Golang raster.NewRasterizer函數代碼示例

// NewGraphicContext creates a new Graphic context from an image.
func NewGraphicContext(width, height int) *GraphicContext {
	gc := &GraphicContext{
		draw2dbase.NewStackGraphicContext(),
		NewPainter(),
		raster.NewRasterizer(width, height),
		raster.NewRasterizer(width, height),
	}
	return gc
}

// NewGraphicContextWithPainter creates a new Graphic context from an image and a Painter (see Freetype-go)
func NewGraphicContextWithPainter(img draw.Image, painter Painter) *GraphicContext {
	width, height := img.Bounds().Dx(), img.Bounds().Dy()
	dpi := 92
	gc := &GraphicContext{
		draw2dbase.NewStackGraphicContext(),
		img,
		painter,
		raster.NewRasterizer(width, height),
		raster.NewRasterizer(width, height),
		truetype.NewGlyphBuf(),
		dpi,
	}
	return gc
}

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)
	}
}

// NewContext creates a new Context.
func NewContext() *Context {
	return &Context{
		r:        raster.NewRasterizer(0, 0),
		fontSize: 12,
		dpi:      72,
		scale:    12 << 6,
	}
}

func main() {
	const (
		w = 400
		h = 400
	)
	r := raster.NewRasterizer(w, h)
	r.UseNonZeroWinding = true

	cjs := []struct {
		c raster.Capper
		j raster.Joiner
	}{
		{raster.RoundCapper, raster.RoundJoiner},
		{raster.ButtCapper, raster.BevelJoiner},
		{raster.SquareCapper, raster.BevelJoiner},
	}

	for i, cj := range cjs {
		var path raster.Path
		path.Start(fixed.P(30+100*i, 30+120*i))
		path.Add1(fixed.P(180+100*i, 80+120*i))
		path.Add1(fixed.P(50+100*i, 130+120*i))
		raster.Stroke(r, path, fixed.I(20), cj.c, cj.j)
	}

	rgba := image.NewRGBA(image.Rect(0, 0, w, h))
	draw.Draw(rgba, rgba.Bounds(), image.Black, image.Point{}, draw.Src)
	p := raster.NewRGBAPainter(rgba)
	p.SetColor(color.RGBA{0x7f, 0x7f, 0x7f, 0xff})
	r.Rasterize(p)

	white := color.RGBA{0xff, 0xff, 0xff, 0xff}
	for i := range cjs {
		rgba.SetRGBA(30+100*i, 30+120*i, white)
		rgba.SetRGBA(180+100*i, 80+120*i, white)
		rgba.SetRGBA(50+100*i, 130+120*i, white)
	}

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

// NewContext creates a new Context.
func NewContext() *Context {
	return &Context{
		r:        raster.NewRasterizer(0, 0),
		glyphBuf: truetype.NewGlyphBuf(),
		fontSize: 12,
		dpi:      108,
		scale:    12 << 6,
	}
}

func main() {
	// Draw a rounded corner that is one pixel wide.
	r := raster.NewRasterizer(50, 50)
	r.Start(p(5, 5))
	r.Add1(p(5, 25))
	r.Add2(p(5, 45), p(25, 45))
	r.Add1(p(45, 45))
	r.Add1(p(45, 44))
	r.Add1(p(26, 44))
	r.Add2(p(6, 44), p(6, 24))
	r.Add1(p(6, 5))
	r.Add1(p(5, 5))

	// Rasterize that curve multiple times at different gammas.
	const (
		w = 600
		h = 200
	)
	rgba := image.NewRGBA(image.Rect(0, 0, w, h))
	draw.Draw(rgba, image.Rect(0, 0, w, h/2), image.Black, image.ZP, draw.Src)
	draw.Draw(rgba, image.Rect(0, h/2, w, h), image.White, image.ZP, draw.Src)
	mask := image.NewAlpha(image.Rect(0, 0, 50, 50))
	painter := raster.NewAlphaSrcPainter(mask)
	gammas := []float64{1.0 / 10.0, 1.0 / 3.0, 1.0 / 2.0, 2.0 / 3.0, 4.0 / 5.0, 1.0, 5.0 / 4.0, 3.0 / 2.0, 2.0, 3.0, 10.0}
	for i, g := range gammas {
		draw.Draw(mask, mask.Bounds(), image.Transparent, image.ZP, draw.Src)
		r.Rasterize(raster.NewGammaCorrectionPainter(painter, g))
		x, y := 50*i+25, 25
		draw.DrawMask(rgba, image.Rect(x, y, x+50, y+50), image.White, image.ZP, mask, image.ZP, draw.Over)
		y += 100
		draw.DrawMask(rgba, image.Rect(x, y, x+50, y+50), image.Black, image.ZP, mask, image.ZP, draw.Over)
	}

