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gotosocial/internal/media/imaging.go

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Go

// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package media
import (
"image"
"image/color"
"math"
)
// NOTE:
// the following code is borrowed from
// github.com/disintegration/imaging
// and collapses in some places for our
// particular usecases and with parallel()
// function (spans work across goroutines)
// removed, instead working synchronously.
//
// at gotosocial we take particular
// care about where we spawn goroutines
// to ensure we're in control of the
// amount of concurrency in relation
// to the amount configured by user.
// resizeDownLinear resizes image to given width x height using linear resampling.
// This is specifically optimized for resizing down (i.e. smaller), else is noop.
func resizeDownLinear(img image.Image, width, height int) image.Image {
srcW, srcH := img.Bounds().Dx(), img.Bounds().Dy()
if srcW <= 0 || srcH <= 0 ||
width < 0 || height < 0 {
return &image.NRGBA{}
}
if width == 0 {
// If no width is given, use aspect preserving width.
tmp := float64(height) * float64(srcW) / float64(srcH)
width = int(math.Max(1.0, math.Floor(tmp+0.5)))
}
if height == 0 {
// If no height is given, use aspect preserving height.
tmp := float64(width) * float64(srcH) / float64(srcW)
height = int(math.Max(1.0, math.Floor(tmp+0.5)))
}
if width < srcW {
// Width is smaller, resize horizontally.
img = resizeHorizontalLinear(img, width)
}
if height < srcH {
// Height is smaller, resize vertically.
img = resizeVerticalLinear(img, height)
}
return img
}
// flipH flips the image horizontally (left to right).
func flipH(img image.Image) image.Image {
src := newScanner(img)
dstW := src.w
dstH := src.h
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
for y := 0; y < dstH; y++ {
i := y * dst.Stride
srcY := y
src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
reverse(dst.Pix[i : i+rowSize])
}
return dst
}
// flipV flips the image vertically (from top to bottom).
func flipV(img image.Image) image.Image {
src := newScanner(img)
dstW := src.w
dstH := src.h
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
for y := 0; y < dstH; y++ {
i := y * dst.Stride
srcY := dstH - y - 1
src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
}
return dst
}
// rotate90 rotates the image 90 counter-clockwise.
func rotate90(img image.Image) image.Image {
src := newScanner(img)
dstW := src.h
dstH := src.w
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
for y := 0; y < dstH; y++ {
i := y * dst.Stride
srcX := dstH - y - 1
src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
}
return dst
}
// rotate180 rotates the image 180 counter-clockwise.
func rotate180(img image.Image) image.Image {
src := newScanner(img)
dstW := src.w
dstH := src.h
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
for y := 0; y < dstH; y++ {
i := y * dst.Stride
srcY := dstH - y - 1
src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
reverse(dst.Pix[i : i+rowSize])
}
return dst
}
// rotate270 rotates the image 270 counter-clockwise.
func rotate270(img image.Image) image.Image {
src := newScanner(img)
dstW := src.h
dstH := src.w
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
for y := 0; y < dstH; y++ {
i := y * dst.Stride
srcX := y
src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
reverse(dst.Pix[i : i+rowSize])
}
return dst
}
// transpose flips the image horizontally and rotates 90 counter-clockwise.
func transpose(img image.Image) image.Image {
src := newScanner(img)
dstW := src.h
dstH := src.w
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
for y := 0; y < dstH; y++ {
i := y * dst.Stride
srcX := y
src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
}
return dst
}
// transverse flips the image vertically and rotates 90 counter-clockwise.
func transverse(img image.Image) image.Image {
src := newScanner(img)
dstW := src.h
dstH := src.w
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
for y := 0; y < dstH; y++ {
i := y * dst.Stride
srcX := dstH - y - 1
src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
reverse(dst.Pix[i : i+rowSize])
}
return dst
}
// resizeHorizontalLinear resizes image to given width using linear resampling.
func resizeHorizontalLinear(img image.Image, dstWidth int) image.Image {
src := newScanner(img)
dst := image.NewRGBA(image.Rect(0, 0, dstWidth, src.h))
weights := precomputeWeightsLinear(dstWidth, src.w)
scanLine := make([]uint8, src.w*4)
for y := 0; y < src.h; y++ {
src.scan(0, y, src.w, y+1, scanLine)
j0 := y * dst.Stride
for x := range weights {
var r, g, b, a float64
for _, w := range weights[x] {
i := w.index * 4
s := scanLine[i : i+4 : i+4]
aw := float64(s[3]) * w.weight
r += float64(s[0]) * aw
g += float64(s[1]) * aw
b += float64(s[2]) * aw
a += aw
}
if a != 0 {
aInv := 1 / a
j := j0 + x*4
d := dst.Pix[j : j+4 : j+4]
d[0] = clampFloat(r * aInv)
d[1] = clampFloat(g * aInv)
d[2] = clampFloat(b * aInv)
d[3] = clampFloat(a)
}
}
}
return dst
}
// resizeVerticalLinear resizes image to given height using linear resampling.
