test_tiff_ifdrational.py

from helper import unittest, PillowTestCase, hopper

from PIL import TiffImagePlugin, Image
from PIL.TiffImagePlugin import IFDRational

from fractions import Fraction


class Test_IFDRational(PillowTestCase):

    def _test_equal(self, num, denom, target):

        t = IFDRational(num, denom)

        self.assertEqual(target, t)
        self.assertEqual(t, target)

    def test_sanity(self):

        self._test_equal(1, 1, 1)
        self._test_equal(1, 1, Fraction(1, 1))

        self._test_equal(2, 2, 1)
        self._test_equal(1.0, 1, Fraction(1, 1))

        self._test_equal(Fraction(1, 1), 1, Fraction(1, 1))
        self._test_equal(IFDRational(1, 1), 1, 1)

        self._test_equal(1, 2, Fraction(1, 2))
        self._test_equal(1, 2, IFDRational(1, 2))

    def test_nonetype(self):
        " Fails if the _delegate function doesn't return a valid function"

        xres = IFDRational(72)
        yres = IFDRational(72)
        self.assertIsNotNone(xres._val)
        self.assertIsNotNone(xres.numerator)
        self.assertIsNotNone(xres.denominator)
        self.assertIsNotNone(yres._val)

        self.assertTrue(xres and 1)
        self.assertTrue(xres and yres)

    def test_ifd_rational_save(self):
        methods = (True, False)
        if 'libtiff_encoder' not in dir(Image.core):
            methods = (False,)

        for libtiff in methods:
            TiffImagePlugin.WRITE_LIBTIFF = libtiff

            im = hopper()
            out = self.tempfile('temp.tiff')
            res = IFDRational(301, 1)
            im.save(out, dpi=(res, res), compression='raw')

            reloaded = Image.open(out)
            self.assertEqual(float(IFDRational(301, 1)),
                             float(reloaded.tag_v2[282]))

if __name__ == '__main__':
    unittest.main()