Example #1
0
func p(n node) fixed.Point26_6 {
	x, y := 20+n.x/4, 380-n.y/4
	return fixed.Point26_6{
		X: fixed.Int26_6(x << 6),
		Y: fixed.Int26_6(y << 6),
	}
}
Example #2
0
// unscaledVMetric returns the unscaled vertical metrics for the glyph with
// the given index. yMax is the top of the glyph's bounding box.
func (f *Font) unscaledVMetric(i Index, yMax fixed.Int26_6) (v VMetric) {
	j := int(i)
	if j < 0 || f.nGlyph <= j {
		return VMetric{}
	}
	if 4*j+4 <= len(f.vmtx) {
		return VMetric{
			AdvanceHeight:  fixed.Int26_6(u16(f.vmtx, 4*j)),
			TopSideBearing: fixed.Int26_6(int16(u16(f.vmtx, 4*j+2))),
		}
	}
	// The OS/2 table has grown over time.
	// https://developer.apple.com/fonts/TTRefMan/RM06/Chap6OS2.html
	// says that it was originally 68 bytes. Optional fields, including
	// the ascender and descender, are described at
	// http://www.microsoft.com/typography/otspec/os2.htm
	if len(f.os2) >= 72 {
		sTypoAscender := fixed.Int26_6(int16(u16(f.os2, 68)))
		sTypoDescender := fixed.Int26_6(int16(u16(f.os2, 70)))
		return VMetric{
			AdvanceHeight:  sTypoAscender - sTypoDescender,
			TopSideBearing: sTypoAscender - yMax,
		}
	}
	return VMetric{
		AdvanceHeight:  fixed.Int26_6(f.fUnitsPerEm),
		TopSideBearing: 0,
	}
}
Example #3
0
// rasterize returns the advance width, glyph mask and integer-pixel offset
// to render the given glyph at the given sub-pixel offsets.
// The 26.6 fixed point arguments fx and fy must be in the range [0, 1).
func (c *Context) rasterize(glyph truetype.Index, fx, fy fixed.Int26_6) (
	fixed.Int26_6, *image.Alpha, image.Point, error) {

	if err := c.glyphBuf.Load(c.f, c.scale, glyph, c.hinting); err != nil {
		return 0, nil, image.Point{}, err
	}
	// Calculate the integer-pixel bounds for the glyph.
	xmin := int(fx+c.glyphBuf.Bounds.Min.X) >> 6
	ymin := int(fy-c.glyphBuf.Bounds.Max.Y) >> 6
	xmax := int(fx+c.glyphBuf.Bounds.Max.X+0x3f) >> 6
	ymax := int(fy-c.glyphBuf.Bounds.Min.Y+0x3f) >> 6
	if xmin > xmax || ymin > ymax {
		return 0, nil, image.Point{}, 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 -= fixed.Int26_6(xmin << 6)
	fy -= fixed.Int26_6(ymin << 6)
	// Rasterize the glyph's vectors.
	c.r.Clear()
	e0 := 0
	for _, e1 := range c.glyphBuf.Ends {
		c.drawContour(c.glyphBuf.Points[e0:e1], fx, fy)
		e0 = e1
	}
	a := image.NewAlpha(image.Rect(0, 0, xmax-xmin, ymax-ymin))
	c.r.Rasterize(raster.NewAlphaSrcPainter(a))
	return c.glyphBuf.AdvanceWidth, a, image.Point{xmin, ymin}, nil
}
Example #4
0
// pRot45CCW returns the vector p rotated counter-clockwise by 45 degrees.
//
// Note that the Y-axis grows downwards, so {1, 0}.Rot45CCW is {1/√2, -1/√2}.
func pRot45CCW(p fixed.Point26_6) fixed.Point26_6 {
	// 181/256 is approximately 1/√2, or sin(π/4).
	px, py := int64(p.X), int64(p.Y)
	qx := (+px + py) * 181 / 256
	qy := (-px + py) * 181 / 256
	return fixed.Point26_6{fixed.Int26_6(qx), fixed.Int26_6(qy)}
}
Example #5
0
// TestParse tests that the luxisr.ttf metrics and glyphs are parsed correctly.
// The numerical values can be manually verified by examining luxisr.ttx.
func TestParse(t *testing.T) {
	f, _, err := parseTestdataFont("luxisr")
	if err != nil {
		t.Fatal(err)
	}
	if got, want := f.FUnitsPerEm(), int32(2048); got != want {
		t.Errorf("FUnitsPerEm: got %v, want %v", got, want)
	}
	fupe := fixed.Int26_6(f.FUnitsPerEm())
	if got, want := f.Bounds(fupe), mkBounds(-441, -432, 2024, 2033); got != want {
		t.Errorf("Bounds: got %v, want %v", got, want)
	}

