package filters

import (
  "image"
  "image/draw"
  "image/color"
  "github.com/disintegration/gift"
)

type PosterizeFilter struct {
  Depth uint8
}

func Posterize(depth uint8) gift.Filter {
  return PosterizeFilter{depth}
}

func (filter PosterizeFilter) Bounds(src image.Rectangle) (dst_bounds image.Rectangle) {
  return src
}

func bin(c uint8) uint8 {
  if c <= 64 {
    return 0
  } else {
    return 255
  }
}

func (filter PosterizeFilter) Draw(dst draw.Image, src image.Image, _ *gift.Options) {
  bounds := src.Bounds()

  for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
    for x := bounds.Min.X; x < bounds.Max.X; x++ {
      from := src.At(x, y)
      c := from.(color.NRGBA)
      c.R = bin(c.R)
      c.G = bin(c.G)
      c.B = bin(c.B)
      dst.Set(x, y, c)
    }
  }
}