experiments and stuff

.gitignore

@@ -0,0 +1,4 @@
+child_porn
+imageutils.test
+cpu.out
+profile.out

README.md

@@ -0,0 +1,9 @@
+# imageutils
+## that is exactly image utilities, what i made for myself
+
+||(with a dummy as fuck image rescaling)||
+utilities work in theory, but doing everything very slow.
+i really love Go's image.Image interface type, but its really hard to do something with it well.
+
+TODO: 
+	- create main binary that give access to all implemented things in cmd/

concat.go

@@ -21,9 +21,9 @@ type pair struct {
 }
 
 // Takes color.Model of the first Image.
-func (p pair) ColorModel() color.Model { return p.first.ColorModel() }
+func (p *pair) ColorModel() color.Model { return p.first.ColorModel() }
 
-func (p pair) Bounds() image.Rectangle {
+func (p *pair) Bounds() image.Rectangle {
 	var (
 		b1 = p.first.Bounds()
 		b2 = p.second.Bounds()
@@ -52,7 +52,7 @@ func (p pair) Bounds() image.Rectangle {
 	}
 }
 
-func (p pair) At(x, y int) color.Color {
+func (p *pair) At(x, y int) color.Color {
 	img := image.NewRGBA(p.Bounds())
 
 	point := image.Point{}
@@ -86,7 +86,7 @@ func (p pair) At(x, y int) color.Color {
 	return img.At(x, y)
 }
 
-func render(p pair) image.Image {
+func render(p *pair) image.Image {
 	img := image.NewRGBA(p.Bounds())
 
 	point := image.Point{}
@@ -122,5 +122,5 @@ func render(p pair) image.Image {
 
 // Concat concatenates second image on a given side.
 func Concat(i1, i2 image.Image, s Side) image.Image {
-	return render(pair{i1, i2, s})
+	return render(&pair{i1, i2, s})
 }

concat_test.go

@@ -0,0 +1,24 @@
+package imageutils
+
+import (
+	"image"
+	"image/png"
+	"io"
+	"testing"
+)
+
+func BenchmarkConcat(b *testing.B) {
+	var instance image.Image = image.NewRGBA(image.Rect(0, 0, 0, 0))
+	pixel := SinglePixel{}
+
+	for i := 0; i < b.N; i++ {
+		instance = Concat(instance, pixel, Right)
+	}
+	err := png.Encode(
+		io.Discard,
+		instance,
+	)
+	if err != nil {
+		panic(err)
+	}
+}

genprof

@@ -0,0 +1,2 @@
+go test -cpuprofile=profile.out -bench=$1 &&
+go tool pprof -text profile.out

go.mod

@@ -1,3 +1,8 @@
-module github.com/potassium5703/imageutils
+module git.nkpl.cc/twocookedfaggots/imageutils
 
-go 1.21.4
+go 1.25.5
+
+require (
+	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
+	golang.org/x/image v0.36.0
+)

go.sum

@@ -0,0 +1,4 @@
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
+golang.org/x/image v0.36.0 h1:Iknbfm1afbgtwPTmHnS2gTM/6PPZfH+z2EFuOkSbqwc=
+golang.org/x/image v0.36.0/go.mod h1:YsWD2TyyGKiIX1kZlu9QfKIsQ4nAAK9bdgdrIsE7xy4=

http/blank/blank.go

@@ -0,0 +1,47 @@
+package blank
+
+import (
+	"image"
+	"image/color"
+
+	"git.nkpl.cc/twocookedfaggots/imageutils"
+)
+
+type blank struct {
+	image.Image
+	color.Color
+	imageutils.Side
+}
+
+func (b blank) ColorModel() color.Model { return b.Image.ColorModel() }
+
+func (b blank) Bounds() image.Rectangle {
+	rect := image.Rectangle{}
+	switch b.Side {
+	case imageutils.Left:
+		fallthrough
+	case imageutils.Right:
+		rect = image.Rectangle{
+			image.ZP,
+			image.Point{
+				1, b.Image.Bounds().Dy(),
+			},
+		}
+	case imageutils.Up:
+		fallthrough
+	case imageutils.Down:
+		rect = image.Rectangle{
+			image.ZP,
+			image.Point{
+				b.Image.Bounds().Dx(), 1,
+			},
+		}
+	}
+	return rect
+}
+
+func (b blank) At(x, y int) color.Color { return b.Color }
+
+func Blank(img image.Image, clr color.Color, side imageutils.Side) image.Image {
+	return imageutils.Concat(img, blank{img, clr, side}, side)
+}

