ReportLab PDF Python 3 problems with fonts

Question

I want to generate PDF reports in different languages. I've followed different guides that are using TTFont. I've tried in different languages but no one is working.

For example, for Russian, I use:

self.buffer = BytesIO()
self.pdf_data = []

pdfmetrics.registerFont(TTFont('DejaVuSerif', self.font_dir + 'dejavuserif/DejaVuSerif.ttf'))
font_name = "DejaVuSerif"

self.styles = getSampleStyleSheet()
self.styles.add(ParagraphStyle(name = "HeaderTitle", parent = self.styles['Title'], alignment = TA_CENTER, fontName=font_name))


doc = SimpleDocTemplate(self.buffer)
self.pdf_data.append(Paragraph('Операции - Отчет Август 2020 г.', self.styles['HeaderTitle']))

doc.build(self.pdf_data)
pdf = self.buffer.getvalue()
self.buffer.close()

But the output is:

€•‚ƒ„…†† - €‡ˆ‚‡ „‰Š‹Œ‡ 2020 Š.

What I'm doing wrong?

ReportLab version = 3.5.50

UPDATE

I want to point that in locale the file is correct, but when I attach in a response, the problem persists.

return flask.send_from_directory(file_path, filename, mimetype="application/pdf", as_attachment=True, attachment_filename=filename, cache_timeout=0)

Answer 1

The part of the code you show looks good. In the variable 'pdf' you get back the bytes of the PDF.

One can return the bytes with a flask response like this:

@app.route('/')
def gen_pdf():
    pdf_util = PDFUtil()
    pdf_bytes = pdf_util.generate()
    response = make_response(pdf_bytes)
    response.headers.set('Content-Type', 'application/pdf')
    return response

Please note that the Content-Type header needs to be set to: application/pdf. If you want the browser to download the PDF file instead of displaying it inline, you can add an additional header, e.g:

response.headers.set('Content-Disposition', 'attachment', filename='test.pdf')

So if the font is fine and you these bytes are returned with content-type application/pdf the correct result will be displayed in a browser.

I have only slightly modified your code, saved it in a python script named pdf_flask_demo.py to get a self-contained example with flask response part:

from io import BytesIO

from reportlab.lib.enums import TA_CENTER
from reportlab.lib.styles import ParagraphStyle, getSampleStyleSheet
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.platypus import SimpleDocTemplate, Paragraph
from flask import Flask, make_response

app = Flask(__name__)


@app.route('/')
def gen_pdf():
    pdf_util = PDFUtil()
    pdf_bytes = pdf_util.generate()
    response = make_response(pdf_bytes)
    response.headers.set('Content-Type', 'application/pdf')
    return response


class PDFUtil:
    def __init__(self):
        self.font_dir = "./"

    def generate(self):
        self.buffer = BytesIO()
        self.pdf_data = []

        pdfmetrics.registerFont(TTFont('DejaVuSerif', self.font_dir + 'dejavuserif/DejaVuSerif.ttf'))
        font_name = "DejaVuSerif"

        self.styles = getSampleStyleSheet()
        self.styles.add(
            ParagraphStyle(name="HeaderTitle", parent=self.styles['Title'], alignment=TA_CENTER, fontName=font_name))

        doc = SimpleDocTemplate(self.buffer)
        self.pdf_data.append(Paragraph('Операции - Отчет Август 2020 г.', self.styles['HeaderTitle']))

        doc.build(self.pdf_data)
        pdf = self.buffer.getvalue()
        self.buffer.close()
        return pdf

Alternative

One can also save the PDF file in the local file system and return it flask.send_from_directory. The downloaded PDF on the users browser can then also be displayed correctly when opened in a PDF viewer.

@app.route('/')
def gen_pdf():
    pdf_util = PDFUtil()
    pdf_bytes = pdf_util.generate()
    f = open('/Users/stephan/tmp/mytest.pdf', 'wb')
    f.write(pdf_bytes)
    f.close()
    return flask.send_from_directory('/Users/stephan/tmp/', 'mytest.pdf', mimetype="application/pdf", as_attachment=True,
                                     attachment_filename='mytest.pdf', cache_timeout=0)

Test

On command line I call:

export FLASK_APP=pdf_flask_demo
export FLASK_ENV=development 
flask run

And when using http://127.0.0.1:5000 in the browser I get the desired result: