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first commit

master
nglk 2 years ago
commit
4f016b718b
  1. 2
      .gitignore
  2. BIN
      __pycache__/app.cpython-37.pyc
  3. BIN
      __pycache__/hocrtransformpdf.cpython-37.pyc
  4. 79
      app.py
  5. 518
      hocrtransform-visible-pdf.py
  6. 511
      hocrtransform.py
  7. 518
      hocrtransformpdf.py
  8. BIN
      static/fonts/AC-Poiret.ttf
  9. BIN
      static/fonts/Compagnon-Roman.otf
  10. BIN
      static/fonts/SolideMirage-Etroit.otf
  11. BIN
      static/fonts/greek-bold.ttf
  12. BIN
      static/fonts/greek.ttf
  13. BIN
      static/fonts/zarathustra-v01.otf
  14. 0
      static/hocr/anthropoktonia.hocr
  15. 142
      static/hocr/gynaikoktonia (another copy).hocr
  16. 142
      static/hocr/gynaikoktonia.hocr
  17. BIN
      static/images/anthropoktonia.png
  18. BIN
      static/images/blank.png
  19. BIN
      static/images/closed.gif
  20. BIN
      static/images/open.gif
  21. BIN
      static/images/tongue-emoji.png
  22. 87
      static/styles (copy).css
  23. 112
      static/styles.css
  24. 63
      static/ΔΙΑΒΑΣΕΜΕ.txt
  25. 24
      templates/base.html
  26. 121
      templates/results (copy).html
  27. 116
      templates/results.html
  28. 101
      templates/results_2.html

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.gitignore

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venv/
static/pdf/

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__pycache__/app.cpython-37.pyc

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app.py

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import os
import random
import shutil
import string
import subprocess
from pathlib import Path
from flask import Flask, flash, redirect, render_template, request, url_for
from hocrtransformpdf import *
from werkzeug.utils import secure_filename
from flask_basicauth import BasicAuth
import pdftotree
UPLOAD_FOLDER = 'static/uploads'
ALLOWED_EXTENSIONS = {'pdf'}
app = Flask(__name__)
app.config['BASIC_AUTH_USERNAME'] = 'wordmord'
app.config['BASIC_AUTH_PASSWORD'] = 'tentacles'
basic_auth = BasicAuth(app)
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
@app.route('/', methods=['GET', 'POST'])
@basic_auth.required
def run_script():
# the code below was made in case I was using a button upload but now I use the field input so this has to be uploaded and then transformed
if request.method == 'POST':
# check if the post request has the file part
if 'file' not in request.files:
flash('No file part')
return redirect(request.url)
file = request.files['file']
# if user does not select file, browser also
# submit an empty part without filename
if file.filename == '':
flash('No selected file')
return redirect(request.url)
if file and allowed_file(file.filename):
filename = secure_filename(file.filename)
uploadfilepath=os.path.join(app.config['UPLOAD_FOLDER'], filename)
file.save(uploadfilepath)
# return redirect(url_for('uploaded_file',
# filename=filename))
hocr_result = pdftotree.parse(uploadfilepath)
app.logger.info("test")
hocr = HocrTransform(hocr_filename=hocr_result, dpi=300)
hocr.to_pdf(
out_filename='static/pdf/output-2.pdf',
image_filename='static/images/blank.png',
show_bounding_boxes=False,
interword_spaces=False,
)
hocrfile='static/hocr/gynaikoktonia.hocr'
#hocr = HocrTransform(hocr_filename=hocrfile, dpi=300)
#hocr = HocrTransform(hocr_filename=hocr_result, dpi=300)
#hocr.to_pdf(
# out_filename='static/pdf/output.pdf',
# image_filename='static/images/blank.png',
# show_bounding_boxes=False,
# interword_spaces=False,
#)
# result = subprocess.check_output("python3 hocrtransformpdf.py -i images/blank.png hocr/gynaikoktonia.hocr pdf/gynaikoktonia.pdf", shell=True)
return render_template('results.html', **locals())
def allowed_file(filename):
return '.' in filename and \
filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS
if __name__ == "__main__":
app.run()

518
hocrtransform-visible-pdf.py

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#!/usr/bin/env python3
#
# Copyright (c) 2010, Jonathan Brinley
# Original version from: https://github.com/jbrinley/HocrConverter
#
# Copyright (c) 2013-14, Julien Pfefferkorn
# Modifications
#
# Copyright (c) 2015-16, James R. Barlow
# Set text to transparent
# Copyright (c) 2022, WordMord & Alex Roidl
# Set text back to visible and change bounding boxes
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
import argparse
import os
import re
from itertools import chain
from math import atan, cos, sin
from pathlib import Path
from typing import Any, NamedTuple, Optional, Tuple, Union
from xml.etree import ElementTree
from reportlab.lib.colors import black, cyan, magenta, red
from reportlab.lib.units import inch
from reportlab.pdfgen.canvas import Canvas
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.pdfbase.pdfmetrics import registerFontFamily
# According to Wikipedia these languages are supported in the ISO-8859-1 character
# set, meaning reportlab can generate them and they are compatible with hocr,
# assuming Tesseract has the necessary languages installed. Note that there may
# not be language packs for them.
HOCR_OK_LANGS = frozenset(
[
# Languages fully covered by Latin-1:
'afr', # Afrikaans
'alb', # Albanian
'ast', # Leonese
'baq', # Basque
'bre', # Breton
'cos', # Corsican
'eng', # English
'eus', # Basque
'fao', # Faoese
'gla', # Scottish Gaelic
'glg', # Galician
'glv', # Manx
'ice', # Icelandic
'ind', # Indonesian
'isl', # Icelandic
'ita', # Italian
'ltz', # Luxembourgish
'mal', # Malay Rumi
'mga', # Irish
'nor', # Norwegian
'oci', # Occitan
'por', # Portugeuse
'roh', # Romansh
'sco', # Scots
'sma', # Sami
'spa', # Spanish
'sqi', # Albanian
'swa', # Swahili
'swe', # Swedish
'tgl', # Tagalog
'wln', # Walloon
# Languages supported by Latin-1 except for a few rare characters that OCR
# is probably not trained to recognize anyway:
'cat', # Catalan
'cym', # Welsh
'dan', # Danish
'deu', # German
'dut', # Dutch
'est', # Estonian
'fin', # Finnish
'fra', # French
'hun', # Hungarian
'kur', # Kurdish
'nld', # Dutch
'wel', # Welsh
]
)
Element = ElementTree.Element
class Rect(NamedTuple): # pylint: disable=inherit-non-class
"""A rectangle for managing PDF coordinates."""
x1: Any
y1: Any
x2: Any
y2: Any
class HocrTransformError(Exception):
pass
class HocrTransform:
"""
A class for converting documents from the hOCR format.
For details of the hOCR format, see:
http://kba.cloud/hocr-spec/
"""
box_pattern = re.compile(r'bbox((\s+\d+){4})')
baseline_pattern = re.compile(
r'''
baseline \s+
([\-\+]?\d*\.?\d*) \s+ # +/- decimal float
([\-\+]?\d+) # +/- int''',
re.VERBOSE,
)
ligatures = str.maketrans(
{'': 'ff', '': 'f‌f‌i', '': 'f‌f‌l', '': 'fi', '': 'fl'}
)
def __init__(self, *, hocr_filename: Union[str, Path], dpi: float):
self.dpi = dpi
self.hocr = ElementTree.parse(os.fspath(hocr_filename))
# if the hOCR file has a namespace, ElementTree requires its use to
# find elements
matches = re.match(r'({.*})html', self.hocr.getroot().tag)
self.xmlns = ''
if matches:
self.xmlns = matches.group(1)
# get dimension in pt (not pixel!!!!) of the OCRed image
self.width, self.height = None, None
for div in self.hocr.findall(self._child_xpath('div', 'ocr_page')):
coords = self.element_coordinates(div)
pt_coords = self.pt_from_pixel(coords)
self.width = pt_coords.x2 - pt_coords.x1
self.height = pt_coords.y2 - pt_coords.y1
# there shouldn't be more than one, and if there is, we don't want
# it
break
if self.width is None or self.height is None:
raise HocrTransformError("hocr file is missing page dimensions")
def __str__(self): # pragma: no cover
"""
Return the textual content of the HTML body
"""
if self.hocr is None:
return ''
body = self.hocr.find(self._child_xpath('body'))
if body:
return self._get_element_text(body)
else:
return ''
def _get_element_text(self, element: Element):
"""
Return the textual content of the element and its children
"""
text = ''
if element.text is not None:
text += element.text
for child in element:
text += self._get_element_text(child)
if element.tail is not None:
text += element.tail
return text
@classmethod
def element_coordinates(cls, element: Element) -> Rect:
"""
Returns a tuple containing the coordinates of the bounding box around
an element
"""
out = Rect._make(0 for _ in range(4))
if 'title' in element.attrib:
matches = cls.box_pattern.search(element.attrib['title'])
if matches:
coords = matches.group(1).split()
out = Rect._make(int(coords[n]) for n in range(4))
return out
@classmethod
def baseline(cls, element: Element) -> Tuple[float, float]:
"""
Returns a tuple containing the baseline slope and intercept.
"""
if 'title' in element.attrib:
matches = cls.baseline_pattern.search(element.attrib['title'])
if matches:
return float(matches.group(1)), int(matches.group(2))
return (0.0, 0.0)
def pt_from_pixel(self, pxl) -> Rect:
"""
Returns the quantity in PDF units (pt) given quantity in pixels
"""
return Rect._make((c / self.dpi * inch) for c in pxl)
def _child_xpath(self, html_tag: str, html_class: Optional[str] = None) -> str:
xpath = f".//{self.xmlns}{html_tag}"
if html_class:
xpath += f"[@class='{html_class}']"
return xpath
@classmethod
def replace_unsupported_chars(cls, s: str) -> str:
"""
Given an input string, returns the corresponding string that:
* is available in the Helvetica facetype
* does not contain any ligature (to allow easy search in the PDF file)
"""
return s.translate(cls.ligatures)
def topdown_position(self, element):
pxl_line_coords = self.element_coordinates(element)
line_box = self.pt_from_pixel(pxl_line_coords)
# Coordinates here are still in the hocr coordinate system, so 0 on the y axis
# is the top of the page and increasing values of y will move towards the
# bottom of the page.
return line_box.y2
def to_pdf(
self,
*,
out_filename: Path,
image_filename: Optional[Path] = None,
show_bounding_boxes: bool = False,
fontname: str = "Helvetica",
invisible_text: bool = False,
interword_spaces: bool = False,
) -> None:
"""
Creates a PDF file with an image superimposed on top of the text.
Text is positioned according to the bounding box of the lines in
the hOCR file.
The image need not be identical to the image used to create the hOCR
file.
It can have a lower resolution, different color mode, etc.
Arguments:
out_filename: Path of PDF to write.
image_filename: Image to use for this file. If omitted, the OCR text
is shown.
show_bounding_boxes: Show bounding boxes around various text regions,
for debugging.
fontname: Name of font to use.
invisible_text: If True, text is rendered invisible so that is
selectable but never drawn. If False, text is visible and may
be seen if the image is skipped or deleted in Acrobat.
interword_spaces: If True, insert spaces between words rather than
drawing each word without spaces. Generally this improves text
extraction.
