bornhack-website/src/utils/pdf.py

import logging
import io
import os

from django.contrib.auth.models import AnonymousUser
from wkhtmltopdf.views import PDFTemplateResponse
from PyPDF2 import PdfFileWriter, PdfFileReader
from django.test.client import RequestFactory
from django.conf import settings
logger = logging.getLogger("bornhack.%s" % __name__)


def generate_pdf_letter(filename, template, formatdict):
    # conjure up a fake request for PDFTemplateResponse
    request = RequestFactory().get('/')
    request.user = AnonymousUser()
    request.session = {}

    # produce text-only PDF from template
    pdfgenerator = PDFTemplateResponse(
        request=request,
        template=template,
        context=formatdict,
        cmd_options={
            'margin-top': 50,
            'margin-bottom': 50,
        },
    )
    textonlypdf = io.BytesIO()
    textonlypdf.write(pdfgenerator.rendered_content)

    # create a blank pdf to work with
    finalpdf = PdfFileWriter()

    # open the text-only pdf
    pdfreader = PdfFileReader(textonlypdf)

    # get watermark from watermark file
    watermark = PdfFileReader(
        open(
            os.path.join(
                settings.STATICFILES_DIRS[0],
                'pdf',
                settings.PDF_LETTERHEAD_FILENAME
            ),
            'rb'
        )
    )

    # add the watermark to all pages
    for pagenum in range(pdfreader.getNumPages()):
        page = watermark.getPage(0)
        try:
            page.mergePage(pdfreader.getPage(pagenum))
        except ValueError:
            # watermark pdf might be broken?
            return False
        # add page to output
        finalpdf.addPage(page)

    # save the generated pdf to the archive
    fullpath = os.path.join(settings.PDF_ARCHIVE_PATH, filename)
    with open(fullpath, 'wb') as fh:
        finalpdf.write(fh)
        logger.info('Saved pdf to archive: %s' % fullpath)

    returnfile = io.BytesIO()
    finalpdf.write(returnfile)
    return returnfile