Simple QR code generator in Python for Casper

By Pfed-prog | BlockChain Tech | 28 Nov 2021

As part of the Gitcoin bounty for Casper hackathon we developed web application in python Flask that generates QR code. We hosted the application at on AWS Elastic Beanstalk with GitHub pipeline.

The GitHub repository for the project.

The overview of the project

The app generates QR codes for transactions on Casper local nodes, and accounting for the user’s inputs. After displaying the QR Code the user can use the button to download the image for transactions on Testnet.


import base64
from flask import Flask, render_template, request, send_from_directory
from PIL import Image
from io import BytesIO

import qrcode
from qrcode.image.styledpil import StyledPilImage
from qrcode.image.styles.moduledrawers import RoundedModuleDrawer
from qrcode.image.styles.colormasks import SquareGradiantColorMask

application = Flask(__name__)
app = application

def return_image(image):
    data = BytesIO(), "PNG")
    encoded_img_data = base64.b64encode(data.getvalue())
    return encoded_img_data

def generate_image(address:str='', amount=0, message:str='', transaction:str='', network:str='casper'):

    QRcode = qrcode.QRCode(
        error_correction=qrcode.constants.ERROR_CORRECT_H, box_size=8, version=1,

    # taking url or text
    if network =='casper':
        url = f"{network}:{address}?amount={amount}&message={message}&transfer_id={transaction}"
        url = f"{network}?recipient={address}&amount={amount}&transfer_id={transaction}"
    # addingg URL or text to QRcode

    # generating QR code

    # get the logo and resize it
    Logo_link = './static/logo3.png'
    # taking base width
    basewidth = 100
    logo =
    # adjust image size
    wpercent = (basewidth/float(logo.size[0]))
    hsize = int((float(logo.size[1])*float(wpercent)))
    logo = logo.resize((basewidth, hsize), Image.ANTIALIAS)

    # adding color to QR code
    QRimg = QRcode.make_image(

    # position the logo
    pos = ((QRimg.size[0] - logo.size[0]) // 2,
            (QRimg.size[1] - logo.size[1]) // 2)
    QRimg.paste(logo,pos)# put QRimg.paste(logo,pos,log) to make the logo fully transparent

    # set size of QR code
    return QRimg.resize((400, 400), Image.ANTIALIAS)

@app.route("/", methods=["GET","POST"])
def home():
    if request.method == "POST":
        data = [x for x in request.form.values()]
        image = generate_image(data[0], data[1], data[2], data[3], data[4])

        image = generate_image()'./static/output.png')
    img_data = return_image(image)
    return render_template("home.html", img_data = img_data.decode('utf-8'), mth=request.method)

@app.route("/img", methods=["GET"])
def send():
    return send_from_directory(directory='./static/',path='output.png',as_attachment=True)

if __name__ == "__main__":

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