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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
commit43a123c1ae6613b3efeed291fa552ecd909d3acf (patch)
treefd92518b7024bc74031f78a1cf9e454b65e73665 /src/image/draw/draw.go
parentInitial commit. (diff)
downloadgolang-1.20-upstream.tar.xz
golang-1.20-upstream.zip
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/image/draw/draw.go')
-rw-r--r--src/image/draw/draw.go1086
1 files changed, 1086 insertions, 0 deletions
diff --git a/src/image/draw/draw.go b/src/image/draw/draw.go
new file mode 100644
index 0000000..920ebb9
--- /dev/null
+++ b/src/image/draw/draw.go
@@ -0,0 +1,1086 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package draw provides image composition functions.
+//
+// See "The Go image/draw package" for an introduction to this package:
+// https://golang.org/doc/articles/image_draw.html
+package draw
+
+import (
+ "image"
+ "image/color"
+ "image/internal/imageutil"
+)
+
+// m is the maximum color value returned by image.Color.RGBA.
+const m = 1<<16 - 1
+
+// Image is an image.Image with a Set method to change a single pixel.
+type Image interface {
+ image.Image
+ Set(x, y int, c color.Color)
+}
+
+// RGBA64Image extends both the Image and image.RGBA64Image interfaces with a
+// SetRGBA64 method to change a single pixel. SetRGBA64 is equivalent to
+// calling Set, but it can avoid allocations from converting concrete color
+// types to the color.Color interface type.
+type RGBA64Image interface {
+ image.RGBA64Image
+ Set(x, y int, c color.Color)
+ SetRGBA64(x, y int, c color.RGBA64)
+}
+
+// Quantizer produces a palette for an image.
+type Quantizer interface {
+ // Quantize appends up to cap(p) - len(p) colors to p and returns the
+ // updated palette suitable for converting m to a paletted image.
+ Quantize(p color.Palette, m image.Image) color.Palette
+}
+
+// Op is a Porter-Duff compositing operator.
+type Op int
+
+const (
+ // Over specifies ``(src in mask) over dst''.
+ Over Op = iota
+ // Src specifies ``src in mask''.
+ Src
+)
+
+// Draw implements the Drawer interface by calling the Draw function with this
+// Op.
+func (op Op) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
+ DrawMask(dst, r, src, sp, nil, image.Point{}, op)
+}
+
+// Drawer contains the Draw method.
+type Drawer interface {
+ // Draw aligns r.Min in dst with sp in src and then replaces the
+ // rectangle r in dst with the result of drawing src on dst.
+ Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
+}
+
+// FloydSteinberg is a Drawer that is the Src Op with Floyd-Steinberg error
+// diffusion.
+var FloydSteinberg Drawer = floydSteinberg{}
+
+type floydSteinberg struct{}
+
+func (floydSteinberg) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
+ clip(dst, &r, src, &sp, nil, nil)
+ if r.Empty() {
+ return
+ }
+ drawPaletted(dst, r, src, sp, true)
+}
+
+// clip clips r against each image's bounds (after translating into the
+// destination image's coordinate space) and shifts the points sp and mp by
+// the same amount as the change in r.Min.
+func clip(dst Image, r *image.Rectangle, src image.Image, sp *image.Point, mask image.Image, mp *image.Point) {
+ orig := r.Min
+ *r = r.Intersect(dst.Bounds())
+ *r = r.Intersect(src.Bounds().Add(orig.Sub(*sp)))
+ if mask != nil {
+ *r = r.Intersect(mask.Bounds().Add(orig.Sub(*mp)))
+ }
+ dx := r.Min.X - orig.X
+ dy := r.Min.Y - orig.Y
+ if dx == 0 && dy == 0 {
+ return
+ }
+ sp.X += dx
+ sp.Y += dy
+ if mp != nil {
+ mp.X += dx
+ mp.Y += dy
+ }
+}
+
+func processBackward(dst image.Image, r image.Rectangle, src image.Image, sp image.Point) bool {
+ return dst == src &&
+ r.Overlaps(r.Add(sp.Sub(r.Min))) &&
+ (sp.Y < r.Min.Y || (sp.Y == r.Min.Y && sp.X < r.Min.X))
+}
+
+// Draw calls DrawMask with a nil mask.
+func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op) {
+ DrawMask(dst, r, src, sp, nil, image.Point{}, op)
+}
+
+// DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r
+// in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque.
+func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) {
+ clip(dst, &r, src, &sp, mask, &mp)
+ if r.Empty() {
+ return
+ }
+
+ // Fast paths for special cases. If none of them apply, then we fall back
+ // to general but slower implementations.
+ //
+ // For NRGBA and NRGBA64 image types, the code paths aren't just faster.
+ // They also avoid the information loss that would otherwise occur from
+ // converting non-alpha-premultiplied color to and from alpha-premultiplied
+ // color. See TestDrawSrcNonpremultiplied.
+ switch dst0 := dst.(type) {
+ case *image.RGBA:
+ if op == Over {
+ if mask == nil {
+ switch src0 := src.(type) {
+ case *image.Uniform:
+ sr, sg, sb, sa := src0.RGBA()
+ if sa == 0xffff {
+ drawFillSrc(dst0, r, sr, sg, sb, sa)
+ } else {
+ drawFillOver(dst0, r, sr, sg, sb, sa)
+ }
+ return
+ case *image.RGBA:
+ drawCopyOver(dst0, r, src0, sp)
+ return
+ case *image.NRGBA:
+ drawNRGBAOver(dst0, r, src0, sp)
+ return
+ case *image.YCbCr:
+ // An image.YCbCr is always fully opaque, and so if the
+ // mask is nil (i.e. fully opaque) then the op is
+ // effectively always Src. Similarly for image.Gray and
+ // image.CMYK.
