Tkinter toplevel loop

Question

I have this script where I want to choose image from directory using Tkinter and then choose pixel on it but looks like tkinter.mainloop() never ends. Please help

import tkinter.filedialog
from PIL import Image, ImageTk


def callback(event):
    print("Starting pixel of object is: ", event.x, event.y)
    global ps
    ps[0] = event.x
    ps[1] = event.y
    return event.x, event.y


tkinter.Tk().withdraw()
image = tkinter.filedialog.askopenfilename()
ps = [0, 0]
window = tkinter.Toplevel()
img = Image.open(image)
canvas = tkinter.Canvas(window, width=img.size[0], height=img.size[1])
canvas.pack()
image_tk = ImageTk.PhotoImage(img)
canvas.create_image(img.size[0] // 2, img.size[1] // 2, image=image_tk)
canvas.bind("<Button-1>", callback)
tkinter.mainloop()
print(ps)

Answer 1

Use deiconify() to show back Tk() window and use it instead of Toplevel()

BTW: callback doesn't have to return value because there is nobody to receive this value.

import tkinter.filedialog
from PIL import Image, ImageTk

# --- functions ---

def callback(event):
    global ps # at the beginning to make it more readable

    print("Starting pixel of object is: ", event.x, event.y)
    ps[0] = event.x
    ps[1] = event.y

# --- main ---

ps = [0, 0]

root = tkinter.Tk()
root.withdraw()

image = tkinter.filedialog.askopenfilename()

img = Image.open(image)
image_tk = ImageTk.PhotoImage(img)

root.deiconify() # <-- show `root` again

canvas = tkinter.Canvas(root, width=img.size[0], height=img.size[1])
canvas.pack()
canvas.create_image(img.size[0] // 2, img.size[1] // 2, image=image_tk)
canvas.bind("<Button-1>", callback)

tkinter.mainloop()

print(ps)

BTW: you can use Label to display it

import tkinter
import tkinter.filedialog
from PIL import Image, ImageTk

def callback(event):
    global ps

    print("Starting pixel of object is: ", event.x, event.y)
    ps[0] = event.x
    ps[1] = event.y

    label['text'] = str(ps)

# --- main ---

ps = [0, 0]

root = tkinter.Tk()
root.withdraw()

image = tkinter.filedialog.askopenfilename()

img = Image.open(image)
image_tk = ImageTk.PhotoImage(img)

root.deiconify()

canvas = tkinter.Canvas(root, width=img.size[0], height=img.size[1])
canvas.pack()
canvas.create_image(img.size[0] // 2, img.size[1] // 2, image=image_tk)
canvas.bind("<Button-1>", callback)

label = tkinter.Label(root)
label.pack()

tkinter.mainloop()

print(ps)