"""
# create the PDF file
# page size in points (1/72 in.)
pdfmetrics.registerFont(TTFont('Greek', 'static/fonts/greek.ttf'))
pdfmetrics.registerFont(TTFont('GreekB', 'static/fonts/greek-bold.ttf'))
registerFontFamily('Greek', normal='Greek', bold='GreekB')
pdf = Canvas(
os.fspath(out_filename),
pagesize=(self.width, self.height),
pageCompression=1,
)
if image_filename is not None:
pdf.drawImage(
os.fspath(image_filename), 0, 0, width=self.width, height=self.height
)
# draw bounding box for each paragraph
# light blue for bounding box of paragraph
pdf.setStrokeColor(black)
# light blue for bounding box of paragraph
pdf.setFillColor(black)
pdf.setLineWidth(1) # no line for bounding box
for elem in self.hocr.iterfind(self._child_xpath('p', 'ocr_par')):
elemtxt = self._get_element_text(elem).rstrip()
if len(elemtxt) == 0:
continue
pxl_coords = self.element_coordinates(elem)
pt = self.pt_from_pixel(pxl_coords)
# draw the bbox border
if show_bounding_boxes: # pragma: no cover
pdf.rect(
pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1, fill=1
)
found_lines = False
for line in sorted(
chain(
self.hocr.iterfind(self._child_xpath('span', 'ocr_header')),
self.hocr.iterfind(self._child_xpath('span', 'ocr_line')),
self.hocr.iterfind(self._child_xpath('span', 'ocr_textfloat')),
),
key=self.topdown_position,
):
found_lines = True
self._do_line(
pdf,
line,
"ocrx_word",
fontname,
invisible_text,
interword_spaces,
show_bounding_boxes,
)
if not found_lines:
# Tesseract did not report any lines (just words)
root = self.hocr.find(self._child_xpath('div', 'ocr_page'))
self._do_line(
pdf,
root,
"ocrx_word",
fontname,
invisible_text,
interword_spaces,
show_bounding_boxes,
)
# put the image on the page, scaled to fill the page
# finish up the page and save it
pdf.showPage()
pdf.save()
@classmethod
def polyval(cls, poly, x): # pragma: no cover
return x * poly[0] + poly[1]
def _do_line(
self,
pdf: Canvas,
line: Optional[Element],
elemclass: str,
fontname: str,
invisible_text: bool,
interword_spaces: bool,
show_bounding_boxes: bool,
):
if not line:
return
pxl_line_coords = self.element_coordinates(line)
line_box = self.pt_from_pixel(pxl_line_coords)
line_height = line_box.y2 - line_box.y1
slope, pxl_intercept = self.baseline(line)
if abs(slope) < 0.005:
slope = 0.0
angle = atan(slope)
cos_a, sin_a = cos(angle), sin(angle)
text = pdf.beginText()
intercept = pxl_intercept / self.dpi * inch
# Don't allow the font to break out of the bounding box. Division by
# cos_a accounts for extra clearance between the glyph's vertical axis
# on a sloped baseline and the edge of the bounding box.
fontsize = (line_height - abs(intercept)) / cos_a * 1.2
#fontsize = 10.5
text.setFont('Greek', fontsize)
#if invisible_text:
# text.setTextRenderMode(3) # Invisible (indicates OCR text)
# Intercept is normally negative, so this places it above the bottom
# of the line box
baseline_y2 = self.height - (line_box.y2 + intercept)
if False: # pragma: no cover
# draw the baseline in magenta, dashed
pdf.setDash()
pdf.setStrokeColor(magenta)
pdf.setLineWidth(0.5)
# negate slope because it is defined as a rise/run in pixel
# coordinates and page coordinates have the y axis flipped
pdf.line(
line_box.x1,
baseline_y2,
line_box.x2,
self.polyval((-slope, baseline_y2), line_box.x2 - line_box.x1),
)
# light green for bounding box of word/line
pdf.setDash(6, 3)
pdf.setStrokeColor(red)
#text.setTextTransform(cos_a, -sin_a, sin_a, cos_a, line_box.x1, baseline_y2)
text.setTextOrigin(line_box.x1, baseline_y2)
##pdf.translate(line_box.x1, baseline_y2)
pdf.setFillColor(black) # text in black
elements = line.findall(self._child_xpath('span', elemclass))
for elem in elements:
elemtxt = self._get_element_text(elem).strip()
elemtxt = self.replace_unsupported_chars(elemtxt)
if elemtxt == '':
continue
pxl_coords = self.element_coordinates(elem)
box = self.pt_from_pixel(pxl_coords)
if False:
# if `--interword-spaces` is true, append a space
# to the end of each text element to allow simpler PDF viewers
# such as PDF.js to better recognize words in search and copy
# and paste. Do not remove space from last word in line, even
# though it would look better, because it will interfere with
# naive text extraction. \n does not work either.
elemtxt += ' '
box = Rect._make(
(
box.x1,
line_box.y1,
box.x2 + pdf.stringWidth(' ', fontname, line_height),
line_box.y2,
)
)
box_width = box.x2 - box.x1
font_width = pdf.stringWidth(elemtxt, fontname, fontsize)
# draw the bbox border
if False: # pragma: no cover
pdf.rect(
box.x1, self.height - line_box.y2, box_width, line_height, fill=0
)
