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package gift
import (
"image"
"image/draw"
)
type rankMode int
const (
rankMedian rankMode = iota
rankMin
rankMax
)
type rankFilter struct {
ksize int
disk bool
mode rankMode
}
func (p *rankFilter) Bounds(srcBounds image.Rectangle) (dstBounds image.Rectangle) {
dstBounds = image.Rect(0, 0, srcBounds.Dx(), srcBounds.Dy())
return
}
func (p *rankFilter) Draw(dst draw.Image, src image.Image, options *Options) {
if options == nil {
options = &defaultOptions
}
srcb := src.Bounds()
dstb := dst.Bounds()
if srcb.Dx() <= 0 || srcb.Dy() <= 0 {
return
}
ksize := p.ksize
if ksize%2 == 0 {
ksize--
}
if ksize <= 1 {
copyimage(dst, src, options)
return
}
kradius := ksize / 2
opaque := isOpaque(src)
var disk []float32
if p.disk {
disk = genDisk(ksize)
}
pixGetter := newPixelGetter(src)
pixSetter := newPixelSetter(dst)
parallelize(options.Parallelization, srcb.Min.Y, srcb.Max.Y, func(start, stop int) {
pxbuf := []pixel{}
var rbuf, gbuf, bbuf, abuf []float32
if p.mode == rankMedian {
rbuf = make([]float32, 0, ksize*ksize)
gbuf = make([]float32, 0, ksize*ksize)
bbuf = make([]float32, 0, ksize*ksize)
if !opaque {
abuf = make([]float32, 0, ksize*ksize)
}
}
for y := start; y < stop; y++ {
// Init buffer.
pxbuf = pxbuf[:0]
for i := srcb.Min.X - kradius; i <= srcb.Min.X+kradius; i++ {
for j := y - kradius; j <= y+kradius; j++ {
kx, ky := i, j
if kx < srcb.Min.X {
kx = srcb.Min.X
} else if kx > srcb.Max.X-1 {
kx = srcb.Max.X - 1
}
if ky < srcb.Min.Y {
ky = srcb.Min.Y
} else if ky > srcb.Max.Y-1 {
ky = srcb.Max.Y - 1
}
pxbuf = append(pxbuf, pixGetter.getPixel(kx, ky))
}
}
for x := srcb.Min.X; x < srcb.Max.X; x++ {
var r, g, b, a float32
if p.mode == rankMedian {
rbuf = rbuf[:0]
gbuf = gbuf[:0]
bbuf = bbuf[:0]
if !opaque {
abuf = abuf[:0]
}
} else if p.mode == rankMin {
r, g, b, a = 1, 1, 1, 1
} else if p.mode == rankMax {
r, g, b, a = 0, 0, 0, 0
}
sz := 0
for i := 0; i < ksize; i++ {
for j := 0; j < ksize; j++ {
if p.disk {
if disk[i*ksize+j] == 0 {
continue
}
}
px := pxbuf[i*ksize+j]
if p.mode == rankMedian {
rbuf = append(rbuf, px.r)
gbuf = append(gbuf, px.g)
bbuf = append(bbuf, px.b)
if !opaque {
abuf = append(abuf, px.a)
}
} else if p.mode == rankMin {
r = minf32(r, px.r)
g = minf32(g, px.g)
b = minf32(b, px.b)
if !opaque {
a = minf32(a, px.a)
}
} else if p.mode == rankMax {
r = maxf32(r, px.r)
g = maxf32(g, px.g)
b = maxf32(b, px.b)
if !opaque {
a = maxf32(a, px.a)
}
}
sz++
}
}
if p.mode == rankMedian {
sort(rbuf)
sort(gbuf)
sort(bbuf)
if !opaque {
sort(abuf)
}
idx := sz / 2
r, g, b = rbuf[idx], gbuf[idx], bbuf[idx]
if !opaque {
a = abuf[idx]
}
}
if opaque {
a = 1
}
pixSetter.setPixel(dstb.Min.X+x-srcb.Min.X, dstb.Min.Y+y-srcb.Min.Y, pixel{r, g, b, a})
// Rotate buffer columns.
if x < srcb.Max.X-1 {
copy(pxbuf[0:], pxbuf[ksize:])
pxbuf = pxbuf[0 : ksize*(ksize-1)]
kx := x + 1 + kradius
if kx > srcb.Max.X-1 {
kx = srcb.Max.X - 1
}
for j := y - kradius; j <= y+kradius; j++ {
ky := j
if ky < srcb.Min.Y {
ky = srcb.Min.Y
} else if ky > srcb.Max.Y-1 {
ky = srcb.Max.Y - 1
}
pxbuf = append(pxbuf, pixGetter.getPixel(kx, ky))
}
}
}
}
})
}
// Median creates a median image filter.
// Picks a median value per channel in neighborhood for each pixel.
// The ksize parameter is the kernel size. It must be an odd positive integer (for example: 3, 5, 7).
// If the disk parameter is true, a disk-shaped neighborhood will be used instead of a square neighborhood.
func Median(ksize int, disk bool) Filter {
return &rankFilter{
ksize: ksize,
disk: disk,
mode: rankMedian,
}
}
// Minimum creates a local minimum image filter.
// Picks a minimum value per channel in neighborhood for each pixel.
// The ksize parameter is the kernel size. It must be an odd positive integer (for example: 3, 5, 7).
// If the disk parameter is true, a disk-shaped neighborhood will be used instead of a square neighborhood.
func Minimum(ksize int, disk bool) Filter {
return &rankFilter{
ksize: ksize,
disk: disk,
mode: rankMin,
}
}
// Maximum creates a local maximum image filter.
// Picks a maximum value per channel in neighborhood for each pixel.
// The ksize parameter is the kernel size. It must be an odd positive integer (for example: 3, 5, 7).
// If the disk parameter is true, a disk-shaped neighborhood will be used instead of a square neighborhood.
func Maximum(ksize int, disk bool) Filter {
return &rankFilter{
ksize: ksize,
disk: disk,
mode: rankMax,
}
}
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