	i0 := f.Index('A')
	i1 := f.Index('V')
	if i0 != 36 || i1 != 57 {
		t.Fatalf("Index: i0, i1 = %d, %d, want 36, 57", i0, i1)
	}
	if got, want := f.HMetric(fupe, i0), (HMetric{1366, 19}); got != want {
		t.Errorf("HMetric: got %v, want %v", got, want)
	}
	if got, want := f.VMetric(fupe, i0), (VMetric{2465, 553}); got != want {
		t.Errorf("VMetric: got %v, want %v", got, want)
	}
	if got, want := f.Kern(fupe, i0, i1), fixed.Int26_6(-144); got != want {
		t.Errorf("Kern: got %v, want %v", got, want)
	}

	g := &GlyphBuf{}
	err = g.Load(f, fupe, i0, font.HintingNone)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	g0 := &GlyphBuf{
		Bounds: g.Bounds,
		Points: g.Points,
		Ends:   g.Ends,
	}
	g1 := &GlyphBuf{
		Bounds: mkBounds(19, 0, 1342, 1480),
		Points: []Point{
			{19, 0, 51},
			{581, 1480, 1},
			{789, 1480, 51},
			{1342, 0, 1},
			{1116, 0, 35},
			{962, 410, 3},
			{368, 410, 33},
			{214, 0, 3},
			{428, 566, 19},
			{904, 566, 33},
			{667, 1200, 3},
		},
		Ends: []int{8, 11},
	}
	if got, want := fmt.Sprint(g0), fmt.Sprint(g1); got != want {
		t.Errorf("GlyphBuf:\ngot  %v\nwant %v", got, want)
	}
}
Example #6
0
// scale returns x divided by f.fUnitsPerEm, rounded to the nearest integer.
func (f *Font) scale(x fixed.Int26_6) fixed.Int26_6 {
	if x >= 0 {
		x += fixed.Int26_6(f.fUnitsPerEm) / 2
	} else {
		x -= fixed.Int26_6(f.fUnitsPerEm) / 2
	}
	return x / fixed.Int26_6(f.fUnitsPerEm)
}
Example #7
0
// pNorm returns the vector p normalized to the given length, or zero if p is
// degenerate.
func pNorm(p fixed.Point26_6, length fixed.Int26_6) fixed.Point26_6 {
	d := pLen(p)
	if d == 0 {
		return fixed.Point26_6{}
	}
	s, t := int64(length), int64(d)
	x := int64(p.X) * s / t
	y := int64(p.Y) * s / t
	return fixed.Point26_6{fixed.Int26_6(x), fixed.Int26_6(y)}
}
Example #8
0
// dotProduct returns the dot product of [x, y] and q. It is almost the same as
//	px := int64(x)
//	py := int64(y)
//	qx := int64(q[0])
//	qy := int64(q[1])
//	return fixed.Int26_6((px*qx + py*qy + 1<<13) >> 14)
// except that the computation is done with 32-bit integers to produce exactly
// the same rounding behavior as C Freetype.
func dotProduct(x, y fixed.Int26_6, q [2]f2dot14) fixed.Int26_6 {
	// Compute x*q[0] as 64-bit value.
	l := uint32((int32(x) & 0xFFFF) * int32(q[0]))
	m := (int32(x) >> 16) * int32(q[0])

	lo1 := l + (uint32(m) << 16)
	hi1 := (m >> 16) + (int32(l) >> 31) + bool2int32(lo1 < l)

	// Compute y*q[1] as 64-bit value.
	l = uint32((int32(y) & 0xFFFF) * int32(q[1]))
	m = (int32(y) >> 16) * int32(q[1])

	lo2 := l + (uint32(m) << 16)
	hi2 := (m >> 16) + (int32(l) >> 31) + bool2int32(lo2 < l)

	// Add them.
	lo := lo1 + lo2
	hi := hi1 + hi2 + bool2int32(lo < lo1)

