// 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,
}
}
// 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)}
}
// GetStringBounds returns the approximate pixel bounds of the string s at x, y.
// The the left edge of the em square of the first character of s
// and the baseline intersect at 0, 0 in the returned coordinates.
// Therefore the top and left coordinates may well be negative.
func (gc *GraphicContext) GetStringBounds(s string) (left, top, right, bottom float64) {
f, err := gc.loadCurrentFont()
if err != nil {
log.Println(err)
return 0, 0, 0, 0
}
top, left, bottom, right = 10e6, 10e6, -10e6, -10e6
cursor := 0.0
prev, hasPrev := truetype.Index(0), false
for _, rune := range s {
index := f.Index(rune)
if hasPrev {
cursor += fUnitsToFloat64(f.Kern(fixed.Int26_6(gc.Current.Scale), prev, index))
}
if err := gc.glyphBuf.Load(gc.Current.Font, fixed.Int26_6(gc.Current.Scale), index, font.HintingNone); err != nil {
log.Println(err)
return 0, 0, 0, 0
}
e0 := 0
for _, e1 := range gc.glyphBuf.Ends {
ps := gc.glyphBuf.Points[e0:e1]
for _, p := range ps {
x, y := pointToF64Point(p)
top = math.Min(top, y)
bottom = math.Max(bottom, y)
left = math.Min(left, x+cursor)
right = math.Max(right, x+cursor)
}
}
cursor += fUnitsToFloat64(f.HMetric(fixed.Int26_6(gc.Current.Scale), index).AdvanceWidth)
prev, hasPrev = index, true
}
return left, top, right, bottom
}
// 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)
}
}
// 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)
}
// 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)}
}
// 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
}
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
}
// 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))
}
// 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))),
}
}
// 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--
}
}
}
// Extents returns the FontExtents for a font.
// TODO needs to read this https://developer.apple.com/fonts/TrueType-Reference-Manual/RM02/Chap2.html#intro
func Extents(font *truetype.Font, size float64) FontExtents {
bounds := font.Bounds(fixed.Int26_6(font.FUnitsPerEm()))
scale := size / float64(font.FUnitsPerEm())
return FontExtents{
Ascent: float64(bounds.Max.Y) * scale,
Descent: float64(bounds.Min.Y) * scale,
Height: float64(bounds.Max.Y-bounds.Min.Y) * scale,
}
}
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
}
func (gc *GraphicContext) drawGlyph(glyph truetype.Index, dx, dy float64) error {
if err := gc.glyphBuf.Load(gc.Current.Font, fixed.Int26_6(gc.Current.Scale), glyph, font.HintingNone); err != nil {
return err
}
e0 := 0
for _, e1 := range gc.glyphBuf.Ends {
DrawContour(gc, gc.glyphBuf.Points[e0:e1], dx, dy)
e0 = e1
}
return nil
}
// CreateStringPath creates a path from the string s at x, y, and returns the string width.
// The text is placed so that the left edge of the em square of the first character of s
// and the baseline intersect at x, y. The majority of the affected pixels will be
// above and to the right of the point, but some may be below or to the left.
// For example, drawing a string that starts with a 'J' in an italic font may
// affect pixels below and left of the point.
func (gc *GraphicContext) CreateStringPath(s string, x, y float64) float64 {
f, err := gc.loadCurrentFont()
if err != nil {
log.Println(err)
return 0.0
}
startx := x
prev, hasPrev := truetype.Index(0), false
for _, rune := range s {
index := f.Index(rune)
if hasPrev {
x += fUnitsToFloat64(f.Kern(fixed.Int26_6(gc.Current.Scale), prev, index))
}
err := gc.drawGlyph(index, x, y)
if err != nil {
log.Println(err)
return startx - x
}
x += fUnitsToFloat64(f.HMetric(fixed.Int26_6(gc.Current.Scale), index).AdvanceWidth)
prev, hasPrev = index, true
}
return x - startx
}
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
}
}
}
// 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
}
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)))
}
}
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
}
// 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
}
// 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
}
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
}
// Add1 adds a linear segment to the current curve.
func (r *Rasterizer) Add1(b fixed.Point26_6) {
x0, y0 := r.a.X, r.a.Y
x1, y1 := b.X, b.Y
dx, dy := x1-x0, y1-y0
// Break the 26.6 fixed point Y co-ordinates into integral and fractional
// parts.
y0i := int(y0) / 64
y0f := y0 - fixed.Int26_6(64*y0i)
y1i := int(y1) / 64
y1f := y1 - fixed.Int26_6(64*y1i)
if y0i == y1i {
// There is only one scanline.
r.scan(y0i, x0, y0f, x1, y1f)
} else if dx == 0 {
// This is a vertical line segment. We avoid calling r.scan and instead
// manipulate r.area and r.cover directly.
var (
edge0, edge1 fixed.Int26_6
yiDelta int
)
if dy > 0 {
edge0, edge1, yiDelta = 0, 64, 1
} else {
edge0, edge1, yiDelta = 64, 0, -1
}
x0i, yi := int(x0)/64, y0i
x0fTimes2 := (int(x0) - (64 * x0i)) * 2
// Do the first pixel.
dcover := int(edge1 - y0f)
darea := int(x0fTimes2 * dcover)
r.area += darea
r.cover += dcover
yi += yiDelta
r.setCell(x0i, yi)
// Do all the intermediate pixels.
dcover = int(edge1 - edge0)
darea = int(x0fTimes2 * dcover)
for yi != y1i {
r.area += darea
r.cover += dcover
yi += yiDelta
r.setCell(x0i, yi)
}
// Do the last pixel.
dcover = int(y1f - edge0)
darea = int(x0fTimes2 * dcover)
r.area += darea
r.cover += dcover
} else {
// There are at least two scanlines. Apart from the first and last
// scanlines, all intermediate scanlines go through the full height of
// the row, or 64 units in 26.6 fixed point format.
var (
p, q, edge0, edge1 fixed.Int26_6
yiDelta int
)
if dy > 0 {
p, q = (64-y0f)*dx, dy
edge0, edge1, yiDelta = 0, 64, 1
} else {
p, q = y0f*dx, -dy
edge0, edge1, yiDelta = 64, 0, -1
}
xDelta, xRem := p/q, p%q
if xRem < 0 {
xDelta -= 1
xRem += q
}
// Do the first scanline.
