func (r *Rasterizer) Fill(img *image.Alpha, p Polygon, nonZeroWindingRule bool) {
r.table = make([]*Intersection, img.Bounds().Dy())
var xmin, ymin, xmax, ymax float64
xmin = p[0]
ymin = p[1]
xmax = xmin
ymax = ymin
var x, y float64
for i := 2; i < len(p); i += 2 {
x, y = p[i], p[i+1]
if x > xmax {
xmax = x
} else if x < xmin {
xmin = x
}
if y > ymax {
ymax = y
} else if y < ymin {
ymin = y
}
}
prevX, prevY := p[0], p[1]
for i := 2; i < len(p); i += 2 {
x, y = p[i], p[i+1]
r.edge(prevX, prevY, x, y)
prevX, prevY = x, y
}
r.edge(x, y, p[0], p[1])
if nonZeroWindingRule {
r.scanNonZero(img, int(ymin), int(ymax+0.5))
} else {
r.scanEvenOdd(img, int(ymin), int(ymax+0.5))
}
}
func (z *Rasterizer) rasterizeDstAlphaSrcOpaqueOpSrc(dst *image.Alpha, r image.Rectangle) {
// TODO: non-zero vs even-odd winding?
if r == dst.Bounds() && r == z.Bounds() {
// We bypass the z.accumulateMask step and convert straight from
// z.bufF32 or z.bufU32 to dst.Pix.
if z.useFloatingPointMath {
if haveFloatingAccumulateSIMD {
floatingAccumulateOpSrcSIMD(dst.Pix, z.bufF32)
} else {
floatingAccumulateOpSrc(dst.Pix, z.bufF32)
}
} else {
if haveFixedAccumulateSIMD {
fixedAccumulateOpSrcSIMD(dst.Pix, z.bufU32)
} else {
fixedAccumulateOpSrc(dst.Pix, z.bufU32)
}
}
return
}
z.accumulateMask()
pix := dst.Pix[dst.PixOffset(r.Min.X, r.Min.Y):]
for y, y1 := 0, r.Max.Y-r.Min.Y; y < y1; y++ {
for x, x1 := 0, r.Max.X-r.Min.X; x < x1; x++ {
ma := z.bufU32[y*z.size.X+x]
// This formula is like rasterizeOpSrc's, simplified for the
// concrete dst type and opaque src assumption.
pix[y*dst.Stride+x] = uint8(ma >> 8)
}
}
}
func (z *Rasterizer) rasterizeDstAlphaSrcOpaqueOpSrc(dst *image.Alpha, r image.Rectangle) {
// TODO: add SIMD implementations.
// TODO: add a fixed point math implementation.
// TODO: non-zero vs even-odd winding?
if r == dst.Bounds() && r == z.Bounds() {
floatingAccumulate(dst.Pix, z.area)
return
}
println("TODO: the general case")
}
// checkCornersCenter checks that the corners of the image are all 0x00 and the
// center is 0xff.
func checkCornersCenter(m *image.Alpha) error {
if err := checkCorners(m); err != nil {
return err
}
size := m.Bounds().Size()
center := m.Pix[(size.Y/2)*m.Stride+(size.X/2)]
if center != 0xff {
return fmt.Errorf("center: got %#02x, want 0xff", center)
}
return nil
}
// checkCorners checks that the corners of the image are all 0x00.
func checkCorners(m *image.Alpha) error {
size := m.Bounds().Size()
corners := [4]uint8{
m.Pix[(0*size.Y+0)*m.Stride+(0*size.X+0)],
m.Pix[(0*size.Y+0)*m.Stride+(1*size.X-1)],
m.Pix[(1*size.Y-1)*m.Stride+(0*size.X+0)],
m.Pix[(1*size.Y-1)*m.Stride+(1*size.X-1)],
}
if corners != [4]uint8{} {
return fmt.Errorf("corners were not all zero: %v", corners)
}
return nil
}
func Context(dst *image.Alpha, bold bool) *freetype.Context {
c := freetype.NewContext()
c.SetDPI(dpi)
if bold {
c.SetFont(bld)
} else {
c.SetFont(reg)
}
c.SetFontSize(size)
c.SetClip(dst.Bounds())
c.SetDst(dst)
c.SetSrc(image.Opaque)
return c
}
func bilinearAlpha(src *image.Alpha, x, y float32) color.Alpha {
p := findLinearSrc(src.Bounds(), x, y)
// Slice offsets for the surrounding pixels.
