generates a ppm of github identicon.

github_identicon.py

# what? i was bored.

class Identicon(object):
    def __init__(self, bg, fg, border=35, block=71, count=5):
        self.bg = bg
        self.fg = fg
        self.border = border
        self.block = block
        self.count = count

    def gen(self, blockdat, size=None):
        size = size or self.pixsize()
        rv = [self.bg] * (size * size)
        for y in xrange(0, size):
            for x in xrange(0, size):
                if self.border <= x < size - self.border and \
                        self.border <= y < size - self.border:
                    bx = (x - self.border) / self.block
                    by = (y - self.border) / self.block
                    if blockdat[by * self.count + bx]:
                        rv[y * size + x] = self.fg
        return rv

    def pixsize(self):
        return self.border * 2 + self.block * self.count

def to_ppm(array, width, height):
    fmt = """P3
%d %d
255
%s"""
    pixdat = chunks(("%d %d %d" % a for a in array), width)
    pixdat = "\n".join(" ".join(row) for row in pixdat)
    return fmt % (width, height, pixdat)

def chunks(it, n):
    from itertools import izip
    i = iter(it)
    its = [i] * n
    return izip(*its)

def rgb(s):
    s = int(s, 16)
    return (s >> 16, (s >> 8) & 0xff, s & 0xff)

old = Identicon(rgb("f0f0f0"), rgb("d1d47c"))
new = Identicon(rgb("f0f0f0"), rgb("00356b"))
pat = [bool(int(c)) for c in "1010100000110110010010101"]
# "B"
block = [bool(int(c))
         for c in "".join(('11110', '10001', '11110', '10001', '11110'))]
z = to_ppm(new.gen(pat), new.pixsize(), new.pixsize())