Automatically Moving Shape? Python 3.5 Tkinter

Question

In python, I am currently making a 'game' using tkinter, but it has decided not to work. What I am trying to do is have one rectangle movable by the mouse, and the other rectangle that moves up and down continuously without the player doing anything. Here is my code:

from tkinter import *
import time
root = Tk()
root.title("Game")
root.geometry("800x800")

def motion():
    canvas.delete(ALL)
    a = canvas.create_rectangle(event.x-50, event.y-50, event.x+50, event.y+50, fill='red')

def motion2():
    b = canvas.create_rectangle(10, 100, 100, 10, fill='blue')
    y = -15
    x = 0
    time.sleep(0.025)
    canvas.move(b, x, -y)
    canvas.update()

canvas = Canvas(root, width=1000, height=5000, bg='white')
canvas.bind("", motion)
canvas.pack(pady=0)

mainloop()

I hope this can be resolved soon. I've been working on this for the past few days, still no answer. Thanks for your time :) -Jake

furas · Accepted Answer

You can use root.after(milliseconds, function_name) to run function periodically and it can use canvas.move(object_id, offset_x, offset_y) to move object automatically.

And you can use canvas.coords(object_id, x1, y1, x2, y2) to set new position using mouse position. bind exeecutes function with one argument (object event) so function has to receive this argument.

import tkinter as tk

# --- functions ---

def move_a(event):
    canvas.coords(a, event.x-50, event.y-50, event.x+50, event.y+50)

def move_b():
    canvas.move(b, 1, 0)
    # move again after 25ms (0.025s)
    root.after(25, move_b)

# --- main ---

# init
root = tk.Tk()

# create canvas
canvas = tk.Canvas(root)
canvas.pack()

# create objects
a = canvas.create_rectangle(0, 0, 100, 100, fill='red')
b = canvas.create_rectangle(0, 0, 100, 100, fill='blue')

# start moving `a` with mouse
canvas.bind("", move_a)

# start moving `b` automatically
move_b()

# start program
root.mainloop()

EDIT: to move up and down you have to use variable with speed so you can change it from speed to -speed and againt to speed. And you can also use move_down = True/False to check current direction (or you can use speed to check direction but b_move_down can be more readable for people)

import tkinter as tk

# --- functions ---

def move_a(event):
    canvas.coords(a, event.x-50, event.y-50, event.x+50, event.y+50)

def move_b():
    # inform function to use external/global variable 
    # because we use `=` to change its value
    global b_speed
    global b_move_down

    canvas.move(b, 0, b_speed)

    # get current position        
    x1, y1, x2, y2 = canvas.coords(b)

    # check if you have to change direction
    #if b_speed > 0:
    if b_move_down:
        # if it reachs bottom
        if y2 > 300:
            # change direction
            #b_move_down = False
            b_move_down = not b_move_down
            b_speed = -b_speed
    else:
        # if it reachs top
        if y1 < 0:
            # change direction
            #b_move_down = True
            b_move_down = not b_move_down
            b_speed = -b_speed

    # move again after 25 ms (0.025s)
    root.after(25, move_b)

# --- main ---

# init
root = tk.Tk()

# create canvas
canvas = tk.Canvas(root, width=500, height=300)
canvas.pack()

# create objects
a = canvas.create_rectangle(0, 0, 100, 100, fill='red')
b = canvas.create_rectangle(0, 0, 100, 100, fill='blue')
# create global variables
b_move_down = True
b_speed = 5

# start moving `a` with mouse
canvas.bind("", move_a)

# start moving `b` automatically
move_b()

# start program
root.mainloop()

EDIT: move around the canvas

import tkinter as tk

# --- functions ---

def move_a(event):
    canvas.coords(a, event.x-50, event.y-50, event.x+50, event.y+50)

def move_b():
    # inform function to use external/global variable 
    # because we use `=` to change its value
    global b_speed_x
    global b_speed_y
    global b_direction

    canvas.move(b, b_speed_x, b_speed_y)