# Adjust relative position of cursor
# This is equivalent to:
# text.setTextOrigin(pt.x1, self.height - line_box.y2)
# but the former generates a full text reposition matrix (Tm) in the
# content stream while this issues a "offset" (Td) command.
# .moveCursor() is relative to start of the text line, where the
# "text line" means whatever reportlab defines it as. Do not use
# use .getCursor(), since moveCursor() rather unintuitively plans
# its moves relative to .getStartOfLine().
# For skewed lines, in the text transform we set up a rotated
# coordinate system, so we don't have to account for the
# incremental offset. Surprisingly most PDF viewers can handle this.
cursor = text.getStartOfLine()
dx = box.x1 - cursor[0]
dy = baseline_y2 - cursor[1]
text.moveCursor(dx, dy)
# If reportlab tells us this word is 0 units wide, our best seems
# to be to suppress this text
if font_width > 0:
#text.setHorizScale(100 * box_width / font_width)
text.textOut(elemtxt)
pdf.drawText(text)
if __name__ == "__main__":
parser = argparse.ArgumentParser(description='Convert hocr file to PDF')
parser.add_argument(
'-b',
'--boundingboxes',
action="store_true",
default=False,
help='Show bounding boxes borders',
)
parser.add_argument(
'-r',
'--resolution',
type=int,
default=300,
help='Resolution of the image that was OCRed',
)
parser.add_argument(
'-i',
'--image',
default=None,
help='Path to the image to be placed above the text',
)
parser.add_argument(
'--interword-spaces',
action='store_true',
default=False,
help='Add spaces between words',
)
parser.add_argument('hocrfile', help='Path to the hocr file to be parsed')
parser.add_argument('outputfile', help='Path to the PDF file to be generated')
args = parser.parse_args()
hocr = HocrTransform(hocr_filename=args.hocrfile, dpi=args.resolution)
hocr.to_pdf(
out_filename=args.outputfile,
image_filename=args.image,
show_bounding_boxes=args.boundingboxes,
interword_spaces=args.interword_spaces,
)

511
hocrtransform.py

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#!/usr/bin/env python3
#
# Copyright (c) 2010, Jonathan Brinley
# Original version from: https://github.com/jbrinley/HocrConverter
#
# Copyright (c) 2013-14, Julien Pfefferkorn
# Modifications
#
# Copyright (c) 2015-16, James R. Barlow
# Set text to transparent
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
import argparse
import os
import re
from itertools import chain
from math import atan, cos, sin
from pathlib import Path
from typing import Any, NamedTuple, Optional, Tuple, Union
from xml.etree import ElementTree
from reportlab.lib.colors import black, cyan, magenta, red
from reportlab.lib.units import inch
from reportlab.pdfgen.canvas import Canvas
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.pdfbase.pdfmetrics import registerFontFamily
# According to Wikipedia these languages are supported in the ISO-8859-1 character
# set, meaning reportlab can generate them and they are compatible with hocr,
# assuming Tesseract has the necessary languages installed. Note that there may
# not be language packs for them.
HOCR_OK_LANGS = frozenset(
[
# Languages fully covered by Latin-1:
'afr', # Afrikaans
'alb', # Albanian
'ast', # Leonese
'baq', # Basque
'bre', # Breton
'cos', # Corsican
'eng', # English
'eus', # Basque
'fao', # Faoese
'gla', # Scottish Gaelic
'glg', # Galician
'glv', # Manx
'ice', # Icelandic
'ind', # Indonesian
'isl', # Icelandic
'ita', # Italian
'ltz', # Luxembourgish
'mal', # Malay Rumi
'mga', # Irish
'nor', # Norwegian
'oci', # Occitan
'por', # Portugeuse
'roh', # Romansh
'sco', # Scots
'sma', # Sami
'spa', # Spanish
'sqi', # Albanian
'swa', # Swahili
'swe', # Swedish
'tgl', # Tagalog
'wln', # Walloon
# Languages supported by Latin-1 except for a few rare characters that OCR
# is probably not trained to recognize anyway:
'cat', # Catalan
'cym', # Welsh
'dan', # Danish
'deu', # German
'dut', # Dutch
'est', # Estonian
'fin', # Finnish
'fra', # French
'hun', # Hungarian
'kur', # Kurdish
'nld', # Dutch
'wel', # Welsh
]
)
Element = ElementTree.Element
class Rect(NamedTuple): # pylint: disable=inherit-non-class
"""A rectangle for managing PDF coordinates."""
x1: Any
y1: Any
x2: Any
y2: Any
class HocrTransformError(Exception):
pass
class HocrTransform:
"""
A class for converting documents from the hOCR format.
For details of the hOCR format, see:
http://kba.cloud/hocr-spec/
"""
box_pattern = re.compile(r'bbox((\s+\d+){4})')
baseline_pattern = re.compile(
r'''
baseline \s+
([\-\+]?\d*\.?\d*) \s+ # +/- decimal float
([\-\+]?\d+) # +/- int''',
re.VERBOSE,
)
ligatures = str.maketrans(
{'': 'ff', '': 'f‌f‌i', '': 'f‌f‌l', '': 'fi', '': 'fl'}
)
def __init__(self, *, hocr_filename: Union[str, Path], dpi: float):
self.dpi = dpi
self.hocr = ElementTree.parse(os.fspath(hocr_filename))
# if the hOCR file has a namespace, ElementTree requires its use to
# find elements
matches = re.match(r'({.*})html', self.hocr.getroot().tag)
self.xmlns = ''
if matches:
self.xmlns = matches.group(1)
# get dimension in pt (not pixel!!!!) of the OCRed image
self.width, self.height = None, None
for div in self.hocr.findall(self._child_xpath('div', 'ocr_page')):
coords = self.element_coordinates(div)
pt_coords = self.pt_from_pixel(coords)
self.width = pt_coords.x2 - pt_coords.x1
self.height = pt_coords.y2 - pt_coords.y1
# there shouldn't be more than one, and if there is, we don't want
# it
break
if self.width is None or self.height is None:
raise HocrTransformError("hocr file is missing page dimensions")
def __str__(self): # pragma: no cover
"""
Return the textual content of the HTML body
"""
if self.hocr is None:
return ''
body = self.hocr.find(self._child_xpath('body'))
if body:
return self._get_element_text(body)
else:
return ''
def _get_element_text(self, element: Element):
"""
Return the textual content of the element and its children
"""
text = ''
if element.text is not None:
text += element.text
for child in element:
text += self._get_element_text(child)
if element.tail is not None:
text += element.tail
return text
@classmethod
def element_coordinates(cls, element: Element) -> Rect:
"""
Returns a tuple containing the coordinates of the bounding box around
an element
"""
out = Rect._make(0 for _ in range(4))
if 'title' in element.attrib:
matches = cls.box_pattern.search(element.attrib['title'])
if matches:
coords = matches.group(1).split()
out = Rect._make(int(coords[n]) for n in range(4))
return out
@classmethod
def baseline(cls, element: Element) -> Tuple[float, float]:
"""
Returns a tuple containing the baseline slope and intercept.
