เขียนโปรแกรมเตือนให้พักสายตาด้วย Python

import cv2
import time
import easygui

face_cascade = cv2.CascadeClassifier('data/haarcascades/haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('data/haarcascades/haarcascade_eye_tree_eyeglasses.xml')

cap = cv2.VideoCapture(0)

last_time = time.time()
elapse = 0

while True:
    if elapse <= 20*60:
        ret, img = cap.read()
        gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
        faces = face_cascade.detectMultiScale(gray, 1.3, 5)

        for (x,y,w,h) in faces:
            cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)

            roi_gray = gray[y:y+h, x:x+w]
            roi_color = img[y:y+h, x:x+w]
            eyes = eye_cascade.detectMultiScale(roi_gray)
            for (ex,ey,ew,eh) in eyes:
                cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(0,255,0),2)
                if (ex,ey,ew,eh) != None:
                    elapse = time.time() - last_time
    else :
        print('Rest your eye!')
        easygui.msgbox('Rest your eye!', 'Eye love you.')
        time.sleep(30)
        elapse = 0
        last_time = time.time()