49 lines
1.6 KiB
Python
49 lines
1.6 KiB
Python
# pdf-segmented: Generate PDFs using separate compression for foreground and background
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# Copyright (C) 2025 Lee Yingtong Li
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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from . import CompressedLayer
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from ..util import assert_has_jbig2
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from PIL import Image
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from dataclasses import dataclass
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import os
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import subprocess
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import tempfile
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@dataclass
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class JBIG2Layer(CompressedLayer):
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data: bytes
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def jbig2_compress_layer(layer: Image, tempdir: str) -> JBIG2Layer:
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assert_has_jbig2('JBIG2 compression requires jbig2enc')
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# Save image to PNG temporarily
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_, png_file = tempfile.mkstemp(suffix='.png', dir=tempdir)
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try:
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layer.save(png_file, format='png')
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# Compress using JBIG2
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# Passing "-s" uses lossly JBIG2 encoding, so we do not pass this option
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jbig2_proc = subprocess.run(['jbig2', '-p', '-v', png_file], cwd=tempdir, check=True, capture_output=True)
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jbig2_data = jbig2_proc.stdout
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finally:
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# Clean up
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os.unlink(png_file)
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return JBIG2Layer(data=jbig2_data)
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