彈跳球游戲的python代碼，不知道出了什么問題

Question

使用tkinter的彈跳球游戲。 當我運行它時，球會移動，但是應該由左右箭頭控制的桿不會移動。 我不知道這是怎么回事。 請幫助。

from tkinter import *
import random
import time

tk = Tk()
tk.title("Game")
tk.resizable(0, 0)
tk.wm_attributes("-topmost", 1)
canvas = Canvas(tk, width=500, height=400, bd=0, highlightthickness=0)
canvas.pack()
tk.update()

class Ball:
    def __init__(self, canvas, paddle, color):
        self.canvas = canvas
        self.paddle = paddle
        self.id = canvas.create_oval(10, 10, 25, 25, fill=color)
        self.canvas.move(self.id, 245, 100)
        starts = [-3, -2, -1, 1, 2, 3]
        random.shuffle(starts)
        self.x = starts[0]
        self.y = -3
        self.canvas_height = self.canvas.winfo_height()
        self.canvas_width = self.canvas.winfo_width()
        self.hit_bottom = False

    def draw(self):
        self.canvas.move(self.id, self.x, self.y)
        pos = self.canvas.coords(self.id)
        if pos[1] <= 0:
            self.y = 3
        if self.hit_paddle(pos) == True:
            self.y = -3
        if pos[3] >= self.canvas_height:
            self.hit_bottom = True
        if pos[0] <= 0:
            self.x = 3
        if pos[2] >= self.canvas_width:
            self.x = -3

    def hit_paddle(self, pos):
        paddle_pos = self.canvas.coords(self.paddle.id)
        if pos[2] >= paddle_pos[0] and pos[0] <= paddle_pos[2]:
            if pos[3] >= paddle_pos[1] and pos[3] <= paddle_pos[3]:
                return True
        return False

class Paddle:
    def __init__(self, canvas, color):
        self.canvas = canvas
        self.id = canvas.create_rectangle(0, 0, 100, 10, fill=color)
        self.canvas.move(self.id, 200, 300)
        self.x = 0
        self.canvas_width = self.canvas.winfo_width()
        self.canvas.bind_all('<Left>', self.turn_left)
        self.canvas.bind_all('<Right>', self.turn_right)

    def turn_left(self, evt):
        self.x = -2

    def turn_right(self, evt):
        self.x = 2

    def draw(self):
        self.canvas.move(self.id, self.x, 0)
        pos = self.canvas.coords(self.id)
        if pos[0] <= 0:
            self.x = 0
        elif pos[2] >= self.canvas_width:
            self.x = 0

paddle = Paddle(canvas, 'blue')
ball = Ball(canvas, paddle, 'red')

while 1:
    if ball.hit_bottom == False:
        ball.draw()
        paddle.draw()
    tk.update_idletasks()
    tk.update()
    time.sleep(0.01)

這是我運行代碼后在python shell中顯示的內容：

Traceback (most recent call last):
  File "/Users/linziyi/Downloads/PythonForKidsCode/chapter14/bounce9.py", line 79, in <module>
    tk.update_idletasks()
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/tkinter/__init__.py", line 1019, in update_idletasks
    self.tk.call('update', 'idletasks')
_tkinter.TclError: can't invoke "update" command:  application has been destroyed

Answer 1

Tkinter在無限循環中不能很好地工作，因為它有自己的無限mainloop 。 您要執行的操作是使用after方法，該方法會在一段時間后調用一個函數。 嘗試用以下代碼替換while循環：

def update_game():
    if ball.hit_bottom == False:
        ball.draw()
        paddle.draw()
    tk.update_idletasks()
    tk.after(10, update_game)

tk.after(10, update_game)
tk.mainloop()

這將每10毫秒update_game一次update_game ，而不會阻塞Tkinter的mainloop 。