+ if imageutil.DrawYCbCr(dst0, r, src0, sp) {
+ return
+ }
+ case *image.Gray:
+ drawGray(dst0, r, src0, sp)
+ return
+ case *image.CMYK:
+ drawCMYK(dst0, r, src0, sp)
+ return
+ }
+ } else if mask0, ok := mask.(*image.Alpha); ok {
+ switch src0 := src.(type) {
+ case *image.Uniform:
+ drawGlyphOver(dst0, r, src0, mask0, mp)
+ return
+ case *image.RGBA:
+ drawRGBAMaskOver(dst0, r, src0, sp, mask0, mp)
+ return
+ case *image.Gray:
+ drawGrayMaskOver(dst0, r, src0, sp, mask0, mp)
+ return
+ // Case order matters. The next case (image.RGBA64Image) is an
+ // interface type that the concrete types above also implement.
+ case image.RGBA64Image:
+ drawRGBA64ImageMaskOver(dst0, r, src0, sp, mask0, mp)
+ return
+ }
+ }
+ } else {
+ if mask == nil {
+ switch src0 := src.(type) {
+ case *image.Uniform:
+ sr, sg, sb, sa := src0.RGBA()
+ drawFillSrc(dst0, r, sr, sg, sb, sa)
+ return
+ case *image.RGBA:
+ d0 := dst0.PixOffset(r.Min.X, r.Min.Y)
+ s0 := src0.PixOffset(sp.X, sp.Y)
+ drawCopySrc(
+ dst0.Pix[d0:], dst0.Stride, r, src0.Pix[s0:], src0.Stride, sp, 4*r.Dx())
+ return
+ case *image.NRGBA:
+ drawNRGBASrc(dst0, r, src0, sp)
+ return
+ case *image.YCbCr:
+ if imageutil.DrawYCbCr(dst0, r, src0, sp) {
+ return
+ }
+ case *image.Gray:
+ drawGray(dst0, r, src0, sp)
+ return
+ case *image.CMYK:
+ drawCMYK(dst0, r, src0, sp)
+ return
+ }
+ }
+ }
+ drawRGBA(dst0, r, src, sp, mask, mp, op)
+ return
+ case *image.Paletted:
+ if op == Src && mask == nil {
+ if src0, ok := src.(*image.Uniform); ok {
+ colorIndex := uint8(dst0.Palette.Index(src0.C))
+ i0 := dst0.PixOffset(r.Min.X, r.Min.Y)
+ i1 := i0 + r.Dx()
+ for i := i0; i < i1; i++ {
+ dst0.Pix[i] = colorIndex
+ }
+ firstRow := dst0.Pix[i0:i1]
+ for y := r.Min.Y + 1; y < r.Max.Y; y++ {
+ i0 += dst0.Stride
+ i1 += dst0.Stride
+ copy(dst0.Pix[i0:i1], firstRow)
+ }
+ return
+ } else if !processBackward(dst, r, src, sp) {
+ drawPaletted(dst0, r, src, sp, false)
+ return
+ }
+ }
+ case *image.NRGBA:
+ if op == Src && mask == nil {
+ if src0, ok := src.(*image.NRGBA); ok {
+ d0 := dst0.PixOffset(r.Min.X, r.Min.Y)
+ s0 := src0.PixOffset(sp.X, sp.Y)
+ drawCopySrc(
+ dst0.Pix[d0:], dst0.Stride, r, src0.Pix[s0:], src0.Stride, sp, 4*r.Dx())
+ return
+ }
+ }
+ case *image.NRGBA64:
+ if op == Src && mask == nil {
+ if src0, ok := src.(*image.NRGBA64); ok {
+ d0 := dst0.PixOffset(r.Min.X, r.Min.Y)
+ s0 := src0.PixOffset(sp.X, sp.Y)
+ drawCopySrc(
+ dst0.Pix[d0:], dst0.Stride, r, src0.Pix[s0:], src0.Stride, sp, 8*r.Dx())
+ return
+ }
+ }
+ }
+
+ x0, x1, dx := r.Min.X, r.Max.X, 1
+ y0, y1, dy := r.Min.Y, r.Max.Y, 1
+ if processBackward(dst, r, src, sp) {
+ x0, x1, dx = x1-1, x0-1, -1
+ y0, y1, dy = y1-1, y0-1, -1
+ }
+
+ // FALLBACK1.17
+ //
+ // Try the draw.RGBA64Image and image.RGBA64Image interfaces, part of the
+ // standard library since Go 1.17. These are like the draw.Image and
+ // image.Image interfaces but they can avoid allocations from converting
+ // concrete color types to the color.Color interface type.
+
+ if dst0, _ := dst.(RGBA64Image); dst0 != nil {
+ if src0, _ := src.(image.RGBA64Image); src0 != nil {
+ if mask == nil {
+ sy := sp.Y + y0 - r.Min.Y
+ my := mp.Y + y0 - r.Min.Y
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ sx := sp.X + x0 - r.Min.X
+ mx := mp.X + x0 - r.Min.X
+ for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
+ if op == Src {
+ dst0.SetRGBA64(x, y, src0.RGBA64At(sx, sy))
+ } else {
+ srgba := src0.RGBA64At(sx, sy)
+ a := m - uint32(srgba.A)
+ drgba := dst0.RGBA64At(x, y)
+ dst0.SetRGBA64(x, y, color.RGBA64{
+ R: uint16((uint32(drgba.R)*a)/m) + srgba.R,
+ G: uint16((uint32(drgba.G)*a)/m) + srgba.G,
+ B: uint16((uint32(drgba.B)*a)/m) + srgba.B,
+ A: uint16((uint32(drgba.A)*a)/m) + srgba.A,
+ })
+ }
+ }
+ }
+ return
+
+ } else if mask0, _ := mask.(image.RGBA64Image); mask0 != nil {
+ sy := sp.Y + y0 - r.Min.Y
+ my := mp.Y + y0 - r.Min.Y
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ sx := sp.X + x0 - r.Min.X
+ mx := mp.X + x0 - r.Min.X
+ for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
+ ma := uint32(mask0.RGBA64At(mx, my).A)
+ switch {
+ case ma == 0:
+ if op == Over {
+ // No-op.
