sonice.py

#!/usr/bin/env python2
"""Display a rainbow color gradiant"""
from __future__ import print_function
from collections import namedtuple

__activity_ctx = 0.0
Color = namedtuple("Color", ["red", "green", "blue"])

def rainbow(seed=0, frequency=0.01):
    """Return a color"""
    from math import sin, fmod, pi
    qsin = lambda x: int((sin(x) * 127) + 128)
    tau = 2.0 * pi

    p0 = 0
    p1 = (2.0 / 3.0) * pi
    p2 = (4.0 / 3.0) * pi


    phase = fmod(seed, tau)
    dphase = tau * frequency

    red = qsin(phase + p0)
    green = qsin(phase + p1)
    blue = qsin(phase + p2)

    phase = fmod(phase + dphase, tau)

    return Color(red, green, blue), phase


def rainbow_line(seed=0, width=80):
    """Draw a rainbow line"""
    line = ""
    for _ in xrange(width):
        color, seed = rainbow(seed)
        r, g, b = color
        line += "\x1b[48;2;{};{};{}m ".format(r, g, b)
    line += "\x1b[0m"
    return line, seed


def show_activity(rows=4, cols=80):
    """Show some activity in console"""
    from sys import stdout
    global __activity_ctx
    seed = __activity_ctx
    if stdout.isatty():
        line, seed = rainbow_line(seed, width=cols)
        pline = "{}\n".format(line) * rows
        print("{}\x1b[{}A".format(pline, rows), end="")
        stdout.flush()
        __activity_ctx = seed
    else:
        # Do nothing
        pass

if __name__ == "__main__":
    from time import sleep
    try:
        while True:
            #show_activity(rows=8, cols=100)
            show_activity(rows=26, cols=125)
            sleep(0.1)
    except KeyboardInterrupt:
        pass