"""
if 'title' in element.attrib:
matches = cls.baseline_pattern.search(element.attrib['title'])
if matches:
return float(matches.group(1)), int(matches.group(2))
return (0.0, 0.0)
def pt_from_pixel(self, pxl) -> Rect:
"""
Returns the quantity in PDF units (pt) given quantity in pixels
"""
return Rect._make((c / self.dpi * inch) for c in pxl)
def _child_xpath(self, html_tag: str, html_class: Optional[str] = None) -> str:
xpath = f".//{self.xmlns}{html_tag}"
if html_class:
xpath += f"[@class='{html_class}']"
return xpath
@classmethod
def replace_unsupported_chars(cls, s: str) -> str:
"""
Given an input string, returns the corresponding string that:
* is available in the Helvetica facetype
* does not contain any ligature (to allow easy search in the PDF file)
"""
return s.translate(cls.ligatures)
def topdown_position(self, element):
pxl_line_coords = self.element_coordinates(element)
line_box = self.pt_from_pixel(pxl_line_coords)
# Coordinates here are still in the hocr coordinate system, so 0 on the y axis
# is the top of the page and increasing values of y will move towards the
# bottom of the page.
return line_box.y2
def to_pdf(
self,
*,
out_filename: Path,
image_filename: Optional[Path] = None,
show_bounding_boxes: bool = False,
fontname: str = "Helvetica",
invisible_text: bool = False,
interword_spaces: bool = False,
) -> None:
"""
Creates a PDF file with an image superimposed on top of the text.
Text is positioned according to the bounding box of the lines in
the hOCR file.
The image need not be identical to the image used to create the hOCR
file.
It can have a lower resolution, different color mode, etc.
Arguments:
out_filename: Path of PDF to write.
image_filename: Image to use for this file. If omitted, the OCR text
is shown.
show_bounding_boxes: Show bounding boxes around various text regions,
for debugging.
fontname: Name of font to use.
invisible_text: If True, text is rendered invisible so that is
selectable but never drawn. If False, text is visible and may
be seen if the image is skipped or deleted in Acrobat.
interword_spaces: If True, insert spaces between words rather than
drawing each word without spaces. Generally this improves text
extraction.
"""
# create the PDF file
# page size in points (1/72 in.)
pdfmetrics.registerFont(TTFont('Greek', 'static/fonts/greek.ttf'))
pdfmetrics.registerFont(TTFont('GreekB', 'static/fonts/greek-bold.ttf'))
registerFontFamily('Greek', normal='Greek', bold='GreekB')
pdf = Canvas(
os.fspath(out_filename),
pagesize=(self.width, self.height),
pageCompression=1,
)
# draw bounding box for each paragraph
# light blue for bounding box of paragraph
pdf.setStrokeColor(cyan)
# light blue for bounding box of paragraph
pdf.setFillColor(cyan)
pdf.setLineWidth(0) # no line for bounding box
for elem in self.hocr.iterfind(self._child_xpath('p', 'ocr_par')):
elemtxt = self._get_element_text(elem).rstrip()
if len(elemtxt) == 0:
continue
pxl_coords = self.element_coordinates(elem)
pt = self.pt_from_pixel(pxl_coords)
# draw the bbox border
if show_bounding_boxes: # pragma: no cover
pdf.rect(
pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1, fill=1
)
found_lines = False
for line in sorted(
chain(
self.hocr.iterfind(self._child_xpath('span', 'ocr_header')),
self.hocr.iterfind(self._child_xpath('span', 'ocr_line')),
self.hocr.iterfind(self._child_xpath('span', 'ocr_textfloat')),
),
key=self.topdown_position,
):
found_lines = True
self._do_line(
pdf,
line,
"ocrx_word",
fontname,
invisible_text,
interword_spaces,
show_bounding_boxes,
)
if not found_lines:
# Tesseract did not report any lines (just words)
root = self.hocr.find(self._child_xpath('div', 'ocr_page'))
self._do_line(
pdf,
root,
"ocrx_word",
fontname,
invisible_text,
interword_spaces,
show_bounding_boxes,
)
# put the image on the page, scaled to fill the page
if image_filename is not None:
pdf.drawImage(
os.fspath(image_filename), 0, 0, width=self.width, height=self.height
)
# finish up the page and save it
pdf.showPage()
pdf.save()
@classmethod
def polyval(cls, poly, x): # pragma: no cover
return x * poly[0] + poly[1]
def _do_line(
self,
pdf: Canvas,
line: Optional[Element],
elemclass: str,
fontname: str,
invisible_text: bool,
interword_spaces: bool,
show_bounding_boxes: bool,
):
if not line:
return
pxl_line_coords = self.element_coordinates(line)
line_box = self.pt_from_pixel(pxl_line_coords)
line_height = line_box.y2 - line_box.y1
slope, pxl_intercept = self.baseline(line)
if abs(slope) < 0.005:
slope = 0.0
angle = atan(slope)
cos_a, sin_a = cos(angle), sin(angle)
text = pdf.beginText()
