Cam for school

cam.py

import cv2
import time
import keyboard
import random
import threading
import pygame

BLOCKSIZE = 4
STOP_VID = False

def pg():
    global STOP_VID

    screen = pygame.display.set_mode((400, 400))
    
    run = True
    while run:
        screen.fill((0, 0, 255))
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False
            elif event.type == pygame.MOUSEBUTTONDOWN:
                if event.button == 1:
                    x, y = pygame.mouse.get_pos()

                    if 0 <= x <= 200 and 0 <= y <= 200:
                        STOP_VID = not STOP_VID

        pygame.draw.rect(screen, (0, 255, 0) if STOP_VID else (255, 0, 0), (0, 0, 200, 200))
        
        pygame.display.update()
        
    pygame.quit()
    

def check_keypress():
    global STOP_VID
    
    while True:
        if keyboard.is_pressed('space'):
            STOP_VID = not STOP_VID
            print("Stopping:", STOP_VID)

        if keyboard.is_pressed('esc'):
            break

def change_resolution(cam, img):
    global BLOCKSIZE
    height, width = img.shape[:2]

    if random.random() >= .7:
        BLOCKSIZE = random.randint(4,5)
    
    for y in range(height // BLOCKSIZE):
        for x in range(width // BLOCKSIZE):
            startY, startX = y * BLOCKSIZE, x * BLOCKSIZE

            colors = []

            for dx in range(BLOCKSIZE):
                for dy in range(BLOCKSIZE):
                    b, g, r = img[startY+dy,startX+dx]
                    colors.append((r, g, b))

            ave_rgb = [0, 0, 0]

            for color in colors:
                ave_rgb[0] += color[0]
                ave_rgb[1] += color[1]
                ave_rgb[2] += color[2]

            ave_rgb[0] //= len(colors)
            ave_rgb[1] //= len(colors)
            ave_rgb[2] //= len(colors)
            
            img[startY:startY+BLOCKSIZE,startX:startX+BLOCKSIZE] = (ave_rgb[2], ave_rgb[1], ave_rgb[0])
            
    return img

def show_webcam(mirror=False):
    global STOP_VID
    cam = cv2.VideoCapture(0)

    _, old_vid = cam.read()
    
    run = True
    while run:
        ret_val, img = cam.read()

        if len(img) == 0 or not ret_val:
            continue
        
        if mirror: 
            img = cv2.flip(img, 1)
       
        img = change_resolution(cam, img) 
        time.sleep(random.randint(1, 10)/17)
        # [n for n in range(10**6)]

        if STOP_VID:
            cv2.imshow('Webcam-0xf3Winx7f', old_vid)
        else:
            cv2.imshow('Webcam-0xf3Winx7f', img)
            old_vid = img
        
        if cv2.waitKey(1) == 27:
            run = False
            break
        
    cv2.destroyAllWindows()


def main():
    t = threading.Thread(target=pg)
    t.start()
    show_webcam(mirror=True)


if __name__ == '__main__':
    main()