Python Pygame Lines Screensaver Effect

Python Pygame script to create lines screensaver effect.

import pygame
import sys
from random import randint

# ? 2019 TheFlyingKeyboard and released under MIT License
# theflyingkeyboard.net

screenXSize = 1920
screenYSize = 1080

backgroundColor = (0, 0, 0)

pygame.init()
screen = pygame.display.set_mode((screenXSize, screenYSize))
screen.fill(backgroundColor)

clock = pygame.time.Clock()

fps = 3

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                pygame.quit()
                sys.exit()
            if event.key == pygame.K_r:
                screen.fill(backgroundColor)
            if event.key == pygame.K_q:
                fps += 1
            if event.key == pygame.K_a:
                fps -= 1
                if fps == 0:
                    fps = 1

    pygame.display.set_caption("Lines " + str(fps) + "fps")

    pygame.draw.line(screen, (randint(0, 255), randint(0, 255), randint(0, 255)),
                       (randint(0, screenXSize), randint(0, screenYSize)),
                       (randint(0, screenXSize), randint(0, screenYSize)), 7)

    pygame.display.update()

    msElapsed = clock.tick(fps)