如何在 Python OpenCV 中使用 cv2.waitKey(1)

Question

I am doing some OpenCV python code and I have below code at the end:

if cv2.waitKey(1) & 0xFF == ord('q'):
    break

So whenever I press q , the code breaks which is working fine. But below code is not working:

if cv2.waitKey(1) & 0xFF == ord('q'):
    break
if cv2.waitKey(1) & 0xFF == ord('a'):
    print('a')

In above code, only q is working but if I press a , it is not printing a . Why is this not working. Can anyone please suggest me what is wrong here. Thanks

CODE:

cam = cv2.VideoCapture(0)
while True:
    ret_val, image = cam.read()

    cv2.imshow('my webcam', image)

    if cv2.waitKey(1) & 0xFF == ord('a'):  
        print("a")
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cv2.destroyAllWindows()

Answer 1

waitKey returns the ASCII value of key that's pressed while ord converts a character into its ASCII value. So something like this will work

key = cv2.waitKey(1)
if key == ord('q') :
 break
elif key == ord('a'):
 print('a')