How to print every x seconds while rest of code runs without being stopped?-CodePudding

I've seen ways of using the time.sleep() function, however that stops the rest of the code from running.

I'm making a hand recognition script and want the video output to be hindered by a certain value being printed every second.

This is my code:

import cv2
from cvzone.HandTrackingModule import HandDetector
import time

cap = cv2.VideoCapture(0)
detector = HandDetector(maxHands=1, detectionCon=0.7)
length = 0
while True:
    success, img = cap.read()
    hands, img = detector.findHands(img)

    if hands:
        hand1 = hands[0]
        lmlist1 = hand1["lmList"]
        bbox = hand1["bbox"]
        cp1 = hand1["center"]
        HandType = hand1["type"]
        #fingers1 = detector.fingersUp(hand1)
        #print(fingers1)
        length, info, img = detector.findDistance(lmlist1[8], lmlist1[5], img)
        
    
    print(length)
    time.sleep(1)
        
    
    cv2.imshow("Image", img)
    cv2.waitKey(1) 
    if cv2.waitKey(1) == ord("q"):
        break
    

cap.release()
cv2.destroyAllWindows()

The problem is that because of:

print(length) 
time.sleep(1)

the frame rate of the video is reduced to 1fps.

Is there a way to run the printing command so that it doesn't affect the frame rate?

Thanks.

CodePudding user response：

One way is to use time.time to measure how much time has passed (will print 'hi' every 5 seconds or so, this is less precise because if some part of the loop takes more time, it may print later than expected):

import time


start = time.time()
while True:
    # run some code

    current_time = time.time()
    if current_time - start >= 5:
        print('hi')
        start = current_time

Or use threading module to run a loop concurrently (will print 'hi' every 5 seconds, this is also more precise, because the time measurement is not affected by the speed of the "main" loop (as is the case with the above code)):

import time
import threading


def loop():
    while True:
        time.sleep(5)
        print('hi')


threading.Thread(target=loop).start()

while True:
    # run some code
    pass  # this can be removed after you add the actual code