import random
from tkinter import *
class Application(Frame):
def __init__(self, master=None):
super().__init__(master)
self.master = master
self.pack()
self.createWidget()
def createWidget(self):
self.canvas=Canvas(self,width=300,height=200,bg="green")
self.canvas.pack()
self.canvas.create_line(0,0,10,10,20,30,50,80)
self.canvas.create_rectangle( 50, 50, 100, 100)
self.canvas.create_oval(50,50,100,100)
Button(self,text="画10个矩形",command=self.rectan).pack(side="left")
def rectan(self):
for i in range(0,10):
x1=random.randrange(int(self.canvas["width"])/2)
y1 = random.randrange(int(self.canvas["height"])/2)
x2=x1+random.randrange(int(self.canvas["width"])/2)
y2=y1+random.randrange(int(self.canvas["height"] )/2)
self.canvas.create_rectangle(x1,y1,x2,y2)
if __name__ == '__main__':
root = Tk()
root.geometry("400x300+200+300")
app=Application(master=root)
root.mainloop()

打开代码能运行,能运行怎么还报错呢,请老师指点一下应该怎么纠正