Golang raster.NewRGBAPainter函數代碼示例

/**
 * Create a new Graphic context from an image
 */
func NewGraphicContext(img draw.Image) *ImageGraphicContext {
	var painter Painter
	switch selectImage := img.(type) {
	case *image.RGBA:
		painter = raster.NewRGBAPainter(selectImage)
	//case *image.NRGBA:
	//	painter = NewNRGBAPainter(selectImage)
	default:
		panic("Image type not supported")
	}
	width, height := img.Bounds().Dx(), img.Bounds().Dy()
	dpi := 92
	ftContext := freetype.NewContext()
	ftContext.SetDPI(dpi)
	ftContext.SetClip(img.Bounds())
	ftContext.SetDst(img)
	gc := &ImageGraphicContext{
		NewStackGraphicContext(),
		img,
		painter,
		raster.NewRasterizer(width, height),
		raster.NewRasterizer(width, height),
		ftContext,
		dpi,
	}
	return gc
}

func TestFreetypeNonZeroWinding(t *testing.T) {
	var p Path
	p.LineTo(10, 190)
	c := curve.CubicCurveFloat64{10, 190, 10, 10, 190, 10, 190, 190}
	c.Segment(&p, flatteningThreshold)
	poly := Polygon(p.points)
	color := color.RGBA{0, 0, 0, 0xff}

	img := image.NewRGBA(image.Rect(0, 0, 200, 200))
	rasterizer := raster.NewRasterizer(200, 200)
	rasterizer.UseNonZeroWinding = true
	rasterizer.Start(raster.Point{
		X: raster.Fix32(10 * 256),
		Y: raster.Fix32(190 * 256)})
	for j := 0; j < len(poly); j = j + 2 {
		rasterizer.Add1(raster.Point{
			X: raster.Fix32(poly[j] * 256),
			Y: raster.Fix32(poly[j+1] * 256)})
	}
	painter := raster.NewRGBAPainter(img)
	painter.SetColor(color)
	rasterizer.Rasterize(painter)

	savepng("../output/raster/TestFreetypeNonZeroWinding.png", img)
}

func BenchmarkFreetype(b *testing.B) {
	var p Path
	p.LineTo(10, 190)
	c := curve.CubicCurveFloat64{10, 190, 10, 10, 190, 10, 190, 190}
	c.Segment(&p, flatteningThreshold)
	poly := Polygon(p.points)
	color := color.RGBA{0, 0, 0, 0xff}

	for i := 0; i < b.N; i++ {
		img := image.NewRGBA(image.Rect(0, 0, 200, 200))
		rasterizer := raster.NewRasterizer(200, 200)
		rasterizer.UseNonZeroWinding = false
		rasterizer.Start(raster.Point{
			X: raster.Fix32(10 * 256),
			Y: raster.Fix32(190 * 256)})
		for j := 0; j < len(poly); j = j + 2 {
			rasterizer.Add1(raster.Point{
				X: raster.Fix32(poly[j] * 256),
				Y: raster.Fix32(poly[j+1] * 256)})
		}
		painter := raster.NewRGBAPainter(img)
		painter.SetColor(color)
		rasterizer.Rasterize(painter)
	}
}

func TestFreetypeRasterizerNonZeroWinding(t *testing.T) {
	var p Path
	p.LineTo(10, 190)
	draw2dbase.TraceCubic(&p, []float64{10, 190, 10, 10, 190, 10, 190, 190}, 0.5)
	poly := Polygon(p.points)
	color := color.RGBA{0, 0, 0, 0xff}

	img := image.NewRGBA(image.Rect(0, 0, 200, 200))
	rasterizer := raster.NewRasterizer(200, 200)
	rasterizer.UseNonZeroWinding = true
	rasterizer.Start(raster.Point{
		X: raster.Fix32(10 * 256),
		Y: raster.Fix32(190 * 256)})
	for j := 0; j < len(poly); j = j + 2 {
		rasterizer.Add1(raster.Point{
			X: raster.Fix32(poly[j] * 256),
			Y: raster.Fix32(poly[j+1] * 256)})
	}
	painter := raster.NewRGBAPainter(img)
	painter.SetColor(color)
	rasterizer.Rasterize(painter)

	err := draw2dimg.SaveToPngFile("output/TestFreetypeRasterizerNonZeroWinding.png", img)
	if err != nil {
		fmt.Println(err)
	}
}

func BenchmarkFreetypeNonZeroWinding(b *testing.B) {
	var p Path
	p.LineTo(10, 190)
	draw2dbase.TraceCubic(&p, []float64{10, 190, 10, 10, 190, 10, 190, 190}, 0.5)

	poly := Polygon(p.points)
	color := color.RGBA{0, 0, 0, 0xff}

	for i := 0; i < b.N; i++ {
		img := image.NewRGBA(image.Rect(0, 0, 200, 200))
		rasterizer := raster.NewRasterizer(200, 200)
		rasterizer.UseNonZeroWinding = true
		rasterizer.Start(raster.Point{
			X: raster.Fix32(10 * 256),
			Y: raster.Fix32(190 * 256)})
		for j := 0; j < len(poly); j = j + 2 {
			rasterizer.Add1(raster.Point{
				X: raster.Fix32(poly[j] * 256),
				Y: raster.Fix32(poly[j+1] * 256)})
		}
		painter := raster.NewRGBAPainter(img)
		painter.SetColor(color)
		rasterizer.Rasterize(painter)
	}
}

