# Tk_grainy_rgb_scroll.py

# Tk_grainy_rgb_scroll.py

from tkinter import *
from PIL import Image, ImageTk
import math
import random

ww = 600
hh = 600

def draw():
    image.putdata(rgb)
    photo = ImageTk.PhotoImage(image)
    canvas.create_image(0,0,image=photo,anchor=NW)
    canvas.update()

root = Tk()
root.title("Tk_grainy_rgb_scroll")
root.geometry("%dx%d+0+0"%(ww,hh))

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

image = Image.new("RGB", (ww,hh), (255,255,255))

zzz = [i for i in range(255)]
zzz = zzz[1:-1] + zzz[::-1]
L = len(zzz)

rgb = [(128,128,128)]*(ww*hh)
ref = rgb[:ww*2]

while 1:
    buf = []
    iii = 1
    while len(buf) < ww:
        r = g = b = 0
        for i in [iii-1,iii,iii+1]:
            r += ref[i][0]
            g += ref[i][1]
            b += ref[i][2]
        ttt = []
        for t in (r,g,b):
            t = t//3
            t += random.randint(-t//15,10)
            ttt.append(t)
        buf += [tuple(ttt)]
        iii += 1
    ref = buf * 2
    ref = [ref[-1]] + ref
    rgb.extend(buf[:ww])
    rgb = rgb[-ww*hh:]
    draw()