http/http.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"net/http"
+	"log"
+)
+
+type imageTransform struct {
+	image.Image
+	TransformFunc func(image.Image) image.Image
+}
+
+type BlankFill struct {
+}
+
+func (t imageTransform) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+
+}
+
+func indexHTML(w http.ResponseWriter, r *http.Request) {
+	f, err := os.Open("")
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		log.Fatalln("error opening file:", err)
+		return
+	}
+	_, err := io.Copy(w, f)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		log.Println("copy error:", err)
+		return
+	}	
+}
+
+func main() {
+	http.HandleFunc("/", indexHTML)
+	http.Handle("POST /upload", imageTransform)
+
+	err := http.ListenAndServe(":8080", nil) 
+	if err != nil {
+		log.Panicln(err)
+	}
+}

http/index.html

@@ -0,0 +1,4 @@
+<form action="/upload" method="POST" enctype="multipart/form-data">
+    <input type="file" name="image" accept="image/*" required>
+    <button type="submit">Upload Image</button>
+</form>

http/test.go

@@ -0,0 +1,49 @@
+//go:build ignore
+
+// works as i wanted
+
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"image/jpeg"
+	"os"
+"git.nkpl.cc/twocookedfaggots/imageutils"
+	"git.nkpl.cc/twocookedfaggots/imageutils/http/blank"
+)
+
+func BlankFillWhite(img image.Image) image.Image {
+	dy := img.Bounds().Dy()
+	up, down := dy*2/3, dy*1/3
+	for i := 0; i < up; i++ {
+		img = blank.Blank(img, color.White, imageutils.Up)
+	}
+	for i := 0; i < down; i++ {
+		img = blank.Blank(img, color.White, imageutils.Down)
+	}
+	return img
+}
+
+func ProcessImageStdio(f func(image.Image) image.Image) error {
+	img, err := jpeg.Decode(os.Stdin)
+	if err != nil {
+		return err
+	}
+	img = f(img)
+	err = png.Encode(os.Stdout, img)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func main() {
+	err := ProcessImageStdio(
+		BlankFillWhite,
+	)
+	if err != nil {
+		panic(err)
+	}
+}

pkg/dithering/cmd/jpg2png.go

@@ -0,0 +1,20 @@
+//go:build ignore
+
+package main
+
+import (
+	"image/jpeg"
+	"image/png"
+	"os"
+)
+
+func main() {
+	img, err := jpeg.Decode(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+	err = png.Encode(os.Stdout, img)
+	if err != nil {
+		panic(err)
+	}
+}

pkg/dithering/cmd/main.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"image"
+
+	"git.nkpl.cc/twocookedfaggots/imageutils/pkg/dithering"
+	"git.nkpl.cc/twocookedfaggots/imageutils/util"
+)
+
+func main() {
+	err := util.ProcessStdio(func(img image.Image) image.Image {
+		return dithering.Dithering{img}
+	})
+	if err != nil {
+		panic(err)
+	}
+}

