test_tiff_ifdrational.py

from __future__ import annotations

from fractions import Fraction
from pathlib import Path

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

from .helper import hopper


def _test_equal(num, denom, target) -> None:
    t = IFDRational(num, denom)

    assert target == t
    assert t == target


def test_sanity() -> None:
    _test_equal(1, 1, 1)
    _test_equal(1, 1, Fraction(1, 1))

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

    _test_equal(Fraction(1, 1), 1, Fraction(1, 1))
    _test_equal(IFDRational(1, 1), 1, 1)

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

    _test_equal(7, 5, 1.4)


def test_ranges() -> None:
    for num in range(1, 10):
        for denom in range(1, 10):
            assert IFDRational(num, denom) == IFDRational(num, denom)


def test_nonetype() -> None:
    # Fails if the _delegate function doesn't return a valid function

    xres = IFDRational(72)
    yres = IFDRational(72)
    assert xres._val is not None
    assert xres.numerator is not None
    assert xres.denominator is not None
    assert yres._val is not None

    assert xres and 1
    assert xres and yres


def test_ifd_rational_save(tmp_path: Path) -> None:
    methods = [True]
    if features.check("libtiff"):
        methods.append(False)

    for libtiff in methods:
        TiffImagePlugin.WRITE_LIBTIFF = libtiff

        im = hopper()
        out = str(tmp_path / "temp.tiff")
        res = IFDRational(301, 1)
        im.save(out, dpi=(res, res), compression="raw")

        with Image.open(out) as reloaded:
            assert float(IFDRational(301, 1)) == float(reloaded.tag_v2[282])