# Tk_follow_slowdown.py

# Tk_follow_slowdown.py

from tkinter import *
from math import sin
import random

ww = 400
hh = 400

root=Tk()
root.geometry("%dx%d+-10+0"%(ww,hh))
canvas = Canvas(root,width=ww,height=hh,bg='yellow')
canvas.grid(row=0,column=0,sticky=N+S+E+W)
root.update()

def rgb2hex(r,g,b):
    return '#%02X%02X%02X'%(r,g,b)

def circle(x, y, r=25):
    canvas.create_oval((x-r, y-r, x+r, y+r), fill=color, tags=('dot'), width=0)

X = ww/2
Y = hh/2
xm = X
ym = Y

delay = 1000
r = 30

def mouse_move(event):
    global xm, ym
    xm, ym = event.x, event.y

root.bind('<Motion>', mouse_move)

i = 0

while 1:
    canvas.delete('dot')
    X += (xm-X)/delay
    Y += (ym-Y)/delay
    color = rgb2hex(0,121,184)
    circle(X, Y, r+sin(i)*5)
    color = 'white'
    circle(X, Y, 15+sin(i-1)*7)
    i += 0.01
    root.update()

root.mainloop()