python - tkinter.TclError: invalid command name ".!canvas"

Question

I'm pretty new to python and to programming in general. I'm trying to make the game Bounce. The game runs as expected but as soon as I close the window, it shows an error. This is the code:

from tkinter import *
import random
import time

# Creating the window:
window = Tk()
window.title("Bounce")
window.geometry('600x600')
window.resizable(False, False)

# Creating the canvas containing the game:
canvas = Canvas(window, width = 450, height = 450, bg = "black")
canvas.pack(padx = 50, pady= 50)
score = canvas.create_text(10, 20, fill = "white")

window.update()   


# Creating the ball:
class Ball:
    def __init__(self, canvas1, paddle1, color):
        self.canvas = canvas1
        self.paddle = paddle1
        self.id = canvas1.create_oval(10, 10, 25, 25, fill = color)  # The starting point of the ball
        self.canvas.move(self.id, 190, 160)
        starting_direction = [-3, -2, -1, 0, 1, 2, 3]
        random.shuffle(starting_direction)
        self.x = starting_direction[0]
        self.y = -3
        self.canvas_height = self.canvas.winfo_height()
        self.canvas_width = self.canvas.winfo_width()

    # Detecting the collision between the ball and the paddle:
    def hit_paddle(self, ballcoords):
        paddle_pos = self.canvas.coords(self.paddle.id)
        if ballcoords[0] <= paddle_pos[2] and ballcoords[2] >= paddle_pos[0]:
            if paddle_pos[3] >= ballcoords[3] >= paddle_pos[1]:
                return True
        return False

    # Detecting the collision between the the ball and the canvas sides:
    def draw(self):
        self.canvas.move(self.id, self.x, self.y)
        ballcoords = self.canvas.coords(self.id)
        if ballcoords[1] <= 0:
            self.y = 3
        if ballcoords[3] >= self.canvas_height:
            self.y = 0
            self.x = 0
            self.canvas.create_text(225, 150, text = "Game Over!", font = ("Arial", 16), fill = "white")
        if ballcoords[0] <= 0:
            self.x = 3
        if ballcoords[2] >= self.canvas_width:
            self.x = -3
        if self.hit_paddle(ballcoords):
            self.y = -3


class Paddle:
    def __init__(self, canvas1, color):
        self.canvas1 = canvas
        self.id = canvas.create_rectangle(0, 0, 100, 10, fill = color)
        self.canvas1.move(self.id, 180, 350)
        self.x = 0
        self.y = 0
        self.canvas1_width = canvas1.winfo_width()
        self.canvas1.bind_all("<Left>", self.left)
        self.canvas1.bind_all("<Right>", self.right)

    def draw(self):
        self.canvas1.move(self.id, self.x, 0)
        paddlecoords = self.canvas1.coords(self.id)
        if paddlecoords[0] <= 0:
            self.x = 0
        if paddlecoords[2] >= self.canvas1_width:
            self.x = 0

    def right(self, event):
        self.x = 3

    def left(self, event):
        self.x = -3


paddle = Paddle(canvas, color = "white")
ball = Ball(canvas, paddle, color = "red")

while True:
    ball.draw()
    paddle.draw()
    window.update_idletasks()
    window.update()
    time.sleep(0.001)
   

This is the error:

 Traceback (most recent call last):
  File "D:CSCI201Arcade Games ProjectBounceBounce_Game.py", line 111, in <module>
    ball.draw()
  File "D:CSCI201Arcade Games ProjectBounceBounce_Game.py", line 64, in draw
    self.canvas.move(self.id, self.x, self.y)
  File "C:UsersM.YoussryAppDataLocalProgramsPythonPython39libkinter\__init__.py", line 2916, in move
    self.tk.call((self._w, 'move') + args)
_tkinter.TclError: invalid command name ".!canvas"

I've tried inserting .mainloop() as suggested to another user having the same problem but it hasn't worked for me.

question from:https://stackoverflow.com/questions/65643645/tkinter-tclerror-invalid-command-name-canvas

Answer 1

It is caused by close button on top-right corner of window, the only way you have to stop script. After you click close button, window destried, so no widget, like canvas, exist.

You can set a flag to identify if while loop should stop and exit in handler of window close button event.

window.protocol("WM_DELETE_WINDOW", handler)

Here, you can exit script any time by click close button of window.

from tkinter import *
import random
import time

# Creating the window:
window = Tk()
window.title("Bounce")
window.geometry('600x600')
window.resizable(False, False)

# Creating the canvas containing the game:
canvas = Canvas(window, width = 450, height = 450, bg = "black")
canvas.pack(padx = 50, pady= 50)
score = canvas.create_text(10, 20, fill = "white")

window.update()


# Creating the ball:
class Ball:
    def __init__(self, canvas1, paddle1, color):
        self.canvas = canvas1
        self.paddle = paddle1
        self.id = canvas1.create_oval(10, 10, 25, 25, fill = color)  # The starting point of the ball
        self.canvas.move(self.id, 190, 160)
        starting_direction = [-3, -2, -1, 0, 1, 2, 3]
        random.shuffle(starting_direction)
        self.x = starting_direction[0]
        self.y = -3
        self.canvas_height = self.canvas.winfo_height()
        self.canvas_width = self.canvas.winfo_width()

    # Detecting the collision between the ball and the paddle:
    def hit_paddle(self, ballcoords):
        paddle_pos = self.canvas.coords(self.paddle.id)
        if ballcoords[0] <= paddle_pos[2] and ballcoords[2] >= paddle_pos[0]:
            if paddle_pos[3] >= ballcoords[3] >= paddle_pos[1]:
                return True
        return False

    # Detecting the collision between the the ball and the canvas sides:
    def draw(self):
        self.canvas.move(self.id, self.x, self.y)
        ballcoords = self.canvas.coords(self.id)
        if ballcoords[1] <= 0:
            self.y = 3
        if ballcoords[3] >= self.canvas_height:
            self.y = 0
            self.x = 0
            self.canvas.create_text(225, 150, text = "Game Over!", font = ("Arial", 16), fill = "white")
        if ballcoords[0] <= 0:
            self.x = 3
        if ballcoords[2] >= self.canvas_width:
            self.x = -3
        if self.hit_paddle(ballcoords):
            self.y = -3


class Paddle:
    def __init__(self, canvas1, color):
        self.canvas1 = canvas
        self.id = canvas.create_rectangle(0, 0, 100, 10, fill = color)
        self.canvas1.move(self.id, 180, 350)
        self.x = 0
        self.y = 0
        self.canvas1_width = canvas1.winfo_width()
        self.canvas1.bind_all("<Left>", self.left)
        self.canvas1.bind_all("<Right>", self.right)

    def draw(self):
        self.canvas1.move(self.id, self.x, 0)
        paddlecoords = self.canvas1.coords(self.id)
        if paddlecoords[0] <= 0:
            self.x = 0
        if paddlecoords[2] >= self.canvas1_width:
            self.x = 0

    def right(self, event):
        self.x = 3

    def left(self, event):
        self.x = -3


paddle = Paddle(canvas, color = "white")
ball = Ball(canvas, paddle, color = "red")

# New code after here
def handler():
    global run
    run = False

window.protocol("WM_DELETE_WINDOW", handler)
run = True

while run:
    # New code before here
    ball.draw()
    paddle.draw()
    window.update_idletasks()
    window.update()
    time.sleep(0.01)

window.destroy()    # should always destroy window before exit