Python - ReportLab 和 PyPDF 编辑 PDF 问题

Question

我正在尝试使用

PyPDF

和

ReportLab

编辑现有的 pdf 文件。当我尝试定位红色圆圈和红色文本时，它似乎隐藏在白色容器或其他东西后面。如果我将它放在其他任何地方，它就可以正常工作。是什么原因造成的？

from PyPDF2 import PdfWriter, PdfReader
import io
from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import letter
from reportlab.lib.colors import red

def main():
    packet = io.BytesIO()
    can = canvas.Canvas(packet, pagesize=letter)
    can.setFillColorRGB(1, 0, 0)
    can.circle(370,780,20,fill=1)
    can.setFillColor(red)
    can.setFont("Times-Roman", 14)
    can.drawString(352, 785, "Customer Group #22")
    can.save()

    packet.seek(0)
    new_pdf = PdfReader(packet)

    existing_pdf = PdfReader(open("testing.pdf", "rb"))
    output = PdfWriter()

    page = existing_pdf.pages[1]
    page.merge_page(new_pdf.pages[0])
    output.add_page(page)

    outputStream = open("finalPDF.pdf", "wb")
    output.write(outputStream)
    outputStream.close()
if __name__ == "__main__":
    main()