James R. Barlow
1b2849ec0a
This is mainly to permit the use of --tesseract-timeout 0 as a way of disabling OCR but still allowing deskew and orientation detection to work. The better solution will be introducing an explicit argument to "don't ocr my pdf", but that will take more rework.
339 lines
9.8 KiB
Python
339 lines
9.8 KiB
Python
# SPDX-FileCopyrightText: 2022 James R. Barlow
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# SPDX-License-Identifier: MPL-2.0
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from __future__ import annotations
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import operator
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from io import BytesIO
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from math import cos, pi, sin
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from os import fspath
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import img2pdf
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import pikepdf
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import pytest
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from ocrmypdf._exec import ghostscript
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from ocrmypdf._plugin_manager import get_plugin_manager
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from ocrmypdf.helpers import IMG2PDF_KWARGS, Resolution
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from ocrmypdf.pdfinfo import PdfInfo
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from PIL import Image, ImageChops
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from reportlab.pdfgen.canvas import Canvas
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from .conftest import check_ocrmypdf, run_ocrmypdf
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# pylintx: disable=unused-variable
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# Remove this workaround when we require Pillow >= 10
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try:
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Transpose = Image.Transpose # type: ignore
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except AttributeError:
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# Pillow 9 shim
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Transpose = Image # type: ignore
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RENDERERS = ['hocr', 'sandwich']
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def compare_images_monochrome(
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outdir, reference_pdf, reference_pageno, test_pdf, test_pageno
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):
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reference_png = outdir / f'{reference_pdf.name}.ref{reference_pageno:04d}.png'
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test_png = outdir / f'{test_pdf.name}.test{test_pageno:04d}.png'
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def rasterize(pdf, pageno, png):
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if png.exists():
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print(png)
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return
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ghostscript.rasterize_pdf(
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pdf,
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png,
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raster_device='pngmono',
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raster_dpi=Resolution(100, 100),
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pageno=pageno,
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rotation=0,
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)
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rasterize(reference_pdf, reference_pageno, reference_png)
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rasterize(test_pdf, test_pageno, test_png)
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with Image.open(reference_png) as reference_im, Image.open(test_png) as test_im:
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assert reference_im.mode == test_im.mode == '1'
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difference = ImageChops.logical_xor(reference_im, test_im)
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assert difference.mode == '1'
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histogram = difference.histogram()
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assert (
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len(histogram) == 256
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), "Expected Pillow to convert to grayscale for histogram"
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# All entries other than first and last will be 0
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count_same = histogram[0]
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count_different = histogram[-1]
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total = count_same + count_different
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return count_same / (total)
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def test_monochrome_comparison(resources, outdir):
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# Self test: check that an incorrect rotated image has poor
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# comparison with reference
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cmp = compare_images_monochrome(
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outdir,
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reference_pdf=resources / 'cardinal.pdf',
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reference_pageno=1, # north facing page
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test_pdf=resources / 'cardinal.pdf',
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test_pageno=3, # south facing page
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)
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assert cmp < 0.90
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cmp = compare_images_monochrome(
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outdir,
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reference_pdf=resources / 'cardinal.pdf',
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reference_pageno=2,
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test_pdf=resources / 'cardinal.pdf',
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test_pageno=2,
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)
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assert cmp > 0.95
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@pytest.mark.slow
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@pytest.mark.parametrize('renderer', RENDERERS)
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def test_autorotate(renderer, resources, outdir):
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# cardinal.pdf contains four copies of an image rotated in each cardinal
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# direction - these ones are "burned in" not tagged with /Rotate
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check_ocrmypdf(
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resources / 'cardinal.pdf',
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outdir / 'out.pdf',
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'-r',
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'-v',
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'1',
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'--pdf-renderer',
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renderer,
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'--plugin',
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'tests/plugins/tesseract_cache.py',
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)
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for n in range(1, 4 + 1):
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cmp = compare_images_monochrome(
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outdir,
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reference_pdf=resources / 'cardinal.pdf',
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reference_pageno=1,
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test_pdf=outdir / 'out.pdf',
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test_pageno=n,
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)
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assert cmp > 0.95
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@pytest.mark.parametrize(
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'threshold, op, comparison_threshold',
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[
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('1', operator.ge, 0.95), # Low thresh -> always rotate -> high score
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('99', operator.le, 0.90), # High thres -> never rotate -> low score
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],
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)
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def test_autorotate_threshold(threshold, op, comparison_threshold, resources, outdir):
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check_ocrmypdf(
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resources / 'cardinal.pdf',
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outdir / 'out.pdf',
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'--rotate-pages-threshold',
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threshold,
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'-r',
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# '-v',
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# '1',
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'--plugin',
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'tests/plugins/tesseract_cache.py',
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)
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cmp = compare_images_monochrome( # pylint: disable=unused-variable
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outdir,
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reference_pdf=resources / 'cardinal.pdf',
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reference_pageno=1,
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test_pdf=outdir / 'out.pdf',
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test_pageno=3,
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)
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assert op(cmp, comparison_threshold)
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def test_rotated_skew_timeout(resources, outpdf):
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"""This document contains an image that is rotated 90 into place with a
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/Rotate tag and intentionally skewed by altering the transformation matrix.
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This tests for a bug where the combination of preprocessing and a tesseract
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timeout produced a page whose dimensions did not match the original's.
