def update_food(settings, stats, screen, snake_head, snake_parts, foods):
# 生成食物
while len(foods) < settings.food_limit and not check_bonus_food(foods):
food = Food(screen, settings)
food.random_pos(snake_head, snake_parts, foods)
# 变大？
if len(foods) == settings.food_limit - 1 and not check_big_food(foods):
if randint(1, settings.big_food_chance) == 1:
food.become_big(snake_head, snake_parts, foods)
foods.add(food)
# 产生bonus？
if check_bonus(settings, food, foods):
stats.bonus = True
# 加载大食物的countdown
for food in foods:
if food.style == 'big':
food.update_countdown()
if food.existing_time > 9:
foods.remove(food)
break