x, yi := x0, y0i
r.scan(yi, x, y0f, x+xDelta, edge1)
x, yi = x+xDelta, yi+yiDelta
r.setCell(int(x)/64, yi)
if yi != y1i {
// Do all the intermediate scanlines.
p = 64 * dx
fullDelta, fullRem := p/q, p%q
if fullRem < 0 {
fullDelta -= 1
fullRem += q
}
xRem -= q
for yi != y1i {
xDelta = fullDelta
xRem += fullRem
if xRem >= 0 {
xDelta += 1
xRem -= q
}
r.scan(yi, x, edge0, x+xDelta, edge1)
x, yi = x+xDelta, yi+yiDelta
r.setCell(int(x)/64, yi)
}
}
// Do the last scanline.
r.scan(yi, x, edge0, x1, y1f)
}
// The next lineTo starts from b.
r.a = b
}
// Add3 adds a cubic segment to the current curve.
func (r *Rasterizer) Add3(b, c, d fixed.Point26_6) {
// Calculate nSplit (the number of recursive decompositions) based on how
// 'curvy' it is.
dev2 := maxAbs(r.a.X-3*(b.X+c.X)+d.X, r.a.Y-3*(b.Y+c.Y)+d.Y) / fixed.Int26_6(r.splitScale2)
dev3 := maxAbs(r.a.X-2*b.X+d.X, r.a.Y-2*b.Y+d.Y) / fixed.Int26_6(r.splitScale3)
nsplit := 0
for dev2 > 0 || dev3 > 0 {
dev2 /= 8
dev3 /= 4
nsplit++
}
// devN 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: Add3 nsplit too large: " + strconv.Itoa(nsplit))
}
// Recursively decompose the curve nSplit levels deep.
var (
pStack [3*maxNsplit + 4]fixed.Point26_6
sStack [maxNsplit + 1]int
i int
)
sStack[0] = nsplit
pStack[0] = d
pStack[1] = c
pStack[2] = b
pStack[3] = r.a
for i >= 0 {
s := sStack[i]
p := pStack[3*i:]
if s > 0 {
// Split the cubic curve p[:4] into an equivalent set of two
// shorter curves: p[:4] and p[3:7]. The new p[6] is the old p[3],
// and p[0] is unchanged.
m01x := (p[0].X + p[1].X) / 2
m12x := (p[1].X + p[2].X) / 2
m23x := (p[2].X + p[3].X) / 2
p[6].X = p[3].X
p[5].X = m23x
p[1].X = m01x
p[2].X = (m01x + m12x) / 2
p[4].X = (m12x + m23x) / 2
p[3].X = (p[2].X + p[4].X) / 2
m01y := (p[0].Y + p[1].Y) / 2
m12y := (p[1].Y + p[2].Y) / 2
m23y := (p[2].Y + p[3].Y) / 2
p[6].Y = p[3].Y
p[5].Y = m23y
p[1].Y = m01y
p[2].Y = (m01y + m12y) / 2
p[4].Y = (m12y + m23y) / 2
p[3].Y = (p[2].Y + p[4].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 cubic with a two-linear-piece approximation.
midx := (p[0].X + 3*(p[1].X+p[2].X) + p[3].X) / 8
midy := (p[0].Y + 3*(p[1].Y+p[2].Y) + p[3].Y) / 8
r.Add1(fixed.Point26_6{midx, midy})
r.Add1(p[0])
i--
}
}
}
// 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)
}
func (h *hinter) iupInterp(interpY bool, p1, p2, ref1, ref2 int) {
if p1 > p2 {
return
}
if ref1 >= len(h.points[glyphZone][current]) ||
ref2 >= len(h.points[glyphZone][current]) {
return
}
var ifu1, ifu2 fixed.Int26_6
if interpY {
ifu1 = h.points[glyphZone][inFontUnits][ref1].Y
ifu2 = h.points[glyphZone][inFontUnits][ref2].Y
} else {
ifu1 = h.points[glyphZone][inFontUnits][ref1].X
ifu2 = h.points[glyphZone][inFontUnits][ref2].X
}
if ifu1 > ifu2 {
ifu1, ifu2 = ifu2, ifu1
ref1, ref2 = ref2, ref1
}
var unh1, unh2, delta1, delta2 fixed.Int26_6
if interpY {
unh1 = h.points[glyphZone][unhinted][ref1].Y
unh2 = h.points[glyphZone][unhinted][ref2].Y
delta1 = h.points[glyphZone][current][ref1].Y - unh1
delta2 = h.points[glyphZone][current][ref2].Y - unh2
} else {
unh1 = h.points[glyphZone][unhinted][ref1].X
unh2 = h.points[glyphZone][unhinted][ref2].X
delta1 = h.points[glyphZone][current][ref1].X - unh1
delta2 = h.points[glyphZone][current][ref2].X - unh2
}
var xy, ifuXY fixed.Int26_6
if ifu1 == ifu2 {
for i := p1; i <= p2; i++ {
if interpY {
xy = h.points[glyphZone][unhinted][i].Y
} else {
xy = h.points[glyphZone][unhinted][i].X
}
if xy <= unh1 {
xy += delta1
} else {
xy += delta2
}
if interpY {
h.points[glyphZone][current][i].Y = xy
} else {
h.points[glyphZone][current][i].X = xy
}
}
return
}
scale, scaleOK := int64(0), false
for i := p1; i <= p2; i++ {
if interpY {
xy = h.points[glyphZone][unhinted][i].Y
ifuXY = h.points[glyphZone][inFontUnits][i].Y
} else {
xy = h.points[glyphZone][unhinted][i].X
ifuXY = h.points[glyphZone][inFontUnits][i].X
}
if xy <= unh1 {
xy += delta1
} else if xy >= unh2 {
xy += delta2
} else {
if !scaleOK {
scaleOK = true
scale = mulDiv(int64(unh2+delta2-unh1-delta1), 0x10000, int64(ifu2-ifu1))
}
numer := int64(ifuXY-ifu1) * scale
if numer >= 0 {
numer += 0x8000
} else {
numer -= 0x8000
}
xy = unh1 + delta1 + fixed.Int26_6(numer/0x10000)
}
if interpY {
h.points[glyphZone][current][i].Y = xy
} else {
h.points[glyphZone][current][i].X = xy
}
}
}
// fmul returns x*y in 26.6 fixed point arithmetic.