	// Divide the result by 2^14 with rounding.
	s := hi >> 31
	l = lo + uint32(s)
	hi += s + bool2int32(l < lo)
	lo = l

	l = lo + 0x2000
	hi += bool2int32(l < lo)

	return fixed.Int26_6((uint32(hi) << 18) | (l >> 14))
}
Example #9
0
// NewFace returns a new font.Face for the given Font.
func NewFace(f *Font, opts *Options) font.Face {
	a := &face{
		f:          f,
		hinting:    opts.hinting(),
		scale:      fixed.Int26_6(0.5 + (opts.size() * opts.dpi() * 64 / 72)),
		glyphCache: make([]glyphCacheEntry, opts.glyphCacheEntries()),
	}
	a.subPixelX, a.subPixelBiasX, a.subPixelMaskX = opts.subPixelsX()
	a.subPixelY, a.subPixelBiasY, a.subPixelMaskY = opts.subPixelsY()

	// Fill the cache with invalid entries. Valid glyph cache entries have fx
	// and fy in the range [0, 64). Valid index cache entries have rune >= 0.
	for i := range a.glyphCache {
		a.glyphCache[i].key.fy = 0xff
	}
	for i := range a.indexCache {
		a.indexCache[i].rune = -1
	}

	// Set the rasterizer's bounds to be big enough to handle the largest glyph.
	b := f.Bounds(a.scale)
	xmin := +int(b.Min.X) >> 6
	ymin := -int(b.Max.Y) >> 6
	xmax := +int(b.Max.X+63) >> 6
	ymax := -int(b.Min.Y-63) >> 6
	a.maxw = xmax - xmin
	a.maxh = ymax - ymin
	a.masks = image.NewAlpha(image.Rect(0, 0, a.maxw, a.maxh*len(a.glyphCache)))
	a.r.SetBounds(a.maxw, a.maxh)
	a.p = facePainter{a}

	return a
}
Example #10
0
func (f *subface) GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool) {
	r -= f.firstRune
	if r < 0 || f.n <= int(r) {
		return 0, false
	}
	return fixed.Int26_6(f.fontchars[r].width) << 6, true
}
Example #11
0
func main() {
	flag.Parse()
	fmt.Printf("Loading fontfile %q\n", *fontfile)
	b, err := ioutil.ReadFile(*fontfile)
	if err != nil {
		log.Println(err)
		return
	}
	f, err := truetype.Parse(b)
	if err != nil {
		log.Println(err)
		return
	}
	fupe := fixed.Int26_6(f.FUnitsPerEm())
	printBounds(f.Bounds(fupe))
	fmt.Printf("FUnitsPerEm:%d\n\n", fupe)

	c0, c1 := 'A', 'V'

