Why do I get this error: "error: video system not initialized"?

Question

The error occurs when I call

keys_pressed = pygame.key.get_pressed()

Here is the full code:

import pygame

pygame.font.init()

pygame.init()

WIDTH, HEIGHT = 900,500

WIN = pygame.display.set_mode((WIDTH, HEIGHT))

pygame.display.set_caption('BattleGrounds!!!')

WHITE = (255,255,255)

BLACK=(0,0,0)

BLUE=(0,0,255)

WINNER_FONT=pygame.font.SysFont('comicsans',100)

RED=(255,0,0)

YELLOW=(255,255,0)

GREEN=(0,255,0)

FPS=60
YELLOW_HIT=pygame.USEREVENT+1

RED_HIT=pygame.USEREVENT+2

VEL=5

MAX_BULLETs = 3

RDM=(100,60,20)

BULLET_VEL=10

HEALTH_FONT = pygame.font.SysFont('comicsans',20)

BORDER=pygame.Rect(WIDTH//2-5,0,10,HEIGHT)

GUN_WIDTH,GUN_HEIGHT= 50,40

YELLOW_GUN_IMAGE=pygame.image.load('gun1.png')

YELLOW_GUN =pygame.transform.rotate(pygame.transform.scale(YELLOW_GUN_IMAGE,(100,60)),0)

RED_GUN_IMAGE=pygame.image.load('gun.png')

RED_GUN=pygame.transform.rotate(pygame.transform.scale(RED_GUN_IMAGE,(100,60)),0)

BG = pygame.image.load('download.jpg')

BG1=pygame.transform.scale(BG,(WIDTH,HEIGHT))

def draw_window(red,yellow,red_bullets,yellow_bullets,red_health,yellow_health):
    WIN.fill(WHITE)
    WIN.blit(BG1, (0,0))

    red_health_text=HEALTH_FONT.render('Health:'+str(red_health),1,RED)
    yellow_health_text = HEALTH_FONT.render('Health:' + str(yellow_health), 1, YELLOW)
    WIN.blit(red_health_text,(725,0))
    WIN.blit(yellow_health_text,(0,0))
    WIN.blit(YELLOW_GUN,(yellow.x,yellow.y))
    WIN.blit(RED_GUN,(red.x,red.y))
    for bullet in red_bullets:
        pygame.draw.rect(WIN,RED,bullet)
    for bullet in yellow_bullets:
        pygame.draw.rect(WIN,GREEN,bullet)
    pygame.display.update()

def draw_winner(text):
    draw_text=WINNER_FONT.render(text,1,BLUE)
    WIN.blit(draw_text,(WIDTH//2-draw_text.get_width()//2,HEIGHT//2-draw_text.get_height()//2))
    pygame.display.update()
    pygame.time.delay(5000)
def yellow_movement(keys_pressed,yellow):
    if keys_pressed[pygame.K_a] and yellow.x - VEL > 0:
        yellow.x -= VEL
    if keys_pressed[pygame.K_d] and yellow.x + VEL < BORDER.x-95:
        yellow.x += VEL
    if keys_pressed[pygame.K_w] and yellow.y - VEL > 0:
        yellow.y -= VEL
    if keys_pressed[pygame.K_s] and yellow.y + VEL < HEIGHT-45:
        yellow.y += VEL

def red_movement(keys_pressed,red):
    if keys_pressed[pygame.K_LEFT] and red.x -VEL > 450:
        red.x -= VEL
    if keys_pressed[pygame.K_RIGHT] and red.x + VEL <800:
        red.x += VEL
    if keys_pressed[pygame.K_UP] and red.y - VEL > 0:
        red.y -= VEL
    if keys_pressed[pygame.K_DOWN] and red.y - VEL < HEIGHT-58:
        red.y += VEL

