import cv2
from picamera2 import Picamera2

ESC = 27

face_cascade = cv2.CascadeClassifier('haarcascades/haarcascade_frontalface_alt2.xml')

picam2 = Picamera2()
config = picam2.create_preview_configuration(main={'size': (640, 480), 'format': 'RGB888'})
picam2.configure(config)
picam2.start()

while True:
    frame = picam2.capture_array()
    frame = cv2.flip(frame, -1)
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    faces = face_cascade.detectMultiScale(gray, scaleFactor = 1.1, minNeighbors = 5, minSize = (30, 30))
    print('人臉數: ', len(faces))

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

    cv2.imshow('preview', frame)

    if cv2.waitKey(1) == ESC:
        break

picam2.stop()
cv2.destroyAllWindows()