如何在python中每次更改画布大小时获取画布大小？

import tkinter as tk

def on_canvas_resize(event):
    canvas_width = event.width
    canvas_height = event.height
    print("画布大小：{} x {}".format(canvas_width, canvas_height))

root = tk.Tk()
canvas = tk.Canvas(root, width=400, height=300)
canvas.pack(fill=tk.BOTH, expand=True)

canvas.bind("<Configure>", on_canvas_resize)

root.mainloop()