+ } else {
+ dst0.SetRGBA64(x, y, color.RGBA64{})
+ }
+ case ma == m && op == Src:
+ dst0.SetRGBA64(x, y, src0.RGBA64At(sx, sy))
+ default:
+ srgba := src0.RGBA64At(sx, sy)
+ if op == Over {
+ drgba := dst0.RGBA64At(x, y)
+ a := m - (uint32(srgba.A) * ma / m)
+ dst0.SetRGBA64(x, y, color.RGBA64{
+ R: uint16((uint32(drgba.R)*a + uint32(srgba.R)*ma) / m),
+ G: uint16((uint32(drgba.G)*a + uint32(srgba.G)*ma) / m),
+ B: uint16((uint32(drgba.B)*a + uint32(srgba.B)*ma) / m),
+ A: uint16((uint32(drgba.A)*a + uint32(srgba.A)*ma) / m),
+ })
+ } else {
+ dst0.SetRGBA64(x, y, color.RGBA64{
+ R: uint16(uint32(srgba.R) * ma / m),
+ G: uint16(uint32(srgba.G) * ma / m),
+ B: uint16(uint32(srgba.B) * ma / m),
+ A: uint16(uint32(srgba.A) * ma / m),
+ })
+ }
+ }
+ }
+ }
+ return
+ }
+ }
+ }
+
+ // FALLBACK1.0
+ //
+ // If none of the faster code paths above apply, use the draw.Image and
+ // image.Image interfaces, part of the standard library since Go 1.0.
+
+ var out color.RGBA64
+ sy := sp.Y + y0 - r.Min.Y
+ my := mp.Y + y0 - r.Min.Y
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ sx := sp.X + x0 - r.Min.X
+ mx := mp.X + x0 - r.Min.X
+ for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
+ ma := uint32(m)
+ if mask != nil {
+ _, _, _, ma = mask.At(mx, my).RGBA()
+ }
+ switch {
+ case ma == 0:
+ if op == Over {
+ // No-op.
+ } else {
+ dst.Set(x, y, color.Transparent)
+ }
+ case ma == m && op == Src:
+ dst.Set(x, y, src.At(sx, sy))
+ default:
+ sr, sg, sb, sa := src.At(sx, sy).RGBA()
+ if op == Over {
+ dr, dg, db, da := dst.At(x, y).RGBA()
+ a := m - (sa * ma / m)
+ out.R = uint16((dr*a + sr*ma) / m)
+ out.G = uint16((dg*a + sg*ma) / m)
+ out.B = uint16((db*a + sb*ma) / m)
+ out.A = uint16((da*a + sa*ma) / m)
+ } else {
+ out.R = uint16(sr * ma / m)
+ out.G = uint16(sg * ma / m)
+ out.B = uint16(sb * ma / m)
+ out.A = uint16(sa * ma / m)
+ }
+ // The third argument is &out instead of out (and out is
+ // declared outside of the inner loop) to avoid the implicit
+ // conversion to color.Color here allocating memory in the
+ // inner loop if sizeof(color.RGBA64) > sizeof(uintptr).
+ dst.Set(x, y, &out)
+ }
+ }
+ }
+}
+
+func drawFillOver(dst *image.RGBA, r image.Rectangle, sr, sg, sb, sa uint32) {
+ // The 0x101 is here for the same reason as in drawRGBA.
+ a := (m - sa) * 0x101
+ i0 := dst.PixOffset(r.Min.X, r.Min.Y)
+ i1 := i0 + r.Dx()*4
+ for y := r.Min.Y; y != r.Max.Y; y++ {
+ for i := i0; i < i1; i += 4 {
+ dr := &dst.Pix[i+0]
+ dg := &dst.Pix[i+1]
+ db := &dst.Pix[i+2]
+ da := &dst.Pix[i+3]
+
+ *dr = uint8((uint32(*dr)*a/m + sr) >> 8)
+ *dg = uint8((uint32(*dg)*a/m + sg) >> 8)
+ *db = uint8((uint32(*db)*a/m + sb) >> 8)
+ *da = uint8((uint32(*da)*a/m + sa) >> 8)
+ }
+ i0 += dst.Stride
+ i1 += dst.Stride
+ }
+}
+
+func drawFillSrc(dst *image.RGBA, r image.Rectangle, sr, sg, sb, sa uint32) {
+ sr8 := uint8(sr >> 8)
+ sg8 := uint8(sg >> 8)
+ sb8 := uint8(sb >> 8)
+ sa8 := uint8(sa >> 8)
+ // The built-in copy function is faster than a straightforward for loop to fill the destination with
+ // the color, but copy requires a slice source. We therefore use a for loop to fill the first row, and
+ // then use the first row as the slice source for the remaining rows.
+ i0 := dst.PixOffset(r.Min.X, r.Min.Y)
+ i1 := i0 + r.Dx()*4
+ for i := i0; i < i1; i += 4 {
+ dst.Pix[i+0] = sr8
+ dst.Pix[i+1] = sg8
+ dst.Pix[i+2] = sb8
+ dst.Pix[i+3] = sa8
+ }
+ firstRow := dst.Pix[i0:i1]
+ for y := r.Min.Y + 1; y < r.Max.Y; y++ {
+ i0 += dst.Stride
+ i1 += dst.Stride
+ copy(dst.Pix[i0:i1], firstRow)
+ }
+}
+
+func drawCopyOver(dst *image.RGBA, r image.Rectangle, src *image.RGBA, sp image.Point) {
+ dx, dy := r.Dx(), r.Dy()
+ d0 := dst.PixOffset(r.Min.X, r.Min.Y)
+ s0 := src.PixOffset(sp.X, sp.Y)
+ var (
+ ddelta, sdelta int
+ i0, i1, idelta int
+ )
+ if r.Min.Y < sp.Y || r.Min.Y == sp.Y && r.Min.X <= sp.X {
+ ddelta = dst.Stride
+ sdelta = src.Stride
+ i0, i1, idelta = 0, dx*4, +4
+ } else {
+ // If the source start point is higher than the destination start point, or equal height but to the left,
+ // then we compose the rows in right-to-left, bottom-up order instead of left-to-right, top-down.
