示例#1
0
// rasterize returns the glyph mask and integer-pixel offset to render the
// given glyph at the given sub-pixel offsets.
// The 24.8 fixed point arguments fx and fy must be in the range [0, 1).
func (c *Context) rasterize(glyph truetype.Index, fx, fy raster.Fix32) (*image.Alpha, image.Point, error) {
	if err := c.glyphBuf.Load(c.font, c.scale, glyph, nil); err != nil {
		return nil, image.ZP, err
	}
	// Calculate the integer-pixel bounds for the glyph.
	xmin := int(fx+raster.Fix32(c.glyphBuf.B.XMin<<2)) >> 8
	ymin := int(fy-raster.Fix32(c.glyphBuf.B.YMax<<2)) >> 8
	xmax := int(fx+raster.Fix32(c.glyphBuf.B.XMax<<2)+0xff) >> 8
	ymax := int(fy-raster.Fix32(c.glyphBuf.B.YMin<<2)+0xff) >> 8
	if xmin > xmax || ymin > ymax {
		return nil, image.ZP, errors.New("freetype: negative sized glyph")
	}
	// A TrueType's glyph's nodes can have negative co-ordinates, but the
	// rasterizer clips anything left of x=0 or above y=0. xmin and ymin
	// are the pixel offsets, based on the font's FUnit metrics, that let
	// a negative co-ordinate in TrueType space be non-negative in
	// rasterizer space. xmin and ymin are typically <= 0.
	fx += raster.Fix32(-xmin << 8)
	fy += raster.Fix32(-ymin << 8)
	// Rasterize the glyph's vectors.
	c.r.Clear()
	e0 := 0
	for _, e1 := range c.glyphBuf.End {
		c.drawContour(c.glyphBuf.Point[e0:e1], fx, fy)
		e0 = e1
	}
	a := image.NewAlpha(image.Rect(0, 0, xmax-xmin, ymax-ymin))
	c.r.Rasterize(raster.NewAlphaSrcPainter(a))
	return a, image.Point{xmin, ymin}, nil
}
示例#2
0
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.")
}
示例#3
0
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.
	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.")
}