Python tkinter从画布上擦除线条/形状，而不擦除背景图像

import tkinter as tk

root = tk.Tk()
canvas = tk.Canvas(root, width=400, height=300)
canvas.pack()

line = canvas.create_line(50, 50, 200, 200)  # 绘制一条直线
rectangle = canvas.create_rectangle(100, 100, 300, 200)  # 绘制一个矩形

canvas.delete(line)  # 删除线条
canvas.delete(rectangle)  # 删除矩形

import tkinter as tk

def erase_shape():
    canvas.delete(line)
    canvas.delete(rectangle)

root = tk.Tk()
canvas = tk.Canvas(root, width=400, height=300)
canvas.pack()

line = canvas.create_line(50, 50, 200, 200)
rectangle = canvas.create_rectangle(100, 100, 300, 200)

button = tk.Button(root, text="擦除形状", command=erase_shape)
button.pack()

root.mainloop()