# tk_radial_gradient.py

# tk_radial_gradient.py

from tkinter import *
import time

ww = 600
hh = 600

root = Tk()
root.title('tk_radial_gradient')
root.geometry(f'{ww}x{hh}+0+0')

canvas = Canvas(root, width=ww, height=hh, bg='black')
canvas.pack()

x = ww//2
y = hh//2
gradient = 0
radius = 255 + 1
while gradient < 256:
    color = f"#00{gradient:02x}00"
    canvas.create_oval(x - radius, y - radius, x + radius, y + radius, fill=color, outline="")
    gradient += 1
    radius -= 1

canvas.update()