+ d0 += (dy - 1) * dst.Stride
+ s0 += (dy - 1) * src.Stride
+ ddelta = -dst.Stride
+ sdelta = -src.Stride
+ i0, i1, idelta = (dx-1)*4, -4, -4
+ }
+ for ; dy > 0; dy-- {
+ dpix := dst.Pix[d0:]
+ spix := src.Pix[s0:]
+ for i := i0; i != i1; i += idelta {
+ s := spix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ sr := uint32(s[0]) * 0x101
+ sg := uint32(s[1]) * 0x101
+ sb := uint32(s[2]) * 0x101
+ sa := uint32(s[3]) * 0x101
+
+ // The 0x101 is here for the same reason as in drawRGBA.
+ a := (m - sa) * 0x101
+
+ d := dpix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ d[0] = uint8((uint32(d[0])*a/m + sr) >> 8)
+ d[1] = uint8((uint32(d[1])*a/m + sg) >> 8)
+ d[2] = uint8((uint32(d[2])*a/m + sb) >> 8)
+ d[3] = uint8((uint32(d[3])*a/m + sa) >> 8)
+ }
+ d0 += ddelta
+ s0 += sdelta
+ }
+}
+
+// drawCopySrc copies bytes to dstPix from srcPix. These arguments roughly
+// correspond to the Pix fields of the image package's concrete image.Image
+// implementations, but are offset (dstPix is dst.Pix[dpOffset:] not dst.Pix).
+func drawCopySrc(
+ dstPix []byte, dstStride int, r image.Rectangle,
+ srcPix []byte, srcStride int, sp image.Point,
+ bytesPerRow int) {
+
+ d0, s0, ddelta, sdelta, dy := 0, 0, dstStride, srcStride, r.Dy()
+ if r.Min.Y > sp.Y {
+ // If the source start point is higher than the destination start
+ // point, then we compose the rows in bottom-up order instead of
+ // top-down. Unlike the drawCopyOver function, we don't have to check
+ // the x coordinates because the built-in copy function can handle
+ // overlapping slices.
+ d0 = (dy - 1) * dstStride
+ s0 = (dy - 1) * srcStride
+ ddelta = -dstStride
+ sdelta = -srcStride
+ }
+ for ; dy > 0; dy-- {
+ copy(dstPix[d0:d0+bytesPerRow], srcPix[s0:s0+bytesPerRow])
+ d0 += ddelta
+ s0 += sdelta
+ }
+}
+
+func drawNRGBAOver(dst *image.RGBA, r image.Rectangle, src *image.NRGBA, sp image.Point) {
+ i0 := (r.Min.X - dst.Rect.Min.X) * 4
+ i1 := (r.Max.X - dst.Rect.Min.X) * 4
+ si0 := (sp.X - src.Rect.Min.X) * 4
+ yMax := r.Max.Y - dst.Rect.Min.Y
+
+ y := r.Min.Y - dst.Rect.Min.Y
+ sy := sp.Y - src.Rect.Min.Y
+ for ; y != yMax; y, sy = y+1, sy+1 {
+ dpix := dst.Pix[y*dst.Stride:]
+ spix := src.Pix[sy*src.Stride:]
+
+ for i, si := i0, si0; i < i1; i, si = i+4, si+4 {
+ // Convert from non-premultiplied color to pre-multiplied color.
+ s := spix[si : si+4 : si+4] // Small cap improves performance, see https://golang.org/issue/27857
+ sa := uint32(s[3]) * 0x101
+ sr := uint32(s[0]) * sa / 0xff
+ sg := uint32(s[1]) * sa / 0xff
+ sb := uint32(s[2]) * sa / 0xff
+
+ d := dpix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ dr := uint32(d[0])
+ dg := uint32(d[1])
+ db := uint32(d[2])
+ da := uint32(d[3])
+
+ // The 0x101 is here for the same reason as in drawRGBA.
+ a := (m - sa) * 0x101
+
+ d[0] = uint8((dr*a/m + sr) >> 8)
+ d[1] = uint8((dg*a/m + sg) >> 8)
+ d[2] = uint8((db*a/m + sb) >> 8)
+ d[3] = uint8((da*a/m + sa) >> 8)
+ }
+ }
+}
+
+func drawNRGBASrc(dst *image.RGBA, r image.Rectangle, src *image.NRGBA, sp image.Point) {
+ i0 := (r.Min.X - dst.Rect.Min.X) * 4
+ i1 := (r.Max.X - dst.Rect.Min.X) * 4
+ si0 := (sp.X - src.Rect.Min.X) * 4
+ yMax := r.Max.Y - dst.Rect.Min.Y
+
+ y := r.Min.Y - dst.Rect.Min.Y
+ sy := sp.Y - src.Rect.Min.Y
+ for ; y != yMax; y, sy = y+1, sy+1 {
+ dpix := dst.Pix[y*dst.Stride:]
+ spix := src.Pix[sy*src.Stride:]
+
+ for i, si := i0, si0; i < i1; i, si = i+4, si+4 {
+ // Convert from non-premultiplied color to pre-multiplied color.
