# tk_full_gradient_cycle.py

# tk_full_gradient_cycle2.py

from PIL import Image, ImageTk
import tkinter as tk

WW, HH = 640, 640
WWo, HHo = WW // 8, HH // 8

o255 = [i for i in range(256)]
o255 = o255[1:-1] + o255[::-1]
L = len(o255)

root = tk.Tk()
canvas = tk.Canvas(root, width=WW, height=HH)
root.geometry("%dx%d+10+10" % (WW, HH))
canvas.pack()

img = Image.new("RGB", (WWo, HHo))
pixels = img.load()

grid_colors = {
    (0, 0): (255, 255, 255),  # White
    (0, 1): (255, 255, 0),    # Yellow
    (0, 2): (0, 255, 0),      # Green
    (1, 0): (255, 165, 0),    # Orange
    (1, 1): (128, 128, 128),  # Gray (midpoint)
    (1, 2): (0, 0, 255),      # Blue
    (2, 0): (255, 0, 0),      # Red
    (2, 1): (128, 0, 128),    # Purple
    (2, 2): (0, 0, 0)         # Black
}

def interpolate_color(color1, color2, factor):
    return tuple(int(color1[i] + (color2[i] - color1[i]) * factor) for i in range(3))

for j in range(HHo):
    for i in range(WWo):
        x = i / (WWo - 1) * 2
        y = j / (HHo - 1) * 2
        x0, y0 = int(x), int(y)
        x1, y1 = min(x0 + 1, 2), min(y0 + 1, 2)
        fx, fy = x - x0, y - y0

        color_top = interpolate_color(grid_colors[(x0, y0)], grid_colors[(x1, y0)], fx)
        color_bottom = interpolate_color(grid_colors[(x0, y1)], grid_colors[(x1, y1)], fx)
        color = interpolate_color(color_top, color_bottom, fy)

        pixels[i, j] = color

def update_pixels(v):
    return o255[v]

rgb = img.split()
img = img.resize((WW, HH), Image.ANTIALIAS)
gradient_photo = ImageTk.PhotoImage(img)
canvas.create_image(0, 0, anchor=tk.NW, image=gradient_photo)
canvas.update()

while 1:
    for n in range(L):
        rgb1 = [p.point(lambda v: update_pixels(v - n)) for p in rgb]
        img1 = Image.merge("RGB", rgb1)

        img1 = img1.resize((WW, HH), Image.ANTIALIAS)

        gradient_photo.paste(img1)
        canvas.update()