Draws mandelbrot fractal on sixel-enabled terminal. Worked on @ayosec 's fork of alacritty ( https://github.com/ayosec/alacritty/tree/graphics )

sixel-mandelbrot.py

"""
usage:
  $ python sixel-mandelbrot.py
  or
  $ python sixel-mandelbrot.py 300
"""

import sys
import fcntl, termios, struct

ESC = '\x1b'

_, _, canvas_width, canvas_height = struct.unpack(
    'HHHH',
    fcntl.ioctl(0, termios.TIOCGWINSZ, struct.pack('HHHH', 0, 0, 0, 0))
)

canvas_width = int(sys.argv[1]) if len(sys.argv) > 1 else canvas_width

def calculate_color(x, y):
    z = 0 + 0j
    c = complex(x, y)
    for _ in range(40):
        z = z * z + c
        if abs(z) > 2:
            return 0
    return 1

delta = 3 / canvas_width

sys.stdout.write(ESC + 'Pq')
sys.stdout.write(
    '#0;2;100;100;100'
    '#1;2;0;0;0'
)

code = ord('?')

for sy in range(int(canvas_width / 1.5 / 6)):
    y = -1 + sy * delta * 6
    line = '#1'
    for sx in range(canvas_width):
        x = -2 + sx * delta
        colors = [ calculate_color(x, y + delta * sub_y) for sub_y in range(6) ]
        offset = 0
        for bit in reversed(colors):
            offset = (offset << 1) | bit
        line += chr(code + offset)
    sys.stdout.write(line + '-')

sys.stdout.write(ESC + '\\')