	i0 := f.Index(c0)
	hm := f.HMetric(fupe, i0)
	g := &truetype.GlyphBuf{}
	err = g.Load(f, fupe, i0, font.HintingNone)
	if err != nil {
		log.Println(err)
		return
	}
	fmt.Printf("'%c' glyph\n", c0)
	fmt.Printf("AdvanceWidth:%d LeftSideBearing:%d\n", hm.AdvanceWidth, hm.LeftSideBearing)
	printGlyph(g)
	i1 := f.Index(c1)
	fmt.Printf("\n'%c', '%c' Kern:%d\n", c0, c1, f.Kern(fupe, i0, i1))
}
Example #12
0
// unscaledHMetric returns the unscaled horizontal metrics for the glyph with
// the given index.
func (f *Font) unscaledHMetric(i Index) (h HMetric) {
	j := int(i)
	if j < 0 || f.nGlyph <= j {
		return HMetric{}
	}
	if j >= f.nHMetric {
		p := 4 * (f.nHMetric - 1)
		return HMetric{
			AdvanceWidth:    fixed.Int26_6(u16(f.hmtx, p)),
			LeftSideBearing: fixed.Int26_6(int16(u16(f.hmtx, p+2*(j-f.nHMetric)+4))),
		}
	}
	return HMetric{
		AdvanceWidth:    fixed.Int26_6(u16(f.hmtx, 4*j)),
		LeftSideBearing: fixed.Int26_6(int16(u16(f.hmtx, 4*j+2))),
	}
}
Example #13
0
// Add2 adds a quadratic segment to the current curve.
func (r *Rasterizer) Add2(b, c fixed.Point26_6) {
	// Calculate nSplit (the number of recursive decompositions) based on how
	// 'curvy' it is. Specifically, how much the middle point b deviates from
	// (a+c)/2.
	dev := maxAbs(r.a.X-2*b.X+c.X, r.a.Y-2*b.Y+c.Y) / fixed.Int26_6(r.splitScale2)
	nsplit := 0
	for dev > 0 {
		dev /= 4
		nsplit++
	}
	// dev is 32-bit, and nsplit++ every time we shift off 2 bits, so maxNsplit
	// is 16.
	const maxNsplit = 16
	if nsplit > maxNsplit {
		panic("freetype/raster: Add2 nsplit too large: " + strconv.Itoa(nsplit))
	}
	// Recursively decompose the curve nSplit levels deep.
	var (
		pStack [2*maxNsplit + 3]fixed.Point26_6
		sStack [maxNsplit + 1]int
		i      int
	)
	sStack[0] = nsplit
	pStack[0] = c
	pStack[1] = b
	pStack[2] = r.a
	for i >= 0 {
		s := sStack[i]
		p := pStack[2*i:]
		if s > 0 {
			// Split the quadratic curve p[:3] into an equivalent set of two
			// shorter curves: p[:3] and p[2:5]. The new p[4] is the old p[2],
			// and p[0] is unchanged.
			mx := p[1].X
			p[4].X = p[2].X
			p[3].X = (p[4].X + mx) / 2
			p[1].X = (p[0].X + mx) / 2
			p[2].X = (p[1].X + p[3].X) / 2
			my := p[1].Y
			p[4].Y = p[2].Y
			p[3].Y = (p[4].Y + my) / 2
			p[1].Y = (p[0].Y + my) / 2
			p[2].Y = (p[1].Y + p[3].Y) / 2
			// The two shorter curves have one less split to do.
			sStack[i] = s - 1
			sStack[i+1] = s - 1
			i++
		} else {
			// Replace the level-0 quadratic with a two-linear-piece
			// approximation.
			midx := (p[0].X + 2*p[1].X + p[2].X) / 4
			midy := (p[0].Y + 2*p[1].Y + p[2].Y) / 4
			r.Add1(fixed.Point26_6{midx, midy})
			r.Add1(p[0])
			i--
		}
	}
}
Example #14
0
func (f *Font) parseHead() error {
	if len(f.head) != 54 {
		return FormatError(fmt.Sprintf("bad head length: %d", len(f.head)))
	}
	f.fUnitsPerEm = int32(u16(f.head, 18))
	f.bounds.Min.X = fixed.Int26_6(int16(u16(f.head, 36)))
	f.bounds.Min.Y = fixed.Int26_6(int16(u16(f.head, 38)))
	f.bounds.Max.X = fixed.Int26_6(int16(u16(f.head, 40)))
	f.bounds.Max.Y = fixed.Int26_6(int16(u16(f.head, 42)))
	switch i := u16(f.head, 50); i {
	case 0:
		f.locaOffsetFormat = locaOffsetFormatShort
	case 1:
		f.locaOffsetFormat = locaOffsetFormatLong
	default:
		return FormatError(fmt.Sprintf("bad indexToLocFormat: %d", i))
	}
	return nil
}
Example #15
0
func (h *hinter) move(p *Point, distance fixed.Int26_6, touch bool) {
	fvx := int64(h.gs.fv[0])
	pvx := int64(h.gs.pv[0])
	if fvx == 0x4000 && pvx == 0x4000 {
		p.X += fixed.Int26_6(distance)
		if touch {
			p.Flags |= flagTouchedX
		}
		return
	}

	fvy := int64(h.gs.fv[1])
	pvy := int64(h.gs.pv[1])
	if fvy == 0x4000 && pvy == 0x4000 {
		p.Y += fixed.Int26_6(distance)
		if touch {
			p.Flags |= flagTouchedY
		}
		return
	}

	fvDotPv := (fvx*pvx + fvy*pvy) >> 14

	if fvx != 0 {
		p.X += fixed.Int26_6(mulDiv(fvx, int64(distance), fvDotPv))
		if touch {
			p.Flags |= flagTouchedX
		}
	}

