Scan QR codes from your screen and store them in a file

screenQR.py

import cv2
from pyzbar.pyzbar import decode
import pyautogui
import numpy as np
import time


SLEEP = 5
QR_FILE_PATH = 'qr_codes.txt'


if __name__ == '__main__':
    
    qr_codes = set() # set storing scanned qr codes
    with open(QR_FILE_PATH, 'r') as file:
        line = file.readline()
        qr_codes.add(line)

    print(f'Detecting QR codes at an interval of {SLEEP} seconds..\nPress ctrl+C to exit.\n')

    with open(QR_FILE_PATH, 'a') as file:

        while True:
            
            # Take a screenshot
            screenshot = pyautogui.screenshot()
            # Convert the screenshot to an OpenCV compatible format 
            img_np = np.array(screenshot)
            frame = cv2.cvtColor(img_np, cv2.COLOR_BGR2RGB)
            # Convert frame to grayscale
            gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

            # Decode QR codes in the frame
            qr_codes_detected = decode(gray)
            # Loop over all detected QR codes
            for qr_code in qr_codes_detected:
                # Extract the QR code's data
                data = qr_code.data.decode("utf-8")
                if data not in qr_codes:
                    qr_codes.add(data)
                    file.write('\n')
                    file.write(data)
                    
            time.sleep(SLEEP)

Additional requirements:
pyzbar: pip install pyzbar
pyautogui: pip install PyAutoGUI

Just create a file qr_codes.txt and run this code: python screenQR.py in the background. This will scan unique QR codes that appear on your screen and write them to a file. You can re-run this code when you want to resume. I used this to collect QR codes for a treasure hunt prize in wandb's fully-connected-conference.