reporting-engine/report_qweb_pdf_watermark/models/report.py

# -*- coding: utf-8 -*-
# © 2016 Therp BV <http://therp.nl>
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
from base64 import b64decode
from logging import getLogger
from pyPdf import PdfFileWriter, PdfFileReader
from pyPdf.utils import PdfReadError
from PIL import Image
from StringIO import StringIO
from odoo import api, models, tools
from PIL import PdfImagePlugin # flake8: noqa

# PdfImagePlugin must be loaded in order to work PNG to PDF transformation
# This issue is related to Pillow creation, as can be seen in its source code:
# https://github.com/python-pillow/Pillow/blob/master/PIL/PdfImagePlugin.py

logger = getLogger(__name__)


class Report(models.Model):
    _inherit = 'report'

    @api.model
    def get_pdf(self, docids, report_name, html=None, data=None):
        result = super(Report, self).get_pdf(
            docids, report_name, html=html, data=data)
        report = self._get_report_from_name(report_name)
        watermark = None
        if report.pdf_watermark:
            watermark = b64decode(report.pdf_watermark)
        else:
            watermark = tools.safe_eval(
                report.pdf_watermark_expression or 'None',
                dict(env=self.env, docs=self.env[report.model].browse(docids)),
            )
            if watermark:
                watermark = b64decode(watermark)

        if not watermark:
            return result

        pdf = PdfFileWriter()
        pdf_watermark = None
        try:
            pdf_watermark = PdfFileReader(StringIO(watermark))
        except PdfReadError:
            # let's see if we can convert this with pillow
            try:
                Image.init()
                image = Image.open(StringIO(watermark))
                pdf_buffer = StringIO()
                if image.mode != 'RGB':
                    image = image.convert('RGB')
                resolution = image.info.get(
                    'dpi', report.paperformat_id.dpi or 90
                )
                if isinstance(resolution, tuple):
                    resolution = resolution[0]
                image.save(pdf_buffer, 'pdf', resolution=resolution)
                pdf_watermark = PdfFileReader(pdf_buffer)
            except:
                logger.exception('Failed to load watermark')

        if not pdf_watermark:
            logger.error(
                'No usable watermark found, got %s...', watermark[:100]
            )
            return result

        if pdf_watermark.numPages < 1:
            logger.error('Your watermark pdf does not contain any pages')
            return result
        if pdf_watermark.numPages > 1:
            logger.debug('Your watermark pdf contains more than one page, '
                         'all but the first one will be ignored')

        for page in PdfFileReader(StringIO(result)).pages:
            watermark_page = pdf.addBlankPage(
                page.mediaBox.getWidth(), page.mediaBox.getHeight()
            )
            watermark_page.mergePage(pdf_watermark.getPage(0))
            watermark_page.mergePage(page)

        pdf_content = StringIO()
        pdf.write(pdf_content)

        return pdf_content.getvalue()