title: Issue with Merging PDF and Watermark
body: <p>I have the following code which I got from here. This allows me to use a PDF template and overlay some additional text. Mainly using this to update a PDF template for an invoice.</p>
  <p>I'm having an odd bug where drawstring(0,0) places the text at the bottom left corner, where I would have expected this to be at the top left corner. Increasing the y value moves the cursor up, but it seams counter-intuitive.</p>
  <pre><code>    from PyPDF2 import PdfFileWriter, PdfFileReader, PdfFileMerger
      import io
      from reportlab.pdfgen import canvas
      from reportlab.lib.pagesizes import letter
      
      packet = io.BytesIO()
      can = canvas.Canvas(packet, pagesize=letter)
      can.drawString(0, 0, &quot;Hello world&quot;)
      can.save()
      
      #move to the beginning of the StringIO buffer
      packet.seek(0)
      
      # create a new PDF with Reportlab
      new_pdf = PdfFileReader(packet)
      # read your existing PDF
      existing_pdf = PdfFileReader(open(&quot;C:\\PythonProjects\\invoice_template.pdf&quot;, &quot;rb&quot;))
      output = PdfFileWriter()
      # add the &quot;watermark&quot; (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 &quot;output&quot; to a real file
      outputStream = open(&quot;destination.pdf&quot;, &quot;wb&quot;)
      output.write(outputStream)
      outputStream.close()
  </code></pre>