[Solved] “Stop” Button in Tkinter

Question

You cannot stop each draw statement unless you provide a checker in between each line drawn.

The below code is just a rough mock up of how you could make something to check for a tracking variable used to tell it to no longer draw new lines.

The closest thing you can do to being able to stop drawing is something like this:

import turtle
import tkinter as tk

def start():
    global tracker
    tracker = False
    if tracker == False:
        t.forward(100)
    if tracker == False:
        t.right(90)
    if tracker == False:
        t.forward(100)
    if tracker == False:
        t.left(90)
    if tracker == False:
        t.forward(100)
    if tracker == False:
        t.right(90)
    if tracker == False:
        t.forward(100)
    if tracker == False:
        t.right(90)
    if tracker == False:
        t.forward(100)


def stop():
    global tracker
    tracker = True

def clear():
    canvas.delete("all")

root = tk.Tk()
tracker = False
canvas = tk.Canvas(width = 500, height = 500)
canvas.pack()

t = turtle.RawTurtle(canvas)

tk.Button(text = "Start", command = start).pack(side = tk.LEFT)
tk.Button(text = "Stop", command = stop).pack(side = tk.LEFT)
tk.Button(text = "Clear", command = clear).pack(side = tk.LEFT)

root.mainloop()

This will at least stop drawing after each line but you cannot stop mid line draw.

Just for the fun of it if we add some tracking variables and use some cleaner logic we can start, stop and start again.

Update: From @cdlane’s comment below I have added addition tracking and updated the clear function. This should allow for start stop start without issues and also be able to clear the field.

import turtle
import tkinter as tk

def start(turtle_object, draw_path):
    global tracker, start_ndex, end_ndex, started
    tracker = False
    if started == False:
        started = True
        for i in range(start_ndex, end_ndex):
            if tracker == False and i <= end_ndex:
                pth = draw_path[i]
                if pth[0] == "f":
                    turtle_object.forward(pth[1])
                elif pth[0] == "r":
                    turtle_object.right(pth[1])
                elif pth[0] == "l":
                    turtle_object.left(pth[1])
                start_ndex += 1

def stop():
    global tracker, started
    tracker = True
    started = False

def clear():
    global t, tracker, started, start_ndex
    canvas.delete("all")
    tracker = False
    start_ndex = 0
    started = False
    t = turtle.RawTurtle(canvas)

root = tk.Tk()
tracker = False
start_ndex = 0
started = False # added this tracking variable to prevent issues with spamming the start button.

draw_path = [["f", 100], ["r", 90], ["f", 100], ["l", 90], ["f", 100], ["r", 90], ["f", 100], ["r", 90], ["f", 100]]


end_ndex = len(draw_path)

canvas = tk.Canvas(width = 500, height = 500)
canvas.pack()

t = turtle.RawTurtle(canvas)
tk.Button(text = "Start", command = lambda: start(t, draw_path)).pack(side = tk.LEFT)
tk.Button(text = "Stop", command = stop).pack(side = tk.LEFT)
tk.Button(text = "Clear", command = clear).pack(side = tk.LEFT)
root.mainloop()

Accepted Answer