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-rw-r--r--src/image/draw/bench_test.go206
-rw-r--r--src/image/draw/clip_test.go193
-rw-r--r--src/image/draw/draw.go673
-rw-r--r--src/image/draw/draw_test.go429
4 files changed, 1501 insertions, 0 deletions
diff --git a/src/image/draw/bench_test.go b/src/image/draw/bench_test.go
new file mode 100644
index 000000000..cc62e25f1
--- /dev/null
+++ b/src/image/draw/bench_test.go
@@ -0,0 +1,206 @@
+// Copyright 2011 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
+
+import (
+ "image"
+ "image/color"
+ "testing"
+)
+
+const (
+ dstw, dsth = 640, 480
+ srcw, srch = 400, 300
+)
+
+// bench benchmarks drawing src and mask images onto a dst image with the
+// given op and the color models to create those images from.
+// The created images' pixels are initialized to non-zero values.
+func bench(b *testing.B, dcm, scm, mcm color.Model, op Op) {
+ b.StopTimer()
+
+ var dst Image
+ switch dcm {
+ case color.RGBAModel:
+ dst1 := image.NewRGBA(image.Rect(0, 0, dstw, dsth))
+ for y := 0; y < dsth; y++ {
+ for x := 0; x < dstw; x++ {
+ dst1.SetRGBA(x, y, color.RGBA{
+ uint8(5 * x % 0x100),
+ uint8(7 * y % 0x100),
+ uint8((7*x + 5*y) % 0x100),
+ 0xff,
+ })
+ }
+ }
+ dst = dst1
+ case color.RGBA64Model:
+ dst1 := image.NewRGBA64(image.Rect(0, 0, dstw, dsth))
+ for y := 0; y < dsth; y++ {
+ for x := 0; x < dstw; x++ {
+ dst1.SetRGBA64(x, y, color.RGBA64{
+ uint16(53 * x % 0x10000),
+ uint16(59 * y % 0x10000),
+ uint16((59*x + 53*y) % 0x10000),
+ 0xffff,
+ })
+ }
+ }
+ dst = dst1
+ default:
+ b.Fatal("unknown destination color model", dcm)
+ }
+
+ var src image.Image
+ switch scm {
+ case nil:
+ src = &image.Uniform{C: color.RGBA{0x11, 0x22, 0x33, 0xff}}
+ case color.RGBAModel:
+ src1 := image.NewRGBA(image.Rect(0, 0, srcw, srch))
+ for y := 0; y < srch; y++ {
+ for x := 0; x < srcw; x++ {
+ src1.SetRGBA(x, y, color.RGBA{
+ uint8(13 * x % 0x80),
+ uint8(11 * y % 0x80),
+ uint8((11*x + 13*y) % 0x80),
+ 0x7f,
+ })
+ }
+ }
+ src = src1
+ case color.RGBA64Model:
+ src1 := image.NewRGBA64(image.Rect(0, 0, srcw, srch))
+ for y := 0; y < srch; y++ {
+ for x := 0; x < srcw; x++ {
+ src1.SetRGBA64(x, y, color.RGBA64{
+ uint16(103 * x % 0x8000),
+ uint16(101 * y % 0x8000),
+ uint16((101*x + 103*y) % 0x8000),
+ 0x7fff,
+ })
+ }
+ }
+ src = src1
+ case color.NRGBAModel:
+ src1 := image.NewNRGBA(image.Rect(0, 0, srcw, srch))
+ for y := 0; y < srch; y++ {
+ for x := 0; x < srcw; x++ {
+ src1.SetNRGBA(x, y, color.NRGBA{
+ uint8(13 * x % 0x100),
+ uint8(11 * y % 0x100),
+ uint8((11*x + 13*y) % 0x100),
+ 0x7f,
+ })
+ }
+ }
+ src = src1
+ case color.YCbCrModel:
+ yy := make([]uint8, srcw*srch)
+ cb := make([]uint8, srcw*srch)
+ cr := make([]uint8, srcw*srch)
+ for i := range yy {
+ yy[i] = uint8(3 * i % 0x100)
+ cb[i] = uint8(5 * i % 0x100)
+ cr[i] = uint8(7 * i % 0x100)
+ }
+ src = &image.YCbCr{
+ Y: yy,
+ Cb: cb,
+ Cr: cr,
+ YStride: srcw,
+ CStride: srcw,
+ SubsampleRatio: image.YCbCrSubsampleRatio444,
+ Rect: image.Rect(0, 0, srcw, srch),
+ }
+ default:
+ b.Fatal("unknown source color model", scm)
+ }
+
+ var mask image.Image
+ switch mcm {
+ case nil:
+ // No-op.