pkg/dithering/grid.go

@@ -0,0 +1,63 @@
+package dithering
+
+import (
+	"image"
+	"image/color"
+)
+
+const side = 16
+
+type grid struct {
+	color.Gray
+}
+
+func (_ grid) ColorModel() color.Model {
+	return color.RGBAModel
+}
+
+func (_ grid) Bounds() image.Rectangle {
+	return image.Rect(0, 0, side, side)
+}
+
+func (g grid) At(x, y int) color.Color {
+	n := uint8(g.Gray.Y * 10)
+
+	if n == 0 {
+		return color.Black
+	}
+	step := int((side*side-1) / n)
+	if (y*side+x)%step == 0 {
+		return color.White
+	}
+	return color.Black
+}
+
+type uniformGrid struct {
+	image.Image
+}
+
+func (g uniformGrid) ColorModel() color.Model {
+	return g.Image.ColorModel()
+}
+
+func (g uniformGrid) Bounds() image.Rectangle {
+	// just need to return something
+	return g.Image.Bounds()
+}
+
+func (g uniformGrid) At(x, y int) color.Color {
+	dx, dy := g.Image.Bounds().Dx(), g.Image.Bounds().Dy()
+	return g.Image.At(x%dx, y%dy)
+}
+
+type Dithering struct {
+	image.Image
+}
+
+func (d Dithering) ColorModel() color.Model { return color.GrayModel }
+func (d Dithering) Bounds() image.Rectangle { return d.Image.Bounds() }
+func (d Dithering) At(x, y int) color.Color {
+	c := color.GrayModel.Convert(d.Image.At(x, y))
+	return uniformGrid{grid{c.(color.Gray)}}.
+		At(x, y)
+}

pkg/dithering/grid_test.go

@@ -0,0 +1,73 @@
+package dithering
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"math/rand"
+	"os"
+	"os/exec"
+	"testing"
+	"time"
+
+	"git.nkpl.cc/twocookedfaggots/imageutils"
+)
+
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
+func callImage(img image.Image) {
+	for y := 0; y < img.Bounds().Dy(); y++ {
+		for x := 0; x < img.Bounds().Dx(); x++ {
+			_ = img.At(x, y)
+		}
+	}
+}
+
+func TestGrid(t *testing.T) {
+	command := exec.Command("imv", "-")
+	w, err := command.StdinPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = command.Start()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	n := uint8(rand.Int() % 256)
+	t.Log(n)
+	img := imageutils.Scale(1<<6, grid{color.Gray{n}})
+	err = png.Encode(w, img)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	callImage(grid{color.Gray{4}})
+	callImage(grid{color.Gray{0}})
+}
+
+func TestDithering(t *testing.T) {
+	r, err := os.Open("/home/potassium/documents/wallpaper/8.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r.Close()
+
+	w, err := os.Create("sample.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer w.Close()
+
+	img, err := png.Decode(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = png.Encode(w, Dithering{img})
+	if err != nil {
+		t.Fatal(err)
+	}
+}

pkg/downscale/downscale.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"errors"
+	"image"
+	"image/color"
+)
+
+var errOutOfBounds error = errors.New("downscale: out of bounds")
+
+type Downscaled struct {
+	image.Image
+	Factor int
+}
+
+func isOutOfBounds(pt image.Point, img image.Image) bool {
+	x, y := img.Bounds().Dx(), img.Bounds().Dy()
+	if pt.X > x || pt.Y > y {
+		return true
+	}
+	return false
+}
+
+func meanColor(palette color.Palette) color.Color {
+	var r, g, b int
+	for _, v := range palette {
+		c := color.RGBAModel.Convert(v).(color.RGBA)
+		r += int(c.R)
+		g += int(c.G)
+		b += int(c.B)
+	}
+	r, g, b = r/len(palette), g/len(palette), b/len(palette)
+	return color.RGBA{uint8(r), uint8(g), uint8(b), 0xff}
+}
+
+func (d Downscaled) ColorModel() color.Model { return d.Image.ColorModel() }
+func (d Downscaled) Bounds() image.Rectangle {
+	return image.Rect(0, 0, d.Image.Bounds().Dx()/d.Factor, d.Image.Bounds().Dy()/d.Factor)
+}
+func (d Downscaled) At(x, y int) color.Color {
+	palette := color.Palette{}
+	pt := image.Point{x * d.Factor, y * d.Factor}
+	if isOutOfBounds(pt, d.Image) {
+		panic(errOutOfBounds)
+	}
+	for i := 0; i < d.Factor; i++ {
+		for j := 0; j < d.Factor; j++ {
+			currentPt := image.Point{pt.X + i, pt.Y + j}
+			if i > 0 || j > 0 {
+				if isOutOfBounds(currentPt, d.Image) {
+					continue
+				}
+			}
+			palette = append(palette, d.Image.At(currentPt.X, currentPt.Y))
+		}
+	}
+	return palette.Convert(meanColor(palette))
+}