+ s := spix[si : si+4 : si+4] // Small cap improves performance, see https://golang.org/issue/27857
+ sa := uint32(s[3]) * 0x101
+ sr := uint32(s[0]) * sa / 0xff
+ sg := uint32(s[1]) * sa / 0xff
+ sb := uint32(s[2]) * sa / 0xff
+
+ d := dpix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ d[0] = uint8(sr >> 8)
+ d[1] = uint8(sg >> 8)
+ d[2] = uint8(sb >> 8)
+ d[3] = uint8(sa >> 8)
+ }
+ }
+}
+
+func drawGray(dst *image.RGBA, r image.Rectangle, src *image.Gray, sp image.Point) {
+ i0 := (r.Min.X - dst.Rect.Min.X) * 4
+ i1 := (r.Max.X - dst.Rect.Min.X) * 4
+ si0 := (sp.X - src.Rect.Min.X) * 1
+ yMax := r.Max.Y - dst.Rect.Min.Y
+
+ y := r.Min.Y - dst.Rect.Min.Y
+ sy := sp.Y - src.Rect.Min.Y
+ for ; y != yMax; y, sy = y+1, sy+1 {
+ dpix := dst.Pix[y*dst.Stride:]
+ spix := src.Pix[sy*src.Stride:]
+
+ for i, si := i0, si0; i < i1; i, si = i+4, si+1 {
+ p := spix[si]
+ d := dpix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ d[0] = p
+ d[1] = p
+ d[2] = p
+ d[3] = 255
+ }
+ }
+}
+
+func drawCMYK(dst *image.RGBA, r image.Rectangle, src *image.CMYK, sp image.Point) {
+ i0 := (r.Min.X - dst.Rect.Min.X) * 4
+ i1 := (r.Max.X - dst.Rect.Min.X) * 4
+ si0 := (sp.X - src.Rect.Min.X) * 4
+ yMax := r.Max.Y - dst.Rect.Min.Y
+
+ y := r.Min.Y - dst.Rect.Min.Y
+ sy := sp.Y - src.Rect.Min.Y
+ for ; y != yMax; y, sy = y+1, sy+1 {
+ dpix := dst.Pix[y*dst.Stride:]
+ spix := src.Pix[sy*src.Stride:]
+
+ for i, si := i0, si0; i < i1; i, si = i+4, si+4 {
+ s := spix[si : si+4 : si+4] // Small cap improves performance, see https://golang.org/issue/27857
+ d := dpix[i : i+4 : i+4]
+ d[0], d[1], d[2] = color.CMYKToRGB(s[0], s[1], s[2], s[3])
+ d[3] = 255
+ }
+ }
+}
+
+func drawGlyphOver(dst *image.RGBA, r image.Rectangle, src *image.Uniform, mask *image.Alpha, mp image.Point) {
+ i0 := dst.PixOffset(r.Min.X, r.Min.Y)
+ i1 := i0 + r.Dx()*4
+ mi0 := mask.PixOffset(mp.X, mp.Y)
+ sr, sg, sb, sa := src.RGBA()
+ for y, my := r.Min.Y, mp.Y; y != r.Max.Y; y, my = y+1, my+1 {
+ for i, mi := i0, mi0; i < i1; i, mi = i+4, mi+1 {
+ ma := uint32(mask.Pix[mi])
+ if ma == 0 {
+ continue
+ }
+ ma |= ma << 8
+
+ // The 0x101 is here for the same reason as in drawRGBA.
+ a := (m - (sa * ma / m)) * 0x101
+
+ d := dst.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ d[0] = uint8((uint32(d[0])*a + sr*ma) / m >> 8)
+ d[1] = uint8((uint32(d[1])*a + sg*ma) / m >> 8)
+ d[2] = uint8((uint32(d[2])*a + sb*ma) / m >> 8)
+ d[3] = uint8((uint32(d[3])*a + sa*ma) / m >> 8)
+ }
+ i0 += dst.Stride
+ i1 += dst.Stride
+ mi0 += mask.Stride
+ }
+}
+
+func drawGrayMaskOver(dst *image.RGBA, r image.Rectangle, src *image.Gray, sp image.Point, mask *image.Alpha, mp image.Point) {
+ x0, x1, dx := r.Min.X, r.Max.X, 1
+ y0, y1, dy := r.Min.Y, r.Max.Y, 1
+ if r.Overlaps(r.Add(sp.Sub(r.Min))) {
+ if sp.Y < r.Min.Y || sp.Y == r.Min.Y && sp.X < r.Min.X {
+ x0, x1, dx = x1-1, x0-1, -1
+ y0, y1, dy = y1-1, y0-1, -1
+ }
+ }
+
+ sy := sp.Y + y0 - r.Min.Y
+ my := mp.Y + y0 - r.Min.Y
+ sx0 := sp.X + x0 - r.Min.X
+ mx0 := mp.X + x0 - r.Min.X
+ sx1 := sx0 + (x1 - x0)
+ i0 := dst.PixOffset(x0, y0)
+ di := dx * 4
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ for i, sx, mx := i0, sx0, mx0; sx != sx1; i, sx, mx = i+di, sx+dx, mx+dx {
+ mi := mask.PixOffset(mx, my)
+ ma := uint32(mask.Pix[mi])
+ ma |= ma << 8
+ si := src.PixOffset(sx, sy)
+ sy := uint32(src.Pix[si])
+ sy |= sy << 8
+ sa := uint32(0xffff)
+
+ d := dst.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ dr := uint32(d[0])
+ dg := uint32(d[1])
+ db := uint32(d[2])
+ da := uint32(d[3])
+
+ // dr, dg, db and da are all 8-bit color at the moment, ranging in [0,255].
+ // We work in 16-bit color, and so would normally do:
+ // dr |= dr << 8
+ // and similarly for dg, db and da, but instead we multiply a
+ // (which is a 16-bit color, ranging in [0,65535]) by 0x101.
+ // This yields the same result, but is fewer arithmetic operations.