+ case color.AlphaModel:
+ mask1 := image.NewAlpha(image.Rect(0, 0, srcw, srch))
+ for y := 0; y < srch; y++ {
+ for x := 0; x < srcw; x++ {
+ a := uint8((23*x + 29*y) % 0x100)
+ // Glyph masks are typically mostly zero,
+ // so we only set a quarter of mask1's pixels.
+ if a >= 0xc0 {
+ mask1.SetAlpha(x, y, color.Alpha{a})
+ }
+ }
+ }
+ mask = mask1
+ default:
+ b.Fatal("unknown mask color model", mcm)
+ }
+
+ b.StartTimer()
+ for i := 0; i < b.N; i++ {
+ // Scatter the destination rectangle to draw into.
+ x := 3 * i % (dstw - srcw)
+ y := 7 * i % (dsth - srch)
+
+ DrawMask(dst, dst.Bounds().Add(image.Pt(x, y)), src, image.ZP, mask, image.ZP, op)
+ }
+}
+
+// The BenchmarkFoo functions exercise a drawFoo fast-path function in draw.go.
+
+func BenchmarkFillOver(b *testing.B) {
+ bench(b, color.RGBAModel, nil, nil, Over)
+}
+
+func BenchmarkFillSrc(b *testing.B) {
+ bench(b, color.RGBAModel, nil, nil, Src)
+}
+
+func BenchmarkCopyOver(b *testing.B) {
+ bench(b, color.RGBAModel, color.RGBAModel, nil, Over)
+}
+
+func BenchmarkCopySrc(b *testing.B) {
+ bench(b, color.RGBAModel, color.RGBAModel, nil, Src)
+}
+
+func BenchmarkNRGBAOver(b *testing.B) {
+ bench(b, color.RGBAModel, color.NRGBAModel, nil, Over)
+}
+
+func BenchmarkNRGBASrc(b *testing.B) {
+ bench(b, color.RGBAModel, color.NRGBAModel, nil, Src)
+}
+
+func BenchmarkYCbCr(b *testing.B) {
+ bench(b, color.RGBAModel, color.YCbCrModel, nil, Over)
+}
+
+func BenchmarkGlyphOver(b *testing.B) {
+ bench(b, color.RGBAModel, nil, color.AlphaModel, Over)
+}
+
+func BenchmarkRGBA(b *testing.B) {
+ bench(b, color.RGBAModel, color.RGBA64Model, nil, Src)
+}
+
+// The BenchmarkGenericFoo functions exercise the generic, slow-path code.
+
+func BenchmarkGenericOver(b *testing.B) {
+ bench(b, color.RGBA64Model, color.RGBA64Model, nil, Over)
+}
+
+func BenchmarkGenericMaskOver(b *testing.B) {
+ bench(b, color.RGBA64Model, color.RGBA64Model, color.AlphaModel, Over)
+}
+
+func BenchmarkGenericSrc(b *testing.B) {
+ bench(b, color.RGBA64Model, color.RGBA64Model, nil, Src)
+}
+
+func BenchmarkGenericMaskSrc(b *testing.B) {
+ bench(b, color.RGBA64Model, color.RGBA64Model, color.AlphaModel, Src)
+}
diff --git a/src/image/draw/clip_test.go b/src/image/draw/clip_test.go
new file mode 100644
index 000000000..65381f72f
--- /dev/null
+++ b/src/image/draw/clip_test.go
@@ -0,0 +1,193 @@
+// Copyright 2011 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
+
+import (
+ "image"
+ "testing"
+)
+
+type clipTest struct {
+ desc string
+ r, dr, sr, mr image.Rectangle
+ sp, mp image.Point
+ nilMask bool
+ r0 image.Rectangle
+ sp0, mp0 image.Point
+}
+
+var clipTests = []clipTest{
+ // The following tests all have a nil mask.
