Adding printing margin to PDF files

pdfmargin.py

#!/usr/bin/env python
"""
Adds a printing margin to pdf files by scaling down the content and moving it to the center. 
Scale factor must be adapted to the needs.

Usage: pdfmargin.py file1.pdf file2.pdf ...
"""

import os
import sys
from decimal import Decimal

from PyPDF2 import PageObject, PdfReader, PdfWriter, Transformation


__author__ = "Flandersen"
__copyright__ = "Copyright 2023"


scale = 0.95

for input_file in sys.argv[1:]:
    file_without_ext = os.path.splitext(input_file)[0]
    output_file = "{0}_margin.pdf".format(file_without_ext)
    
    pdf = PdfReader(input_file)
    writer = PdfWriter()

    for page in pdf.pages:
        original_width = page.artbox.width
        original_height = page.artbox.height

        op = Transformation().scale(sx=scale, sy=scale)
        page.add_transformation(op)

        new_width = original_width * Decimal(scale)
        new_height = original_height * Decimal(scale)

        tx = (original_width - new_width) / Decimal(2.0)
        ty = (original_height - new_height) / Decimal(2.0)

        op = Transformation().translate(tx, ty)
        page.add_transformation(op)

        new_page = PageObject.create_blank_page(pdf, original_width, original_height)
        new_page.merge_page(page)

        writer.add_page(new_page)

    with open(output_file, "wb+") as f:
        writer.write(f)

# EOF