func fmul(x, y fixed.Int26_6) fixed.Int26_6 {
return fixed.Int26_6((int64(x)*int64(y) + 1<<5) >> 6)
}
// fdiv returns x/y in 26.6 fixed point arithmetic.
func fdiv(x, y fixed.Int26_6) fixed.Int26_6 {
return fixed.Int26_6((int64(x) << 6) / int64(y))
}
func (liner FtLineBuilder) LineTo(x, y float64) {
liner.Adder.Add1(fixed.Point26_6{X: fixed.Int26_6(x * 64), Y: fixed.Int26_6(y * 64)})
}
func (h *hinter) run(program []byte, pCurrent, pUnhinted, pInFontUnits []Point, ends []int) error {
h.gs = h.defaultGS
h.points[glyphZone][current] = pCurrent
h.points[glyphZone][unhinted] = pUnhinted
h.points[glyphZone][inFontUnits] = pInFontUnits
h.ends = ends
if len(program) > 50000 {
return errors.New("truetype: hinting: too many instructions")
}
var (
steps, pc, top int
opcode uint8
callStack [32]callStackEntry
callStackTop int
)
for 0 <= pc && pc < len(program) {
steps++
if steps == 100000 {
return errors.New("truetype: hinting: too many steps")
}
opcode = program[pc]
if top < int(popCount[opcode]) {
return errors.New("truetype: hinting: stack underflow")
}
switch opcode {
case opSVTCA0:
h.gs.pv = [2]f2dot14{0, 0x4000}
h.gs.fv = [2]f2dot14{0, 0x4000}
h.gs.dv = [2]f2dot14{0, 0x4000}
case opSVTCA1:
h.gs.pv = [2]f2dot14{0x4000, 0}
h.gs.fv = [2]f2dot14{0x4000, 0}
h.gs.dv = [2]f2dot14{0x4000, 0}
case opSPVTCA0:
h.gs.pv = [2]f2dot14{0, 0x4000}
h.gs.dv = [2]f2dot14{0, 0x4000}
case opSPVTCA1:
h.gs.pv = [2]f2dot14{0x4000, 0}
h.gs.dv = [2]f2dot14{0x4000, 0}
case opSFVTCA0:
h.gs.fv = [2]f2dot14{0, 0x4000}
case opSFVTCA1:
h.gs.fv = [2]f2dot14{0x4000, 0}
case opSPVTL0, opSPVTL1, opSFVTL0, opSFVTL1:
top -= 2
p1 := h.point(0, current, h.stack[top+0])
p2 := h.point(0, current, h.stack[top+1])
if p1 == nil || p2 == nil {
return errors.New("truetype: hinting: point out of range")
}
dx := f2dot14(p1.X - p2.X)
dy := f2dot14(p1.Y - p2.Y)
if dx == 0 && dy == 0 {
dx = 0x4000
} else if opcode&1 != 0 {
// Counter-clockwise rotation.
dx, dy = -dy, dx
}
v := normalize(dx, dy)
if opcode < opSFVTL0 {
h.gs.pv = v
h.gs.dv = v
} else {
h.gs.fv = v
}
case opSPVFS:
top -= 2
h.gs.pv = normalize(f2dot14(h.stack[top]), f2dot14(h.stack[top+1]))
h.gs.dv = h.gs.pv
case opSFVFS:
top -= 2
h.gs.fv = normalize(f2dot14(h.stack[top]), f2dot14(h.stack[top+1]))
case opGPV:
if top+1 >= len(h.stack) {
return errors.New("truetype: hinting: stack overflow")
}
h.stack[top+0] = int32(h.gs.pv[0])
h.stack[top+1] = int32(h.gs.pv[1])
top += 2
case opGFV:
if top+1 >= len(h.stack) {
return errors.New("truetype: hinting: stack overflow")
}
h.stack[top+0] = int32(h.gs.fv[0])
h.stack[top+1] = int32(h.gs.fv[1])
top += 2
case opSFVTPV:
h.gs.fv = h.gs.pv
case opISECT:
top -= 5
p := h.point(2, current, h.stack[top+0])
a0 := h.point(1, current, h.stack[top+1])
a1 := h.point(1, current, h.stack[top+2])
b0 := h.point(0, current, h.stack[top+3])
b1 := h.point(0, current, h.stack[top+4])
if p == nil || a0 == nil || a1 == nil || b0 == nil || b1 == nil {
return errors.New("truetype: hinting: point out of range")
}
dbx := b1.X - b0.X
dby := b1.Y - b0.Y
dax := a1.X - a0.X
day := a1.Y - a0.Y
dx := b0.X - a0.X
dy := b0.Y - a0.Y
discriminant := mulDiv(int64(dax), int64(-dby), 0x40) +
mulDiv(int64(day), int64(dbx), 0x40)
dotProduct := mulDiv(int64(dax), int64(dbx), 0x40) +
mulDiv(int64(day), int64(dby), 0x40)
// The discriminant above is actually a cross product of vectors
// da and db. Together with the dot product, they can be used as
// surrogates for sine and cosine of the angle between the vectors.
