// 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
}
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 (p *glyphPage) add(rune rune, g *glyph) bool {
if _, found := p.offsets[rune]; found {
panic("Glyph already added to glyph page")
}
w, h := g.size(p.resolution).WH()
x, y := p.nextPoint.X, p.nextPoint.Y
if x+w > p.size.W {
// Row full, start new line
x = 0
y += p.rowHeight + glyphPadding
p.rowHeight = 0
}
if y+h > p.size.H {
return false // Page full
}
// Build the raster contours
p.rast.Clear()
fx := -raster.Fix32((int64(g.B.XMin) * int64(p.resolution)) >> 14)
fy := +raster.Fix32((int64(g.B.YMax) * int64(p.resolution)) >> 14)
e0 := 0
for _, e1 := range g.End {
p.drawContour(g.Point[e0:e1], fx, fy)
e0 = e1
}
// Perform the rasterization
a := &image.Alpha{
Pix: p.image.Pix[x+y*p.image.Stride:],
Stride: p.image.Stride,
Rect: image.Rect(0, 0, w, h),
}
p.rast.Rasterize(raster.NewAlphaSrcPainter(a))
p.offsets[rune] = math.Point{X: x, Y: y}
p.nextPoint = math.Point{X: x + w + glyphPadding, Y: y}
if h > p.rowHeight {
p.rowHeight = h
}
if p.tex != nil {
p.tex.Release()
p.tex = nil
}
return true
}
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.")
}
func TestFreetype(t *testing.T) {
var p Path
p.LineTo(10, 190)
c := curve.CubicCurveFloat64{10, 190, 10, 10, 190, 10, 190, 190}
c.Segment(&p, flattening_threshold)
poly := Polygon(p.points)
rgba := color.RGBA{0, 0, 0, 0xff}
bounds := image.Rect(0, 0, 200, 200)
mask := image.NewAlpha(bounds)
img := image.NewRGBA(bounds)
rasterizer := raster.NewRasterizer(200, 200)
rasterizer.UseNonZeroWinding = false
rasterizer.Start(raster.Point{raster.Fix32(10 * 256), raster.Fix32(190 * 256)})
for j := 0; j < len(poly); j = j + 2 {
rasterizer.Add1(raster.Point{raster.Fix32(poly[j] * 256), raster.Fix32(poly[j+1] * 256)})
}
painter := raster.NewAlphaSrcPainter(mask)
rasterizer.Rasterize(painter)
DrawSolidRGBA(img, mask, rgba)
savepng("_testFreetype.png", img)
}
func genGlyphs(font *truetype.Font, size int, text string) (glyphs []*glyph) {
scale := int32(float64(size) * dpi * (64.0 / 72.0))
clip := image.Rect(0, 0, width, height)
// Calculate the rasterizer's bounds to handle the largest glyph.
b := font.Bounds(scale)
xmin := int(b.XMin) >> 6
ymin := -int(b.YMax) >> 6
xmax := int(b.XMax+63) >> 6
ymax := -int(b.YMin-63) >> 6
r := raster.NewRasterizer(xmax-xmin, ymax-ymin)
buf := truetype.NewGlyphBuf()
for _, variant := range []string{strings.ToUpper(text), strings.ToLower(text)} {
pt := Pt(30, 10+int(pointToFix32(float64(size))>>8))
for _, char := range variant {
idx := font.Index(char)
buf.Load(font, scale, idx, truetype.FullHinting)
// Calculate the integer-pixel bounds for the glyph.
xmin := int(raster.Fix32(buf.B.XMin<<2)) >> 8
ymin := int(-raster.Fix32(buf.B.YMax<<2)) >> 8
xmax := int(raster.Fix32(buf.B.XMax<<2)+0xff) >> 8
ymax := int(-raster.Fix32(buf.B.YMin<<2)+0xff) >> 8
fx := raster.Fix32(-xmin << 8)
fy := raster.Fix32(-ymin << 8)
ix := int(pt.X >> 8)
iy := int(pt.Y >> 8)
// Rasterize the glyph's vectors.
r.Clear()
e0 := 0
for _, e1 := range buf.End {
drawContour(r, buf.Point[e0:e1], fx, fy)
e0 = e1
}
mask := image.NewAlpha(image.Rect(0, 0, xmax-xmin, ymax-ymin))
r.Rasterize(raster.NewAlphaSrcPainter(mask))
pt.X += raster.Fix32(buf.AdvanceWidth << 2)
offset := image.Point{xmin + ix, ymin + iy}
glyphRect := mask.Bounds().Add(offset)
dr := clip.Intersect(glyphRect)
mp := image.Point{0, dr.Min.Y - glyphRect.Min.Y}
glyphs = append(glyphs, &glyph{
mask: mask,
mp: mp,
dr: dr,
})
}
}
return
}