off00 := src.PixOffset(p.low.X, p.low.Y)
off01 := src.PixOffset(p.high.X, p.low.Y)
off10 := src.PixOffset(p.low.X, p.high.Y)
off11 := src.PixOffset(p.high.X, p.high.Y)
fa := float32(src.Pix[off00]) * p.frac00
fa += float32(src.Pix[off01]) * p.frac01
fa += float32(src.Pix[off10]) * p.frac10
fa += float32(src.Pix[off11]) * p.frac11
return color.Alpha{A: uint8(fa + 0.5)}
}
// Renders the mask to the canvas
func DrawSolidRGBA(dest *image.RGBA, mask *image.Alpha, rgba color.RGBA) {
rect := dest.Bounds().Intersect(mask.Bounds())
minX := uint32(rect.Min.X)
minY := uint32(rect.Min.Y)
maxX := uint32(rect.Max.X)
maxY := uint32(rect.Max.Y)
pixColor := *(*uint32)(unsafe.Pointer(&rgba))
cs1 := pixColor & 0xff00ff
cs2 := (pixColor >> 8) & 0xff00ff
stride1 := uint32(dest.Stride)
stride2 := uint32(mask.Stride)
maxY *= stride1
var pix, pixm []uint8
var pixelx uint32
var x, y1, y2 uint32
for y1, y2 = minY*stride1, minY*stride2; y1 < maxY; y1, y2 = y1+stride1, y2+stride2 {
pix = dest.Pix[y1:]
pixm = mask.Pix[y2:]
pixelx = minX * 4
for x = minX; x < maxX; x++ {
alpha := uint32(pixm[x])
p := (*uint32)(unsafe.Pointer(&pix[pixelx]))
if alpha != 0 {
invAlpha := 0xff - alpha
ct1 := (*p & 0xff00ff) * invAlpha
ct2 := ((*p >> 8) & 0xff00ff) * invAlpha
ct1 = ((ct1 + cs1*alpha) >> 8) & 0xff00ff
ct2 = (ct2 + cs2*alpha) & 0xff00ff00
*p = ct1 + ct2
}
pixelx += 4
}
}
}
func FindSDFAlpha(img *image.Alpha, x, y, maxRadius int) int {
w := img.Bounds().Dx()
distance := maxRadius*maxRadius + 1
alpha := uint8(0)
if (image.Point{x, y}.In(img.Bounds())) {
alpha = img.Pix[y*w+x]
}
a := uint8(0)
for radius := 1; (radius <= maxRadius) && (radius*radius < distance); radius++ {
for line := -radius; line <= radius; line++ {
nx, ny := x+line, y+radius
if (image.Point{nx, ny}.In(img.Bounds())) {
a = img.Pix[ny*w+nx]
} else {
a = 0
}
//fmt.Println(line, x, ny, a, alpha)
if a != alpha {
nx = x - nx
ny = y - ny
d := (nx * nx) + (ny * ny)
if d < distance {
distance = d
}
}
//}
}
for line := -radius; line <= radius; line++ {
nx, ny := x+line, y-radius
if (image.Point{nx, ny}.In(img.Bounds())) {
a = img.Pix[ny*w+nx]
} else {
a = 0
}
if a != alpha {
nx = x - nx
ny = y - ny
d := (nx * nx) + (ny * ny)
if d < distance {
distance = d
}
}
//}
}
for line := -radius; line < radius; line++ {
nx, ny := x+radius, y+line
if (image.Point{nx, ny}.In(img.Bounds())) {
a = img.Pix[ny*w+nx]
} else {
a = 0
}
if a != alpha {
nx = x - nx
ny = y - ny
d := (nx * nx) + (ny * ny)
if d < distance {
distance = d
}
}
//}
}
for line := -radius; line < radius; line++ {
nx, ny := x-radius, y+line
if (image.Point{nx, ny}.In(img.Bounds())) {
a = img.Pix[ny*w+nx]
} else {
a = 0
}
if a != alpha {
nx = x - nx
ny = y - ny
d := (nx * nx) + (ny * ny)
if d < distance {
distance = d
}
}
//}
}
}
SDF := float32(math.Sqrt(float64(distance)))
if alpha == 0 {
SDF = -SDF
}
SDF *= 127.5 / float32(maxRadius)
SDF += 127.5
if SDF < 0 {
SDF = 0
} else if SDF > 255 {
SDF = 255
}
return int(SDF + 0.5)
}
func resizeAlpha(src *image.Alpha, size int) *image.Alpha {
dst := image.NewAlpha(image.Rect(0, 0, size, size))
draw.ApproxBiLinear.Scale(dst, dst.Bounds(), src, src.Bounds(), draw.Src, nil)
return dst
}