// Indeed,
// dotproduct = |da||db|cos(angle)
// discriminant = |da||db|sin(angle)
// We use these equations to reject grazing intersections by
// thresholding abs(tan(angle)) at 1/19, corresponding to 3 degrees.
absDisc, absDotP := discriminant, dotProduct
if absDisc < 0 {
absDisc = -absDisc
}
if absDotP < 0 {
absDotP = -absDotP
}
if 19*absDisc > absDotP {
val := mulDiv(int64(dx), int64(-dby), 0x40) +
mulDiv(int64(dy), int64(dbx), 0x40)
rx := mulDiv(val, int64(dax), discriminant)
ry := mulDiv(val, int64(day), discriminant)
p.X = a0.X + fixed.Int26_6(rx)
p.Y = a0.Y + fixed.Int26_6(ry)
} else {
p.X = (a0.X + a1.X + b0.X + b1.X) / 4
p.Y = (a0.Y + a1.Y + b0.Y + b1.Y) / 4
}
p.Flags |= flagTouchedX | flagTouchedY
case opSRP0, opSRP1, opSRP2:
top--
h.gs.rp[opcode-opSRP0] = h.stack[top]
case opSZP0, opSZP1, opSZP2:
top--
h.gs.zp[opcode-opSZP0] = h.stack[top]
case opSZPS:
top--
h.gs.zp[0] = h.stack[top]
h.gs.zp[1] = h.stack[top]
h.gs.zp[2] = h.stack[top]
case opSLOOP:
top--
if h.stack[top] <= 0 {
return errors.New("truetype: hinting: invalid data")
}
h.gs.loop = h.stack[top]
case opRTG:
h.gs.roundPeriod = 1 << 6
h.gs.roundPhase = 0
h.gs.roundThreshold = 1 << 5
h.gs.roundSuper45 = false
case opRTHG:
h.gs.roundPeriod = 1 << 6
h.gs.roundPhase = 1 << 5
h.gs.roundThreshold = 1 << 5
h.gs.roundSuper45 = false
case opSMD:
top--
h.gs.minDist = fixed.Int26_6(h.stack[top])
case opELSE:
opcode = 1
goto ifelse
case opJMPR:
top--
pc += int(h.stack[top])
continue
case opSCVTCI:
top--
h.gs.controlValueCutIn = fixed.Int26_6(h.stack[top])
case opSSWCI:
top--
h.gs.singleWidthCutIn = fixed.Int26_6(h.stack[top])
case opSSW:
top--
h.gs.singleWidth = h.font.scale(h.scale * fixed.Int26_6(h.stack[top]))
case opDUP:
if top >= len(h.stack) {
return errors.New("truetype: hinting: stack overflow")
}
h.stack[top] = h.stack[top-1]
top++
case opPOP:
top--
case opCLEAR:
top = 0
case opSWAP:
h.stack[top-1], h.stack[top-2] = h.stack[top-2], h.stack[top-1]
case opDEPTH:
if top >= len(h.stack) {
return errors.New("truetype: hinting: stack overflow")
}
h.stack[top] = int32(top)
top++
case opCINDEX, opMINDEX:
x := int(h.stack[top-1])
if x <= 0 || x >= top {
return errors.New("truetype: hinting: invalid data")
}
h.stack[top-1] = h.stack[top-1-x]
if opcode == opMINDEX {
copy(h.stack[top-1-x:top-1], h.stack[top-x:top])
top--
}
case opALIGNPTS:
top -= 2
p := h.point(1, current, h.stack[top])
q := h.point(0, current, h.stack[top+1])
if p == nil || q == nil {
return errors.New("truetype: hinting: point out of range")
}
d := dotProduct(fixed.Int26_6(q.X-p.X), fixed.Int26_6(q.Y-p.Y), h.gs.pv) / 2
h.move(p, +d, true)
h.move(q, -d, true)
case opUTP:
top--
p := h.point(0, current, h.stack[top])
if p == nil {
return errors.New("truetype: hinting: point out of range")
}
p.Flags &^= flagTouchedX | flagTouchedY
case opLOOPCALL, opCALL:
if callStackTop >= len(callStack) {
return errors.New("truetype: hinting: call stack overflow")
}
top--
f, ok := h.functions[h.stack[top]]
if !ok {
return errors.New("truetype: hinting: undefined function")
}
callStack[callStackTop] = callStackEntry{program, pc, 1}
if opcode == opLOOPCALL {
top--
if h.stack[top] == 0 {
break
}
callStack[callStackTop].loopCount = h.stack[top]
}
callStackTop++
program, pc = f, 0
continue
case opFDEF:
// Save all bytecode up until the next ENDF.
startPC := pc + 1
fdefloop:
for {
pc++
if pc >= len(program) {
return errors.New("truetype: hinting: unbalanced FDEF")
}
switch program[pc] {
case opFDEF:
return errors.New("truetype: hinting: nested FDEF")
case opENDF:
top--
h.functions[h.stack[top]] = program[startPC : pc+1]
break fdefloop
default:
var ok bool
pc, ok = skipInstructionPayload(program, pc)
if !ok {
return errors.New("truetype: hinting: unbalanced FDEF")
}
}
}
case opENDF:
if callStackTop == 0 {
return errors.New("truetype: hinting: call stack underflow")
}
callStackTop--
callStack[callStackTop].loopCount--
if callStack[callStackTop].loopCount != 0 {
callStackTop++
pc = 0
continue
}
program, pc = callStack[callStackTop].program, callStack[callStackTop].pc
case opMDAP0, opMDAP1:
top--
i := h.stack[top]
p := h.point(0, current, i)
if p == nil {
return errors.New("truetype: hinting: point out of range")
}
distance := fixed.Int26_6(0)
if opcode == opMDAP1 {
distance = dotProduct(p.X, p.Y, h.gs.pv)
// TODO: metrics compensation.
distance = h.round(distance) - distance
}
h.move(p, distance, true)
h.gs.rp[0] = i
h.gs.rp[1] = i
case opIUP0, opIUP1:
iupY, mask := opcode == opIUP0, uint32(flagTouchedX)
if iupY {
mask = flagTouchedY
}
prevEnd := 0
for _, end := range h.ends {
for i := prevEnd; i < end; i++ {
for i < end && h.points[glyphZone][current][i].Flags&mask == 0 {
i++
}
if i == end {
break
}
firstTouched, curTouched := i, i
i++
for ; i < end; i++ {
if h.points[glyphZone][current][i].Flags&mask != 0 {
h.iupInterp(iupY, curTouched+1, i-1, curTouched, i)
curTouched = i
}
}
if curTouched == firstTouched {
h.iupShift(iupY, prevEnd, end, curTouched)
} else {
h.iupInterp(iupY, curTouched+1, end-1, curTouched, firstTouched)
if firstTouched > 0 {
h.iupInterp(iupY, prevEnd, firstTouched-1, curTouched, firstTouched)
}
}
}
prevEnd = end
}
case opSHP0, opSHP1:
if top < int(h.gs.loop) {
return errors.New("truetype: hinting: stack underflow")
}
_, _, d, ok := h.displacement(opcode&1 == 0)
if !ok {
return errors.New("truetype: hinting: point out of range")
}
for ; h.gs.loop != 0; h.gs.loop-- {
top--
p := h.point(2, current, h.stack[top])
if p == nil {
return errors.New("truetype: hinting: point out of range")
}
h.move(p, d, true)
}
h.gs.loop = 1
case opSHC0, opSHC1:
top--
zonePointer, i, d, ok := h.displacement(opcode&1 == 0)
if !ok {
return errors.New("truetype: hinting: point out of range")
}
if h.gs.zp[2] == 0 {
// TODO: implement this when we have a glyph that does this.
