Pillow/Tests/test_tiff_ifdrational.py

from __future__ import print_function

from helper import 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.assert_(xres._val is not None)
        self.assert_(xres.numerator is not None)
        self.assert_(xres.denominator is not None)
        self.assert_(yres._val is not None)
        
        self.assert_(xres and 1)
        self.assert_(xres and yres)


    def test_ifd_rational_save(self):
        for libtiff in (True, False):
            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]))