intercept = pxl_intercept / self.dpi * inch
# Don't allow the font to break out of the bounding box. Division by
# cos_a accounts for extra clearance between the glyph's vertical axis
# on a sloped baseline and the edge of the bounding box.
fontsize = (line_height - abs(intercept)) / cos_a * 1.2
#fontsize = 10.5
text.setFont('Greek', fontsize)
if invisible_text:
text.setTextRenderMode(3) # Invisible (indicates OCR text)
# Intercept is normally negative, so this places it above the bottom
# of the line box
baseline_y2 = self.height - (line_box.y2 + intercept)
if False: # pragma: no cover
# draw the baseline in magenta, dashed
pdf.setDash()
pdf.setStrokeColor(magenta)
pdf.setLineWidth(0.5)
# negate slope because it is defined as a rise/run in pixel
# coordinates and page coordinates have the y axis flipped
pdf.line(
line_box.x1,
baseline_y2,
line_box.x2,
self.polyval((-slope, baseline_y2), line_box.x2 - line_box.x1),
)
# light green for bounding box of word/line
pdf.setDash(6, 3)
pdf.setStrokeColor(red)
#text.setTextTransform(cos_a, -sin_a, sin_a, cos_a, line_box.x1, baseline_y2)
text.setTextOrigin(line_box.x1, baseline_y2)
pdf.setFillColor(black) # text in black
elements = line.findall(self._child_xpath('span', elemclass))
for elem in elements:
elemtxt = self._get_element_text(elem).strip()
elemtxt = self.replace_unsupported_chars(elemtxt)
if elemtxt == '':
continue
pxl_coords = self.element_coordinates(elem)
box = self.pt_from_pixel(pxl_coords)
if interword_spaces:
# if `--interword-spaces` is true, append a space
# to the end of each text element to allow simpler PDF viewers
# such as PDF.js to better recognize words in search and copy
# and paste. Do not remove space from last word in line, even
# though it would look better, because it will interfere with
# naive text extraction. \n does not work either.
elemtxt += ' '
box = Rect._make(
(
box.x1,
line_box.y1,
box.x2 + pdf.stringWidth(' ', fontname, line_height),
line_box.y2,
)
)
box_width = box.x2 - box.x1
font_width = pdf.stringWidth(elemtxt, fontname, fontsize)
# draw the bbox border
if False: # pragma: no cover
pdf.rect(
box.x1, self.height - line_box.y2, box_width, line_height, fill=0
)
# Adjust relative position of cursor
# This is equivalent to:
# text.setTextOrigin(pt.x1, self.height - line_box.y2)
# but the former generates a full text reposition matrix (Tm) in the
# content stream while this issues a "offset" (Td) command.
# .moveCursor() is relative to start of the text line, where the
# "text line" means whatever reportlab defines it as. Do not use
# use .getCursor(), since moveCursor() rather unintuitively plans
# its moves relative to .getStartOfLine().
# For skewed lines, in the text transform we set up a rotated
# coordinate system, so we don't have to account for the
# incremental offset. Surprisingly most PDF viewers can handle this.
cursor = text.getStartOfLine()
dx = box.x1 - cursor[0]
dy = baseline_y2 - cursor[1]
text.moveCursor(dx, dy)
# If reportlab tells us this word is 0 units wide, our best seems
# to be to suppress this text
if font_width > 0:
#text.setHorizScale(100 * box_width / font_width)
text.textOut(elemtxt)
pdf.drawText(text)
if __name__ == "__main__":
parser = argparse.ArgumentParser(description='Convert hocr file to PDF')
parser.add_argument(
'-b',
'--boundingboxes',
action="store_true",
default=False,
help='Show bounding boxes borders',
)
parser.add_argument(
'-r',
'--resolution',
type=int,
default=300,
help='Resolution of the image that was OCRed',
)
parser.add_argument(
'-i',
'--image',
default=None,
help='Path to the image to be placed above the text',
)
parser.add_argument(
'--interword-spaces',
action='store_true',
default=False,
help='Add spaces between words',
)
parser.add_argument('hocrfile', help='Path to the hocr file to be parsed')
parser.add_argument('outputfile', help='Path to the PDF file to be generated')
args = parser.parse_args()
hocr = HocrTransform(hocr_filename=args.hocrfile, dpi=args.resolution)
hocr.to_pdf(
out_filename=args.outputfile,
image_filename=args.image,
show_bounding_boxes=args.boundingboxes,
interword_spaces=args.interword_spaces,
)

518
hocrtransformpdf.py

@ -0,0 +1,518 @@
#!venv/bin python3
#
# Copyright (c) 2010, Jonathan Brinley
# Original version from: https://github.com/jbrinley/HocrConverter
#
# Copyright (c) 2013-14, Julien Pfefferkorn
# Modifications
#
# Copyright (c) 2015-16, James R. Barlow
# Set text to transparent
# Copyright (c) 2022, WordMord & Alex Roidl
# Set text back to visible and change bounding boxes
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
import argparse
import os
import re
from itertools import chain
from math import atan, cos, sin
from pathlib import Path
from typing import Any, NamedTuple, Optional, Tuple, Union
from xml.etree import ElementTree
from reportlab.lib.colors import black, cyan, magenta, red
from reportlab.lib.units import inch
from reportlab.pdfgen.canvas import Canvas
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.pdfbase.pdfmetrics import registerFontFamily
