dither

'''
dither.py: test program to simulate color dithering algorithms.
'''

from Tkinter import *
import random as r

# Number of squares in x and y dimensions.
nx = 40
ny = 40

# Size of square side in pixels.
ss = 10

# Total dimensions of display.
dx = nx * ss
dy = ny * ss

# Colors (hi, lo)
red   = ('ff', 'ee')
green = ('ff', 'ee')
blue  = ('ff', 'ee')

# Dithering pattern.
dp = [0, 0, 0, 1]

root = Tk()
root.geometry("%sx%s" % (dx, dy))
c = Canvas(root, width=800, height=600)
c.pack()

def make_color():
    '''Make a color.  Red, green and blue components vary independently.'''
    color_red   = red[r.choice(dp)]
    color_green = green[r.choice(dp)]
    color_blue  = blue[r.choice(dp)]
    return '#' + color_red + color_green + color_blue

def make_color2():
    '''Make a color.  Red, green and blue components vary together.'''
    select = r.choice(dp)
    color_red   = red[select]
    color_green = green[select]
    color_blue  = blue[select]
    return '#' + color_red + color_green + color_blue

def make_square(x, y, color):
    return c.create_rectangle(x * ss, y * ss, (x+1) * ss, (y+1) * ss,
                              fill=color, outline=color)

def make_squares():
    squares = []
    for x in range(nx):
        squares.append([])
        for y in range(ny):
            squares[x].append(make_square(x, y, make_color()))
    return squares

squares = make_squares()

def change_colors(squares):
    '''Change each square color independent of other squares.'''
    for x in range(len(squares)):
        for y in range(len(squares[x])):
            h = squares[x][y]
            color = make_color()
            c.itemconfig(h, fill=color, outline=color)

def change_colors2(squares):
    '''Change the color of all squares simultaneously.'''
    color = make_color()
    for x in range(len(squares)):
        for y in range(len(squares[x])):
            h = squares[x][y]
            c.itemconfig(h, fill=color, outline=color)

done = False
def quit_handler(event):
    global done
    done = True

# Left mouse button click on canvas terminates the program.
root.bind('<Button-1>', quit_handler)

while not done:
    change_colors(squares)
    root.update()