Illustration of a bug (a feature?) in pyMuPDF

keep_proportion.py

import fitz
import io
import requests

PDF_URL = "https://github.com/pymupdf/PyMuPDF/raw/master/examples/colordbHSV.pdf"
PNG_URL = "https://www.onlygfx.com/wp-content/uploads/2018/07/12-grunge-brush-stroke-banner-11.png"


def handle(_):
    pdf = requests.get(PDF_URL).content
    png = requests.get(PNG_URL).content
    rect = fitz.Rect(0, 0, 400, 50)
    document = fitz.open(stream=pdf, filetype="pdf")

    for page in document:
        page.insertImage(rect, stream=png, keep_proportion=True)

    return document.write()


if __name__ == "__main__":
    result = handle(None)
    with open("result.pdf", "wb") as file:
        file.write(result)