	if fvy != 0 {
		p.Y += fixed.Int26_6(mulDiv(fvy, int64(distance), fvDotPv))
		if touch {
			p.Flags |= flagTouchedY
		}
	}
}
Example #16
0
func (h *hinter) initializeScaledCVT() {
	h.scaledCVTInitialized = true
	if n := len(h.font.cvt) / 2; n <= cap(h.scaledCVT) {
		h.scaledCVT = h.scaledCVT[:n]
	} else {
		if n < 32 {
			n = 32
		}
		h.scaledCVT = make([]fixed.Int26_6, len(h.font.cvt)/2, n)
	}
	for i := range h.scaledCVT {
		unscaled := uint16(h.font.cvt[2*i])<<8 | uint16(h.font.cvt[2*i+1])
		h.scaledCVT[i] = h.font.scale(h.scale * fixed.Int26_6(int16(unscaled)))
	}
}
Example #17
0
// rasterize returns the advance width, integer-pixel offset to render at, and
// the width and height of the given glyph at the given sub-pixel offsets.
//
// The 26.6 fixed point arguments fx and fy must be in the range [0, 1).
func (a *face) rasterize(index Index, fx, fy fixed.Int26_6) (v glyphCacheVal, ok bool) {
	if err := a.glyphBuf.Load(a.f, a.scale, index, a.hinting); err != nil {
		return glyphCacheVal{}, false
	}
	// Calculate the integer-pixel bounds for the glyph.
	xmin := int(fx+a.glyphBuf.Bounds.Min.X) >> 6
	ymin := int(fy-a.glyphBuf.Bounds.Max.Y) >> 6
	xmax := int(fx+a.glyphBuf.Bounds.Max.X+0x3f) >> 6
	ymax := int(fy-a.glyphBuf.Bounds.Min.Y+0x3f) >> 6
	if xmin > xmax || ymin > ymax {
		return glyphCacheVal{}, false
	}
	// 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 -= fixed.Int26_6(xmin << 6)
	fy -= fixed.Int26_6(ymin << 6)
	// Rasterize the glyph's vectors.
	a.r.Clear()
	pixOffset := a.paintOffset * a.maxw
	clear(a.masks.Pix[pixOffset : pixOffset+a.maxw*a.maxh])
	e0 := 0
	for _, e1 := range a.glyphBuf.Ends {
		a.drawContour(a.glyphBuf.Points[e0:e1], fx, fy)
		e0 = e1
	}
	a.r.Rasterize(a.p)
	return glyphCacheVal{
		a.glyphBuf.AdvanceWidth,
		image.Point{xmin, ymin},
		xmax - xmin,
		ymax - ymin,
	}, true
}
Example #18
0
func (f *subface) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.Int26_6, ok bool) {
	r -= f.firstRune
	if r < 0 || f.n <= int(r) {
		return fixed.Rectangle26_6{}, 0, false
	}
	i := &f.fontchars[r+0]
	j := &f.fontchars[r+1]

	bounds = fixed.R(
		int(i.left),
		int(i.top)-f.ascent,
		int(i.left)+int(j.x-i.x),
		int(i.bottom)-f.ascent,
	)
	return bounds, fixed.Int26_6(i.width) << 6, true
}
Example #19
0
// recalc recalculates scale and bounds values from the font size, screen
// resolution and font metrics, and invalidates the glyph cache.
func (c *Context) recalc() {
	c.scale = fixed.Int26_6(c.fontSize * c.dpi * (64.0 / 72.0))
	if c.f == nil {
		c.r.SetBounds(0, 0)
	} else {
		// Set the rasterizer's bounds to be big enough to handle the largest glyph.
		b := c.f.Bounds(c.scale)
		xmin := +int(b.Min.X) >> 6
		ymin := -int(b.Max.Y) >> 6
		xmax := +int(b.Max.X+63) >> 6
		ymax := -int(b.Min.Y-63) >> 6
		c.r.SetBounds(xmax-xmin, ymax-ymin)
	}
	for i := range c.cache {
		c.cache[i] = cacheEntry{}
	}
}
Example #20
0
// Kern returns the horizontal adjustment for the given glyph pair. A positive
// kern means to move the glyphs further apart.
func (f *Font) Kern(scale fixed.Int26_6, i0, i1 Index) fixed.Int26_6 {
	if f.nKern == 0 {
		return 0
	}
	g := uint32(i0)<<16 | uint32(i1)
	lo, hi := 0, f.nKern
	for lo < hi {
		i := (lo + hi) / 2
		ig := u32(f.kern, 18+6*i)
		if ig < g {
			lo = i + 1
		} else if ig > g {
			hi = i
		} else {
			return f.scale(scale * fixed.Int26_6(int16(u16(f.kern, 22+6*i))))
		}
	}
	return 0
}
Example #21
0
// scalingTestParse parses a line of points like
// 213 -22 -111 236 555;-22 -111 1, 178 555 1, 236 555 1, 36 -111 1
// The line will not have a trailing "\n".
func scalingTestParse(line string) (ret scalingTestData) {
	next := func(s string) (string, fixed.Int26_6) {
		t, i := "", strings.Index(s, " ")
		if i != -1 {
			s, t = s[:i], s[i+1:]
		}
		x, _ := strconv.Atoi(s)
		return t, fixed.Int26_6(x)
	}

