to save up a progress

pkg/dithering/grid.go

@@ -7,10 +7,14 @@ import (
 
 const side = 16
 
+type Options struct {
+	Factor float64
+}
+
 // tile
 type grid struct {
 	color.Gray
-	Factor float64
+	Options
 }
 
 func (_ grid) ColorModel() color.Model {
@@ -22,7 +26,7 @@ func (_ grid) Bounds() image.Rectangle {
 }
 
 func (g grid) At(x, y int) color.Color {
-	n := uint8(float64(g.Gray.Y) * g.Factor)
+	n := uint8(float64(g.Gray.Y) * g.Options.Factor)
 
 	if n == 0 {
 		return color.Black
@@ -54,13 +58,13 @@ func (g uniformGrid) At(x, y int) color.Color {
 
 type Dithering struct {
 	image.Image
-	Factor float64
+	Options
 }
 
 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), d.Factor}}.
+	return uniformGrid{grid{c.(color.Gray), d.Options.Factor}}.
 		At(x, y)
 }