pkg/downscale/main.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"image/jpeg"
+	"image/png"
+	"os"
+)
+
+func main() {
+	// open image
+	img, err := jpeg.Decode(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+	// no pre-processing needed so we just
+	// write image
+	err = png.Encode(os.Stdout, Downscaled{img, 3})
+	if err != nil {
+		panic(err)
+	}
+}

pkg/grayscale/main.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"os"
+)
+
+// processImage takes input png image from stdin, processes it with f and outputs it to stdout.
+func processImage(f func(image.Image) image.Image) error {
+	img, err := png.Decode(os.Stdin)
+	if err != nil {
+		return err
+	}
+	err = png.Encode(os.Stdout, f(img))
+	if err != nil {
+		return err
+	}
+	return err
+}
+
+type convert struct {
+	image.Image
+	color.Model
+}
+
+func (c convert) ColorModel() color.Model { return c.Model }
+func (c convert) Bounds() image.Rectangle { return c.Image.Bounds() }
+func (c convert) At(x, y int) color.Color { return c.Model.Convert(c.Image.At(x, y)) }
+
+func grayscale(img image.Image) image.Image {
+	return convert{img, color.GrayModel}
+}
+
+func main() {
+	err := processImage(grayscale)
+	if err != nil {
+		panic(err)
+	}
+}

pkg/mesh/9p.go

@@ -0,0 +1,41 @@
+//go:build ignore
+
+package main
+
+func ListenAndServe(addr string, filesystem fs.FS) error {
+	styx.HandlerFunc(func(s *styx.Session) {
+		for s.Next() {
+			switch msg := s.Request.(type) {
+			case styx.Twalk:
+				msg.Rwalk(fs.Stat(filesystem, msg.Path()))
+			case styx.Topen:
+				msg.Ropen(filesystem.Open(msg.Path()))
+			case styx.Tstat:
+				msg.Rstat(fs.Stat(filesystem, msg.Path()))
+			}
+		}
+	},
+	)
+}
+
+type FS struct {
+	meshFile
+}
+
+type meshFile struct {
+}
+
+type meshFileInfo struct {
+	bufio.Reader
+	time.Time
+}
+
+func (f meshFileInfo) Name() string       { return "mesh" }
+func (f meshFileInfo) Size() int64        { return f.Reader.Size() }
+func (f meshFileInfo) Mode() fs.FileMode  { return fs.ModePerm }
+func (f meshFileInfo) ModTime() time.Time { return f.Time }
+func (f meshFileInfo) IsDir() bool        { return false }
+func (f meshFileInfo) Sys() any           { return nil }
+
+func (f meshFile) Stat() (fs.FileInfo, error) {
+}

pkg/mesh/mesh.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"flag"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"os"
+	"time"
+
+	"github.com/golang/freetype/truetype"
+	"golang.org/x/image/font"
+	"golang.org/x/image/font/gofont/gomono"
+	"golang.org/x/image/math/fixed"
+	//	"github.com/droyo/styx"
+	//	"io/fs"
+)
+
+type Mesh struct {
+	image.Image
+	X, Y int // divide
+}
+
+// using source's color.Model
+func (mesh Mesh) ColorModel() color.Model { return mesh.Image.ColorModel() }
+
+// using source's image.Rectangle
+func (mesh Mesh) Bounds() image.Rectangle { return mesh.Image.Bounds() }
+func (mesh Mesh) At(x, y int) color.Color {
+	dx, dy := mesh.Image.Bounds().Dx(), mesh.Image.Bounds().Dy()
+	if (x%(dx/mesh.X)) == 0 || (y%(dy/mesh.Y)) == 0 {
+		return color.Black
+	}
+	return mesh.Image.At(x, y)
+}
+
+func render(img image.Image) draw.Image {
+	dst := image.NewRGBA(img.Bounds())
+	draw.Draw(dst, dst.Bounds(), img, image.Point{}, draw.Src)
+	return dst
+}
+
+func main() {
+//	x := flag.Int("x", 2, "use to grid by x axis")
+//	y := flag.Int("y", 2, "use to grid by y axis")
+	flag.Parse() // now flags is ready to use
+
+	img, err := png.Decode(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+//		Mesh{ // our image modifyer
+//			Image: img,
+//			X:     *x,
+//			Y:     *y,
+//		},
+
+	dst := render(
+	img,
+	)
+
+	f, err := truetype.Parse(gomono.TTF)
+	if err != nil {
+		panic(err)
+	}
+	face := truetype.NewFace(f, &truetype.Options{
+		Size:    float64(img.Bounds().Dx() / 19),
+		DPI:     72,
+		Hinting: font.HintingNone,
+	})
+
+	d := &font.Drawer{
+		Dst:  dst,
+		Src:  image.NewUniform(color.Black),
+		Face: face,
+		Dot: fixed.Point26_6{fixed.Int26_6(img.Bounds().Dx() /
+			9*64,
+		),
+			fixed.Int26_6(img.Bounds().Dy() /
+				5*64,
+			),
+		},
+	}
+	d.DrawString(time.Now().Format(time.Kitchen))
+
+	err = png.Encode(os.Stdout, dst)
+	if err != nil {
+		panic(err)
+	}
+}

