reporting-engine/report_qweb_pdf_watermark/models/report.py

# © 2016 Therp BV <http://therp.nl>
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
from base64 import b64decode
from io import BytesIO
from logging import getLogger

from PIL import Image

from flectra import api, fields, models
from flectra.tools.safe_eval import safe_eval

try:
    # we need this to be sure PIL has loaded PDF support
    from PIL import PdfImagePlugin  # noqa: F401
except ImportError:
    pass

logger = getLogger(__name__)

try:
    from PyPDF2 import PdfFileReader, PdfFileWriter  # pylint: disable=W0404
    from PyPDF2.utils import PdfReadError  # pylint: disable=W0404
except ImportError:
    logger.debug("Can not import PyPDF2")


class Report(models.Model):
    _inherit = "ir.actions.report"

    pdf_watermark = fields.Binary("Watermark")
    pdf_watermark_expression = fields.Char(
        "Watermark expression",
        help="An expression yielding the base64 "
        "encoded data to be used as watermark. \n"
        "You have access to variables `env` and `docs`",
    )

    def _render_qweb_pdf(self, res_ids=None, data=None):
        if not self.env.context.get("res_ids"):
            return super(Report, self.with_context(res_ids=res_ids))._render_qweb_pdf(
                res_ids=res_ids, data=data
            )
        return super(Report, self)._render_qweb_pdf(res_ids=res_ids, data=data)

    @api.model
    def _run_wkhtmltopdf(
        self,
        bodies,
        header=None,
        footer=None,
        landscape=False,
        specific_paperformat_args=None,
        set_viewport_size=False,
    ):
        result = super(Report, self)._run_wkhtmltopdf(
            bodies,
            header=header,
            footer=footer,
            landscape=landscape,
            specific_paperformat_args=specific_paperformat_args,
            set_viewport_size=set_viewport_size,
        )

        docids = self.env.context.get("res_ids", False)
        watermark = None
        if self.pdf_watermark:
            watermark = b64decode(self.pdf_watermark)
        elif docids:
            watermark = safe_eval(
                self.pdf_watermark_expression or "None",
                dict(env=self.env, docs=self.env[self.model].browse(docids)),
            )
            if watermark:
                watermark = b64decode(watermark)

        if not watermark:
            return result

        pdf = PdfFileWriter()
        pdf_watermark = None
        try:
            pdf_watermark = PdfFileReader(BytesIO(watermark))
        except PdfReadError:
            # let's see if we can convert this with pillow
            try:
                Image.init()
                image = Image.open(BytesIO(watermark))
                pdf_buffer = BytesIO()
                if image.mode != "RGB":
                    image = image.convert("RGB")
                resolution = image.info.get("dpi", self.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 Exception as e:
                logger.exception("Failed to load watermark", e)

        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(BytesIO(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 = BytesIO()
        pdf.write(pdf_content)

        return pdf_content.getvalue()