	i := strings.Index(line, ";")
	prefix, line := line[:i], line[i+1:]

	prefix, ret.advanceWidth = next(prefix)
	prefix, ret.bounds.Min.X = next(prefix)
	prefix, ret.bounds.Min.Y = next(prefix)
	prefix, ret.bounds.Max.X = next(prefix)
	prefix, ret.bounds.Max.Y = next(prefix)

	ret.points = make([]Point, 0, 1+strings.Count(line, ","))
	for len(line) > 0 {
		s := line
		if i := strings.Index(line, ","); i != -1 {
			s, line = line[:i], line[i+1:]
			for len(line) > 0 && line[0] == ' ' {
				line = line[1:]
			}
		} else {
			line = ""
		}
		s, x := next(s)
		s, y := next(s)
		s, f := next(s)
		ret.points = append(ret.points, Point{X: x, Y: y, Flags: uint32(f)})
	}
	return ret
}
Example #22
0
func (f *subface) Glyph(dot fixed.Point26_6, r rune) (
	dr image.Rectangle, mask image.Image, maskp image.Point, advance fixed.Int26_6, ok bool) {

	r -= f.firstRune
	if r < 0 || f.n <= int(r) {
		return image.Rectangle{}, nil, image.Point{}, 0, false
	}
	i := &f.fontchars[r+0]
	j := &f.fontchars[r+1]

	minX := int(dot.X+32)>>6 + int(i.left)
	minY := int(dot.Y+32)>>6 + int(i.top) - f.ascent
	dr = image.Rectangle{
		Min: image.Point{
			X: minX,
			Y: minY,
		},
		Max: image.Point{
			X: minX + int(j.x-i.x),
			Y: minY + int(i.bottom) - int(i.top),
		},
	}
	return dr, f.img, image.Point{int(i.x), int(i.top)}, fixed.Int26_6(i.width) << 6, true
}
Example #23
0
func p(x, y int) fixed.Point26_6 {
	return fixed.Point26_6{
		X: fixed.Int26_6(x * 64),
		Y: fixed.Int26_6(y * 64),
	}
}
Example #24
0
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.")
}
Example #25
0
// Load loads a glyph's contours from a Font, overwriting any previously loaded
// contours for this GlyphBuf. scale is the number of 26.6 fixed point units in
// 1 em, i is the glyph index, and h is the hinting policy.
func (g *GlyphBuf) Load(f *Font, scale fixed.Int26_6, i Index, h font.Hinting) error {
	g.Points = g.Points[:0]
	g.Unhinted = g.Unhinted[:0]
	g.InFontUnits = g.InFontUnits[:0]
	g.Ends = g.Ends[:0]
	g.font = f
	g.hinting = h
	g.scale = scale
	g.pp1x = 0
	g.phantomPoints = [4]Point{}
	g.metricsSet = false

	if h != font.HintingNone {
		if err := g.hinter.init(f, scale); err != nil {
			return err
		}
	}
	if err := g.load(0, i, true); err != nil {
		return err
	}
	// TODO: this selection of either g.pp1x or g.phantomPoints[0].X isn't ideal,
	// and should be cleaned up once we have all the testScaling tests passing,
	// plus additional tests for Freetype-Go's bounding boxes matching C Freetype's.
	pp1x := g.pp1x
	if h != font.HintingNone {
		pp1x = g.phantomPoints[0].X
	}
	if pp1x != 0 {
		for i := range g.Points {
			g.Points[i].X -= pp1x
		}
	}

	advanceWidth := g.phantomPoints[1].X - g.phantomPoints[0].X
	if h != font.HintingNone {
		if len(f.hdmx) >= 8 {
			if n := u32(f.hdmx, 4); n > 3+uint32(i) {
				for hdmx := f.hdmx[8:]; uint32(len(hdmx)) >= n; hdmx = hdmx[n:] {
					if fixed.Int26_6(hdmx[0]) == scale>>6 {
						advanceWidth = fixed.Int26_6(hdmx[2+i]) << 6
						break
					}
				}
			}
		}
		advanceWidth = (advanceWidth + 32) &^ 63
	}
	g.AdvanceWidth = advanceWidth

