Python初学者使用变量更改Tkinter画布项目

import tkinter as tk

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

shape = None

def draw_shape():
    global shape
    if shape:
        canvas.delete(shape)  # 删除之前的图形
    x = 100  # 图形的x坐标
    y = 100  # 图形的y坐标
    width = 200  # 图形的宽度
    height = 200  # 图形的高度
    shape = canvas.create_rectangle(x, y, x + width, y + height, fill="blue")  # 绘制矩形图形

button = tk.Button(root, text="绘制图形", command=draw_shape)
button.pack()

root.mainloop()