return errors.New("hinting: unimplemented SHC instruction")
}
contour := h.stack[top]
if contour < 0 || len(ends) <= int(contour) {
return errors.New("truetype: hinting: contour out of range")
}
j0, j1 := int32(0), int32(h.ends[contour])
if contour > 0 {
j0 = int32(h.ends[contour-1])
}
move := h.gs.zp[zonePointer] != h.gs.zp[2]
for j := j0; j < j1; j++ {
if move || j != i {
h.move(h.point(2, current, j), d, true)
}
}
case opSHZ0, opSHZ1:
top--
zonePointer, i, d, ok := h.displacement(opcode&1 == 0)
if !ok {
return errors.New("truetype: hinting: point out of range")
}
// As per C Freetype, SHZ doesn't move the phantom points, or mark
// the points as touched.
limit := int32(len(h.points[h.gs.zp[2]][current]))
if h.gs.zp[2] == glyphZone {
limit -= 4
}
for j := int32(0); j < limit; j++ {
if i != j || h.gs.zp[zonePointer] != h.gs.zp[2] {
h.move(h.point(2, current, j), d, false)
}
}
case opSHPIX:
top--
d := fixed.Int26_6(h.stack[top])
if top < int(h.gs.loop) {
return errors.New("truetype: hinting: stack underflow")
}
for ; h.gs.loop != 0; h.gs.loop-- {
top--
p := h.point(2, current, h.stack[top])
if p == nil {
return errors.New("truetype: hinting: point out of range")
}
h.move(p, d, true)
}
h.gs.loop = 1
case opIP:
if top < int(h.gs.loop) {
return errors.New("truetype: hinting: stack underflow")
}
pointType := inFontUnits
twilight := h.gs.zp[0] == 0 || h.gs.zp[1] == 0 || h.gs.zp[2] == 0
if twilight {
pointType = unhinted
}
p := h.point(1, pointType, h.gs.rp[2])
oldP := h.point(0, pointType, h.gs.rp[1])
oldRange := dotProduct(p.X-oldP.X, p.Y-oldP.Y, h.gs.dv)
p = h.point(1, current, h.gs.rp[2])
curP := h.point(0, current, h.gs.rp[1])
curRange := dotProduct(p.X-curP.X, p.Y-curP.Y, h.gs.pv)
for ; h.gs.loop != 0; h.gs.loop-- {
top--
i := h.stack[top]
p = h.point(2, pointType, i)
oldDist := dotProduct(p.X-oldP.X, p.Y-oldP.Y, h.gs.dv)
p = h.point(2, current, i)
curDist := dotProduct(p.X-curP.X, p.Y-curP.Y, h.gs.pv)
newDist := fixed.Int26_6(0)
if oldDist != 0 {
if oldRange != 0 {
newDist = fixed.Int26_6(mulDiv(int64(oldDist), int64(curRange), int64(oldRange)))
} else {
newDist = -oldDist
}
}
h.move(p, newDist-curDist, true)
}
h.gs.loop = 1
case opMSIRP0, opMSIRP1:
top -= 2
i := h.stack[top]
distance := fixed.Int26_6(h.stack[top+1])
// TODO: special case h.gs.zp[1] == 0 in C Freetype.
ref := h.point(0, current, h.gs.rp[0])
p := h.point(1, current, i)
if ref == nil || p == nil {
return errors.New("truetype: hinting: point out of range")
}
curDist := dotProduct(p.X-ref.X, p.Y-ref.Y, h.gs.pv)
// Set-RP0 bit.
if opcode == opMSIRP1 {
h.gs.rp[0] = i
}
h.gs.rp[1] = h.gs.rp[0]
h.gs.rp[2] = i
// Move the point.
h.move(p, distance-curDist, true)
case opALIGNRP:
if top < int(h.gs.loop) {
return errors.New("truetype: hinting: stack underflow")
}
ref := h.point(0, current, h.gs.rp[0])
if ref == nil {
return errors.New("truetype: hinting: point out of range")
}
for ; h.gs.loop != 0; h.gs.loop-- {
top--
p := h.point(1, current, h.stack[top])
if p == nil {
return errors.New("truetype: hinting: point out of range")
}
h.move(p, -dotProduct(p.X-ref.X, p.Y-ref.Y, h.gs.pv), true)
}
h.gs.loop = 1
case opRTDG:
h.gs.roundPeriod = 1 << 5
h.gs.roundPhase = 0
h.gs.roundThreshold = 1 << 4
h.gs.roundSuper45 = false
case opMIAP0, opMIAP1:
top -= 2
i := h.stack[top]
distance := h.getScaledCVT(h.stack[top+1])
if h.gs.zp[0] == 0 {
p := h.point(0, unhinted, i)
q := h.point(0, current, i)
p.X = fixed.Int26_6((int64(distance) * int64(h.gs.fv[0])) >> 14)
p.Y = fixed.Int26_6((int64(distance) * int64(h.gs.fv[1])) >> 14)
*q = *p
}
p := h.point(0, current, i)
oldDist := dotProduct(p.X, p.Y, h.gs.pv)
if opcode == opMIAP1 {
if fabs(distance-oldDist) > h.gs.controlValueCutIn {
distance = oldDist
}
// TODO: metrics compensation.