	// Set g.Bounds to the 'control box', which is the bounding box of the
	// Bézier curves' control points. This is easier to calculate, no smaller
	// than and often equal to the tightest possible bounding box of the curves
	// themselves. This approach is what C Freetype does. We can't just scale
	// the nominal bounding box in the glyf data as the hinting process and
	// phantom point adjustment may move points outside of that box.
	if len(g.Points) == 0 {
		g.Bounds = fixed.Rectangle26_6{}
	} else {
		p := g.Points[0]
		g.Bounds.Min.X = p.X
		g.Bounds.Max.X = p.X
		g.Bounds.Min.Y = p.Y
		g.Bounds.Max.Y = p.Y
		for _, p := range g.Points[1:] {
			if g.Bounds.Min.X > p.X {
				g.Bounds.Min.X = p.X
			} else if g.Bounds.Max.X < p.X {
				g.Bounds.Max.X = p.X
			}
			if g.Bounds.Min.Y > p.Y {
				g.Bounds.Min.Y = p.Y
			} else if g.Bounds.Max.Y < p.Y {
				g.Bounds.Max.Y = p.Y
			}
		}
		// Snap the box to the grid, if hinting is on.
		if h != font.HintingNone {
			g.Bounds.Min.X &^= 63
			g.Bounds.Min.Y &^= 63
			g.Bounds.Max.X += 63
			g.Bounds.Max.X &^= 63
			g.Bounds.Max.Y += 63
			g.Bounds.Max.Y &^= 63
		}
	}
	return nil
}
Example #26
0
// subPixels returns q and the bias and mask that leads to q quantized
// sub-pixel locations per full pixel.
//
// For example, q == 4 leads to a bias of 8 and a mask of 0xfffffff0, or -16,
// because we want to round fractions of fixed.Int26_6 as:
//	-  0 to  7 rounds to 0.
//	-  8 to 23 rounds to 16.
//	- 24 to 39 rounds to 32.
//	- 40 to 55 rounds to 48.
//	- 56 to 63 rounds to 64.
// which means to add 8 and then bitwise-and with -16, in two's complement
// representation.
//
// When q ==  1, we want bias == 32 and mask == -64.
// When q ==  2, we want bias == 16 and mask == -32.
// When q ==  4, we want bias ==  8 and mask == -16.
// ...
// When q == 64, we want bias ==  0 and mask ==  -1. (The no-op case).
// The pattern is clear.
func subPixels(q int) (value uint32, bias, mask fixed.Int26_6) {
	return uint32(q), 32 / fixed.Int26_6(q), -64 / fixed.Int26_6(q)
}
Example #27
0
// PointToFixed converts the given number of points (as in "a 12 point font")
// into a 26.6 fixed point number of pixels.
func (c *Context) PointToFixed(x float64) fixed.Int26_6 {
	return fixed.Int26_6(x * float64(c.dpi) * (64.0 / 72.0))
}
Example #28
0
// Pt converts from a co-ordinate pair measured in pixels to a fixed.Point26_6
// co-ordinate pair measured in fixed.Int26_6 units.
func Pt(x, y int) fixed.Point26_6 {
	return fixed.Point26_6{
		X: fixed.Int26_6(x << 6),
		Y: fixed.Int26_6(y << 6),
	}
}
Example #29
0
// addArc adds a circular arc from pivot+n0 to pivot+n1 to p. The shorter of
// the two possible arcs is taken, i.e. the one spanning <= 180 degrees. The
// two vectors n0 and n1 must be of equal length.
func addArc(p Adder, pivot, n0, n1 fixed.Point26_6) {
	// r2 is the square of the length of n0.
	r2 := pDot(n0, n0)
	if r2 < epsilon {
		// The arc radius is so small that we collapse to a straight line.
		p.Add1(pivot.Add(n1))
		return
	}
	// We approximate the arc by 0, 1, 2 or 3 45-degree quadratic segments plus