# According to Wikipedia these languages are supported in the ISO-8859-1 character
# set, meaning reportlab can generate them and they are compatible with hocr,
# assuming Tesseract has the necessary languages installed. Note that there may
# not be language packs for them.
HOCR_OK_LANGS = frozenset(
[
# Languages fully covered by Latin-1:
'afr', # Afrikaans
'alb', # Albanian
'ast', # Leonese
'baq', # Basque
'bre', # Breton
'cos', # Corsican
'eng', # English
'eus', # Basque
'fao', # Faoese
'gla', # Scottish Gaelic
'glg', # Galician
'glv', # Manx
'ice', # Icelandic
'ind', # Indonesian
'isl', # Icelandic
'ita', # Italian
'ltz', # Luxembourgish
'mal', # Malay Rumi
'mga', # Irish
'nor', # Norwegian
'oci', # Occitan
'por', # Portugeuse
'roh', # Romansh
'sco', # Scots
'sma', # Sami
'spa', # Spanish
'sqi', # Albanian
'swa', # Swahili
'swe', # Swedish
'tgl', # Tagalog
'wln', # Walloon
# Languages supported by Latin-1 except for a few rare characters that OCR
# is probably not trained to recognize anyway:
'cat', # Catalan
'cym', # Welsh
'dan', # Danish
'deu', # German
'dut', # Dutch
'est', # Estonian
'fin', # Finnish
'fra', # French
'hun', # Hungarian
'kur', # Kurdish
'nld', # Dutch
'wel', # Welsh
]
)
Element = ElementTree.Element
class Rect(NamedTuple): # pylint: disable=inherit-non-class
"""A rectangle for managing PDF coordinates."""
x1: Any
y1: Any
x2: Any
y2: Any
class HocrTransformError(Exception):
pass
class HocrTransform:
"""
A class for converting documents from the hOCR format.
For details of the hOCR format, see:
http://kba.cloud/hocr-spec/
"""
box_pattern = re.compile(r'bbox((\s+\d+){4})')
baseline_pattern = re.compile(
r'''
baseline \s+
([\-\+]?\d*\.?\d*) \s+ # +/- decimal float
([\-\+]?\d+) # +/- int''',
re.VERBOSE,
)
ligatures = str.maketrans(
{'': 'ff', '': 'f‌f‌i', '': 'f‌f‌l', '': 'fi', '': 'fl'}
)
def __init__(self, *, hocr_filename: Union[str, Path], dpi: float):
self.dpi = dpi
self.hocr = ElementTree.parse(os.fspath(hocr_filename))
# if the hOCR file has a namespace, ElementTree requires its use to
# find elements
matches = re.match(r'({.*})html', self.hocr.getroot().tag)
self.xmlns = ''
if matches:
self.xmlns = matches.group(1)
# get dimension in pt (not pixel!!!!) of the OCRed image
self.width, self.height = None, None
for div in self.hocr.findall(self._child_xpath('div', 'ocr_page')):
coords = self.element_coordinates(div)
pt_coords = self.pt_from_pixel(coords)
self.width = pt_coords.x2 - pt_coords.x1
self.height = pt_coords.y2 - pt_coords.y1
# there shouldn't be more than one, and if there is, we don't want
# it
break
if self.width is None or self.height is None:
raise HocrTransformError("hocr file is missing page dimensions")
def __str__(self): # pragma: no cover
"""
Return the textual content of the HTML body
"""
if self.hocr is None:
return ''
body = self.hocr.find(self._child_xpath('body'))
if body:
return self._get_element_text(body)
else:
return ''
def _get_element_text(self, element: Element):
"""
Return the textual content of the element and its children
"""
text = ''
if element.text is not None:
text += element.text
for child in element:
text += self._get_element_text(child)
if element.tail is not None:
text += element.tail
return text
@classmethod
def element_coordinates(cls, element: Element) -> Rect:
"""
Returns a tuple containing the coordinates of the bounding box around
an element
"""
out = Rect._make(0 for _ in range(4))
if 'title' in element.attrib:
matches = cls.box_pattern.search(element.attrib['title'])
if matches:
coords = matches.group(1).split()
out = Rect._make(int(coords[n]) for n in range(4))
return out
@classmethod
def baseline(cls, element: Element) -> Tuple[float, float]:
"""
Returns a tuple containing the baseline slope and intercept.
"""
if 'title' in element.attrib:
matches = cls.baseline_pattern.search(element.attrib['title'])
if matches:
return float(matches.group(1)), int(matches.group(2))
return (0.0, 0.0)
def pt_from_pixel(self, pxl) -> Rect:
"""
Returns the quantity in PDF units (pt) given quantity in pixels
"""
return Rect._make((c / self.dpi * inch) for c in pxl)
def _child_xpath(self, html_tag: str, html_class: Optional[str] = None) -> str:
xpath = f".//{self.xmlns}{html_tag}"
if html_class:
xpath += f"[@class='{html_class}']"
return xpath
@classmethod
def replace_unsupported_chars(cls, s: str) -> str:
"""
Given an input string, returns the corresponding string that:
* is available in the Helvetica facetype
* does not contain any ligature (to allow easy search in the PDF file)
"""
return s.translate(cls.ligatures)
def topdown_position(self, element):
pxl_line_coords = self.element_coordinates(element)
line_box = self.pt_from_pixel(pxl_line_coords)
# Coordinates here are still in the hocr coordinate system, so 0 on the y axis
# is the top of the page and increasing values of y will move towards the
# bottom of the page.
return line_box.y2
def to_pdf(
self,
*,
out_filename: Path,
image_filename: Optional[Path] = None,
show_bounding_boxes: bool = False,
fontname: str = "Helvetica",
invisible_text: bool = False,
interword_spaces: bool = False,
) -> None:
"""
Creates a PDF file with an image superimposed on top of the text.
Text is positioned according to the bounding box of the lines in
the hOCR file.
The image need not be identical to the image used to create the hOCR
file.
It can have a lower resolution, different color mode, etc.
