Pygame点击J键加分时旧分数残留无法覆盖如何解决？

问题核心原因 #

• 你在J键的触发逻辑中，调用完score_increase()绘制了最新分数后，额外执行了一行screen.blit(surface, (0, 0))，此处的surface是代码最开始初始化时渲染的初始0分文本，相当于刚画完新分数又被旧分数覆盖，导致看起来旧文本残留。
• 事件判断逻辑层级错误，QUIT退出事件和ESC按键的判断被写在了KEYDOWN事件的分支内，导致关闭窗口、按ESC退出的功能失效。
• 重复创建字体对象没有必要，字体只需要全局初始化一次即可，不需要每次加分、渲染文本都重新创建。

修正方案 #

首先删掉J键触发逻辑里多余的screen.blit(surface, (0, 0))行，再调整事件判断的层级，优化重复创建字体的逻辑即可。

修正后完整代码 #

import pygame, sys, random
from pygame.locals import *

pygame.init()

pygame.display.set_caption("waht da dog doin")

screen = pygame.display.set_mode((800, 600))
bg_color = (35, 140, 120)
text_color = (130, 46, 75)
# 全局提前创建字体，不用重复生成
score_font = pygame.font.SysFont("Comic Sans", 50, True, False)
troll_font = pygame.font.SysFont("Comic Sans", 30, True, True)
tip_font = pygame.font.SysFont("Comic Sans", 50, True, False)

screen.fill(bg_color)

dog = pygame.image.load("resources/dog.jpg").convert()

score = 0

# 初始分数渲染
surface = score_font.render(str(score), True, text_color)
screen.blit(surface, (0, 0))

troll = ["corned", "balled", "chimkened", "torkelled", "kanaquined", "khazaqed", "bo burnam'd", "talal'd", "chammaked", "australiad", "lotto pie'd", "tetrised", "caca'd", "scrutinized", "bulbasaured"]
troll_item = random.choice(troll)

dog_y = random.randint(0, 400)
dog_x = random.randint(0, 500)

text_y = random.randint(0, 400)
text_x = random.randint(0, 500)

def score_increase():
    global score
    score += 1    
    surface = score_font.render(str(score), True, text_color)
    pygame.draw.rect(screen, bg_color, (0, 0, 100, 75)) # 加宽覆盖区域，避免分数到两位数后覆盖不全
    screen.blit(surface, (0, 0)) 
    
def print_trolled():
    screen.fill(bg_color)
    screen.blit(dog, (dog_x, dog_y))   
    surface_text = troll_font.render("u have been" + " " + troll_item, True, text_color)
    screen.blit(surface_text, (text_x, text_y))  

def start_print():   
    surface = tip_font.render("press 'j' plsz", True, text_color)
    screen.blit(surface, (250, 250))

start_print()

while True:
    for event in pygame.event.get():
        # 退出事件判断放到最外层，不要嵌套在KEYDOWN里
        if event.type == QUIT:
            sys.exit()
        if event.type == KEYDOWN:
            if event.key == K_j:
                print_trolled() 
                score_increase()
                # 删掉多余的旧surface绘制逻辑
                dog_y = random.randint(0, 400)
                dog_x = random.randint(0, 500)
                text_y = random.randint(0, 400)
                text_x = random.randint(0, 500)
                troll_item = random.choice(troll)
            if event.key == K_ESCAPE:
                sys.exit()
    pygame.display.update()

额外优化说明 #

• 覆盖分数的矩形宽度从50调整到100，避免分数到两位数之后，文本宽度超过覆盖范围，还是出现残留
• 把重复用到的颜色、字体都提前提取成全局变量，减少冗余代码，运行效率更高
• 修正了sys.exit后面漏加括号的问题，原来的写法不会触发退出

内容的提问来源于stack exchange，提问作者Annsh