pkg/mkpalette/palette.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"encoding/csv"
+	"fmt"
+	"image/color"
+	"image/png"
+	"maps"
+	"os"
+	"slices"
+
+	imgutil "git.nkpl.cc/twocookedfaggots/imageutils/pkg"
+)
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+type Set[S comparable] map[S]struct{}
+
+func (s Set[S]) Add(v S) {
+	s[v] = struct{}{}
+}
+
+func (s Set[S]) Contains(v S) bool {
+	_, ok := s[v]
+	return ok
+}
+
+func Map[S1 ~[]T1, S2 ~[]T2, T1, T2 any](s S1, f func(T1) T2) S2 {
+	result := make(S2, len(s))
+	for i := range s {
+		result[i] = f(s[i])
+	}
+	return result
+}
+
+type hex string
+
+func (h hex) String() string {
+	return string(fmt.Sprintf("hex value: %s\n", string(h)))
+}
+
+func main() {
+	img, err := png.Decode(os.Stdin)
+	check(err)
+	p := Set[color.Color]{}
+	for y := 0; y < img.Bounds().Dy(); y++ {
+		for x := 0; x < img.Bounds().Dx(); x++ {
+			p.Add(img.At(x, y))
+		}
+	}
+	w := csv.NewWriter(os.Stdout)
+	s := Map[color.Palette, []string](
+		slices.Collect(maps.Keys(p)), imgutil.ColorToHex,
+	)
+	/*
+	h := make([]hex, 0, len(s))
+	for i := range s {
+		h = append(h, hex(s[i]))
+	}
+	*/
+	err = w.Write(s)
+	check(err)
+}

pkg/negate/minus19blue.go

@@ -0,0 +1,39 @@
+//go:build ignore
+
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"os"
+)
+
+type Reshade struct{ image.Image }
+
+func (rs Reshade) ColorModel() color.Model { return rs.Image.ColorModel() }
+func (rs Reshade) Bounds() image.Rectangle { return rs.Image.Bounds() }
+func (rs Reshade) At(x, y int) color.Color {
+	c := rs.Image.At(x, y)
+	r, g, b, a := c.RGBA()
+	// minus 19 blue
+	return color.RGBA{
+		uint8(r >> 8),
+		uint8(g >> 8),
+		uint8(b>>8) - 8*8,
+		uint8(a >> 8),
+	}
+}
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func main() {
+	img, err := png.Decode(os.Stdin)
+	check(err)
+	err = png.Encode(os.Stdout, Reshade{img})
+	check(err)
+}

