test_afm.py

from io import BytesIO
import pytest
import logging

from matplotlib import afm
from matplotlib import font_manager as fm


# See note in afm.py re: use of comma as decimal separator in the
# UnderlineThickness field and re: use of non-ASCII characters in the Notice
# field.
AFM_TEST_DATA = b"""StartFontMetrics 2.0
Comment Comments are ignored.
Comment Creation Date:Mon Nov 13 12:34:11 GMT 2017
FontName MyFont-Bold
EncodingScheme FontSpecific
FullName My Font Bold
FamilyName Test Fonts
Weight Bold
ItalicAngle 0.0
IsFixedPitch false
UnderlinePosition -100
UnderlineThickness 56,789
Version 001.000
Notice Copyright \xa9 2017 No one.
FontBBox 0 -321 1234 369
StartCharMetrics 3
C 0 ; WX 250 ; N space ; B 0 0 0 0 ;
C 42 ; WX 1141 ; N foo ; B 40 60 800 360 ;
C 99 ; WX 583 ; N bar ; B 40 -10 543 210 ;
EndCharMetrics
EndFontMetrics
"""


def test_nonascii_str():
    # This tests that we also decode bytes as utf-8 properly.
    # Else, font files with non ascii characters fail to load.
    inp_str = "привет"
    byte_str = inp_str.encode("utf8")

    ret = afm._to_str(byte_str)
    assert ret == inp_str


def test_parse_header():
    fh = BytesIO(AFM_TEST_DATA)
    header = afm._parse_header(fh)
    assert header == {
        b'StartFontMetrics': 2.0,
        b'FontName': 'MyFont-Bold',
        b'EncodingScheme': 'FontSpecific',
        b'FullName': 'My Font Bold',
        b'FamilyName': 'Test Fonts',
        b'Weight': 'Bold',
        b'ItalicAngle': 0.0,
        b'IsFixedPitch': False,
        b'UnderlinePosition': -100,
        b'UnderlineThickness': 56.789,
        b'Version': '001.000',
        b'Notice': b'Copyright \xa9 2017 No one.',
        b'FontBBox': [0, -321, 1234, 369],
        b'StartCharMetrics': 3,
    }


def test_parse_char_metrics():
    fh = BytesIO(AFM_TEST_DATA)
    afm._parse_header(fh)  # position
    metrics = afm._parse_char_metrics(fh)
    assert metrics == (
        {0: (250.0, 'space', [0, 0, 0, 0]),
         42: (1141.0, 'foo', [40, 60, 800, 360]),
         99: (583.0, 'bar', [40, -10, 543, 210]),
         },
        {'space': (250.0, 'space', [0, 0, 0, 0]),
         'foo': (1141.0, 'foo', [40, 60, 800, 360]),
         'bar': (583.0, 'bar', [40, -10, 543, 210]),
         })


def test_get_familyname_guessed():
    fh = BytesIO(AFM_TEST_DATA)
    font = afm.AFM(fh)
    del font._header[b'FamilyName']  # remove FamilyName, so we have to guess
    assert font.get_familyname() == 'My Font'


def test_font_manager_weight_normalization():
    font = afm.AFM(BytesIO(
        AFM_TEST_DATA.replace(b"Weight Bold\n", b"Weight Custom\n")))
    assert fm.afmFontProperty("", font).weight == "normal"


@pytest.mark.parametrize(
    "afm_data",
    [
        b"""nope
really nope""",
        b"""StartFontMetrics 2.0
Comment Comments are ignored.
Comment Creation Date:Mon Nov 13 12:34:11 GMT 2017
FontName MyFont-Bold
EncodingScheme FontSpecific""",
    ],
)
def test_bad_afm(afm_data):
    fh = BytesIO(afm_data)
    with pytest.raises(RuntimeError):
        header = afm._parse_header(fh)


@pytest.mark.parametrize(
    "afm_data",
    [
        b"""StartFontMetrics 2.0
Comment Comments are ignored.
Comment Creation Date:Mon Nov 13 12:34:11 GMT 2017
Aardvark bob
FontName MyFont-Bold
EncodingScheme FontSpecific
StartCharMetrics 3""",
        b"""StartFontMetrics 2.0
Comment Comments are ignored.
Comment Creation Date:Mon Nov 13 12:34:11 GMT 2017
ItalicAngle zero degrees
FontName MyFont-Bold
EncodingScheme FontSpecific
StartCharMetrics 3""",
    ],
)
def test_malformed_header(afm_data, caplog):
    fh = BytesIO(afm_data)
    with caplog.at_level(logging.ERROR):
        header = afm._parse_header(fh)

    assert len(caplog.records) == 1