I have a python 3.7 and OpenCV 3 programming running on windows 10 and raspberry pi. The program has three threads. The first thread is a main loop, the second thread is a camera, and the third thread is writing videos and images. I searched many references and put together what I think is a way to catch the correct "stop" keyboard signals. I tested on win10 and RPI using the threading packages and it appears to work. I am wondering if there is a more approriate way to handle keyboard input? I had to put the keyboard handler in main as I wasn't able to catch it in the wile loop. The following example doesn't show threading but in my larger program it worked also.
import signal
import cv2
class main():
def __init__(self):
self.stop_by_signal = False
return
def signal_term_handler(self,signal, frame):
self.stop_by_signal = True
return
def run(self):
signal.signal(signal.SIGTERM, self.signal_term_handler)
self.cap = cv2.VideoCapture(0)
print("starting")
while True:
# read cameras and display
ret, frame = self.cap.read()
if not ret: break
cv2.imshow('frame',frame)
# look for kill, ctl-c or cv2.waitkey to stop
if self.stop_by_signal == True:
print("main: stopping loop via kill")
break
key = cv2.waitKey(1) & 0xFF
if key == ord('q') or key == 27:
print("main: cv2 esc or q entered to stop")
break
elif key != 255:
print('key: %s' % [chr(key)])
self.cap.release()
cv2.destroyAllWindows()
if __name__ == '__main__':
try:
main = main()
main.run()
except KeyboardInterrupt:
main.cap.release()
print("__main:__ ctl-c entered to stop.")