	// 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, rgba)
	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.")
}

func createGlyphPage(resolution resolution, glyphMaxSizePixels math.Size) *glyphPage {
	// Handle exceptionally large glyphs.
	size := math.Size{W: glyphPageWidth, H: glyphPageHeight}.Max(glyphMaxSizePixels)
	size.W = align(size.W, glyphSizeAlignment)
	size.H = align(size.H, glyphSizeAlignment)

	return &glyphPage{
		resolution:         resolution,
		glyphMaxSizePixels: glyphMaxSizePixels,
		size:               size,
		image:              image.NewAlpha(image.Rect(0, 0, size.W, size.H)),
		offsets:            make(map[rune]math.Point),
		rowHeight:          0,
		rast:               raster.NewRasterizer(glyphMaxSizePixels.W, glyphMaxSizePixels.H),
	}
}

func main() {
	// Rasterize the contours to a mask image.
	const (
		w = 400
		h = 400
	)
	r := raster.NewRasterizer(w, h)
	contour(r, outside)
	contour(r, inside)
	mask := image.NewAlpha(image.Rect(0, 0, w, h))
	p := raster.NewAlphaSrcPainter(mask)
	r.Rasterize(p)

	// Draw the mask image (in gray) onto an RGBA image.
	rgba := image.NewRGBA(image.Rect(0, 0, w, h))
	gray := image.NewUniform(color.Alpha{0x1f})
	draw.Draw(rgba, rgba.Bounds(), image.Black, image.ZP, draw.Src)
	draw.DrawMask(rgba, rgba.Bounds(), gray, image.ZP, mask, image.ZP, draw.Over)
	showNodes(rgba, outside)
	showNodes(rgba, inside)

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

func TestFreetypeNonZeroWinding(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)

	draw2dimg.SaveToPngFile("../output/raster/TestFreetypeNonZeroWinding.png", img)
}

func main() {
	const (
		n = 17
		r = 64 * 80
	)
	s := fixed.Int26_6(r * math.Sqrt(2) / 2)
	t := fixed.Int26_6(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 := fixed.Int26_6(6400 + 12800*(i%4))
		cy := fixed.Int26_6(640 + 8000*(i/4))
		c := fixed.Point26_6{X: cx, Y: cy}
		theta := math.Pi * (0.5 + 0.5*float64(i)/(n-1))
		dx := fixed.Int26_6(r * math.Cos(theta))
		dy := fixed.Int26_6(r * math.Sin(theta))
		d := fixed.Point26_6{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(fixed.Point26_6{X: r, Y: 0}))
		z.Add2(c.Add(fixed.Point26_6{X: r, Y: t}), c.Add(fixed.Point26_6{X: s, Y: s}))
		z.Add2(c.Add(fixed.Point26_6{X: t, Y: r}), c.Add(fixed.Point26_6{X: 0, Y: r}))
		// Add another quadratic segment whose angle ranges between 0 and 90
		// degrees. For an explanation of the magic constants 128, 150, 181 and
		// 256, read the comments in the freetype/raster package.
		dot := 256 * pDot(d, fixed.Point26_6{X: 0, Y: r}) / (r * r)
		multiple := fixed.Int26_6(150-(150-128)*(dot-181)/(256-181)) >> 2
		z.Add2(c.Add(fixed.Point26_6{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 := fixed.Int26_6(6400 + 12800*(i%4))
		cy := fixed.Int26_6(640 + 8000*(i/4))
		for j := 0; j < n; j++ {
			theta := math.Pi * float64(j) / (n - 1)
			dx := fixed.Int26_6(r * math.Cos(theta))
			dy := fixed.Int26_6(r * math.Sin(theta))
			m.Set(int((cx+dx)/64), int((cy+dy)/64), color.RGBA{255, 255, 0, 255})
		}
	}

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

func (s *Sparkline) Draw(dst draw.Image) {
	if len(s.data) == 0 {
		return
	}

	min := s.data[0]
	max := s.data[0]
	for _, n := range s.data[1:] {
		if n < min {
			min = n
		}
		if n > max {
			max = n
		}
	}

	// try to be helpful when there's limited data
	if max < 1.0 {
		max = 1.0
	}
	if min > max-1.0 {
		min = max - 1.0
		if min < 0.0 {
			min = 0.0
		}
	}

	bounds := dst.Bounds()
	dx, dy := bounds.Dx(), bounds.Dy()

	tmp := image.NewRGBA(image.Rectangle{Max: image.Point{X: dx, Y: dy}})
	p := raster.NewRGBAPainter(tmp)

	r := raster.NewRasterizer(dx, dy)
	r.UseNonZeroWinding = true

	var q raster.Path
	q.Start(s.scale(0, s.data[0], min, max, dx, dy))
	for i, n := range s.data[1:] {
		pt := s.scale(i+1, n, min, max, dx, dy)
		q.Add1(pt)
	}
	const strokeWidth = fixed.Int26_6(5 << 6)
	r.AddStroke(q, strokeWidth, raster.RoundCapper, raster.RoundJoiner)
	p.SetColor(s.fg)
	r.Rasterize(p)

