问pygame -实时2倍尺度低分辨率

EN

import pygame
import sys
import random
from Bullet import Bullet

bullets = []

pygame.init()
fps_clock = pygame.time.Clock()

# Our final window layer
window = pygame.display.set_mode((480, 640))

# This is the layer that gets scaled
render_layer = pygame.Surface((240, 320))

red = (255, 0, 0)
white = (255, 255, 255)
dkred =(127, 0, 0) 

counter = 0;

# Sprite resources
bullet_sprite = pygame.image.load("shot1.png")
bullet_sprite2 = pygame.image.load("shot2.png")

while True:
    render_layer.fill(dkred)

    for i in bullets:
        i.tick()
        if i.sprite == "bullet_sprite1":
            render_layer.blit(bullet_sprite, (i.x - 12, i.y -12))
        else:
            render_layer.blit(bullet_sprite2, (i.x - 12, i.y -12))

        pygame.transform.scale2x(render_layer, window)

        if i.x < 0 or i.y < 0 or i.x > 240 or i.y > 320:
            i.dead = True

    bullets = [x for x in bullets if x.dead == False]
    counter += 3.33
    for i in range(10):
        if i % 2 == 0:
            bullets.append(Bullet(120,120,360.0/10*i - counter, 3, -1,
                                  sprite = "bullet_sprite1"))
        else:
            bullets.append(Bullet(120,120,360.0/10*i - counter, 3, -1,
                                  sprite = "bullet_sprite2"))
    for e in pygame.event.get():

        if e.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

        if e.type == pygame.KEYDOWN:
            if e.key == pygame.K_ESCAPE:
                pygame.event.post(pygame.event.Event(pygame.QUIT))

    pygame.display.update()
    fps_clock.tick(60)