func resizeVerticalLinear(img image.Image, height int) image.Image {
src := newScanner(img)
dst := image.NewNRGBA(image.Rect(0, 0, src.w, height))
weights := precomputeWeightsLinear(height, src.h)
scanLine := make([]uint8, src.h*4)
for x := 0; x < src.w; x++ {
src.scan(x, 0, x+1, src.h, scanLine)
for y := range weights {
var r, g, b, a float64
for _, w := range weights[y] {
i := w.index * 4
s := scanLine[i : i+4 : i+4]
aw := float64(s[3]) * w.weight
r += float64(s[0]) * aw
g += float64(s[1]) * aw
b += float64(s[2]) * aw
a += aw
}
if a != 0 {
aInv := 1 / a
j := y*dst.Stride + x*4
d := dst.Pix[j : j+4 : j+4]
d[0] = clampFloat(r * aInv)
d[1] = clampFloat(g * aInv)
d[2] = clampFloat(b * aInv)
d[3] = clampFloat(a)
}
}
}
return dst
}
type indexWeight struct {
index int
weight float64
}
func precomputeWeightsLinear(dstSize, srcSize int) [][]indexWeight {
du := float64(srcSize) / float64(dstSize)
scale := du
if scale < 1.0 {
scale = 1.0
}
ru := math.Ceil(scale)
out := make([][]indexWeight, dstSize)
tmp := make([]indexWeight, 0, dstSize*int(ru+2)*2)
for v := 0; v < dstSize; v++ {
fu := (float64(v)+0.5)*du - 0.5
begin := int(math.Ceil(fu - ru))
if begin < 0 {
begin = 0
}
end := int(math.Floor(fu + ru))
if end > srcSize-1 {
end = srcSize - 1
}
var sum float64
for u := begin; u <= end; u++ {
w := resampleLinear((float64(u) - fu) / scale)
if w != 0 {
sum += w
tmp = append(tmp, indexWeight{index: u, weight: w})
}
}
if sum != 0 {
for i := range tmp {
tmp[i].weight /= sum
}
}
out[v] = tmp
tmp = tmp[len(tmp):]
}
return out
}
// resampleLinear is the resample kernel func for linear filtering.
func resampleLinear(x float64) float64 {
x = math.Abs(x)
if x < 1.0 {
return 1.0 - x
}
return 0
}
// scanner wraps an image.Image for
// easier size access and image type
// agnostic access to data at coords.
type scanner struct {
image image.Image
w, h int
palette []color.NRGBA
}
// newScanner wraps an image.Image in scanner{} type.
func newScanner(img image.Image) *scanner {
b := img.Bounds()
s := &scanner{
image: img,
w: b.Dx(),
h: b.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) // #nosec G115 -- Overflow desired.
d[1] = uint8(g16 * 0xff / a16) // #nosec G115 -- Overflow desired.
d[2] = uint8(b16 * 0xff / a16) // #nosec G115 -- Overflow desired.
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) // #nosec G115 -- Overflow desired.
d[1] = uint8((g32 * 0xffff / a32) >> 8) // #nosec G115 -- Overflow desired.
d[2] = uint8((b32 * 0xffff / a32) >> 8) // #nosec G115 -- Overflow desired.
}
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 { //nolint:gosec
r >>= 16
} else {
r = ^(r >> 31)
}
g := yy1 - 22554*cb1 - 46802*cr1
if uint32(g)&0xff000000 == 0 { //nolint:gosec
g >>= 16
} else {
g = ^(g >> 31)
}
b := yy1 + 116130*cb1
if uint32(b)&0xff000000 == 0 { //nolint:gosec
b >>= 16
} else {
b = ^(b >> 31)
}
d := dst[j : j+4 : j+4]
d[0] = uint8(r) // #nosec G115 -- Overflow desired.
d[1] = uint8(g) // #nosec G115 -- Overflow desired.
d[2] = uint8(b) // #nosec G115 -- Overflow desired.
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) // #nosec G115 -- Overflow desired.
d[1] = uint8(g16 >> 8) // #nosec G115 -- Overflow desired.
d[2] = uint8(b16 >> 8) // #nosec G115 -- Overflow desired.
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) // #nosec G115 -- Overflow desired.
d[1] = uint8(((g16 * 0xffff) / a16) >> 8) // #nosec G115 -- Overflow desired.
d[2] = uint8(((b16 * 0xffff) / a16) >> 8) // #nosec G115 -- Overflow desired.
d[3] = uint8(a16 >> 8) // #nosec G115 -- Overflow desired.
}
j += 4
}
}
}
}
// reverse reverses the data
// in contained pixel slice.
func reverse(pix []uint8) {
if len(pix) <= 4 {
return
}
i := 0
j := len(pix) - 4
for i < j {
pi := pix[i : i+4 : i+4]
pj := pix[j : j+4 : j+4]
pi[0], pj[0] = pj[0], pi[0]
pi[1], pj[1] = pj[1], pi[1]
pi[2], pj[2] = pj[2], pi[2]
pi[3], pj[3] = pj[3], pi[3]
i += 4
j -= 4
}
}
// clampFloat rounds and clamps float64 value to fit into uint8.
func clampFloat(x float64) uint8 {
v := int64(x + 0.5)
if v > 255 {
return 255
}
if v > 0 {
return uint8(v) // #nosec G115 -- Just checked.
}
return 0
}