def handle_bullets(yellow_bullets,red_bullets,yellow, red):
    for bullet in yellow_bullets:
        bullet.x+=BULLET_VEL
        if red.colliderect(bullet):
            pygame.event.post(pygame.event.Event(RED_HIT))
            yellow_bullets.remove(bullet)
        elif bullet.x > WIDTH:
            yellow_bullets.remove(bullet)
    for bullet in red_bullets:
        bullet.x-=BULLET_VEL
        if yellow.colliderect(bullet):
            pygame.event.post(pygame.event.Event(YELLOW_HIT))
            red_bullets.remove(bullet)
        elif bullet.x<0:
            red_bullets.remove(bullet)



red = pygame.Rect(700, 300,GUN_WIDTH,GUN_HEIGHT)
yellow = pygame.Rect(100, 300, GUN_WIDTH, GUN_HEIGHT)
red_bullets = []
yellow_bullets=[]
red_health=5
yellow_health=5
clock=pygame.time.Clock()
run=True
while run:
    clock.tick(FPS)
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            run=False
            pygame.quit()
            if event.type==pygame.KEYDOWN:
                if event.key==pygame.K_LCTRL and len(yellow_bullets)<MAX_BULLETs:
                    bullet=pygame.Rect(yellow.x+yellow.width,yellow.y+yellow.height//2-2,10,5)
                    yellow_bullets.append(bullet)

                if event.key==pygame.K_RCTRL and len(red_bullets)< MAX_BULLETs:
                    bullet=pygame.Rect(red.x,red.y+red.height//2-2,10,5)
                    red_bullets.append(bullet)
            if event.type==RED_HIT:
                red_health-=1

            if event.type==YELLOW_HIT:
                yellow_health-=1
        winner_text=""
        if red_health<=0:
            winner_text='YELLOW WINS'

        if yellow_health<=0:
            winner_text='RED WINS'

        if winner_text!="":
            draw_winner(winner_text)
            break


        keys_pressed = pygame.key.get_pressed()
        yellow_movement(keys_pressed,yellow)
        red_movement(keys_pressed,red)
        handle_bullets(yellow_bullets,red_bullets,yellow , red)
        draw_window(red,yellow,red_bullets,yellow_bullets,red_health,yellow_health)

Answer 1

Let me first point out that the block introduced by if event.type==pygame.KEYDOWN: here:

            pygame.quit()
            if event.type==pygame.KEYDOWN:

will never be processed because it is directly under if event.type==pygame.QUIT:, and an event can't be pygame.QUIT and pygame.KEYDOWN at the same time.

---

You're shy on details: you don't say when the error occurs. I suppose it's when you quit the game.

When you call pygame.quit(), the engine will uninitialize all of the modules. Then, further down, you try to access one of those deleted modules (pygame.key.get_pressed()). Hence, the first call to pygame.* crashes your game.

Here is something that should help you get a bit further:

1. When you detect that you need to quit, then make sure that no code is executed before the end of the loop.
2. Make sure the indentation is correct: an event can't be two things at the same time.
3. Don't draw your game at every event, draw it once per frame.

Here is a new version of your game loop:

while run:
    clock.tick(FPS)
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            run=False
            break
        if event.type==pygame.KEYDOWN:
            if event.key==pygame.K_LCTRL and len(yellow_bullets)<MAX_BULLETs:
                bullet=pygame.Rect(yellow.x+yellow.width,yellow.y+yellow.height//2-2,10,5)
                yellow_bullets.append(bullet)

            if event.key==pygame.K_RCTRL and len(red_bullets)< MAX_BULLETs:
                bullet=pygame.Rect(red.x,red.y+red.height//2-2,10,5)
                red_bullets.append(bullet)
        if event.type==RED_HIT:
            red_health-=1

        if event.type==YELLOW_HIT:
            yellow_health-=1
        
        winner_text=""
        
        if red_health<=0:
            winner_text='YELLOW WINS'

        if yellow_health<=0:
            winner_text='RED WINS'

        if winner_text!="":
            draw_winner(winner_text)
            break


    keys_pressed = pygame.key.get_pressed()
    yellow_movement(keys_pressed,yellow)
    red_movement(keys_pressed,red)
    handle_bullets(yellow_bullets,red_bullets,yellow , red)
    draw_window(red,yellow,red_bullets,yellow_bullets,red_health,yellow_health)
        
pygame.quit()