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 openerp import api, models, tools
logger = getLogger(__name__)


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

    @api.v7
    def get_pdf(
        self, cr, uid, ids, report_name, html=None, data=None, context=None
    ):
        # pylint: disable=R8110
        # this override cannot be done in v8 api
        result = super(Report, self).get_pdf(
            cr, uid, ids, report_name, html=html, data=data,
            context=context
        )
        report = self._get_report_from_name(cr, uid, report_name)
        watermark = None
        if report.pdf_watermark:
            watermark = b64decode(report.pdf_watermark)
        else:
            env = api.Environment(cr, uid, context)
            watermark = tools.safe_eval(
                report.pdf_watermark_expression or 'None',
                dict(env=env, docs=env[report.model].browse(ids)),
            )
            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 = 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()