Listener does not update [closed]

edit

Good afternoon friends

I can get an image of the camera from the gazebo: /camera/image_raw. But if you change the qr code, the listener does not update.

Can anyone help me with this?

#! /usr/bin/python

import rospy
import numpy as np
import cv2
import cv
import zbar

from std_msgs.msg import String
from sensor_msgs.msg import Image
from cv_bridge import CvBridge

bridge = CvBridge()

def callback(msg):
    cv2_img = bridge.imgmsg_to_cv2(msg, "bgr8")
    scanner = zbar.ImageScanner()
    scanner.parse_config('enable')

    while not rospy.is_shutdown():
        gray = cv2.cvtColor(cv2_img, cv2.COLOR_BGR2GRAY, dstCn=0)

        frame = np.array(gray)
        width, height = frame.shape[1], frame.shape[0]

        raw = frame.tostring()

        image = zbar.Image(width, height, 'Y800', raw)
        scanner.scan(image)

        qrc = None

        for symbol in image:
            qrc = symbol.data

        if qrc != None:
            qr_str = qrc
            rospy.loginfo(qr_str)

def qr_main():
    rospy.init_node('qr_listener')

    rospy.Subscriber("/camera/image_raw", Image, callback)

    rospy.spin()

if __name__ == '__main__':
    qr_main()