pkg/negate/mixed.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"math/rand"
+	"os"
+)
+
+type MixedNegation struct {
+	src     image.Image
+	counter int
+}
+
+func toRGBA(c color.Color) color.RGBA {
+	r, g, b, a := c.RGBA()
+	return color.RGBA{
+		R: uint8(r >> 8),
+		G: uint8(g >> 8),
+		B: uint8(b >> 8),
+		A: uint8(a >> 8),
+	}
+}
+
+func negateRGBA(c color.RGBA) color.RGBA {
+	c.R = 255 - c.R
+	c.G = 255 - c.G
+	c.B = 255 - c.B
+	return c
+}
+
+func Negate(c color.Color) color.Color {
+	return negateRGBA(toRGBA(c))
+}
+
+func randomBool() bool {
+	return rand.Intn(3) == 0
+}
+
+func (mn MixedNegation) ColorModel() color.Model { return mn.src.ColorModel() }
+func (mn MixedNegation) Bounds() image.Rectangle { return mn.src.Bounds() }
+func (mn *MixedNegation) At(x, y int) color.Color {
+	if (x%1 != 0) && (y%8 != 0) {
+		if randomBool() {
+			return Negate(mn.src.At(x, y))
+		}
+
+	}
+	return mn.src.At(x, y)
+}
+
+func pixelCount(img image.Image) int {
+	return img.Bounds().Dx() * img.Bounds().Dy()
+}
+
+func main() {
+	img, err := png.Decode(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+
+	n := pixelCount(img)
+	println(n)
+
+	err = png.Encode(os.Stdout, &MixedNegation{src: img, counter: n})
+	if err != nil {
+		panic(err)
+	}
+}

pkg/negate/negate.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"os"
+)
+
+func NegateRGBA(c color.RGBA) color.RGBA {
+	c.R = 255 - c.R
+	c.G = 255 - c.G
+	c.B = 255 - c.B
+	return c
+}
+
+type Negate struct{ image.Image }
+
+func (n Negate) ColorModel() color.Model { return n.Image.ColorModel() }
+func (n Negate) Bounds() image.Rectangle { return n.Image.Bounds() }
+func (n Negate) At(x, y int) color.Color {
+	c := n.Image.At(x, y)
+	r, g, b, a := c.RGBA()
+	RGBAColor := color.RGBA{
+		R: uint8(r >> 8),
+		G: uint8(g >> 8),
+		B: uint8(b >> 8),
+		A: uint8(a >> 8),
+	}
+	return NegateRGBA(RGBAColor)
+}
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func main() {
+	img, err := png.Decode(os.Stdin)
+	check(err)
+	err = png.Encode(os.Stdout, Negate{img})
+	check(err)
+}

pkg/showpalette/show.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"encoding/csv"
+	"image"
+	"image/color"
+	"image/png"
+	"math"
+	"os"
+
+	imgutil "git.nkpl.cc/twocookedfaggots/imageutils/pkg"
+)
+
+func nearestHighSqrt(n int) int {
+	if math.Mod(math.Sqrt(float64(n)), 1) == 0 {
+		return n
+	}
+	return nearestHighSqrt(n + 1)
+}
+
+type showColors struct {
+	color.Palette
+}
+
+func (s showColors) ColorModel() color.Model {
+	return color.RGBAModel
+}
+
+func (s showColors) Bounds() image.Rectangle {
+	n := nearestHighSqrt(len(s.Palette))
+	return image.Rect(0, 0, n, n)
+}
+
+func (s showColors) At(x, y int) color.Color {
+	n := nearestHighSqrt(len(s.Palette))
+	return s.Palette[y*n+x]
+}
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func Must[T any](v T, err error) T {
+	check(err)
+	return v
+}
+
+func Map[S1 ~[]T1, S2 ~[]T2, T1, T2 any](s S1, f func(T1) T2) S2 {
+	result := make(S2, len(s))
+	for i := range s {
+		result[i] = f(s[i])
+	}
+	return result
+}
+
+func main() {
+	r := csv.NewReader(os.Stdin)
+	r.TrailingComma = true
+	colors, err := r.Read()
+	check(err)
+	palette := color.Palette(
+		Map[[]string, color.Palette](colors,
+			func(v string) color.Color {
+				println(v + "cat-v")
+				return Must(imgutil.ParseHexColor(v))
+			},
+		),
+	)
+	
+	err = png.Encode(os.Stdout, showColors{palette})
+	check(err)
+}

scale.go

@@ -38,7 +38,7 @@ func (r rescaled) At(x, y int) color.Color {
 // Scale scales image.Image to a given scale
 // and then returns image.Image.
 // For now it will work only with positive integers.
-func Scale(img image.Image, scale int) image.Image {
+func Scale(scale int, img image.Image) image.Image {
 	if scale < 1 {
 		scale = 1
 	}

