Imported Upstream version 1.4upstream/1.4

1 files changed, 0 insertions, 673 deletions

diff --git a/src/pkg/image/draw/draw.go b/src/pkg/image/draw/draw.go
deleted file mode 100644
index 661230e7c..000000000
--- a/src/pkg/image/draw/draw.go
+++ /dev/null
@@ -1,673 +0,0 @@
-// 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:
-// http://golang.org/doc/articles/image_draw.html
-package draw
-
-import (
-	"image"
-	"image/color"
-)
-
-// 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)
-}
-
-// 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 co-ordinate 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
-	(*mp).X += dx
-	(*mp).Y += dy
-}
-
-func processBackward(dst Image, r image.Rectangle, src image.Image, sp image.Point) bool {
-	return image.Image(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 a general but slow implementation.
-	switch dst0 := dst.(type) {
-	case *image.RGBA:
-		if op == Over {
-			if mask == nil {
-				switch src0 := src.(type) {
-				case *image.Uniform:
-					drawFillOver(dst0, r, src0)
-					return
-				case *image.RGBA:
-					drawCopyOver(dst0, r, src0, sp)
-					return
-				case *image.NRGBA:
-					drawNRGBAOver(dst0, r, src0, sp)
-					return
-				case *image.YCbCr:
-					if drawYCbCr(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
-				}
-			}
-		} else {
-			if mask == nil {
-				switch src0 := src.(type) {
-				case *image.Uniform:
-					drawFillSrc(dst0, r, src0)
-					return
-				case *image.RGBA:
-					drawCopySrc(dst0, r, src0, sp)
-					return
-				case *image.NRGBA:
-					drawNRGBASrc(dst0, r, src0, sp)
-					return
-				case *image.YCbCr:
-					if drawYCbCr(dst0, r, src0, sp) {
-						return
-					}
-				}
-			}
-		}
-		drawRGBA(dst0, r, src, sp, mask, mp, op)
-		return
-	case *image.Paletted:
-		if op == Src && mask == nil && !processBackward(dst, r, src, sp) {
-			drawPaletted(dst0, r, src, sp, false)
-		}
-	}
-
-	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
-	}
-
-	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, src *image.Uniform) {
-	sr, sg, sb, sa := src.RGBA()
-	// 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 := uint32(dst.Pix[i+0])
-			dg := uint32(dst.Pix[i+1])
-			db := uint32(dst.Pix[i+2])
-			da := uint32(dst.Pix[i+3])
-
-			dst.Pix[i+0] = uint8((dr*a/m + sr) >> 8)
-			dst.Pix[i+1] = uint8((dg*a/m + sg) >> 8)
-			dst.Pix[i+2] = uint8((db*a/m + sb) >> 8)
-			dst.Pix[i+3] = uint8((da*a/m + sa) >> 8)
-		}
-		i0 += dst.Stride
-		i1 += dst.Stride
-	}
-}
-
-func drawFillSrc(dst *image.RGBA, r image.Rectangle, src *image.Uniform) {
-	sr, sg, sb, sa := src.RGBA()
-	// 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] = uint8(sr >> 8)
-		dst.Pix[i+1] = uint8(sg >> 8)
-		dst.Pix[i+2] = uint8(sb >> 8)
-		dst.Pix[i+3] = uint8(sa >> 8)
-	}
-	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 {
-			sr := uint32(spix[i+0]) * 0x101
-			sg := uint32(spix[i+1]) * 0x101
-			sb := uint32(spix[i+2]) * 0x101
-			sa := uint32(spix[i+3]) * 0x101
-
-			dr := uint32(dpix[i+0])
-			dg := uint32(dpix[i+1])
-			db := uint32(dpix[i+2])
-			da := uint32(dpix[i+3])
-
-			// The 0x101 is here for the same reason as in drawRGBA.
-			a := (m - sa) * 0x101
-
-			dpix[i+0] = uint8((dr*a/m + sr) >> 8)
-			dpix[i+1] = uint8((dg*a/m + sg) >> 8)
-			dpix[i+2] = uint8((db*a/m + sb) >> 8)
-			dpix[i+3] = uint8((da*a/m + sa) >> 8)
-		}
-		d0 += ddelta
-		s0 += sdelta
-	}
-}
-
-func drawCopySrc(dst *image.RGBA, r image.Rectangle, src *image.RGBA, sp image.Point) {
-	n, dy := 4*r.Dx(), r.Dy()
-	d0 := dst.PixOffset(r.Min.X, r.Min.Y)
-	s0 := src.PixOffset(sp.X, sp.Y)
-	var ddelta, sdelta int
-	if r.Min.Y <= sp.Y {
-		ddelta = dst.Stride
-		sdelta = src.Stride
-	} else {
-		// 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 co-ordinates because the built-in copy function can handle overlapping slices.
