python - 在 python3 中通过 PDF 写入文本

Question

我正在尝试在某个位置将一些字符串写入 PDF 文件。 我找到了一种方法来执行此操作并像这样实现它:

from PyPDF2 import PdfFileWriter, PdfFileReader
import io
from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import letter

packet = io.StringIO()
# create a new PDF with Reportlab
can = canvas.Canvas(packet, pagesize=letter)
can.drawString(10, 100, "Hello world")
can.save()

#move to the beginning of the StringIO buffer
packet.seek(0)
new_pdf = PdfFileReader(packet)
# read your existing PDF
existing_pdf = PdfFileReader(file("original.pdf", "rb"))
output = PdfFileWriter()
# add the "watermark" (which is the new pdf) on the existing page
page = existing_pdf.getPage(0)
page.mergePage(new_pdf.getPage(0))
output.addPage(page)
# finally, write "output" to a real file
outputStream = file("destination.pdf", "wb")
output.write(outputStream)
outputStream.close()

它在 can.save() 行抛出一个错误

错误:

File "/home/corleone/miniconda3/lib/python3.6/site-packages/reportlab/pdfgen/canvas.py", line 1237, in save
    self._doc.SaveToFile(self._filename, self)
  File "/home/corleone/miniconda3/lib/python3.6/site-packages/reportlab/pdfbase/pdfdoc.py", line 224, in SaveToFile
    f.write(data)
TypeError: string argument expected, got 'bytes'

已在互联网上的很多地方阅读。发现到处都是一样的方法。是不是做法不对。我错过了什么吗？

Answer 1

发现我只需要使用 BytesIO 而不是 StringsIO。

还有 open() 而不是 file() 因为我使用的是 Python3。

这是工作脚本:

from PyPDF2 import PdfFileWriter, PdfFileReader
import io
from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import letter

packet = io.BytesIO()
# Create a new PDF with Reportlab
can = canvas.Canvas(packet, pagesize=letter)
can.setFont('Helvetica-Bold', 24)
can.drawString(10, 100, "Hello world")
can.showPage()
can.save()

# Move to the beginning of the StringIO buffer
packet.seek(0)
new_pdf = PdfFileReader(packet)
# Read your existing PDF
existing_pdf = PdfFileReader(open("original.pdf", "rb"))
output = PdfFileWriter()
# Add the "watermark" (which is the new pdf) on the existing page
page = existing_pdf.getPage(0)
page.mergePage(new_pdf.getPage(0))
output.addPage(page)
# Finally, write "output" to a real file
outputStream = open("destination.pdf", "wb")
output.write(outputStream)
outputStream.close()