退出PyQt5应用程序后如何打破循环？

问：

import os
import sys
import pandas as pd
import cv2
import datetime
from pyzbar.pyzbar import decode
from PyQt5 import QtCore
from PyQt5.QtCore import pyqtSlot
from PyQt5.QtGui import QImage, QPixmap
from PyQt5.uic import loadUi
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QDialog, QApplication, QLabel

class QR_Scan_Window(QDialog):
    def __init__(self):
        super(QR_Scan_Window, self).__init__()
        ui_path = os.path.dirname(os.path.abspath(__file__))
        loadUi(os.path.join(ui_path, "QR_Scan_Window.ui"), self)

    def display_image(self):
        self.cap = cv2.VideoCapture(0)
        self.qr_data = 0
        self.qr_type = 0

        while((self.cap.isOpened()) and (widget.currentIndex() == 0)):
            ret, frame = self.cap.read()

            # Decode QR codes from the frame
            self.decoded_objects = decode(frame)

            if(ret == True):
                self.display_frame(frame)
                # Loop through the detected QR codes
                for obj in self.decoded_objects:
                    self.qr_data = obj.data.decode('utf-8')
                    self.qr_type = obj.type

                    # Print the QR code data and type
                    print(f'Type: {self.qr_type}, Data: {self.qr_data}')
                # Jika QR Code telah terbaca, keluar loop
                if self.qr_type == "QRCODE":
                    break
                cv2.waitKey()
            else:
                print("return not found")

        if self.qr_type == "QRCODE":
            #self.goto_Camera_Window()
            pass

    def display_frame(self, img):
        qformat = QImage.Format_Indexed8

        if(len(img.shape) == 3):
            if(img.shape[2] == 4):
                qformat = QImage.Format_RGBA888
            else:
                qformat = QImage.Format_RGB888
        
        img = QImage(img, img.shape[1], img.shape[0], qformat)
        img = img.rgbSwapped()
        self.imgLabel.setPixmap(QPixmap.fromImage(img))
        self.imgLabel.setAlignment(QtCore.Qt.AlignHCenter | QtCore.Qt.AlignVCenter)

    # This function will be called when the window is closed
    def closeEvent(self, event):
        self.cap.release()
        cv2.destroyAllWindows()
        event.accept()  # Accept the close event

app = QApplication(sys.argv)

widget = QtWidgets.QStackedWidget()

qr_scan_window = QR_Scan_Window()

widget.addWidget(qr_scan_window)

widget.setFixedHeight(320)
widget.setFixedWidth(480)

widget.show()

qr_scan_window.display_image()

try:
    sys.exit(app.exec_())
except:
    print("Exiting")
    cv2.destroyAllWindows()

我想退出应用程序/窗口并断开函数中的循环，但不起作用。当我使用此代码并退出时，碰巧我的相机仍然打开并且循环函数仍在运行。帮我修复此代码:(display_imagecloseEventdisplay_image