gotosocial/vendor/github.com/disintegration/imaging/scanner.go

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package imaging
import (
"image"
"image/color"
)
type scanner struct {
image image.Image
w, h int
palette []color.NRGBA
}
func newScanner(img image.Image) *scanner {
s := &scanner{
image: img,
w: img.Bounds().Dx(),
h: img.Bounds().Dy(),
}
if img, ok := img.(*image.Paletted); ok {
s.palette = make([]color.NRGBA, len(img.Palette))
for i := 0; i < len(img.Palette); i++ {
s.palette[i] = color.NRGBAModel.Convert(img.Palette[i]).(color.NRGBA)
}
}
return s
}
// scan scans the given rectangular region of the image into dst.
func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
switch img := s.image.(type) {
case *image.NRGBA:
size := (x2 - x1) * 4
j := 0
i := y1*img.Stride + x1*4
if size == 4 {
for y := y1; y < y2; y++ {
d := dst[j : j+4 : j+4]
s := img.Pix[i : i+4 : i+4]
d[0] = s[0]
d[1] = s[1]
d[2] = s[2]
d[3] = s[3]
j += size
i += img.Stride
}
} else {
for y := y1; y < y2; y++ {
copy(dst[j:j+size], img.Pix[i:i+size])
j += size
i += img.Stride
}
}
case *image.NRGBA64:
j := 0
for y := y1; y < y2; y++ {
i := y*img.Stride + x1*8
for x := x1; x < x2; x++ {
s := img.Pix[i : i+8 : i+8]
d := dst[j : j+4 : j+4]
d[0] = s[0]
d[1] = s[2]
d[2] = s[4]
d[3] = s[6]
j += 4
i += 8
}
}
case *image.RGBA:
j := 0
for y := y1; y < y2; y++ {
i := y*img.Stride + x1*4
for x := x1; x < x2; x++ {
d := dst[j : j+4 : j+4]
a := img.Pix[i+3]
switch a {
case 0:
d[0] = 0
d[1] = 0
d[2] = 0
d[3] = a
case 0xff:
s := img.Pix[i : i+4 : i+4]
d[0] = s[0]
d[1] = s[1]
d[2] = s[2]
d[3] = a
default:
s := img.Pix[i : i+4 : i+4]
r16 := uint16(s[0])
g16 := uint16(s[1])
b16 := uint16(s[2])
a16 := uint16(a)
d[0] = uint8(r16 * 0xff / a16)
d[1] = uint8(g16 * 0xff / a16)
d[2] = uint8(b16 * 0xff / a16)
d[3] = a
}
j += 4
i += 4
}
}
case *image.RGBA64:
j := 0
for y := y1; y < y2; y++ {
i := y*img.Stride + x1*8
for x := x1; x < x2; x++ {
s := img.Pix[i : i+8 : i+8]
d := dst[j : j+4 : j+4]
a := s[6]
switch a {
case 0:
d[0] = 0
d[1] = 0
d[2] = 0
case 0xff:
d[0] = s[0]
d[1] = s[2]
d[2] = s[4]
default:
r32 := uint32(s[0])<<8 | uint32(s[1])
g32 := uint32(s[2])<<8 | uint32(s[3])
b32 := uint32(s[4])<<8 | uint32(s[5])
a32 := uint32(s[6])<<8 | uint32(s[7])
d[0] = uint8((r32 * 0xffff / a32) >> 8)
d[1] = uint8((g32 * 0xffff / a32) >> 8)
d[2] = uint8((b32 * 0xffff / a32) >> 8)
}
d[3] = a
j += 4
i += 8
}
}
case *image.Gray:
j := 0
for y := y1; y < y2; y++ {
i := y*img.Stride + x1
for x := x1; x < x2; x++ {
c := img.Pix[i]
d := dst[j : j+4 : j+4]
d[0] = c
d[1] = c
d[2] = c
d[3] = 0xff
j += 4
i++
}
}
case *image.Gray16:
j := 0
for y := y1; y < y2; y++ {
i := y*img.Stride + x1*2
for x := x1; x < x2; x++ {
c := img.Pix[i]
d := dst[j : j+4 : j+4]
d[0] = c
d[1] = c
d[2] = c
d[3] = 0xff
j += 4
i += 2
}
}
case *image.YCbCr:
j := 0
x1 += img.Rect.Min.X
x2 += img.Rect.Min.X
y1 += img.Rect.Min.Y
y2 += img.Rect.Min.Y
hy := img.Rect.Min.Y / 2
hx := img.Rect.Min.X / 2
for y := y1; y < y2; y++ {
iy := (y-img.Rect.Min.Y)*img.YStride + (x1 - img.Rect.Min.X)
var yBase int
switch img.SubsampleRatio {
case image.YCbCrSubsampleRatio444, image.YCbCrSubsampleRatio422:
yBase = (y - img.Rect.Min.Y) * img.CStride
case image.YCbCrSubsampleRatio420, image.YCbCrSubsampleRatio440:
yBase = (y/2 - hy) * img.CStride
}
for x := x1; x < x2; x++ {
var ic int
switch img.SubsampleRatio {
case image.YCbCrSubsampleRatio444, image.YCbCrSubsampleRatio440:
ic = yBase + (x - img.Rect.Min.X)
case image.YCbCrSubsampleRatio422, image.YCbCrSubsampleRatio420:
ic = yBase + (x/2 - hx)
default:
ic = img.COffset(x, y)
}
yy1 := int32(img.Y[iy]) * 0x10101
cb1 := int32(img.Cb[ic]) - 128
cr1 := int32(img.Cr[ic]) - 128
r := yy1 + 91881*cr1
if uint32(r)&0xff000000 == 0 {
r >>= 16
} else {
r = ^(r >> 31)
}
g := yy1 - 22554*cb1 - 46802*cr1
if uint32(g)&0xff000000 == 0 {
g >>= 16
} else {
g = ^(g >> 31)
}
b := yy1 + 116130*cb1
if uint32(b)&0xff000000 == 0 {
b >>= 16
} else {
b = ^(b >> 31)
}
d := dst[j : j+4 : j+4]
d[0] = uint8(r)
d[1] = uint8(g)
d[2] = uint8(b)
d[3] = 0xff
iy++
j += 4
}
}
case *image.Paletted:
j := 0
for y := y1; y < y2; y++ {
i := y*img.Stride + x1
for x := x1; x < x2; x++ {
c := s.palette[img.Pix[i]]
d := dst[j : j+4 : j+4]
d[0] = c.R
d[1] = c.G
d[2] = c.B
d[3] = c.A
j += 4
i++
}
}
default:
j := 0
b := s.image.Bounds()
x1 += b.Min.X
x2 += b.Min.X
y1 += b.Min.Y
y2 += b.Min.Y
for y := y1; y < y2; y++ {
for x := x1; x < x2; x++ {
r16, g16, b16, a16 := s.image.At(x, y).RGBA()
d := dst[j : j+4 : j+4]
switch a16 {
case 0xffff:
d[0] = uint8(r16 >> 8)
d[1] = uint8(g16 >> 8)
d[2] = uint8(b16 >> 8)
d[3] = 0xff
case 0:
d[0] = 0
d[1] = 0
d[2] = 0
d[3] = 0
default:
d[0] = uint8(((r16 * 0xffff) / a16) >> 8)
d[1] = uint8(((g16 * 0xffff) / a16) >> 8)
d[2] = uint8(((b16 * 0xffff) / a16) >> 8)
d[3] = uint8(a16 >> 8)
}
j += 4
}
}
}
}