	r.Clear()
	q.Clear()
	headPt := s.scale(len(s.data)-1, s.data[len(s.data)-1], min, max, dx, dy)
	q.Start(headPt)
	// miniscule nudge so something actually is output
	q.Add1(headPt.Add(fixed.Point26_6{X: 1, Y: 1}))
	const headWidth = fixed.Int26_6(8 << 6)
	r.AddStroke(q, headWidth, raster.RoundCapper, raster.RoundJoiner)
	// TODO really decide between uint64 vs float32 vs uint32 etc
	//	value := uint64((s.data[len(s.data)-1] - min) / max * float32(^uint64(0)))
	value := uint64(s.data[len(s.data)-1])
	headColor := PickColor(s.thresholds, value)
	p.SetColor(headColor)
	r.Rasterize(p)
	draw.Draw(dst, bounds, tmp, image.ZP, draw.Over)
}

func Handler(w http.ResponseWriter, req *http.Request) {
	const size = 500
	c := image.NewRGBA(image.Rect(0, 0, size, size))
	white := &image.Uniform{C: color.White}
	draw.Draw(c, c.Bounds(), white, image.ZP, draw.Src)

	p := raster.NewRGBAPainter(c)
	p.SetColor(color.Black)
	r := raster.NewRasterizer(500, 500)
	r.UseNonZeroWinding = true
	var path raster.Path
	path.Start(nudge(fixed.P(50, 50)))
	path.Add1(nudge(fixed.P(50, 450)))
	path.Add1(nudge(fixed.P(450, 450)))
	r.AddStroke(path, fixed.I(2), raster.ButtCapper, raster.BevelJoiner)
	r.Rasterize(p)
	r.Clear()

	p.SetColor(color.Gray16{0x7FFF})
	path.Clear()
	r.Clear()
	path.Start(nudge(fixed.P(450, 450)))
	path.Add1(nudge(fixed.P(450, 50)))
	path.Add1(nudge(fixed.P(50, 50)))
	r.AddStroke(path, fixed.I(1), raster.ButtCapper, raster.BevelJoiner)
	r.Rasterize(p)

	p.SetColor(color.Gray16{0x7FFF})
	for x := 50; x <= 450; x += 50 {
		path.Clear()
		path.Start(nudge(fixed.P(x, 450)))
		path.Add1(nudge(fixed.P(x, 460)))
		r.AddStroke(path, fixed.I(1), raster.ButtCapper, raster.BevelJoiner)
	}
	for x := 50; x <= 450; x += 50 {
		path.Clear()
		path.Start(nudge(fixed.P(50, x)))
		path.Add1(nudge(fixed.P(40, x)))
		r.AddStroke(path, fixed.I(1), raster.ButtCapper, raster.BevelJoiner)
	}
	r.Rasterize(p)

	p.SetColor(color.RGBA{0x00, 0x00, 0xFF, 0xFF})
	r.Clear()
	path.Clear()
	path.Start(nudge(fixed.P(50, 450)))
	path.Add1(nudge(fixed.P(450, 50)))
	r.AddStroke(path, fixed.I(1), raster.ButtCapper, raster.BevelJoiner)
	r.Rasterize(p)

	p.SetColor(color.RGBA{0xCC, 0x00, 0x00, 0xFF})
	r.Clear()
	window := fixed.Rectangle26_6{fixed.P(50, 450), fixed.P(450, 50)}
	//	path = plotPath(ratSin, big.NewRat(0, 1), big.NewRat(-1, 1), big.NewRat(10, 1), big.NewRat(1, 1), window)

	//	path = plotPath(ratProb, big.NewRat(0, 1), big.NewRat(0, 1), big.NewRat(1, 1<<57), big.NewRat(1, 1<<57), window)

	var lo, hi *big.Rat
	var locap, hicap, scalecap string
	id, _ := strconv.Atoi(req.FormValue("x"))
	switch id {
	case 0:
		lo = big.NewRat(1<<53-1<<3, 1<<54)
		hi = big.NewRat(1<<53+1<<3, 1<<54)
		locap = "1/2 - 1/2^51"
		hicap = "1/2 + 1/2^51"
		scalecap = "1/2^53"
	case 1:
		lo = big.NewRat(1<<54-1<<4, 1<<54)
		hi = big.NewRat(1<<54, 1<<54)
		locap = "1 - 1/2^50"
		hicap = "1"
		scalecap = "1/2^53"
	case 2:
		lo = big.NewRat(0, 1<<54)
		hi = big.NewRat(1<<4, 1<<54)
		locap = "0"
		hicap = "1/2^50"
		scalecap = "1/2^53"
	case 3:
		lo = big.NewRat(0, 1<<54)
		hi = big.NewRat(1<<2, 1<<62)
		locap = "0"
		hicap = "1/2^59"
		scalecap = "1/2^63"
	}

	mode, _ := strconv.Atoi(req.FormValue("mode"))
	path = plotPath(ratProb(mode), lo, lo, hi, hi, window)
	r.AddStroke(path, fixed.I(1), raster.ButtCapper, raster.BevelJoiner)
	r.Rasterize(p)

	var modestr string
	switch mode {
	case 0:
		modestr = "original behavior (can return 1)"
	case 1:
		modestr = "new behavior (too much 0)"
	case 2:
		modestr = "retry loop"
//.........這裏部分代碼省略.........