display.py

from subprocess import Popen, PIPE
from os import remove, execlp, fork

# constants
XRES = 500
YRES = 500
MAX_COLOR = 255
RED = 0
GREEN = 1
BLUE = 2

DEFAULT_COLOR = [0, 0, 0]


def new_screen(width=XRES, height=YRES):
    screen = []
    for y in range(height):
        row = []
        screen.append(row)
        for x in range(width):
            screen[y].append(DEFAULT_COLOR[:])
    return screen


def plot(screen, color, x, y):
    newy = YRES - 1 - y
    if (x >= 0 and x < XRES and newy >= 0 and newy < YRES):
        screen[newy][x] = color[:]


def clear_screen(screen):
    for y in range(len(screen)):
        for x in range(len(screen[y])):
            screen[y][x] = DEFAULT_COLOR[:]


def save_ppm(screen, fname):
    f = open(fname, 'w')
    ppm = 'P3\n' + str(len(screen[0])) + ' ' + \
        str(len(screen)) + ' ' + str(MAX_COLOR) + '\n'
    for y in range(len(screen)):
        row = ''
        for x in range(len(screen[y])):
            pixel = screen[y][x]
            row += str(pixel[RED]) + ' '
            row += str(pixel[GREEN]) + ' '
            row += str(pixel[BLUE]) + ' '
        ppm += row + '\n'
    f.write(ppm)
    f.close()


def save_extension(screen, fname):
    ppm_name = fname[:fname.find('.')] + '.ppm'
    save_ppm(screen, ppm_name)
    p = Popen(['convert', ppm_name, fname], stdin=PIPE, stdout=PIPE)
    p.communicate()
    remove(ppm_name)


def display(screen):
    ppm_name = 'pic.ppm'
    save_ppm(screen, ppm_name)
    p = Popen(['display', ppm_name], stdin=PIPE, stdout=PIPE)
    p.communicate()
    remove(ppm_name)


def make_animation(name):
    name_arg = 'anim/' + name + '*'
    name = name + '.gif'
    print 'Saving animation as ' + name
    f = fork()
    if f == 0:
        execlp('convert', 'convert', '-delay', '3', name_arg, name)