166 lines
5.0 KiB
Python
166 lines
5.0 KiB
Python
# SPDX-FileCopyrightText: 2022 James R. Barlow
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# SPDX-License-Identifier: MPL-2.0
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"""Built-in plugin to implement PDF page optimization."""
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from __future__ import annotations
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import argparse
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import logging
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from collections.abc import Sequence
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from pathlib import Path
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from ocrmypdf import Executor, PdfContext, hookimpl
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from ocrmypdf._exec import jbig2enc, pngquant
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from ocrmypdf._pipeline import get_pdf_save_settings
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from ocrmypdf.cli import numeric
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from ocrmypdf.optimize import optimize
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from ocrmypdf.subprocess import check_external_program
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log = logging.getLogger(__name__)
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@hookimpl
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def add_options(parser):
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optimizing = parser.add_argument_group(
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"Optimization options", "Control how the PDF is optimized after OCR"
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)
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optimizing.add_argument(
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'-O',
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'--optimize',
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type=int,
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choices=range(0, 4),
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default=1,
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help=(
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"Control how PDF is optimized after processing:"
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"0 - do not optimize; "
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"1 - do safe, lossless optimizations (default); "
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"2 - do lossy JPEG and JPEG2000 optimizations; "
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"3 - do more aggressive lossy JPEG and JPEG2000 optimizations. "
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"To enable lossy JBIG2, see --jbig2-lossy."
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),
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)
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optimizing.add_argument(
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'--jpeg-quality',
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type=numeric(int, 0, 100),
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default=0,
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metavar='Q',
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help=(
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"Adjust JPEG quality level for JPEG optimization. "
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"100 is best quality and largest output size; "
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"1 is lowest quality and smallest output; "
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"0 uses the default."
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),
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)
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optimizing.add_argument(
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'--jpg-quality',
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type=numeric(int, 0, 100),
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default=0,
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metavar='Q',
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dest='jpeg_quality',
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help=argparse.SUPPRESS, # Alias for --jpeg-quality
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)
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optimizing.add_argument(
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'--png-quality',
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type=numeric(int, 0, 100),
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default=0,
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metavar='Q',
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help=(
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"Adjust PNG quality level to use when quantizing PNGs. "
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"Values have same meaning as with --jpeg-quality"
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),
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)
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optimizing.add_argument(
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'--jbig2-lossy',
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action='store_true',
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help=(
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"Enable JBIG2 lossy mode (better compression, not suitable for some "
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"use cases - see documentation). Only takes effect if --optimize 1 or "
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"higher is also enabled."
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),
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)
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optimizing.add_argument(
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'--jbig2-page-group-size',
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type=numeric(int, 1, 10000),
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default=0,
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metavar='N',
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# Adjust number of pages to consider at once for JBIG2 compression
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help=argparse.SUPPRESS,
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)
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optimizing.add_argument(
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'--jbig2-threshold',
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type=numeric(float, 0.4, 0.9),
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default=0.85,
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metavar='T',
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help=(
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"Adjust JBIG2 symbol code classification threshold "
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"(default 0.85), range 0.4 to 0.9."
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),
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)
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@hookimpl
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def check_options(options):
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if options.optimize >= 2:
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check_external_program(
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program='pngquant',
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package='pngquant',
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version_checker=pngquant.version,
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need_version='2.12.2',
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required_for='--optimize {2,3}',
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)
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if options.optimize >= 2:
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# Although we use JBIG2 for optimize=1, don't nag about it unless the
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# user is asking for more optimization
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check_external_program(
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program='jbig2',
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package='jbig2enc',
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version_checker=jbig2enc.version,
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need_version='0.28',
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required_for='--optimize {2,3} | --jbig2-lossy',
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recommended=True if not options.jbig2_lossy else False,
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)
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if options.optimize == 0 and any(
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[options.jbig2_lossy, options.png_quality, options.jpeg_quality]
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):
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log.warning(
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"The arguments --jbig2-lossy, --png-quality, and --jpeg-quality "
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"will be ignored because --optimize=0."
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)
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@hookimpl
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def optimize_pdf(
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input_pdf: Path,
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output_pdf: Path,
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context: PdfContext,
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executor: Executor,
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linearize: bool,
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) -> tuple[Path, Sequence[str]]:
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save_settings = dict(
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linearize=linearize,
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**get_pdf_save_settings(context.options.output_type),
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)
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result_path = optimize(input_pdf, output_pdf, context, save_settings, executor)
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messages = []
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if context.options.optimize == 0:
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messages.append("Optimization was disabled.")
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else:
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image_optimizers = {
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'jbig2': jbig2enc.available(),
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'pngquant': pngquant.available(),
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}
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for name, available in image_optimizers.items():
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if not available:
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messages.append(
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f"The optional dependency '{name}' was not found, so some image "
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f"optimizations could not be attempted."
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)
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return result_path, messages
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@hookimpl
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def is_optimization_enabled(context: PdfContext) -> bool:
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return context.options.optimize != 0
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