# Tk_fizzle.py

import Tkinter as tk
import random

def create_bubbles(canvas):
	bubbles = []
	for __ in range(30):
		x = random.randint(0, 400)
		y = random.randint(0, 400)
		r = random.randint(5, 30)
		bubble = canvas.create_oval(x-r, y-r, x+r, y+r)
		bubbles.append( [bubble, r] )
	return bubbles


def moves_bubbles(canvas, bubbles):
	for bubble, r in bubbles:
		x1, y1, x2, y2 = canvas.coords(bubble)
		sz = 15-int(r/2)
		y1 -= 1+sz
		y2 -= 1+sz
		if y2 <= 0:
			y1 = 300
			y2 = y1 + 2*r

		# set position
		canvas.coords(bubble, x1, y1, x2, y2)

	root.after(40, moves_bubbles, canvas, bubbles)

# --- main ---

root = tk.Tk()

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

bubbles = create_bubbles(canvas)

# run after 40ms - it gives 25FPS
root.after(40, moves_bubbles, canvas, bubbles)

root.mainloop()