new simple downscaling ideas

cmd/playground/circles/circles.go

@@ -27,24 +27,6 @@ func Circles(b image.Rectangle, radius int) chan iu.Circle {
 	return ch
 }
 
-var Opaque, Transparent = color.Alpha{0xff}, color.Alpha{0}
-
-type xor struct{ dst, src image.Image }
-
-func (t xor) ColorModel() color.Model { return t.dst.ColorModel() }
-func (t xor) Bounds() image.Rectangle { return t.src.Bounds() }
-func (t xor) At(x, y int) color.Color {
-	dstColor := t.ColorModel().Convert(t.dst.At(x, y))
-	srcColor := t.ColorModel().Convert(t.src.At(x, y))
-
-	
-	if ((dstColor == color.Opaque) || (srcColor == color.Opaque)) && 
-		!((dstColor == color.Opaque) && (srcColor == color.Opaque)) {
-		return color.Opaque
-	}
-	return color.Transparent
-}
-
 var exchange = color.ModelFunc(
 	func(c color.Color) color.Color {
 		if color.Alpha16Model.Convert(c) == color.Transparent{
@@ -63,29 +45,21 @@ func (e Exchange) At(x, y int) color.Color {
 	return exchange.Convert(c)
 }
 
-func main() {
-	canvas := image.NewAlpha16(square(1024))
-	circles := Circles(canvas.Bounds(), 1024/7)
+var blackAndWhite = color.ModelFunc(
+	func(c color.Color) color.Color {
+		if color.Alpha16Model.Convert(c) == color.Transparent{
+			return color.Black
+		}
+		return color.White
+	},
+)
 
-	// draw n circles
-	for i := 0; i < 500; i++ {
-		c := <-circles
+// Black and white's alpha image.
+type BlackAndWhite struct { image.Image }
 
-		draw.Draw(canvas, c.Bounds(), xor{c, canvas}, c.Bounds().Min, draw.Src)
-		/*
-		draw.DrawMask(
-			canvas, canvas.Bounds(), &image.Uniform{color.White},
-			image.Point{}, xor{c, canvas}, image.Point{}, draw.Src,
-		)
-		*/
-	}
-	/*
-		newCanvas := image.NewRGBA(canvas.Bounds())
-		draw.Draw(newCanvas, newCanvas.Bounds(), &image.Uniform{color.RGBA{255, 255, 0, 255}}, image.ZP, draw.Over)
-		draw.Draw(newCanvas, newCanvas.Bounds(), canvas, image.ZP, draw.Over)
-	*/
-	err := png.Encode(os.Stdout, canvas)
-	if err != nil {
-		panic(err)
-	}
+func (b BlackAndWhite) ColorModel() color.Model { return color.GrayModel }
+func (b BlackAndWhite) Bounds() image.Rectangle { return b.Image.Bounds() }
+func (b BlackAndWhite) At(x, y int) color.Color {
+	c := b.Image.At(x, y)
+	return blackAndWhite.Convert(c)
 }