distance = h.round(distance)
}
h.move(p, distance-oldDist, true)
h.gs.rp[0] = i
h.gs.rp[1] = i
case opNPUSHB:
opcode = 0
goto push
case opNPUSHW:
opcode = 0x80
goto push
case opWS:
top -= 2
i := int(h.stack[top])
if i < 0 || len(h.store) <= i {
return errors.New("truetype: hinting: invalid data")
}
h.store[i] = h.stack[top+1]
case opRS:
i := int(h.stack[top-1])
if i < 0 || len(h.store) <= i {
return errors.New("truetype: hinting: invalid data")
}
h.stack[top-1] = h.store[i]
case opWCVTP:
top -= 2
h.setScaledCVT(h.stack[top], fixed.Int26_6(h.stack[top+1]))
case opRCVT:
h.stack[top-1] = int32(h.getScaledCVT(h.stack[top-1]))
case opGC0, opGC1:
i := h.stack[top-1]
if opcode == opGC0 {
p := h.point(2, current, i)
h.stack[top-1] = int32(dotProduct(p.X, p.Y, h.gs.pv))
} else {
p := h.point(2, unhinted, i)
// Using dv as per C Freetype.
h.stack[top-1] = int32(dotProduct(p.X, p.Y, h.gs.dv))
}
case opSCFS:
top -= 2
i := h.stack[top]
p := h.point(2, current, i)
if p == nil {
return errors.New("truetype: hinting: point out of range")
}
c := dotProduct(p.X, p.Y, h.gs.pv)
h.move(p, fixed.Int26_6(h.stack[top+1])-c, true)
if h.gs.zp[2] != 0 {
break
}
q := h.point(2, unhinted, i)
if q == nil {
return errors.New("truetype: hinting: point out of range")
}
q.X = p.X
q.Y = p.Y
case opMD0, opMD1:
top--
pt, v, scale := pointType(0), [2]f2dot14{}, false
if opcode == opMD0 {
pt = current
v = h.gs.pv
} else if h.gs.zp[0] == 0 || h.gs.zp[1] == 0 {
pt = unhinted
v = h.gs.dv
} else {
pt = inFontUnits
v = h.gs.dv
scale = true
}
p := h.point(0, pt, h.stack[top-1])
q := h.point(1, pt, h.stack[top])
if p == nil || q == nil {
return errors.New("truetype: hinting: point out of range")
}
d := int32(dotProduct(p.X-q.X, p.Y-q.Y, v))
if scale {
d = int32(int64(d*int32(h.scale)) / int64(h.font.fUnitsPerEm))
}
h.stack[top-1] = d
case opMPPEM, opMPS:
if top >= len(h.stack) {
return errors.New("truetype: hinting: stack overflow")
}
// For MPS, point size should be irrelevant; we return the PPEM.
h.stack[top] = int32(h.scale) >> 6
top++
case opFLIPON, opFLIPOFF:
h.gs.autoFlip = opcode == opFLIPON
case opDEBUG:
// No-op.
case opLT:
top--
h.stack[top-1] = bool2int32(h.stack[top-1] < h.stack[top])
case opLTEQ:
top--
h.stack[top-1] = bool2int32(h.stack[top-1] <= h.stack[top])
case opGT:
top--
h.stack[top-1] = bool2int32(h.stack[top-1] > h.stack[top])
case opGTEQ:
top--
h.stack[top-1] = bool2int32(h.stack[top-1] >= h.stack[top])
case opEQ:
top--
h.stack[top-1] = bool2int32(h.stack[top-1] == h.stack[top])
case opNEQ:
top--
h.stack[top-1] = bool2int32(h.stack[top-1] != h.stack[top])
case opODD, opEVEN:
i := h.round(fixed.Int26_6(h.stack[top-1])) >> 6
h.stack[top-1] = int32(i&1) ^ int32(opcode-opODD)
case opIF:
top--
if h.stack[top] == 0 {
opcode = 0
goto ifelse
}
case opEIF:
// No-op.
case opAND:
top--
h.stack[top-1] = bool2int32(h.stack[top-1] != 0 && h.stack[top] != 0)
case opOR:
top--
h.stack[top-1] = bool2int32(h.stack[top-1]|h.stack[top] != 0)
case opNOT:
h.stack[top-1] = bool2int32(h.stack[top-1] == 0)
case opDELTAP1:
goto delta
case opSDB:
top--
h.gs.deltaBase = h.stack[top]
case opSDS:
top--
h.gs.deltaShift = h.stack[top]
case opADD:
top--
h.stack[top-1] += h.stack[top]
case opSUB:
top--
h.stack[top-1] -= h.stack[top]
case opDIV:
top--
if h.stack[top] == 0 {
return errors.New("truetype: hinting: division by zero")
}
h.stack[top-1] = int32(fdiv(fixed.Int26_6(h.stack[top-1]), fixed.Int26_6(h.stack[top])))
case opMUL:
top--
h.stack[top-1] = int32(fmul(fixed.Int26_6(h.stack[top-1]), fixed.Int26_6(h.stack[top])))
case opABS:
if h.stack[top-1] < 0 {
h.stack[top-1] = -h.stack[top-1]
}
case opNEG:
h.stack[top-1] = -h.stack[top-1]
case opFLOOR:
h.stack[top-1] &^= 63
case opCEILING:
h.stack[top-1] += 63
h.stack[top-1] &^= 63
case opROUND00, opROUND01, opROUND10, opROUND11:
// The four flavors of opROUND are equivalent. See the comment below on
// opNROUND for the rationale.
h.stack[top-1] = int32(h.round(fixed.Int26_6(h.stack[top-1])))
case opNROUND00, opNROUND01, opNROUND10, opNROUND11:
// No-op. The spec says to add one of four "compensations for the engine
// characteristics", to cater for things like "different dot-size printers".
// https://developer.apple.com/fonts/TTRefMan/RM02/Chap2.html#engine_compensation
// This code does not implement engine compensation, as we don't expect to
// be used to output on dot-matrix printers.
case opWCVTF:
top -= 2
h.setScaledCVT(h.stack[top], h.font.scale(h.scale*fixed.Int26_6(h.stack[top+1])))
case opDELTAP2, opDELTAP3, opDELTAC1, opDELTAC2, opDELTAC3:
goto delta
case opSROUND, opS45ROUND:
top--
switch (h.stack[top] >> 6) & 0x03 {
case 0:
h.gs.roundPeriod = 1 << 5
case 1, 3:
h.gs.roundPeriod = 1 << 6
case 2:
h.gs.roundPeriod = 1 << 7
}
h.gs.roundSuper45 = opcode == opS45ROUND
if h.gs.roundSuper45 {
// The spec says to multiply by √2, but the C Freetype code says 1/√2.
