exiv2/tests/lens_tests/test_canon_lenses.py

# -*- coding: utf-8 -*-

import re
import os
import system_tests
import math
from lens_tests.utils import extract_lenses_from_cpp

# get directory of the current file
file_dir = os.path.dirname(os.path.realpath(__file__))
# to get the canon maker note cpp file that contains list of all supported lenses
canon_lens_file = os.path.abspath(os.path.join(file_dir, "./../../src/canonmn_int.cpp"))
# tell the below function what the start of the lens array looks like
startpattern = "constexpr TagDetails canonCsLensType[] = {"
# use utils function to extract all lenses
lenses = extract_lenses_from_cpp(canon_lens_file, startpattern)

def aperture_to_raw_exif(aperture):
    #see https://github.com/exiftool/exiftool/blob/master/lib/Image/ExifTool/Canon.pm#L9678
    aperture = float(aperture)
    # for apertures < 1 the below is negative
    num = math.log(aperture)*2/math.log(2)

    # temporarily make the number positive
    if (num < 0):
        num = -num
        sign = -1
    else:
        sign = 1;

    val = int(num)
    frac = num - val

    if (abs(frac - 0.33) < 0.05):
        frac = 0x0c
    elif (abs(frac - 0.67) < 0.05):
        frac = 0x14;
    else:
        frac = int(frac * 0x20 + 0.5)

    return sign * (val * 0x20 + frac);


for (lens_id, lens_desc, meta) in lenses:

    tc = float(meta["tc"] or 1)

    testname = lens_id + "_" + lens_desc

    globals()[testname] = system_tests.CaseMeta(
        "canon_lenses." + testname,
        tuple(),
        {
            "filename": "$data_path/template.exv",
            "commands": [
                '$exiv2 -M"set Exif.CanonCs.LensType $lens_id" -M"set Exif.CanonCs.Lens $focal_length_max $focal_length_min 1" -M"set Exif.CanonCs.MaxAperture $aperture_max" $filename && $exiv2 -pa -K Exif.CanonCs.LensType $filename'
            ],
            "stderr": [""],
            "stdout": ["Exif.CanonCs.LensType                        Short       1  $lens_description\n"],
            "retval": [0],
            "lens_id": lens_id,
            "lens_description": lens_desc,
            "aperture_max": aperture_to_raw_exif(meta["aperture_max_short"]),
            "focal_length_min": int(int(meta["focal_length_min"]) * tc),
            "focal_length_max": int(int(meta["focal_length_max"]) * tc),
        },
    )