// NewGraphicContext creates a new Graphic context from an image.
func NewGraphicContext(img draw.Image) *ImageGraphicContext {
	var painter Painter
	switch selectImage := img.(type) {
	case *image.RGBA:
		painter = raster.NewRGBAPainter(selectImage)
	default:
		panic("Image type not supported")
	}
	return NewGraphicContextWithPainter(img, painter)
}

// Make a new canvas of size w x h.
func NewCanvas(w, h int) *Canvas {
	c := new(Canvas)
	c.RGBA = image.NewRGBA(image.Rect(0, 0, w, h))
	c.Clear(color.White)
	c.painter = raster.NewRGBAPainter(c.RGBA)
	c.rasterizer = raster.NewRasterizer(w, h)
	c.rasterizer.UseNonZeroWinding = true
	c.SetColor(color.Black)
	c.path = make(raster.Path, 0, 100)
	c.resetPath()
	c.SetStroke(1, Round)
	return c
}

// moustache draws a moustache of the specified size and droop
// onto the image m and returns the result. It may overwrite the
// original.
func moustache(m image.Image, x, y, size, droopFactor int) image.Image {
	mrgba := rgba(m)

	p := raster.NewRGBAPainter(mrgba)
	p.SetColor(color.RGBA{0, 0, 0, 255})

	w, h := m.Bounds().Dx(), m.Bounds().Dy()
	r := raster.NewRasterizer(w, h)
	var (
		mag   = raster.Fix32((10 + size) << 8)
		width = pt(20, 0).Mul(mag)
		mid   = pt(x, y)
		droop = pt(0, droopFactor).Mul(mag)
		left  = mid.Sub(width).Add(droop)
		right = mid.Add(width).Add(droop)
		bow   = pt(0, 5).Mul(mag).Sub(droop)
		curlx = pt(10, 0).Mul(mag)
		curly = pt(0, 2).Mul(mag)
		risex = pt(2, 0).Mul(mag)
		risey = pt(0, 5).Mul(mag)
	)
	r.Start(left)
	r.Add3(
		mid.Sub(curlx).Add(curly),
		mid.Sub(risex).Sub(risey),
		mid,
	)
	r.Add3(
		mid.Add(risex).Sub(risey),
		mid.Add(curlx).Add(curly),
		right,
	)
	r.Add2(
		mid.Add(bow),
		left,
	)
	r.Rasterize(p)

	return mrgba
}

// NewPainter returns a Painter that will draw from src onto
// dst using the Porter-Duff composition operator op.
func NewPainter(dst draw.Image, src image.Image, op draw.Op) (p raster.Painter) {
	defer func() { fmt.Printf("newpainter %T\n", p) }()
	if src, ok := src.(*image.Uniform); ok {
		switch dst := dst.(type) {
		case *image.Alpha:
			if _, _, _, a := src.RGBA(); a == 0xffff {
				switch op {
				case draw.Src:
					return &raster.AlphaSrcPainter{dst}
				case draw.Over:
					return &raster.AlphaOverPainter{dst}
				}
			}

		case *image.RGBA:
			p := raster.NewRGBAPainter(dst)
			p.SetColor(src)
			p.Op = op
			return p
		}
	}
	return &genericImagePainter{dst, src, op}
}

// the returned zoneOfColor always has A == 256.
func worldImage(t *testing.T) (im *image.RGBA, zoneOfColor map[color.RGBA]string) {
	scale := *flagScale
	width := int(scale * 360)
	height := int(scale * 180)

	im = image.NewRGBA(image.Rect(0, 0, width, height))
	zoneOfColor = map[color.RGBA]string{}
	tab := crc32.MakeTable(crc32.IEEE + 1)

	drawPoly := func(col color.RGBA, xys ...int) {
		painter := raster.NewRGBAPainter(im)
		painter.SetColor(col)
		r := raster.NewRasterizer(width, height)
		r.Start(raster.Point{X: raster.Fix32(xys[0]) << 8, Y: raster.Fix32(xys[1]) << 8})
		for i := 2; i < len(xys); i += 2 {
			r.Add1(raster.Point{X: raster.Fix32(xys[i]) << 8, Y: raster.Fix32(xys[i+1]) << 8})
		}
		r.Add1(raster.Point{X: raster.Fix32(xys[0]) << 8, Y: raster.Fix32(xys[1]) << 8})
		r.Rasterize(raster.NewMonochromePainter(painter))
	}

	sr, err := shp.Open("world/tz_world.shp")
	if err != nil {
		t.Fatalf("Error opening world/tz_world.shp: %v; unzip it from http://efele.net/maps/tz/world/tz_world.zip", err)
	}
	defer sr.Close()

