eyes.py

import time

import cv2
import serial


SERIAL_PORT = '/dev/ttyUSB0'
CLASSIFIER_YML = 'haarcascade_frontalface_default.xml'


def main(graphical=False):
    # Load the cascade
    face_cascade = cv2.CascadeClassifier(CLASSIFIER_YML)

    # To capture video from webcam. 
    cap = cv2.VideoCapture(0)

    if not graphical:
        ser = serial.Serial(SERIAL_PORT)

    while True:
        try:
            t0 = time.monotonic()
            # Read the frame
            _, img = cap.read()
            height, width, _channels = img.shape
            t1 = time.monotonic()

            # Convert to grayscale
            gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

            t2 = time.monotonic()

            # Detect the faces
            faces = face_cascade.detectMultiScale(gray, 1.1, 5)

            t3 = time.monotonic()

            if len(faces) != 0:
                biggest = max(w*h for x,y,w,h in faces)

            # Draw the rectangle around each face
            for i, (x, y, w, h) in enumerate(faces):
                if graphical:
                    cv2.rectangle(img, (x, y), (x+w, y+h), (255, 0, 0), 2)

                center = x + w/2, y + h/2
                center_norm = center[0] / width, center[1] / height
                center_255 = int(center_norm[0] * 180), int(center_norm[1] * 180)
                if w*h == biggest:
                    print(f'{center_255[0]:03d},{center_255[1]:03d}\n')
                
                if not graphical:
                    if w*h == biggest:
                        ser.write(bytes(f'{center_255[0]:03d},{center_255[1]:03d}\n', encoding="utf-8"))

            t4 = time.monotonic()

            # Display
            if graphical:
                cv2.imshow('img', img)
                # Stop if escape key is pressed
                k = cv2.waitKey(30) & 0xff
                if k==27:
                    break

            print(f"{t1-t0:.2f}, {t2-t1:.2f}, {t3-t2:.2f}, {t4-t3:.2f}")

        except Exception as e:
            print("Failed to determine face", e)

    # Cleanup
    cap.release()
    ser.close()

if __name__ == "__main__":
    main(True)