	// a final quadratic segment from s to n1. Each 45-degree segment has
	// control points {1, 0}, {1, tan(π/8)} and {1/√2, 1/√2} suitably scaled,
	// rotated and translated. tan(π/8) is approximately 106/256.
	const tpo8 = 106
	var s fixed.Point26_6
	// We determine which octant the angle between n0 and n1 is in via three
	// dot products. m0, m1 and m2 are n0 rotated clockwise by 45, 90 and 135
	// degrees.
	m0 := pRot45CW(n0)
	m1 := pRot90CW(n0)
	m2 := pRot90CW(m0)
	if pDot(m1, n1) >= 0 {
		if pDot(n0, n1) >= 0 {
			if pDot(m2, n1) <= 0 {
				// n1 is between 0 and 45 degrees clockwise of n0.
				s = n0
			} else {
				// n1 is between 45 and 90 degrees clockwise of n0.
				p.Add2(pivot.Add(n0).Add(m1.Mul(tpo8)), pivot.Add(m0))
				s = m0
			}
		} else {
			pm1, n0t := pivot.Add(m1), n0.Mul(tpo8)
			p.Add2(pivot.Add(n0).Add(m1.Mul(tpo8)), pivot.Add(m0))
			p.Add2(pm1.Add(n0t), pm1)
			if pDot(m0, n1) >= 0 {
				// n1 is between 90 and 135 degrees clockwise of n0.
				s = m1
			} else {
				// n1 is between 135 and 180 degrees clockwise of n0.
				p.Add2(pm1.Sub(n0t), pivot.Add(m2))
				s = m2
			}
		}
	} else {
		if pDot(n0, n1) >= 0 {
			if pDot(m0, n1) >= 0 {
				// n1 is between 0 and 45 degrees counter-clockwise of n0.
				s = n0
			} else {
				// n1 is between 45 and 90 degrees counter-clockwise of n0.
				p.Add2(pivot.Add(n0).Sub(m1.Mul(tpo8)), pivot.Sub(m2))
				s = pNeg(m2)
			}
		} else {
			pm1, n0t := pivot.Sub(m1), n0.Mul(tpo8)
			p.Add2(pivot.Add(n0).Sub(m1.Mul(tpo8)), pivot.Sub(m2))
			p.Add2(pm1.Add(n0t), pm1)
			if pDot(m2, n1) <= 0 {
				// n1 is between 90 and 135 degrees counter-clockwise of n0.
				s = pNeg(m1)
			} else {
				// n1 is between 135 and 180 degrees counter-clockwise of n0.
				p.Add2(pm1.Sub(n0t), pivot.Sub(m0))
				s = pNeg(m0)
			}
		}
	}
	// The final quadratic segment has two endpoints s and n1 and the middle
	// control point is a multiple of s.Add(n1), i.e. it is on the angle
	// bisector of those two points. The multiple ranges between 128/256 and
	// 150/256 as the angle between s and n1 ranges between 0 and 45 degrees.
	//
	// When the angle is 0 degrees (i.e. s and n1 are coincident) then
	// s.Add(n1) is twice s and so the middle control point of the degenerate
	// quadratic segment should be half s.Add(n1), and half = 128/256.
	//
	// When the angle is 45 degrees then 150/256 is the ratio of the lengths of
	// the two vectors {1, tan(π/8)} and {1 + 1/√2, 1/√2}.
	//
	// d is the normalized dot product between s and n1. Since the angle ranges
	// between 0 and 45 degrees then d ranges between 256/256 and 181/256.
	d := 256 * pDot(s, n1) / r2
	multiple := fixed.Int26_6(150-(150-128)*(d-181)/(256-181)) >> 2
	p.Add2(pivot.Add(s.Add(n1).Mul(multiple)), pivot.Add(n1))
}
Example #30
0
// interpolate returns the point (1-t)*a + t*b.
func interpolate(a, b fixed.Point26_6, t fixed.Int52_12) fixed.Point26_6 {
	s := 1<<12 - t
	x := s*fixed.Int52_12(a.X) + t*fixed.Int52_12(b.X)
	y := s*fixed.Int52_12(a.Y) + t*fixed.Int52_12(b.Y)
	return fixed.Point26_6{fixed.Int26_6(x >> 12), fixed.Int26_6(y >> 12)}
}