+ a := (m - (sa * ma / m)) * 0x101
+
+ d[0] = uint8((dr*a + sy*ma) / m >> 8)
+ d[1] = uint8((dg*a + sy*ma) / m >> 8)
+ d[2] = uint8((db*a + sy*ma) / m >> 8)
+ d[3] = uint8((da*a + sa*ma) / m >> 8)
+ }
+ i0 += dy * dst.Stride
+ }
+}
+
+func drawRGBAMaskOver(dst *image.RGBA, r image.Rectangle, src *image.RGBA, sp image.Point, mask *image.Alpha, mp image.Point) {
+ x0, x1, dx := r.Min.X, r.Max.X, 1
+ y0, y1, dy := r.Min.Y, r.Max.Y, 1
+ if dst == src && r.Overlaps(r.Add(sp.Sub(r.Min))) {
+ if sp.Y < r.Min.Y || sp.Y == r.Min.Y && sp.X < r.Min.X {
+ x0, x1, dx = x1-1, x0-1, -1
+ y0, y1, dy = y1-1, y0-1, -1
+ }
+ }
+
+ sy := sp.Y + y0 - r.Min.Y
+ my := mp.Y + y0 - r.Min.Y
+ sx0 := sp.X + x0 - r.Min.X
+ mx0 := mp.X + x0 - r.Min.X
+ sx1 := sx0 + (x1 - x0)
+ i0 := dst.PixOffset(x0, y0)
+ di := dx * 4
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ for i, sx, mx := i0, sx0, mx0; sx != sx1; i, sx, mx = i+di, sx+dx, mx+dx {
+ mi := mask.PixOffset(mx, my)
+ ma := uint32(mask.Pix[mi])
+ ma |= ma << 8
+ si := src.PixOffset(sx, sy)
+ sr := uint32(src.Pix[si+0])
+ sg := uint32(src.Pix[si+1])
+ sb := uint32(src.Pix[si+2])
+ sa := uint32(src.Pix[si+3])
+ sr |= sr << 8
+ sg |= sg << 8
+ sb |= sb << 8
+ sa |= sa << 8
+ d := dst.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ dr := uint32(d[0])
+ dg := uint32(d[1])
+ db := uint32(d[2])
+ da := uint32(d[3])
+
+ // dr, dg, db and da are all 8-bit color at the moment, ranging in [0,255].
+ // We work in 16-bit color, and so would normally do:
+ // dr |= dr << 8
+ // and similarly for dg, db and da, but instead we multiply a
+ // (which is a 16-bit color, ranging in [0,65535]) by 0x101.
+ // This yields the same result, but is fewer arithmetic operations.
+ a := (m - (sa * ma / m)) * 0x101
+
+ d[0] = uint8((dr*a + sr*ma) / m >> 8)
+ d[1] = uint8((dg*a + sg*ma) / m >> 8)
+ d[2] = uint8((db*a + sb*ma) / m >> 8)
+ d[3] = uint8((da*a + sa*ma) / m >> 8)
+ }
+ i0 += dy * dst.Stride
+ }
+}
+
+func drawRGBA64ImageMaskOver(dst *image.RGBA, r image.Rectangle, src image.RGBA64Image, sp image.Point, mask *image.Alpha, mp image.Point) {
+ x0, x1, dx := r.Min.X, r.Max.X, 1
+ y0, y1, dy := r.Min.Y, r.Max.Y, 1
+ if image.Image(dst) == src && r.Overlaps(r.Add(sp.Sub(r.Min))) {
+ if sp.Y < r.Min.Y || sp.Y == r.Min.Y && sp.X < r.Min.X {
+ x0, x1, dx = x1-1, x0-1, -1
+ y0, y1, dy = y1-1, y0-1, -1
+ }
+ }
+
+ sy := sp.Y + y0 - r.Min.Y
+ my := mp.Y + y0 - r.Min.Y
+ sx0 := sp.X + x0 - r.Min.X
+ mx0 := mp.X + x0 - r.Min.X
+ sx1 := sx0 + (x1 - x0)
+ i0 := dst.PixOffset(x0, y0)
+ di := dx * 4
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ for i, sx, mx := i0, sx0, mx0; sx != sx1; i, sx, mx = i+di, sx+dx, mx+dx {
+ mi := mask.PixOffset(mx, my)
+ ma := uint32(mask.Pix[mi])
+ ma |= ma << 8
+ srgba := src.RGBA64At(sx, sy)
+ d := dst.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ dr := uint32(d[0])
+ dg := uint32(d[1])
+ db := uint32(d[2])
+ da := uint32(d[3])
+
+ // dr, dg, db and da are all 8-bit color at the moment, ranging in [0,255].
+ // We work in 16-bit color, and so would normally do:
+ // dr |= dr << 8
+ // and similarly for dg, db and da, but instead we multiply a
+ // (which is a 16-bit color, ranging in [0,65535]) by 0x101.
+ // This yields the same result, but is fewer arithmetic operations.
+ a := (m - (uint32(srgba.A) * ma / m)) * 0x101
+
+ d[0] = uint8((dr*a + uint32(srgba.R)*ma) / m >> 8)
+ d[1] = uint8((dg*a + uint32(srgba.G)*ma) / m >> 8)
+ d[2] = uint8((db*a + uint32(srgba.B)*ma) / m >> 8)
+ d[3] = uint8((da*a + uint32(srgba.A)*ma) / m >> 8)
+ }
+ i0 += dy * dst.Stride
+ }
+}
+
+func drawRGBA(dst *image.RGBA, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) {
+ x0, x1, dx := r.Min.X, r.Max.X, 1
+ y0, y1, dy := r.Min.Y, r.Max.Y, 1
+ if image.Image(dst) == src && r.Overlaps(r.Add(sp.Sub(r.Min))) {
+ if sp.Y < r.Min.Y || sp.Y == r.Min.Y && sp.X < r.Min.X {
+ x0, x1, dx = x1-1, x0-1, -1
+ y0, y1, dy = y1-1, y0-1, -1
+ }
+ }
+
+ sy := sp.Y + y0 - r.Min.Y
+ my := mp.Y + y0 - r.Min.Y
+ sx0 := sp.X + x0 - r.Min.X
+ mx0 := mp.X + x0 - r.Min.X
+ sx1 := sx0 + (x1 - x0)
+ i0 := dst.PixOffset(x0, y0)
+ di := dx * 4
+
+ // Try the image.RGBA64Image interface, part of the standard library since
+ // Go 1.17.
+ //
+ // This optimization is similar to how FALLBACK1.17 optimizes FALLBACK1.0
+ // in DrawMask, except here the concrete type of dst is known to be
+ // *image.RGBA.
