乌龟图形-背景图像在设置世界后如何在中心进行协调？

import turtle

wn = turtle.Screen()
wn.setup(width=800, height=600)  # 设置世界的宽度和高度

wn.bgpic("background.png")  # 背景图像的文件名

bg_width = wn.bgpic().width()  # 获取背景图像的宽度
bg_height = wn.bgpic().height()  # 获取背景图像的高度

bg_x = -bg_width / 2  # 背景图像在世界中心的x坐标
bg_y = -bg_height / 2  # 背景图像在世界中心的y坐标

turtle.penup()  # 抬起画笔，不绘制图形
turtle.goto(bg_x, bg_y)  # 将乌龟图形移动到背景图像的中心

import turtle

wn = turtle.Screen()
wn.setup(width=800, height=600)
wn.bgpic("background.png")

bg_width = wn.bgpic().width()
bg_height = wn.bgpic().height()

bg_x = -bg_width / 2
bg_y = -bg_height / 2

turtle.penup()
turtle.goto(bg_x, bg_y)