// We go with 1/√2.
h.gs.roundPeriod *= 46341
h.gs.roundPeriod /= 65536
}
h.gs.roundPhase = h.gs.roundPeriod * fixed.Int26_6((h.stack[top]>>4)&0x03) / 4
if x := h.stack[top] & 0x0f; x != 0 {
h.gs.roundThreshold = h.gs.roundPeriod * fixed.Int26_6(x-4) / 8
} else {
h.gs.roundThreshold = h.gs.roundPeriod - 1
}
case opJROT:
top -= 2
if h.stack[top+1] != 0 {
pc += int(h.stack[top])
continue
}
case opJROF:
top -= 2
if h.stack[top+1] == 0 {
pc += int(h.stack[top])
continue
}
case opROFF:
h.gs.roundPeriod = 0
h.gs.roundPhase = 0
h.gs.roundThreshold = 0
h.gs.roundSuper45 = false
case opRUTG:
h.gs.roundPeriod = 1 << 6
h.gs.roundPhase = 0
h.gs.roundThreshold = 1<<6 - 1
h.gs.roundSuper45 = false
case opRDTG:
h.gs.roundPeriod = 1 << 6
h.gs.roundPhase = 0
h.gs.roundThreshold = 0
h.gs.roundSuper45 = false
case opSANGW, opAA:
// These ops are "anachronistic" and no longer used.
top--
case opFLIPPT:
if top < int(h.gs.loop) {
return errors.New("truetype: hinting: stack underflow")
}
points := h.points[glyphZone][current]
for ; h.gs.loop != 0; h.gs.loop-- {
top--
i := h.stack[top]
if i < 0 || len(points) <= int(i) {
return errors.New("truetype: hinting: point out of range")
}
points[i].Flags ^= flagOnCurve
}
h.gs.loop = 1
case opFLIPRGON, opFLIPRGOFF:
top -= 2
i, j, points := h.stack[top], h.stack[top+1], h.points[glyphZone][current]
if i < 0 || len(points) <= int(i) || j < 0 || len(points) <= int(j) {
return errors.New("truetype: hinting: point out of range")
}
for ; i <= j; i++ {
if opcode == opFLIPRGON {
points[i].Flags |= flagOnCurve
} else {
points[i].Flags &^= flagOnCurve
}
}
case opSCANCTRL:
// We do not support dropout control, as we always rasterize grayscale glyphs.
top--
case opSDPVTL0, opSDPVTL1:
top -= 2
for i := 0; i < 2; i++ {
pt := unhinted
if i != 0 {
pt = current
}
p := h.point(1, pt, h.stack[top])
q := h.point(2, pt, h.stack[top+1])
if p == nil || q == nil {
return errors.New("truetype: hinting: point out of range")
}
dx := f2dot14(p.X - q.X)
dy := f2dot14(p.Y - q.Y)
if dx == 0 && dy == 0 {
dx = 0x4000
} else if opcode&1 != 0 {
// Counter-clockwise rotation.
dx, dy = -dy, dx
}
if i == 0 {
h.gs.dv = normalize(dx, dy)
} else {
h.gs.pv = normalize(dx, dy)
}
}
case opGETINFO:
res := int32(0)
if h.stack[top-1]&(1<<0) != 0 {
// Set the engine version. We hard-code this to 35, the same as
// the C freetype code, which says that "Version~35 corresponds
// to MS rasterizer v.1.7 as used e.g. in Windows~98".
res |= 35
}
if h.stack[top-1]&(1<<5) != 0 {
// Set that we support grayscale.
res |= 1 << 12
}
// We set no other bits, as we do not support rotated or stretched glyphs.
h.stack[top-1] = res
case opIDEF:
// IDEF is for ancient versions of the bytecode interpreter, and is no longer used.
return errors.New("truetype: hinting: unsupported IDEF instruction")
case opROLL:
h.stack[top-1], h.stack[top-3], h.stack[top-2] =
h.stack[top-3], h.stack[top-2], h.stack[top-1]
case opMAX:
top--
if h.stack[top-1] < h.stack[top] {
h.stack[top-1] = h.stack[top]
}
case opMIN:
top--
if h.stack[top-1] > h.stack[top] {
h.stack[top-1] = h.stack[top]
}
case opSCANTYPE:
// We do not support dropout control, as we always rasterize grayscale glyphs.
top--
case opINSTCTRL:
// TODO: support instruction execution control? It seems rare, and even when
// nominally used (e.g. Source Sans Pro), it seems conditional on extreme or
// unusual rasterization conditions. For example, the code snippet at
// https://developer.apple.com/fonts/TTRefMan/RM05/Chap5.html#INSTCTRL
// uses INSTCTRL when grid-fitting a rotated or stretched glyph, but
// freetype-go does not support rotated or stretched glyphs.
top -= 2
default:
if opcode < opPUSHB000 {
return errors.New("truetype: hinting: unrecognized instruction")
}
if opcode < opMDRP00000 {
// PUSHxxxx opcode.
if opcode < opPUSHW000 {
opcode -= opPUSHB000 - 1
} else {
opcode -= opPUSHW000 - 1 - 0x80
}
goto push
}
if opcode < opMIRP00000 {
// MDRPxxxxx opcode.
top--
i := h.stack[top]
ref := h.point(0, current, h.gs.rp[0])
p := h.point(1, current, i)
if ref == nil || p == nil {
return errors.New("truetype: hinting: point out of range")
}
oldDist := fixed.Int26_6(0)
if h.gs.zp[0] == 0 || h.gs.zp[1] == 0 {
p0 := h.point(1, unhinted, i)
p1 := h.point(0, unhinted, h.gs.rp[0])
oldDist = dotProduct(p0.X-p1.X, p0.Y-p1.Y, h.gs.dv)
} else {
p0 := h.point(1, inFontUnits, i)
p1 := h.point(0, inFontUnits, h.gs.rp[0])
oldDist = dotProduct(p0.X-p1.X, p0.Y-p1.Y, h.gs.dv)
oldDist = h.font.scale(h.scale * oldDist)
}
// Single-width cut-in test.
if x := fabs(oldDist - h.gs.singleWidth); x < h.gs.singleWidthCutIn {
if oldDist >= 0 {
oldDist = +h.gs.singleWidth
} else {
oldDist = -h.gs.singleWidth
}
}
// Rounding bit.