+ if src0, _ := src.(image.RGBA64Image); src0 != nil {
+ if mask == nil {
+ if op == Over {
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ for i, sx, mx := i0, sx0, mx0; sx != sx1; i, sx, mx = i+di, sx+dx, mx+dx {
+ srgba := src0.RGBA64At(sx, sy)
+ d := dst.Pix[i : i+4 : i+4]
+ dr := uint32(d[0])
+ dg := uint32(d[1])
+ db := uint32(d[2])
+ da := uint32(d[3])
+ a := (m - uint32(srgba.A)) * 0x101
+ d[0] = uint8((dr*a/m + uint32(srgba.R)) >> 8)
+ d[1] = uint8((dg*a/m + uint32(srgba.G)) >> 8)
+ d[2] = uint8((db*a/m + uint32(srgba.B)) >> 8)
+ d[3] = uint8((da*a/m + uint32(srgba.A)) >> 8)
+ }
+ i0 += dy * dst.Stride
+ }
+ } else {
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ for i, sx, mx := i0, sx0, mx0; sx != sx1; i, sx, mx = i+di, sx+dx, mx+dx {
+ srgba := src0.RGBA64At(sx, sy)
+ d := dst.Pix[i : i+4 : i+4]
+ d[0] = uint8(srgba.R >> 8)
+ d[1] = uint8(srgba.G >> 8)
+ d[2] = uint8(srgba.B >> 8)
+ d[3] = uint8(srgba.A >> 8)
+ }
+ i0 += dy * dst.Stride
+ }
+ }
+ return
+
+ } else if mask0, _ := mask.(image.RGBA64Image); mask0 != nil {
+ if op == Over {
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ for i, sx, mx := i0, sx0, mx0; sx != sx1; i, sx, mx = i+di, sx+dx, mx+dx {
+ ma := uint32(mask0.RGBA64At(mx, my).A)
+ srgba := src0.RGBA64At(sx, sy)
+ d := dst.Pix[i : i+4 : i+4]
+ dr := uint32(d[0])
+ dg := uint32(d[1])
+ db := uint32(d[2])
+ da := uint32(d[3])
+ a := (m - (uint32(srgba.A) * ma / m)) * 0x101
+ d[0] = uint8((dr*a + uint32(srgba.R)*ma) / m >> 8)
+ d[1] = uint8((dg*a + uint32(srgba.G)*ma) / m >> 8)
+ d[2] = uint8((db*a + uint32(srgba.B)*ma) / m >> 8)
+ d[3] = uint8((da*a + uint32(srgba.A)*ma) / m >> 8)
+ }
+ i0 += dy * dst.Stride
+ }
+ } else {
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ for i, sx, mx := i0, sx0, mx0; sx != sx1; i, sx, mx = i+di, sx+dx, mx+dx {
+ ma := uint32(mask0.RGBA64At(mx, my).A)
+ srgba := src0.RGBA64At(sx, sy)
+ d := dst.Pix[i : i+4 : i+4]
+ d[0] = uint8(uint32(srgba.R) * ma / m >> 8)
+ d[1] = uint8(uint32(srgba.G) * ma / m >> 8)
+ d[2] = uint8(uint32(srgba.B) * ma / m >> 8)
+ d[3] = uint8(uint32(srgba.A) * ma / m >> 8)
+ }
+ i0 += dy * dst.Stride
+ }
+ }
+ return
+ }
+ }
+
+ // Use the image.Image interface, part of the standard library since Go
+ // 1.0.
+ //
+ // This is similar to FALLBACK1.0 in DrawMask, except here the concrete
+ // type of dst is known to be *image.RGBA.
+ for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
+ for i, sx, mx := i0, sx0, mx0; sx != sx1; i, sx, mx = i+di, sx+dx, mx+dx {
+ ma := uint32(m)
+ if mask != nil {
+ _, _, _, ma = mask.At(mx, my).RGBA()
+ }
+ sr, sg, sb, sa := src.At(sx, sy).RGBA()
+ d := dst.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857
+ if op == Over {
+ dr := uint32(d[0])
+ dg := uint32(d[1])
+ db := uint32(d[2])
+ da := uint32(d[3])
+
+ // dr, dg, db and da are all 8-bit color at the moment, ranging in [0,255].
+ // We work in 16-bit color, and so would normally do:
+ // dr |= dr << 8
+ // and similarly for dg, db and da, but instead we multiply a
+ // (which is a 16-bit color, ranging in [0,65535]) by 0x101.
+ // This yields the same result, but is fewer arithmetic operations.
+ a := (m - (sa * ma / m)) * 0x101
+
+ d[0] = uint8((dr*a + sr*ma) / m >> 8)
+ d[1] = uint8((dg*a + sg*ma) / m >> 8)
+ d[2] = uint8((db*a + sb*ma) / m >> 8)
+ d[3] = uint8((da*a + sa*ma) / m >> 8)
+
+ } else {
+ d[0] = uint8(sr * ma / m >> 8)
+ d[1] = uint8(sg * ma / m >> 8)
+ d[2] = uint8(sb * ma / m >> 8)
+ d[3] = uint8(sa * ma / m >> 8)
+ }
+ }
+ i0 += dy * dst.Stride
+ }
+}
+
+// clamp clamps i to the interval [0, 0xffff].
+func clamp(i int32) int32 {
+ if i < 0 {
+ return 0
+ }
+ if i > 0xffff {
+ return 0xffff
+ }
+ return i
+}
+
+// sqDiff returns the squared-difference of x and y, shifted by 2 so that
+// adding four of those won't overflow a uint32.
+//
+// x and y are both assumed to be in the range [0, 0xffff].
+func sqDiff(x, y int32) uint32 {
+ // This is an optimized code relying on the overflow/wrap around
+ // properties of unsigned integers operations guaranteed by the language
+ // spec. See sqDiff from the image/color package for more details.
+ d := uint32(x - y)
+ return (d * d) >> 2
+}
+
+func drawPaletted(dst Image, r image.Rectangle, src image.Image, sp image.Point, floydSteinberg bool) {
+ // TODO(nigeltao): handle the case where the dst and src overlap.
