Centering window python tkinter

Question

Ive recently started using tkinter in python, and I was having trouble centering the window. I tried all the tips on this website, but whenever I try them, the window is like a line in the middle of the screen. I have widgets already on it, and it works fine without the centering, but I would really appreciate it if someone could help me solve my problem. This is what I have been trying so far.

root = Tk()
root.title("Password")
root.resizable(FALSE,FALSE)

mainframe = ttk.Frame(root, padding="3 3 12 12")
mainframe.grid(column=0, row=0, sticky=(N, W, E, S))
mainframe.columnconfigure(0, weight=1)
mainframe.rowconfigure(0, weight=1)

w = mainframe.winfo_width()
h = mainframe.winfo_height()
ws = root.winfo_screenwidth()
hs = root.winfo_screenheight()
x = (ws/2) - (w/2)
y = (hs/2) - (h/2)
root.geometry('%dx%d+%d+%d' % (w, h, x, y))

Answer 1

Ok I have found and fixed the problem. Piggybacking off of OregonTrail's solution, i found that if the window is the right size and you just want to change the location, then you can easily instead of setting the root's size, you can just move the window to the center.

w = root.winfo_reqwidth()
h = root.winfo_reqheight()
ws = root.winfo_screenwidth()
hs = root.winfo_screenheight()
x = (ws/2) - (w/2)
y = (hs/2) - (h/2)
root.geometry('+%d+%d' % (x, y)) ## this part allows you to only change the location

I think that this answer isn't exactly in the center, probably off by a little since h was returning 200 when it should be less, but it looks to be at the center and works fine.

Answer 2

You need to use winfo_reqwidth() and winfo_reqheight(), because the window does not have a height or width at the time that you call winfo_height() and winfo_width().

An example program:

from tkinter import Tk
from tkinter import ttk

root = Tk()

style = ttk.Style()
style.configure("BW.TLabel", foreground="black", background="white")

l1 = ttk.Label(text="This is the best label in the world", style="BW.TLabel")
l1.pack()

w = l1.winfo_reqwidth()
h = l1.winfo_reqheight()
ws = root.winfo_screenwidth()
hs = root.winfo_screenheight()
x = (ws/2) - (w/2)
y = (hs/2) - (h/2)
print(w, h, x, y)
root.geometry('%dx%d+%d+%d' % (w, h, x, y))

root.mainloop()