// TODO: metrics compensation.
distance := oldDist
if opcode&0x04 != 0 {
distance = h.round(oldDist)
}
// Minimum distance bit.
if opcode&0x08 != 0 {
if oldDist >= 0 {
if distance < h.gs.minDist {
distance = h.gs.minDist
}
} else {
if distance > -h.gs.minDist {
distance = -h.gs.minDist
}
}
}
// Set-RP0 bit.
h.gs.rp[1] = h.gs.rp[0]
h.gs.rp[2] = i
if opcode&0x10 != 0 {
h.gs.rp[0] = i
}
// Move the point.
oldDist = dotProduct(p.X-ref.X, p.Y-ref.Y, h.gs.pv)
h.move(p, distance-oldDist, true)
} else {
// MIRPxxxxx opcode.
top -= 2
i := h.stack[top]
cvtDist := h.getScaledCVT(h.stack[top+1])
if fabs(cvtDist-h.gs.singleWidth) < h.gs.singleWidthCutIn {
if cvtDist >= 0 {
cvtDist = +h.gs.singleWidth
} else {
cvtDist = -h.gs.singleWidth
}
}
if h.gs.zp[1] == 0 {
// TODO: implement once we have a .ttf file that triggers
// this, so that we can step through C's freetype.
return errors.New("truetype: hinting: unimplemented twilight point adjustment")
}
ref := h.point(0, unhinted, h.gs.rp[0])
p := h.point(1, unhinted, i)
if ref == nil || p == nil {
return errors.New("truetype: hinting: point out of range")
}
oldDist := dotProduct(p.X-ref.X, p.Y-ref.Y, h.gs.dv)
ref = h.point(0, current, h.gs.rp[0])
p = h.point(1, current, i)
if ref == nil || p == nil {
return errors.New("truetype: hinting: point out of range")
}
curDist := dotProduct(p.X-ref.X, p.Y-ref.Y, h.gs.pv)
if h.gs.autoFlip && oldDist^cvtDist < 0 {
cvtDist = -cvtDist
}
// Rounding bit.
// TODO: metrics compensation.
distance := cvtDist
if opcode&0x04 != 0 {
// The CVT value is only used if close enough to oldDist.
if (h.gs.zp[0] == h.gs.zp[1]) &&
(fabs(cvtDist-oldDist) > h.gs.controlValueCutIn) {
distance = oldDist
}
distance = h.round(distance)
}
// Minimum distance bit.
if opcode&0x08 != 0 {
if oldDist >= 0 {
if distance < h.gs.minDist {
distance = h.gs.minDist
}
} else {
if distance > -h.gs.minDist {
distance = -h.gs.minDist
}
}
}
// Set-RP0 bit.
h.gs.rp[1] = h.gs.rp[0]
h.gs.rp[2] = i
if opcode&0x10 != 0 {
h.gs.rp[0] = i
}
// Move the point.
h.move(p, distance-curDist, true)
}
}
pc++
continue
ifelse:
// Skip past bytecode until the next ELSE (if opcode == 0) or the
// next EIF (for all opcodes). Opcode == 0 means that we have come
// from an IF. Opcode == 1 means that we have come from an ELSE.
{
ifelseloop:
for depth := 0; ; {
pc++
if pc >= len(program) {
return errors.New("truetype: hinting: unbalanced IF or ELSE")
}
switch program[pc] {
case opIF:
depth++
case opELSE:
if depth == 0 && opcode == 0 {
break ifelseloop
}
case opEIF:
depth--
if depth < 0 {
break ifelseloop
}
default:
var ok bool
pc, ok = skipInstructionPayload(program, pc)
if !ok {
return errors.New("truetype: hinting: unbalanced IF or ELSE")
}
}
}
pc++
continue
}
push:
// Push n elements from the program to the stack, where n is the low 7 bits of
// opcode. If the low 7 bits are zero, then n is the next byte from the program.
// The high bit being 0 means that the elements are zero-extended bytes.
// The high bit being 1 means that the elements are sign-extended words.
{
width := 1
if opcode&0x80 != 0 {
opcode &^= 0x80
width = 2
}
if opcode == 0 {
pc++
if pc >= len(program) {
return errors.New("truetype: hinting: insufficient data")
}
opcode = program[pc]
}
pc++
if top+int(opcode) > len(h.stack) {
return errors.New("truetype: hinting: stack overflow")
}
if pc+width*int(opcode) > len(program) {
return errors.New("truetype: hinting: insufficient data")
}
for ; opcode > 0; opcode-- {
if width == 1 {
h.stack[top] = int32(program[pc])
} else {
h.stack[top] = int32(int8(program[pc]))<<8 | int32(program[pc+1])
}
top++
pc += width
}
continue
}
delta:
{
if opcode >= opDELTAC1 && !h.scaledCVTInitialized {
h.initializeScaledCVT()
}
top--
n := h.stack[top]
if int32(top) < 2*n {
return errors.New("truetype: hinting: stack underflow")
}
for ; n > 0; n-- {
top -= 2
b := h.stack[top]
c := (b & 0xf0) >> 4
switch opcode {
case opDELTAP2, opDELTAC2:
c += 16
case opDELTAP3, opDELTAC3:
c += 32
}
c += h.gs.deltaBase
if ppem := (int32(h.scale) + 1<<5) >> 6; ppem != c {
continue
}
b = (b & 0x0f) - 8
if b >= 0 {
b++
}
b = b * 64 / (1 << uint32(h.gs.deltaShift))
if opcode >= opDELTAC1 {
a := h.stack[top+1]
if a < 0 || len(h.scaledCVT) <= int(a) {
return errors.New("truetype: hinting: index out of range")
}
h.scaledCVT[a] += fixed.Int26_6(b)
} else {
p := h.point(0, current, h.stack[top+1])
if p == nil {
return errors.New("truetype: hinting: point out of range")
}
h.move(p, fixed.Int26_6(b), true)
}
}
pc++
continue
}
}
return nil
}