# Recipe 19: Mirror pixels in a picture along a vertical line

def mirrorVertical(source):
  mirrorpoint = int(getWidth(source) / 2)
  for y in range(1, getHeight(source)+1):
    for xOffset in range(1, mirrorpoint):
      pright = getPixel(source, xOffset + mirrorpoint, y)
      pleft = getPixel(source, mirrorpoint - xOffset, y)
      c = getColor(pleft)
      setColor(pright, c)