    # get current position        
    x1, y1, x2, y2 = canvas.coords(b)

    if b_direction == 'down':
        if y2 >= 300:
            b_direction = 'right'
            b_speed_x = 5
            b_speed_y = 0
    elif b_direction == 'up':
        if y1 <= 0:
            b_direction = 'left'
            b_speed_x = -5
            b_speed_y = 0
    elif b_direction == 'right':
        if x2 >= 500:
            b_direction = 'up'
            b_speed_x = 0
            b_speed_y = -5
    elif b_direction == 'left':
        if x1 <= 0:
            b_direction = 'down'
            b_speed_x = 0
            b_speed_y = 5

    # move again after 25 ms (0.025s)
    root.after(25, move_b)

# --- main ---

# init
root = tk.Tk()

# create canvas
canvas = tk.Canvas(root, width=500, height=300)
canvas.pack()

# create objects
a = canvas.create_rectangle(0, 0, 100, 100, fill='red')
b = canvas.create_rectangle(0, 0, 100, 100, fill='blue')
# create global variables
b_direction = 'down'
b_speed_x = 0
b_speed_y = 5

# start moving `a` with mouse
canvas.bind("", move_a)

# start moving `b` automatically
move_b()

# start program
root.mainloop()

EDIT: last example - key p pauses game

#!/usr/bin/env python3

import tkinter as tk

# --- constants --- (UPPER_CASE names)

DISPLAY_WIDHT = 800
DISPLAY_HEIGHT = 600

# --- classes --- (CamelCase names)

#class Player():
#    pass

#class BlueEnemy():
#    pass

# --- functions --- (lower_case names)

def move_a(event):
    # don't move if gama paused
    if not game_paused:
        canvas.coords(a, event.x-50, event.y-50, event.x+50, event.y+50)

def move_b():
    # inform function to use external/global variable
    # because we use `=` to change its value
    global b_speed_x
    global b_speed_y
    global b_direction

    # don't move if gama paused
    if not game_paused:
        canvas.move(b, b_speed_x, b_speed_y)

        # get current position
        x1, y1, x2, y2 = canvas.coords(b)

        if b_direction == 'down':
            if y2 >= DISPLAY_HEIGHT:
                b_direction = 'right'
                b_speed_x = 5
                b_speed_y = 0
        elif b_direction == 'up':
            if y1 <= 0:
                b_direction = 'left'
                b_speed_x = -5
                b_speed_y = 0
        elif b_direction == 'right':
            if x2 >= DISPLAY_WIDHT:
                b_direction = 'up'
                b_speed_x = 0
                b_speed_y = -5
        elif b_direction == 'left':
            if x1 <= 0:
                b_direction = 'down'
                b_speed_x = 0
                b_speed_y = 5

    # move again after 25 ms (0.025s)
    root.after(25, move_b)

def pause(event):
    global game_paused

    # change True/False
    game_paused = not game_paused

    if game_paused:
        # center text on canvas
        canvas.coords(text_pause, DISPLAY_WIDHT//2, DISPLAY_HEIGHT//2)
    else:
        # move text somewhere outside canvas
        canvas.coords(text_pause, -1000, -1000)

# --- main --- (lower_case names)

# init
root = tk.Tk()

# key `p` pause game
game_paused = False
root.bind('p', pause)

# create canvas
canvas = tk.Canvas(root, width=DISPLAY_WIDHT, height=DISPLAY_HEIGHT)
canvas.pack()

# create objects
a = canvas.create_rectangle(0, 0, 100, 100, fill='red')
b = canvas.create_rectangle(0, 0, 100, 100, fill='blue')
# create global variables
b_direction = 'down'
b_speed_x = 0
b_speed_y = 5

# start moving `a` with mouse
canvas.bind("", move_a)

# start moving `b` automatically
move_b()

# create text somewhere outside canvas - so it will be "invisible"
text_pause = canvas.create_text(-1000, -1000, text="PAUSED", font=(50,))

# start program
root.mainloop()

Automatically Moving Shape? Python 3.5 Tkinter

Answers (1)

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