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"""
Test suite for pydyf.
This module adds a PNG export based on GhostScript, that is released under
AGPL. As "the end user has the ability to opt out of installing the AGPL
version of [Ghostscript] during the install process", and with explicit
aggreement from Artifex, it is OK to distribute this code under BSD.
See https://www.ghostscript.com/license.html.
"""
import io
import os
from pathlib import Path
from subprocess import PIPE, run
from PIL import Image
PIXELS_BY_CHAR = dict(
_=(255, 255, 255), # white
R=(255, 0, 0), # red
B=(0, 0, 255), # blue
G=(0, 255, 0), # lime green
K=(0, 0, 0), # black
z=None, # any color
)
def assert_pixels(document, reference_pixels):
"""Test that the rendered document matches the reference pixels."""
# Transform the PDF document into a list of RGB tuples
pdf = io.BytesIO()
document.write(pdf)
command = [
'gs', '-q', '-dNOPAUSE', '-dSAFER', '-sDEVICE=png16m',
'-r576', '-dDownScaleFactor=8', '-sOutputFile=-', '-']
png = run(command, input=pdf.getvalue(), stdout=PIPE).stdout
image = Image.open(io.BytesIO(png))
pixels = image.getdata()
# Transform reference drawings into a list of RGB tuples
lines = tuple(
line.strip() for line in reference_pixels.splitlines() if line.strip())
assert len({len(line) for line in lines}) == 1, (
'The lines of reference pixels don’t have the same length')
width, height = len(lines[0]), len(lines)
assert (width, height) == image.size, (
f'Reference size is {width}×{height}, '
f'output size is {image.width}×{image.height}')
reference_pixels = tuple(
PIXELS_BY_CHAR[char] for line in lines for char in line)
# Compare pixels
if pixels != reference_pixels: # pragma: no cover
for i, (value, reference) in enumerate(zip(pixels, reference_pixels)):
if reference is None:
continue
if any(value != reference
for value, reference in zip(value, reference)):
name = os.environ.get('PYTEST_CURRENT_TEST')
name = name.split(':')[-1].split(' ')[0]
write_png(f'{name}', pixels, width, height)
reference_pixels = [
pixel or (255, 255, 255) for pixel in reference_pixels]
write_png(f'{name}-reference', reference_pixels, width, height)
x, y = i % width, i // width
assert 0, (
f'Pixel ({x}, {y}) in {name}: '
f'reference rgba{reference}, got rgba{value}')
def write_png(name, pixels, width, height): # pragma: no cover
"""Take a pixel matrix and write a PNG file."""
directory = Path(__file__).parent / 'results'
directory.mkdir(exist_ok=True)
image = Image.new('RGB', (width, height))
image.putdata(pixels)
image.save(directory / f'{name}.png')
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