	for sr.Next() {
		i, s := sr.Shape()
		p, ok := s.(*shp.Polygon)
		if !ok {
			t.Fatalf("Unknown shape %T", p)
		}
		zoneName := sr.ReadAttribute(i, 0)
		if zoneName == "uninhabited" {
			continue
		}
		if _, err := time.LoadLocation(zoneName); err != nil {
			t.Fatalf("Failed to load: %v (%v)", zoneName, err)
		}
		hash := crc32.Checksum([]byte(zoneName), tab)
		col := color.RGBA{uint8(hash >> 24), uint8(hash >> 16), uint8(hash >> 8), 255}
		if name, ok := zoneOfColor[col]; ok {
			if name != zoneName {
				log.Fatalf("Color %+v dup: %s and %s", col, name, zoneName)
			}
		} else {
			zoneOfColor[col] = zoneName
		}

		var xys []int
		for _, pt := range p.Points {
			xys = append(xys, int((pt.X+180)*scale), int((90-pt.Y)*scale))
		}
		drawPoly(col, xys...)
	}

	// adjust point from scale 32 to whatever the user is using.
	ap := func(x int) int { return x * int(scale) / 32 }
	// Fix some rendering glitches:
	// {186 205 234 255} = Europe/Rome
	drawPoly(color.RGBA{186, 205, 234, 255},
		ap(6156), ap(1468),
		ap(6293), ap(1596),
		ap(6293), ap(1598),
		ap(6156), ap(1540))
	// {136 136 180 255} = America/Boise
	drawPoly(color.RGBA{136, 136, 180, 255},
		ap(2145), ap(1468),
		ap(2189), ap(1468),
		ap(2189), ap(1536),
		ap(2145), ap(1536))
	// {120 247 14 255} = America/Denver
	drawPoly(color.RGBA{120, 247, 14, 255},
		ap(2167), ap(1536),
		ap(2171), ap(1536),
		ap(2217), ap(1714),
		ap(2204), ap(1724),
		ap(2160), ap(1537))
	return
}

func main() {
	const (
		n = 17
		r = 256 * 80
	)
	s := raster.Fix32(r * math.Sqrt(2) / 2)
	t := raster.Fix32(r * math.Tan(math.Pi/8))

	m := image.NewRGBA(image.Rect(0, 0, 800, 600))
	draw.Draw(m, m.Bounds(), image.NewUniform(color.RGBA{63, 63, 63, 255}), image.ZP, draw.Src)
	mp := raster.NewRGBAPainter(m)
	mp.SetColor(image.Black)
	z := raster.NewRasterizer(800, 600)

	for i := 0; i < n; i++ {
		cx := raster.Fix32(25600 + 51200*(i%4))
		cy := raster.Fix32(2560 + 32000*(i/4))
		c := raster.Point{X: cx, Y: cy}
		theta := math.Pi * (0.5 + 0.5*float64(i)/(n-1))
		dx := raster.Fix32(r * math.Cos(theta))
		dy := raster.Fix32(r * math.Sin(theta))
		d := raster.Point{X: dx, Y: dy}
		// Draw a quarter-circle approximated by two quadratic segments,
		// with each segment spanning 45 degrees.
		z.Start(c)
		z.Add1(c.Add(raster.Point{X: r, Y: 0}))
		z.Add2(c.Add(raster.Point{X: r, Y: t}), c.Add(raster.Point{X: s, Y: s}))
		z.Add2(c.Add(raster.Point{X: t, Y: r}), c.Add(raster.Point{X: 0, Y: r}))
		// Add another quadratic segment whose angle ranges between 0 and 90 degrees.
		// For an explanation of the magic constants 22, 150, 181 and 256, read the
		// comments in the freetype/raster package.
		dot := 256 * d.Dot(raster.Point{X: 0, Y: r}) / (r * r)
		multiple := raster.Fix32(150 - 22*(dot-181)/(256-181))
		z.Add2(c.Add(raster.Point{X: dx, Y: r + dy}.Mul(multiple)), c.Add(d))
		// Close the curve.
		z.Add1(c)
	}
	z.Rasterize(mp)

	for i := 0; i < n; i++ {
		cx := raster.Fix32(25600 + 51200*(i%4))
		cy := raster.Fix32(2560 + 32000*(i/4))
		for j := 0; j < n; j++ {
			theta := math.Pi * float64(j) / (n - 1)
			dx := raster.Fix32(r * math.Cos(theta))
			dy := raster.Fix32(r * math.Sin(theta))
			m.Set(int((cx+dx)/256), int((cy+dy)/256), color.RGBA{255, 255, 0, 255})
		}
	}

	// Save that RGBA image to disk.
	f, err := os.Create("out.png")
	if err != nil {
		log.Println(err)
		os.Exit(1)
	}
	defer f.Close()
	b := bufio.NewWriter(f)
	err = png.Encode(b, m)
	if err != nil {
		log.Println(err)
		os.Exit(1)
	}
	err = b.Flush()
	if err != nil {
		log.Println(err)
		os.Exit(1)
	}
	fmt.Println("Wrote out.png OK.")
}