James R. Barlow
46a279a49a
The executor system was built around passing only a single argument to workers, which was always PageContext. For other tasks, all actual arguments were packed in a tuple, which meant we needed intermediate functions to unpack the tuple. The situation is now rationlized and resembles how Python handles argument passing to familiar multiprocessing tools.
53 lines
1.4 KiB
Python
53 lines
1.4 KiB
Python
# SPDX-FileCopyrightText: 2022 James R. Barlow
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# SPDX-License-Identifier: MPL-2.0
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"""Interface to pngquant executable."""
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from __future__ import annotations
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from pathlib import Path
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from subprocess import PIPE
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from packaging.version import Version
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from ocrmypdf.exceptions import MissingDependencyError
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from ocrmypdf.subprocess import get_version, run
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def version() -> Version:
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return Version(get_version('pngquant', regex=r'(\d+(\.\d+)*).*'))
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def available():
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try:
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version()
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except MissingDependencyError:
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return False
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return True
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def quantize(input_file: Path, output_file: Path, quality_min: int, quality_max: int):
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"""Quantize a PNG image using pngquant.
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Args:
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input_file: Input PNG image
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output_file: Output PNG image
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quality_min: Minimum quality to use
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quality_max: Maximum quality to use
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"""
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with open(input_file, 'rb') as input_stream:
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args = [
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'pngquant',
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'--force',
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'--skip-if-larger',
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'--quality',
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f'{quality_min}-{quality_max}',
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'--', # pngquant: stop processing arguments
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'-', # pngquant: stream input and output
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]
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result = run(args, stdin=input_stream, stdout=PIPE, stderr=PIPE, check=False)
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if result.returncode == 0:
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# input_file could be the same as output_file, so we defer the write
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output_file.write_bytes(result.stdout)
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