+ // Does it even make sense to try and do Floyd-Steinberg whilst
+ // walking the image backward (right-to-left bottom-to-top)?
+
+ // If dst is an *image.Paletted, we have a fast path for dst.Set and
+ // dst.At. The dst.Set equivalent is a batch version of the algorithm
+ // used by color.Palette's Index method in image/color/color.go, plus
+ // optional Floyd-Steinberg error diffusion.
+ palette, pix, stride := [][4]int32(nil), []byte(nil), 0
+ if p, ok := dst.(*image.Paletted); ok {
+ palette = make([][4]int32, len(p.Palette))
+ for i, col := range p.Palette {
+ r, g, b, a := col.RGBA()
+ palette[i][0] = int32(r)
+ palette[i][1] = int32(g)
+ palette[i][2] = int32(b)
+ palette[i][3] = int32(a)
+ }
+ pix, stride = p.Pix[p.PixOffset(r.Min.X, r.Min.Y):], p.Stride
+ }
+
+ // quantErrorCurr and quantErrorNext are the Floyd-Steinberg quantization
+ // errors that have been propagated to the pixels in the current and next
+ // rows. The +2 simplifies calculation near the edges.
+ var quantErrorCurr, quantErrorNext [][4]int32
+ if floydSteinberg {
+ quantErrorCurr = make([][4]int32, r.Dx()+2)
+ quantErrorNext = make([][4]int32, r.Dx()+2)
+ }
+ pxRGBA := func(x, y int) (r, g, b, a uint32) { return src.At(x, y).RGBA() }
+ // Fast paths for special cases to avoid excessive use of the color.Color
+ // interface which escapes to the heap but need to be discovered for
+ // each pixel on r. See also https://golang.org/issues/15759.
+ switch src0 := src.(type) {
+ case *image.RGBA:
+ pxRGBA = func(x, y int) (r, g, b, a uint32) { return src0.RGBAAt(x, y).RGBA() }
+ case *image.NRGBA:
+ pxRGBA = func(x, y int) (r, g, b, a uint32) { return src0.NRGBAAt(x, y).RGBA() }
+ case *image.YCbCr:
+ pxRGBA = func(x, y int) (r, g, b, a uint32) { return src0.YCbCrAt(x, y).RGBA() }
+ }
+
+ // Loop over each source pixel.
+ out := color.RGBA64{A: 0xffff}
+ for y := 0; y != r.Dy(); y++ {
+ for x := 0; x != r.Dx(); x++ {
+ // er, eg and eb are the pixel's R,G,B values plus the
+ // optional Floyd-Steinberg error.
+ sr, sg, sb, sa := pxRGBA(sp.X+x, sp.Y+y)
+ er, eg, eb, ea := int32(sr), int32(sg), int32(sb), int32(sa)
+ if floydSteinberg {
+ er = clamp(er + quantErrorCurr[x+1][0]/16)
+ eg = clamp(eg + quantErrorCurr[x+1][1]/16)
+ eb = clamp(eb + quantErrorCurr[x+1][2]/16)
+ ea = clamp(ea + quantErrorCurr[x+1][3]/16)
+ }
+
+ if palette != nil {
+ // Find the closest palette color in Euclidean R,G,B,A space:
+ // the one that minimizes sum-squared-difference.
+ // TODO(nigeltao): consider smarter algorithms.
+ bestIndex, bestSum := 0, uint32(1<<32-1)
+ for index, p := range palette {
+ sum := sqDiff(er, p[0]) + sqDiff(eg, p[1]) + sqDiff(eb, p[2]) + sqDiff(ea, p[3])
+ if sum < bestSum {
+ bestIndex, bestSum = index, sum
+ if sum == 0 {
+ break
+ }
+ }
+ }
+ pix[y*stride+x] = byte(bestIndex)
+
+ if !floydSteinberg {
+ continue
+ }
+ er -= palette[bestIndex][0]
+ eg -= palette[bestIndex][1]
+ eb -= palette[bestIndex][2]
+ ea -= palette[bestIndex][3]
+
+ } else {
+ out.R = uint16(er)
+ out.G = uint16(eg)
+ out.B = uint16(eb)
+ out.A = uint16(ea)
+ // The third argument is &out instead of out (and out is
+ // declared outside of the inner loop) to avoid the implicit
+ // conversion to color.Color here allocating memory in the
+ // inner loop if sizeof(color.RGBA64) > sizeof(uintptr).
+ dst.Set(r.Min.X+x, r.Min.Y+y, &out)
+
+ if !floydSteinberg {
+ continue
+ }
+ sr, sg, sb, sa = dst.At(r.Min.X+x, r.Min.Y+y).RGBA()
+ er -= int32(sr)
+ eg -= int32(sg)
+ eb -= int32(sb)
+ ea -= int32(sa)
+ }
+
+ // Propagate the Floyd-Steinberg quantization error.
+ quantErrorNext[x+0][0] += er * 3
+ quantErrorNext[x+0][1] += eg * 3
+ quantErrorNext[x+0][2] += eb * 3
+ quantErrorNext[x+0][3] += ea * 3
+ quantErrorNext[x+1][0] += er * 5
+ quantErrorNext[x+1][1] += eg * 5
+ quantErrorNext[x+1][2] += eb * 5
+ quantErrorNext[x+1][3] += ea * 5
+ quantErrorNext[x+2][0] += er * 1
+ quantErrorNext[x+2][1] += eg * 1
+ quantErrorNext[x+2][2] += eb * 1
+ quantErrorNext[x+2][3] += ea * 1
+ quantErrorCurr[x+2][0] += er * 7
+ quantErrorCurr[x+2][1] += eg * 7
+ quantErrorCurr[x+2][2] += eb * 7
+ quantErrorCurr[x+2][3] += ea * 7
+ }
+
+ // Recycle the quantization error buffers.
+ if floydSteinberg {
+ quantErrorCurr, quantErrorNext = quantErrorNext, quantErrorCurr
+ for i := range quantErrorNext {
+ quantErrorNext[i] = [4]int32{}
+ }
+ }
+ }
+}