如何抓取tkinter窗口截图并保存到文件中？

from PIL import ImageGrab
from tkinter import Tk

def capture_screenshot(window, filename):
    # 隐藏窗口，避免截到窗口边框和标题栏
    window.withdraw()
    
    # 获取屏幕的大小
    screen_width = window.winfo_screenwidth()
    screen_height = window.winfo_screenheight()

    # 使用ImageGrab模块的grab函数来抓取屏幕区域
    image = ImageGrab.grab((0, 0, screen_width, screen_height))

    # 保存截图到文件
    image.save(filename)

    # 恢复窗口显示
    window.deiconify()

if __name__ == "__main__":
    root = Tk()
    # 创建并显示窗口
    # ...

    # 调用截图函数
    capture_screenshot(root, "screenshot.png")