dithering done :)

pkg/dithering/8x8grid.go

@@ -18,16 +18,19 @@ func (_ grid) Bounds() image.Rectangle {
 }
 
 func (g grid) At(x, y int) color.Color {
-	step := int(64 / (g.Gray.Y / 4))
-	if (y*8+x)%step == 0 {
+	n := g.Gray.Y / 4
+	if n == 0 {
 		return color.Black
 	}
-	return color.White
+	step := int(64 / n)
+	if (y*8+x)%step == 0 {
+		return color.White
+	}
+	return color.Black
 }
 
 type uniformGrid struct {
 	image.Image
-	image.Rectangle
 }
 
 func (g uniformGrid) ColorModel() color.Model {
@@ -35,9 +38,23 @@ func (g uniformGrid) ColorModel() color.Model {
 }
 
 func (g uniformGrid) Bounds() image.Rectangle {
-	return g.Rectangle
+	// just need to return something
+	return g.Image.Bounds()
 }
 
 func (g uniformGrid) At(x, y int) color.Color {
-	return color.Color(nil)
+	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/8x8grid_test.go

@@ -1,9 +1,11 @@
 package dithering
 
 import (
+	"image"
 	"image/color"
 	"image/png"
 	"math/rand"
+	"os"
 	"os/exec"
 	"testing"
 	"time"
@@ -11,25 +13,61 @@ import (
 	"git.nkpl.cc/twocookedfaggots/imageutils"
 )
 
-func TestGrid(t *testing.T) {
+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.Error(err)
+		t.Fatal(err)
 	}
-	img := imageutils.Scale(1<<6, grid{color.Gray{uint8(rand.Int() % 64)}})
-
-	go func() {
-		err = png.Encode(w, img)
-		if err != nil {
-			t.Error(err)
-		}
-	}()
-	
 	err = command.Start()
 	if err != nil {
-		t.Error(err)
+		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/dithering/cmd/main.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"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)
+	}
+}