-		d0 += (dy - 1) * dst.Stride
-		s0 += (dy - 1) * src.Stride
-		ddelta = -dst.Stride
-		sdelta = -src.Stride
-	}
-	for ; dy > 0; dy-- {
-		copy(dst.Pix[d0:d0+n], src.Pix[s0:s0+n])
-		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.
-			sa := uint32(spix[si+3]) * 0x101
-			sr := uint32(spix[si+0]) * sa / 0xff
-			sg := uint32(spix[si+1]) * sa / 0xff
-			sb := uint32(spix[si+2]) * sa / 0xff
-
-			dr := uint32(dpix[i+0])
-			dg := uint32(dpix[i+1])
-			db := uint32(dpix[i+2])
-			da := uint32(dpix[i+3])
-
-			// The 0x101 is here for the same reason as in drawRGBA.
-			a := (m - sa) * 0x101
-
-			dpix[i+0] = uint8((dr*a/m + sr) >> 8)
-			dpix[i+1] = uint8((dg*a/m + sg) >> 8)
-			dpix[i+2] = uint8((db*a/m + sb) >> 8)
-			dpix[i+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.
-			sa := uint32(spix[si+3]) * 0x101
-			sr := uint32(spix[si+0]) * sa / 0xff
-			sg := uint32(spix[si+1]) * sa / 0xff
-			sb := uint32(spix[si+2]) * sa / 0xff
-
-			dpix[i+0] = uint8(sr >> 8)
-			dpix[i+1] = uint8(sg >> 8)
-			dpix[i+2] = uint8(sb >> 8)
-			dpix[i+3] = uint8(sa >> 8)
-		}
-	}
-}
-
-func drawYCbCr(dst *image.RGBA, r image.Rectangle, src *image.YCbCr, sp image.Point) (ok bool) {
-	// An image.YCbCr is always fully opaque, and so if the mask is implicitly nil
-	// (i.e. fully opaque) then the op is effectively always Src.
-	x0 := (r.Min.X - dst.Rect.Min.X) * 4
-	x1 := (r.Max.X - dst.Rect.Min.X) * 4
-	y0 := r.Min.Y - dst.Rect.Min.Y
-	y1 := r.Max.Y - dst.Rect.Min.Y
-	switch src.SubsampleRatio {
-	case image.YCbCrSubsampleRatio444:
-		for y, sy := y0, sp.Y; y != y1; y, sy = y+1, sy+1 {
-			dpix := dst.Pix[y*dst.Stride:]
-			yi := (sy-src.Rect.Min.Y)*src.YStride + (sp.X - src.Rect.Min.X)
-			ci := (sy-src.Rect.Min.Y)*src.CStride + (sp.X - src.Rect.Min.X)
-			for x := x0; x != x1; x, yi, ci = x+4, yi+1, ci+1 {
-				rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
-				dpix[x+0] = rr
-				dpix[x+1] = gg
-				dpix[x+2] = bb
-				dpix[x+3] = 255
-			}
-		}
-	case image.YCbCrSubsampleRatio422:
-		for y, sy := y0, sp.Y; y != y1; y, sy = y+1, sy+1 {
-			dpix := dst.Pix[y*dst.Stride:]
-			yi := (sy-src.Rect.Min.Y)*src.YStride + (sp.X - src.Rect.Min.X)
-			ciBase := (sy-src.Rect.Min.Y)*src.CStride - src.Rect.Min.X/2
-			for x, sx := x0, sp.X; x != x1; x, sx, yi = x+4, sx+1, yi+1 {
-				ci := ciBase + sx/2
-				rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
-				dpix[x+0] = rr
-				dpix[x+1] = gg
-				dpix[x+2] = bb
-				dpix[x+3] = 255
-			}
-		}
-	case image.YCbCrSubsampleRatio420:
-		for y, sy := y0, sp.Y; y != y1; y, sy = y+1, sy+1 {
-			dpix := dst.Pix[y*dst.Stride:]
-			yi := (sy-src.Rect.Min.Y)*src.YStride + (sp.X - src.Rect.Min.X)
-			ciBase := (sy/2-src.Rect.Min.Y/2)*src.CStride - src.Rect.Min.X/2
-			for x, sx := x0, sp.X; x != x1; x, sx, yi = x+4, sx+1, yi+1 {
-				ci := ciBase + sx/2
-				rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
-				dpix[x+0] = rr
-				dpix[x+1] = gg
-				dpix[x+2] = bb
-				dpix[x+3] = 255
-			}
-		}
-	case image.YCbCrSubsampleRatio440:
-		for y, sy := y0, sp.Y; y != y1; y, sy = y+1, sy+1 {
-			dpix := dst.Pix[y*dst.Stride:]
-			yi := (sy-src.Rect.Min.Y)*src.YStride + (sp.X - src.Rect.Min.X)
-			ci := (sy/2-src.Rect.Min.Y/2)*src.CStride + (sp.X - src.Rect.Min.X)
-			for x := x0; x != x1; x, yi, ci = x+4, yi+1, ci+1 {
-				rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
-				dpix[x+0] = rr
-				dpix[x+1] = gg
-				dpix[x+2] = bb
-				dpix[x+3] = 255
-			}
-		}
-	default:
-		return false
-	}
-	return true
-}
-
-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
-
-			dr := uint32(dst.Pix[i+0])
-			dg := uint32(dst.Pix[i+1])
-			db := uint32(dst.Pix[i+2])
-			da := uint32(dst.Pix[i+3])
-
-			// The 0x101 is here for the same reason as in drawRGBA.
