Tkinter窗口无法打开

Question

I was trying to create a simple moving block using tkinter in Python 3, and everything was working until I imported time. The window now won't open. I've tried removing the import, and it doesn't help. This is my code:

from tkinter import *
import time

canvas_height = 400
canvas_width = 600
canvas_colour = "grey50"
moveBoolean = "True"

def move():
    global moveBoolean
    while moveBoolean == "True":
        time.sleep(0.005)
        canvas.move(square, 90, 90)
        time.sleep(0.005)
        canvas.move(square, 180, 180)
        time.sleep(0.005)
        canvas.move(square, 50, 100)

window = Tk()

canvas = Canvas(bg=canvas_colour, height=canvas_height, width=canvas_width, highlightthickness=0)
canvas.pack()

square = canvas.create_rectangle(50, 50, 50, 50, width=50, fill="black")

move()

window.mainloop()

Answer 1

These problems are generally solved with the use of classes, which you should learn and use before coding GUIs IMHO. You should not use time() as it can interrupt the infinite Tkinter loop. Use Tkinter's after() instead. Also, you never set moveBoolean to False, so the while statement runs until the program is cancelled, and the second time through the square will be off the canvas, which is why you don't get anything visible. The following solves your problems but again would be better if a class structure were used.

from tkinter import *
from functools import partial

canvas_height = 400
canvas_width = 600
canvas_colour = "grey50"
moveBoolean = "True"

def move_it(ctr=0):
    if ctr < len(coords):
        x, y = coords[ctr]
        ctr += 1
        print ctr, x, y
        canvas.move(square, x, y)
        window.after(1000, partial(move_it, ctr))

window = Tk()

canvas = Canvas(bg=canvas_colour, height=canvas_height,
         width=canvas_width, highlightthickness=0)
canvas.pack()

square = canvas.create_rectangle(50, 50, 50, 50, width=50, fill="black")

coords = ((90, 90),
          (180, 180),
          (50, 50))
move_it()

window.mainloop()