# Tk_id_ani.py

# Tk_id_ani.py

from Tkinter import *

def animation():
    for v in aliens:
        x1, y1, x2, y2 = canvas.bbox(v)
        if x1 < 0 or x2 > 300:
            vx[v] *= -1
        if y1 < 0 or y2 > 300:
            vy[v] *= -1
        canvas.move(v, vx[v], vy[v])
    canvas.after(10, animation)

root = Tk()
canvas = Canvas(root, width=300, height=300)
canvas.pack()

aliens =    [
            [(40, 80, 240, 280), 'purple', 2, -3],
            [(40, 20, 80, 60), 'orange', 9, 6]
            ]
vx = {}
vy = {}
for alien in range(len(aliens)):
    xy,color,x,y=aliens[alien]
    obj = canvas.create_oval(xy, width=0, fill=color)
    aliens[alien] = obj
    vx[obj] = x
    vy[obj] = y
animation()
root.mainloop()