2 orientation bugs

[dtougas]

I have encountered two bugs with regards to image orientation. They both work together to make image thumbnailing create undesirable results for portrait images with exif orientation data, thus I am putting them together in the same issue.

Problem 1

The Engine.get_image_ratio function does not take into account orientation set in the exif data. As a result, the ratio returned for images with an orientation of 5, 6, 7 or 8 will have a landscape ratio returned instead of a portrait one.

Problem 2

The PIL engine should be using the transpose method instead of the rotate method when setting the image orientation. Using the rotate method causes a cropped image with black bars on either side.

To resolve the problem temporarily, I created my own engine with the above changes. I have included it below for reference.

from PIL import Image

from sorl.thumbnail.engines.pil_engine import Engine


class OutsidewaysEngine(Engine):
    def _get_exif(self, image):
        try:
            exif = image._getexif()
        except:
            exif = None
        return exif

    def get_image_ratio(self, image, options):
        ratio = super(OutsidewaysEngine, self).get_image_ratio(image, options)
        exif = self._get_exif(image)
        if exif:
            orientation = exif.get(0x0112)
            if orientation in [5, 6, 7, 8]:
                ratio = 1.0 / ratio
        return ratio

    def _orientation(self, image):
        exif = self._get_exif(image)
        if exif:
            orientation = exif.get(0x0112)
            if orientation == 2:
                image = image.transpose(Image.FLIP_LEFT_RIGHT)
            elif orientation == 3:
                image = image.transpose(Image.ROTATE_180)
            elif orientation == 4:
                image = image.transpose(Image.FLIP_TOP_BOTTOM)
            elif orientation == 5:
                image = image.transpose(Image.ROTATE_270).transpose(
                    Image.FLIP_LEFT_RIGHT)
            elif orientation == 6:
                image = image.transpose(Image.ROTATE_270)
            elif orientation == 7:
                image = image.transpose(Image.ROTATE_90).transpose(
                    Image.FLIP_LEFT_RIGHT)
            elif orientation == 8:
                image = image.transpose(Image.ROTATE_90)
        return image