python-escpos/test/test_image.py

#!/usr/bin/env python
""" Image tests- Check that images from different source formats are correctly
converted to ESC/POS column & raster formats.

:author: `Michael Billington <michael.billington@gmail.com>`_
:organization: `python-escpos <https://github.com/python-escpos>`_
:copyright: Copyright (c) 2016 `Michael Billington <michael.billington@gmail.com>`_
:license: GNU GPL v3
"""

from escpos.image import EscposImage


def test_image_black():
    """
    Test rendering solid black image
    """
    for img_format in ['png', 'jpg', 'gif']:
        _load_and_check_img('canvas_black.' + img_format, 1, 1, b'\x80', [b'\x80'])


def test_image_black_transparent():
    """
    Test rendering black/transparent image
    """
    for img_format in ['png', 'gif']:
        _load_and_check_img('black_transparent.' + img_format, 2, 2, b'\xc0\x00', [b'\x80\x80'])


def test_image_black_white():
    """
    Test rendering black/white image
    """
    for img_format in ['png', 'jpg', 'gif']:
        _load_and_check_img('black_white.' + img_format, 2, 2, b'\xc0\x00', [b'\x80\x80'])


def test_image_white():
    """
    Test rendering solid white image
    """
    for img_format in ['png', 'jpg', 'gif']:
        _load_and_check_img('canvas_white.' + img_format, 1, 1, b'\x00', [b'\x00'])


def test_split():
    """
    test whether the split-function works as expected
    """
    im = EscposImage('test/resources/black_white.png')
    (upper_part, lower_part) = im.split(1)
    upper_part = EscposImage(upper_part)
    lower_part = EscposImage(lower_part)
    assert(upper_part.width == lower_part.width == 2)
    assert(upper_part.height == lower_part.height == 1)
    assert(upper_part.to_raster_format() == b'\xc0')
    assert(lower_part.to_raster_format() == b'\x00')


def _load_and_check_img(filename, width_expected, height_expected, raster_format_expected, column_format_expected):
    """
    Load an image, and test whether raster & column formatted output, sizes, etc match expectations.
    """
    im = EscposImage('test/resources/' + filename)
    assert(im.width == width_expected)
    assert(im.height == height_expected)
    assert(im.to_raster_format() == raster_format_expected)
    i = 0 
    for row in im.to_column_format(False):
        assert(row == column_format_expected[i])
        i += 1