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"""
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input_file = resources / 'rotated_skew.pdf'
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in_pageinfo = PdfInfo(input_file)[0]
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assert (
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in_pageinfo.height_pixels < in_pageinfo.width_pixels
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), "Expected the input page to be landscape"
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assert in_pageinfo.rotation == 90, "Expected a rotated page"
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out = check_ocrmypdf(
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input_file,
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outpdf,
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'--pdf-renderer',
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'hocr',
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'--deskew',
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'--tesseract-timeout',
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'0',
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)
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out_pageinfo = PdfInfo(out)[0]
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w, h = out_pageinfo.width_pixels, out_pageinfo.height_pixels
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assert h > w, "Expected the output page to be portrait"
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assert out_pageinfo.rotation == 0, "Expected no page rotation for output"
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assert (
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in_pageinfo.width_pixels == h and in_pageinfo.height_pixels == w
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), "Expected page rotation to be baked in"
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def test_rotate_deskew_ocr_timeout(resources, outdir):
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check_ocrmypdf(
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resources / 'rotated_skew.pdf',
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outdir / 'deskewed.pdf',
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'--rotate-pages',
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'--rotate-pages-threshold',
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'0',
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'--deskew',
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'--tesseract-timeout',
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'0',
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'--pdf-renderer',
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'sandwich',
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)
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cmp = compare_images_monochrome(
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outdir,
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reference_pdf=resources / 'ccitt.pdf',
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reference_pageno=1,
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test_pdf=outdir / 'deskewed.pdf',
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test_pageno=1,
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)
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# Confirm that the page still got deskewed
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assert cmp > 0.95
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@pytest.mark.slow
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@pytest.mark.parametrize('page_angle', (0, 90, 180, 270))
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@pytest.mark.parametrize('image_angle', (0, 90, 180, 270))
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def test_rotate_page_level(image_angle, page_angle, resources, outdir):
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def make_rotate_test(prefix, image_angle, page_angle):
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memimg = BytesIO()
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with Image.open(fspath(resources / 'typewriter.png')) as im:
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if image_angle != 0:
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ccw_angle = -image_angle % 360
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im = im.transpose(getattr(Transpose, f'ROTATE_{ccw_angle}'))
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im.save(memimg, format='PNG')
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memimg.seek(0)
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mempdf = BytesIO()
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img2pdf.convert(
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memimg.read(),
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layout_fun=img2pdf.get_fixed_dpi_layout_fun((200, 200)),
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outputstream=mempdf,
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**IMG2PDF_KWARGS,
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)
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mempdf.seek(0)
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pike = pikepdf.open(mempdf)
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pike.pages[0].Rotate = page_angle
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target = outdir / f'{prefix}_{image_angle}_{page_angle}.pdf'
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pike.save(target)
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return target
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reference = make_rotate_test('ref', 0, 0)
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test = make_rotate_test('test', image_angle, page_angle)
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out = test.with_suffix('.out.pdf')
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p = run_ocrmypdf(
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test,
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out,
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'-O0',
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'--rotate-pages',
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'--rotate-pages-threshold',
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'0.001',
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text=False,
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)
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err = p.stderr.decode('utf-8', errors='replace')
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assert p.returncode == 0, err
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assert compare_images_monochrome(outdir, reference, 1, out, 1) > 0.2
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def test_rasterize_rotates(resources, tmp_path):
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pm = get_plugin_manager([])
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img = tmp_path / 'img90.png'
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pm.hook.rasterize_pdf_page(
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input_file=resources / 'graph.pdf',
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output_file=img,
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raster_device='pngmono',
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raster_dpi=Resolution(20, 20),
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page_dpi=Resolution(20, 20),
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pageno=1,
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rotation=90,
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filter_vector=False,
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)
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with Image.open(img) as im:
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assert im.size == (83, 200), "Image not rotated"
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img = tmp_path / 'img180.png'
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pm.hook.rasterize_pdf_page(
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input_file=resources / 'graph.pdf',
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output_file=img,
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raster_device='pngmono',
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raster_dpi=Resolution(20, 20),
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page_dpi=Resolution(20, 20),
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pageno=1,
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rotation=180,
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filter_vector=False,
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)
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assert Image.open(img).size == (200, 83), "Image not rotated"
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def test_simulated_scan(outdir):
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canvas = Canvas(
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fspath(outdir / 'fakescan.pdf'),
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pagesize=(209.8, 297.6),
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)
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page_vars = [(2, 36, 250), (91, 170, 240), (179, 190, 36), (271, 36, 36)]
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for n, page_var in enumerate(page_vars):
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text = canvas.beginText()
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text.setFont('Helvetica', 20)
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angle, x, y = page_var
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cos_a, sin_a = cos(angle / 180.0 * pi), sin(angle / 180.0 * pi)
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text.setTextTransform(cos_a, -sin_a, sin_a, cos_a, x, y)
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text.textOut(f'Page {n + 1}')
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canvas.drawText(text)
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canvas.showPage()
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canvas.save()
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check_ocrmypdf(
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outdir / 'fakescan.pdf',
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outdir / 'out.pdf',
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'--force-ocr',
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'--deskew',
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'--rotate-pages',
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'--plugin',
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'tests/plugins/tesseract_debug_rotate.py',
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)
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with pikepdf.open(outdir / 'out.pdf') as pdf:
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assert (
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pdf.pages[1].MediaBox[2] > pdf.pages[1].MediaBox[3]
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), "Wrong orientation: not landscape"
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assert (
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pdf.pages[3].MediaBox[2] > pdf.pages[3].MediaBox[3]
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), "Wrong orientation: Not landscape"
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assert (
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pdf.pages[0].MediaBox[2] < pdf.pages[0].MediaBox[3]
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), "Wrong orientation: Not portrait"
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assert (
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pdf.pages[2].MediaBox[2] < pdf.pages[2].MediaBox[3]
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), "Wrong orientation: Not portrait"
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