some redesign

pkg/dithering/8x8grid.go

@@ -0,0 +1,43 @@
+package dithering
+
+import (
+	"image"
+	"image/color"
+)
+
+type grid struct {
+	color.Gray
+}
+
+func (_ grid) ColorModel() color.Model {
+	return color.RGBAModel
+}
+
+func (_ grid) Bounds() image.Rectangle {
+	return image.Rect(0, 0, 8, 8)
+}
+
+func (g grid) At(x, y int) color.Color {
+	step := int(64 / (g.Gray.Y / 4))
+	if (y*8+x)%step == 0 {
+		return color.Black
+	}
+	return color.White
+}
+
+type uniformGrid struct {
+	image.Image
+	image.Rectangle
+}
+
+func (g uniformGrid) ColorModel() color.Model {
+	return g.Image.ColorModel()
+}
+
+func (g uniformGrid) Bounds() image.Rectangle {
+	return g.Rectangle
+}
+
+func (g uniformGrid) At(x, y int) color.Color {
+	return color.Color(nil)
+}

pkg/dithering/8x8grid_test.go

@@ -0,0 +1,35 @@
+package dithering
+
+import (
+	"image/color"
+	"image/png"
+	"math/rand"
+	"os/exec"
+	"testing"
+	"time"
+
+	"git.nkpl.cc/twocookedfaggots/imageutils"
+)
+
+func TestGrid(t *testing.T) {
+	rand.Seed(time.Now().UnixNano())
+
+	command := exec.Command("imv", "-")
+	w, err := command.StdinPipe()
+	if err != nil {
+		t.Error(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)
+	}
+}

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

@@ -21,11 +21,11 @@ func Render(img image.Image, rect image.Rectangle) image.Image {
 func BenchmarkScale(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		err := png.Encode(io.Discard,
-			Scale(Render(
+			Scale(64, Render(
 				texture.New(color.White,
 					color.Black, 2),
 				image.Rect(0, 0, 64, 64),
-			), 64),
+			)),
 		)
 		if err != nil {
 			panic(err)
@@ -51,7 +51,7 @@ func (s SinglePixel) Bounds() image.Rectangle {
 func BenchmarkSinglePixel(b *testing.B) {
 	instance := SinglePixel{}
 	err := png.Encode(io.Discard,
-		Scale(instance, b.N),
+		Scale(b.N, instance),
 	)
 	if err != nil {
 		panic(err)