Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
}

// FloydSteinberg is a [Drawer] that is the [Src] [Op] with Floyd-Steinberg error
// diffusion.
var FloydSteinberg Drawer = floydSteinberg{}

type floydSteinberg struct{}

func (floydSteinberg) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
	clip(dst, &r, src, &sp, nil, nil)
	if r.Empty() {
		return

		}
	}
	pi := image.NewPaletted(im.Bounds(), []color.Color{
		color.Gray{Y: 255},
		color.Gray{Y: 160},
		color.Gray{Y: 70},
		color.Gray{Y: 35},
		color.Gray{Y: 0},
	})

	draw.FloydSteinberg.Draw(pi, im.Bounds(), im, image.Point{})
	shade := []string{" ", "░", "▒", "▓", "█"}
	for i, p := range pi.Pix {
		fmt.Print(shade[p])
		if (i+1)%width == 0 {
			fmt.Print("\n")
		}
	}

	// palette.Plan9 is used in place of a nil Quantizer.
	Quantizer draw.Quantizer

	// Drawer is used to convert the source image to the desired palette.
	// draw.FloydSteinberg is used in place of a nil Drawer.
	Drawer draw.Drawer
}

// EncodeAll writes the images in g to w in GIF format with the
// given loop count and delay between frames.
func EncodeAll(w io.Writer, g *GIF) error {

	b := image.Rect(0, 0, 640, 480)
	// We can't represent 50% exactly, but 0x7fff / 0xffff is close enough.
	src := &image.Uniform{color.Gray16{0x7fff}}
	dst := image.NewPaletted(b, color.Palette{color.Black, color.White})
	FloydSteinberg.Draw(dst, b, src, image.Point{})
	nErr := 0
	for y := b.Min.Y; y < b.Max.Y; y++ {
		for x := b.Min.X; x < b.Max.X; x++ {
			got := dst.Pix[dst.PixOffset(x, y)]
			want := uint8(x+y) % 2
			if got != want {

		{"Plan9", Var, 2},
		{"WebSafe", Var, 2},
	},
	"image/draw": {
		{"(Op).Draw", Method, 2},
		{"Draw", Func, 0},
		{"DrawMask", Func, 0},
		{"Drawer", Type, 2},
		{"FloydSteinberg", Var, 2},
		{"Image", Type, 0},
		{"Op", Type, 0},
		{"Over", Const, 0},
		{"Quantizer", Type, 2},
		{"RGBA64Image", Type, 17},
		{"Src", Const, 0},
	},
	"image/gif": {

pkg image/draw, type Quantizer interface { Quantize }
pkg image/draw, type Quantizer interface, Quantize(color.Palette, image.Image) color.Palette
pkg image/draw, var FloydSteinberg Drawer
pkg image/gif, func Encode(io.Writer, image.Image, *Options) error
pkg image/gif, func EncodeAll(io.Writer, *GIF) error
pkg image/gif, type Options struct
pkg image/gif, type Options struct, Drawer draw.Drawer