pythonでpdf操作

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https://www.reportlab.com/documentation/faq/#1.3.1

C:\python>python -m venv pdf
C:\python>pdf\Scripts\activate
(pdf) C:\python>cd pdf
(pdf) C:\python\pdf>mkdir src
(pdf) C:\python\pdf>cd src
(pdf) C:\python\pdf\src>pip install PyPDF2 --proxy http://proxy01.xxx
(pdf) C:\python\pdf\src>pip install reportlab --proxy http://proxy01.xxx

フォントはここでダウンロードした。
IPAexフォントのダウンロード

こんな感じで動くっぽい。

import io

from PyPDF2 import PdfFileWriter
from PyPDF2 import PdfFileReader
from reportlab.lib.colors import Color
from reportlab.lib.pagesizes import letter
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.cidfonts import UnicodeCIDFont
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.pdfgen import canvas


pdf = PdfFileReader("./test1.pdf")

pdfmetrics.registerFont(
    TTFont(
        'IPAexGothic',
        './ipaexg.ttf'
    )
)


page = pdf.getPage(0)

packet = io.BytesIO()
#can = canvas.Canvas(packet, pagesize=letter)
can = canvas.Canvas(packet)

font_size = 40
can.setFont('IPAexGothic', font_size)
can.setFillColor(Color(1, 0, 0, alpha=1))
can.drawString(
    000,
    100,
    "検収 2020/06/30 山田 太郎"
)

can.save()

packet.seek(0)
new_pdf = PdfFileReader(packet)
page.mergePage(new_pdf.getPage(0))

tmp = io.BytesIO()

output = PdfFileWriter()
output.addPage(page)
with open("test2.pdf", "wb") as fout:
    output.write(fout)
    output.write(tmp)
    print(type(fout))
    print(tmp.getvalue())