gistfile1.py

def draw_line(pixels, origin, destination):
    x, y = x1, y1 = origin

    x2, y2 = destination

    Δx = abs(x2 - x1)
    Δy = abs(y2 - y1)

    s1 = sign(x2-x1)
    s2 = sign(y2-y1)

    inc_inner, inc_outer = ((0, s2), (s1, 0))

    if Δy > Δx :
        Δx, Δy = Δy, Δx
        inc_inner, inc_outer = inc_outer, inc_inner

    e = 2 * Δy - Δx
    for i in range(1, Δx):
        pixels[x,y] = (0, 0, 0)
        while e >= 0:
            x, y = x + inc_inner[0], y + inc_inner[1]
            e -= 2*Δx
        x, y = x + inc_outer[0], y + inc_outer[1]
        e += 2 * Δy