-			a := (m - (sa * ma / m)) * 0x101
-
-			dst.Pix[i+0] = uint8((dr*a + sr*ma) / m >> 8)
-			dst.Pix[i+1] = uint8((dg*a + sg*ma) / m >> 8)
-			dst.Pix[i+2] = uint8((db*a + sb*ma) / m >> 8)
-			dst.Pix[i+3] = uint8((da*a + sa*ma) / m >> 8)
-		}
-		i0 += dst.Stride
-		i1 += dst.Stride
-		mi0 += mask.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
-	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()
-			if op == Over {
-				dr := uint32(dst.Pix[i+0])
-				dg := uint32(dst.Pix[i+1])
-				db := uint32(dst.Pix[i+2])
-				da := uint32(dst.Pix[i+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
-
-				dst.Pix[i+0] = uint8((dr*a + sr*ma) / m >> 8)
-				dst.Pix[i+1] = uint8((dg*a + sg*ma) / m >> 8)
-				dst.Pix[i+2] = uint8((db*a + sb*ma) / m >> 8)
-				dst.Pix[i+3] = uint8((da*a + sa*ma) / m >> 8)
-
-			} else {
-				dst.Pix[i+0] = uint8(sr * ma / m >> 8)
-				dst.Pix[i+1] = uint8(sg * ma / m >> 8)
-				dst.Pix[i+2] = uint8(sb * ma / m >> 8)
-				dst.Pix[i+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
-}
-
-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 := [][3]int32(nil), []byte(nil), 0
-	if p, ok := dst.(*image.Paletted); ok {
-		palette = make([][3]int32, len(p.Palette))
-		for i, col := range p.Palette {
-			r, g, b, _ := col.RGBA()
-			palette[i][0] = int32(r)
-			palette[i][1] = int32(g)
-			palette[i][2] = int32(b)
-		}
-		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 [][3]int32
-	if floydSteinberg {
-		quantErrorCurr = make([][3]int32, r.Dx()+2)
-		quantErrorNext = make([][3]int32, r.Dx()+2)
-	}
-
-	// 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, _ := src.At(sp.X+x, sp.Y+y).RGBA()
-			er, eg, eb := int32(sr), int32(sg), int32(sb)
-			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)
-			}
-
-			if palette != nil {
-				// Find the closest palette color in Euclidean R,G,B space: the
-				// one that minimizes sum-squared-difference. We shift by 1 bit
-				// to avoid potential uint32 overflow in sum-squared-difference.
-				// TODO(nigeltao): consider smarter algorithms.
-				bestIndex, bestSSD := 0, uint32(1<<32-1)
-				for index, p := range palette {
-					delta := (er - p[0]) >> 1
-					ssd := uint32(delta * delta)
-					delta = (eg - p[1]) >> 1
-					ssd += uint32(delta * delta)
-					delta = (eb - p[2]) >> 1
-					ssd += uint32(delta * delta)
-					if ssd < bestSSD {
-						bestIndex, bestSSD = index, ssd
-						if ssd == 0 {
-							break
-						}
-					}
-				}
-				pix[y*stride+x] = byte(bestIndex)
-
-				if !floydSteinberg {
-					continue
-				}
-				er -= int32(palette[bestIndex][0])
-				eg -= int32(palette[bestIndex][1])
-				eb -= int32(palette[bestIndex][2])
-
-			} else {
-				out.R = uint16(er)
-				out.G = uint16(eg)
-				out.B = uint16(eb)
-				// 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, _ = dst.At(r.Min.X+x, r.Min.Y+y).RGBA()
-				er -= int32(sr)
-				eg -= int32(sg)
-				eb -= int32(sb)
-			}
-
-			// 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+1][0] += er * 5
-			quantErrorNext[x+1][1] += eg * 5
-			quantErrorNext[x+1][2] += eb * 5
-			quantErrorNext[x+2][0] += er * 1
-			quantErrorNext[x+2][1] += eg * 1
-			quantErrorNext[x+2][2] += eb * 1
-			quantErrorCurr[x+2][0] += er * 7
-			quantErrorCurr[x+2][1] += eg * 7
-			quantErrorCurr[x+2][2] += eb * 7
-		}
-
-		// Recycle the quantization error buffers.
-		if floydSteinberg {
-			quantErrorCurr, quantErrorNext = quantErrorNext, quantErrorCurr
-			for i := range quantErrorNext {
-				quantErrorNext[i] = [3]int32{}
-			}
-		}
-	}
-}