File:Line pixel subpixel aa.gif

# Simple animation showing pixel vs subpixel accuracy.
# by Miloslav Ciz, released under CC0 1.0

from PIL import Image
import math

SCALE = 8

FRAMES = 64

RESOLUTION = (48,16)

img = Image.new("RGB",(RESOLUTION[0] * SCALE,RESOLUTION[1] * SCALE),"white")

pixels = img.load()

def setPixel(x, y, c):
  for b in range(SCALE):
    for a in range(SCALE):
      pixels[x * SCALE + a,y * SCALE + b] = (c,c,c)

def drawLine(p0, p1, aa):
  slope = (p1[1] - p0[1]) / float(p1[0] - p0[0])

  for i in range(int(p1[0] - p0[0] + 1)):
    x = int(p0[0] + i) if aa else round(p0[0] + i)
    y = p0[1] + i * slope

    c = int(255 * (y % 1)) if aa else 0

    y = int(y) if aa else round(y)

    setPixel(x,y,c)

    if aa:
      setPixel(x,y + 1,255 - c)

for f in range(FRAMES):
  img.paste((255,255,255),(0,0,img.size[0],img.size[1]))

  t = f / float(FRAMES) * math.pi * 2

  x0 = 0
  x1 = 15

  y0 = 8 + math.sin(t) * 5
  y1 = 7 + math.cos(t) * 3

  drawLine((x0,round(y0)),(x1,round(y1)),False)
  drawLine((x0 + RESOLUTION[0] / 3,y0),(x1 + RESOLUTION[0] / 3,y1),False)
  drawLine((x0 + 2 * RESOLUTION[0] / 3,y0),(x1 + 2 * RESOLUTION[0] / 3,y1),True)

  for i in range(RESOLUTION[1] * SCALE):
    pixels[int(RESOLUTION[0] * SCALE / 3),i] = (0,0,0)
    pixels[int(2 * RESOLUTION[0] * SCALE / 3),i] = (0,0,0)

  img.save("out" + str(f).zfill(2) + ".png")