Arguments:
out_filename: Path of PDF to write.
image_filename: Image to use for this file. If omitted, the OCR text
is shown.
show_bounding_boxes: Show bounding boxes around various text regions,
for debugging.
fontname: Name of font to use.
invisible_text: If True, text is rendered invisible so that is
selectable but never drawn. If False, text is visible and may
be seen if the image is skipped or deleted in Acrobat.
interword_spaces: If True, insert spaces between words rather than
drawing each word without spaces. Generally this improves text
extraction.
"""
# create the PDF file
# page size in points (1/72 in.)
pdfmetrics.registerFont(TTFont('Greek', 'static/fonts/greek.ttf'))
pdfmetrics.registerFont(TTFont('GreekB', 'static/fonts/greek-bold.ttf'))
registerFontFamily('Greek', normal='Greek', bold='GreekB')
pdf = Canvas(
os.fspath(out_filename),
pagesize=(self.width, self.height),
pageCompression=1,
)
if image_filename is not None:
pdf.drawImage(
os.fspath(image_filename), 0, 0, width=self.width, height=self.height
)
# draw bounding box for each paragraph
# light blue for bounding box of paragraph
pdf.setStrokeColor(black)
# light blue for bounding box of paragraph
pdf.setFillColor(black)
pdf.setLineWidth(1) # no line for bounding box
for elem in self.hocr.iterfind(self._child_xpath('p', 'ocr_par')):
elemtxt = self._get_element_text(elem).rstrip()
if len(elemtxt) == 0:
continue
pxl_coords = self.element_coordinates(elem)
pt = self.pt_from_pixel(pxl_coords)
# draw the bbox border
if show_bounding_boxes: # pragma: no cover
pdf.rect(
pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1, fill=1
)
found_lines = False
for line in sorted(
chain(
self.hocr.iterfind(self._child_xpath('span', 'ocr_header')),
self.hocr.iterfind(self._child_xpath('span', 'ocr_line')),
self.hocr.iterfind(self._child_xpath('span', 'ocr_textfloat')),
),
key=self.topdown_position,
):
found_lines = True
self._do_line(
pdf,
line,
"ocrx_word",
fontname,
invisible_text,
interword_spaces,
show_bounding_boxes,
)
if not found_lines:
# Tesseract did not report any lines (just words)
root = self.hocr.find(self._child_xpath('div', 'ocr_page'))
self._do_line(
pdf,
root,
"ocrx_word",
fontname,
invisible_text,
interword_spaces,
show_bounding_boxes,
)
# put the image on the page, scaled to fill the page
# finish up the page and save it
pdf.showPage()
pdf.save()
@classmethod
def polyval(cls, poly, x): # pragma: no cover
return x * poly[0] + poly[1]
def _do_line(
self,
pdf: Canvas,
line: Optional[Element],
elemclass: str,
fontname: str,
invisible_text: bool,
interword_spaces: bool,
show_bounding_boxes: bool,
):
if not line:
return
pxl_line_coords = self.element_coordinates(line)
line_box = self.pt_from_pixel(pxl_line_coords)
line_height = line_box.y2 - line_box.y1
slope, pxl_intercept = self.baseline(line)
if abs(slope) < 0.005:
slope = 0.0
angle = atan(slope)
cos_a, sin_a = cos(angle), sin(angle)
text = pdf.beginText()
intercept = pxl_intercept / self.dpi * inch
# Don't allow the font to break out of the bounding box. Division by
# cos_a accounts for extra clearance between the glyph's vertical axis
# on a sloped baseline and the edge of the bounding box.
fontsize = (line_height - abs(intercept)) / cos_a * 1.2
#fontsize = 10.5
text.setFont('Greek', fontsize)
#if invisible_text:
# text.setTextRenderMode(3) # Invisible (indicates OCR text)
# Intercept is normally negative, so this places it above the bottom
# of the line box
baseline_y2 = self.height - (line_box.y2 + intercept)
if False: # pragma: no cover
# draw the baseline in magenta, dashed
pdf.setDash()
pdf.setStrokeColor(magenta)
pdf.setLineWidth(0.5)
# negate slope because it is defined as a rise/run in pixel
# coordinates and page coordinates have the y axis flipped
pdf.line(
line_box.x1,
baseline_y2,
line_box.x2,
self.polyval((-slope, baseline_y2), line_box.x2 - line_box.x1),
)
# light green for bounding box of word/line
pdf.setDash(6, 3)
pdf.setStrokeColor(red)
#text.setTextTransform(cos_a, -sin_a, sin_a, cos_a, line_box.x1, baseline_y2)
text.setTextOrigin(line_box.x1, baseline_y2)
##pdf.translate(line_box.x1, baseline_y2)
pdf.setFillColor(black) # text in black
elements = line.findall(self._child_xpath('span', elemclass))
for elem in elements:
elemtxt = self._get_element_text(elem).strip()
elemtxt = self.replace_unsupported_chars(elemtxt)
if elemtxt == '':
continue
pxl_coords = self.element_coordinates(elem)
box = self.pt_from_pixel(pxl_coords)
if False:
# if `--interword-spaces` is true, append a space
# to the end of each text element to allow simpler PDF viewers
# such as PDF.js to better recognize words in search and copy
# and paste. Do not remove space from last word in line, even
# though it would look better, because it will interfere with
# naive text extraction. \n does not work either.
elemtxt += ' '
box = Rect._make(
(
box.x1,
line_box.y1,
box.x2 + pdf.stringWidth(' ', fontname, line_height),
line_box.y2,
)
)
box_width = box.x2 - box.x1
font_width = pdf.stringWidth(elemtxt, fontname, fontsize)
# draw the bbox border
if False: # pragma: no cover
pdf.rect(
box.x1, self.height - line_box.y2, box_width, line_height, fill=0
)
# Adjust relative position of cursor
# This is equivalent to: