio with orientation in source, ImageMagick (convert) engine

[challet]

Hello,

When a file needing a orientation change is made into a thumbnail, the aspect ratio is not inverted during the -scale operation. Leading to a distorsion in the result.

Scenario

• source image (orientation 6, size 1800x1200). 1200 being the height of the not re-oriented source image and the width of the intermediate (1200x1800) re-oriented image:
  
• get_thumbnail(source_img, 600). Which should result, taking the orientation into account, to a 600x900 full geometry
• the convert command is actually called with convert sourcefile -auto-orient -colorspace RGB -scale 600x400! -interlace line -quality 95 thumbfile
• leading to the final image :

Additional note

• the dimensions seem to be reversed during a set_size but not at scale operation time

  • sorl-thumbnail/sorl/thumbnail/images.py

    Lines 139 to 145 in 571388b

    	# This is the worst case scenario
    	image = default.engine.get_image(self)
    	size = default.engine.get_image_size(image)
    	if self.flip_dimensions(image):
    	size = list(size)
    	size.reverse()
    	self._size = list(size)

  • sorl-thumbnail/sorl/thumbnail/engines/base.py

    Lines 49 to 54 in 571388b

    	def flip_dimensions(self, image, geometry=None, options=None):
    	options = options or {}
    	reoriented = hasattr(self, 'reoriented')
    	if options.get('orientation', settings.THUMBNAIL_ORIENTATION) and not reoriented:
    	return self._flip_dimensions(image)
    	return False

• I haven't been able to check for the other engines
• most probably related to the first problem of 2 orientation bugs #495

[challet]

sorl-thumbnail/tests/thumbnail_tests/test_engines.py

Lines 333 to 344 in 476594e

	@unittest.skipIf('pil_engine' not in settings.THUMBNAIL_ENGINE, 'the other engines fail this test')
	def test_image_with_orientation(self):
	name = 'data/aspect_test.jpg'
	item, _ = Item.objects.get_or_create(image=name)
	im = ImageFile(item.image)
	th = self.BACKEND.get_thumbnail(im, '50x50')
	# this is a 100x200 image with orientation 6 (90 degrees CW rotate)
	# the thumbnail should end up 25x50
	self.assertEqual(th.x, 25)
	self.assertEqual(th.y, 50)

Just saw a test with the exact same issue. It has been skipped with the reason "the other engines fail this test" and fixed for the pillow engine in #455.