scale_test.go

@@ -0,0 +1,60 @@
+package imageutils
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"io"
+	"testing"
+
+	"git.nkpl.cc/twocookedfaggots/imageutils/pkg/texture"
+)
+
+func Render(img image.Image, rect image.Rectangle) image.Image {
+	newimg := image.NewRGBA(rect)
+	draw.Draw(newimg, rect, image.White, image.ZP, draw.Src)
+	draw.Draw(newimg, rect, img, image.ZP, draw.Over)
+	return newimg
+}
+
+func BenchmarkScale(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		err := png.Encode(io.Discard,
+			Scale(64, Render(
+				texture.New(color.White,
+					color.Black, 2),
+				image.Rect(0, 0, 64, 64),
+			)),
+		)
+		if err != nil {
+			panic(err)
+		}
+	}
+}
+
+
+type SinglePixel struct{}
+
+func (s SinglePixel) At(x, y int) color.Color {
+	return color.White
+}
+
+func (s SinglePixel) ColorModel() color.Model {
+	return color.RGBAModel
+}
+
+func (s SinglePixel) Bounds() image.Rectangle {
+	return image.Rect(0, 0, 1, 1)
+}
+
+func BenchmarkSinglePixel(b *testing.B) {
+	instance := SinglePixel{}
+	err := png.Encode(io.Discard,
+		Scale(b.N, instance),
+	)
+	if err != nil {
+		panic(err)
+	}
+
+}

util/hex.go

@@ -0,0 +1,32 @@
+package util
+
+import (
+	"errors"
+	"fmt"
+	"image/color"
+)
+
+var ParseHexColorErr = errors.New("invalid length, must be 7 or 4")
+
+func ParseHexColor(s string) (c color.RGBA, err error) {
+	c.A = 0xff
+	switch len(s) {
+	case 7:
+		_, err = fmt.Sscanf(s, "#%02x%02x%02x", &c.R, &c.G, &c.B)
+	case 4:
+		_, err = fmt.Sscanf(s, "#%1x%1x%1x", &c.R, &c.G, &c.B)
+		// Double the hex digits:
+		c.R *= 17
+		c.G *= 17
+		c.B *= 17
+	default:
+		err = ParseHexColorErr
+
+	}
+	return
+}
+
+func ColorToHex(c color.Color) string {
+	r, g, b, _ := color.NRGBAModel.Convert(c).RGBA()
+	return fmt.Sprintf("#%02x%02x%02x", byte(r), byte(g), byte(b))
+}

util/hex_test.go

@@ -0,0 +1,47 @@
+package util
+
+import (
+	"fmt"
+	"image/png"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// Returns path of first occured file
+// with png extension in user's home directory.
+func firstPNG(root string) (filename string,
+	err error) {
+	var fn filepath.WalkFunc = func(path string,
+		info os.FileInfo,
+		fileErr error) error {
+		if fileErr != nil {
+			return fileErr
+		}
+		if !info.IsDir() &&
+			filepath.Ext(path) == ".png" {
+			filename = path
+			return nil
+		}
+		return nil
+	}
+	err = filepath.Walk(root, fn)
+	return
+}
+
+func TestColorToHex(t *testing.T) {
+	root := os.Getenv("HOME")
+	path, err := firstPNG(root)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f, err := os.Open(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	img, err := png.Decode(f)
+	if err != nil {
+		t.Fatal(err)
+	}
+	fmt.Println(ColorToHex(img.At(0, 0)))
+}

util/stdio.go

@@ -0,0 +1,20 @@
+package util
+
+import (
+	"image"
+	"image/png"
+	"os"
+)
+
+// ProcessImage takes input png image from stdin, processes it with f and outputs it to stdout.
+func ProcessStdio(f func(image.Image) image.Image) error {
+	img, err := png.Decode(os.Stdin)
+	if err != nil {
+		return err
+	}
+	err = png.Encode(os.Stdout, f(img))
+	if err != nil {
+		return err
+	}
+	return err
+}