+ {
+ "basic",
+ image.Rect(0, 0, 100, 100),
+ image.Rect(0, 0, 100, 100),
+ image.Rect(0, 0, 100, 100),
+ image.ZR,
+ image.ZP,
+ image.ZP,
+ true,
+ image.Rect(0, 0, 100, 100),
+ image.ZP,
+ image.ZP,
+ },
+ {
+ "clip dr",
+ image.Rect(0, 0, 100, 100),
+ image.Rect(40, 40, 60, 60),
+ image.Rect(0, 0, 100, 100),
+ image.ZR,
+ image.ZP,
+ image.ZP,
+ true,
+ image.Rect(40, 40, 60, 60),
+ image.Pt(40, 40),
+ image.ZP,
+ },
+ {
+ "clip sr",
+ image.Rect(0, 0, 100, 100),
+ image.Rect(0, 0, 100, 100),
+ image.Rect(20, 20, 80, 80),
+ image.ZR,
+ image.ZP,
+ image.ZP,
+ true,
+ image.Rect(20, 20, 80, 80),
+ image.Pt(20, 20),
+ image.ZP,
+ },
+ {
+ "clip dr and sr",
+ image.Rect(0, 0, 100, 100),
+ image.Rect(0, 0, 50, 100),
+ image.Rect(20, 20, 80, 80),
+ image.ZR,
+ image.ZP,
+ image.ZP,
+ true,
+ image.Rect(20, 20, 50, 80),
+ image.Pt(20, 20),
+ image.ZP,
+ },
+ {
+ "clip dr and sr, sp outside sr (top-left)",
+ image.Rect(0, 0, 100, 100),
+ image.Rect(0, 0, 50, 100),
+ image.Rect(20, 20, 80, 80),
+ image.ZR,
+ image.Pt(15, 8),
+ image.ZP,
+ true,
+ image.Rect(5, 12, 50, 72),
+ image.Pt(20, 20),
+ image.ZP,
+ },
+ {
+ "clip dr and sr, sp outside sr (middle-left)",
+ image.Rect(0, 0, 100, 100),
+ image.Rect(0, 0, 50, 100),
+ image.Rect(20, 20, 80, 80),
+ image.ZR,
+ image.Pt(15, 66),
+ image.ZP,
+ true,
+ image.Rect(5, 0, 50, 14),
+ image.Pt(20, 66),
+ image.ZP,
+ },
+ {
+ "clip dr and sr, sp outside sr (bottom-left)",
+ image.Rect(0, 0, 100, 100),
+ image.Rect(0, 0, 50, 100),
+ image.Rect(20, 20, 80, 80),
+ image.ZR,
+ image.Pt(15, 91),
+ image.ZP,
+ true,
+ image.ZR,
+ image.Pt(15, 91),
+ image.ZP,
+ },
+ {
+ "clip dr and sr, sp inside sr",
+ image.Rect(0, 0, 100, 100),
+ image.Rect(0, 0, 50, 100),
+ image.Rect(20, 20, 80, 80),
+ image.ZR,
+ image.Pt(44, 33),
+ image.ZP,
+ true,
+ image.Rect(0, 0, 36, 47),
+ image.Pt(44, 33),
+ image.ZP,
+ },
+
+ // The following tests all have a non-nil mask.
+ {
+ "basic mask",
+ image.Rect(0, 0, 80, 80),
+ image.Rect(20, 0, 100, 80),
+ image.Rect(0, 0, 50, 49),
+ image.Rect(0, 0, 46, 47),
+ image.ZP,
+ image.ZP,
+ false,
+ image.Rect(20, 0, 46, 47),
+ image.Pt(20, 0),
+ image.Pt(20, 0),
+ },
+ // TODO(nigeltao): write more tests.
+}
+
+func TestClip(t *testing.T) {
+ dst0 := image.NewRGBA(image.Rect(0, 0, 100, 100))
+ src0 := image.NewRGBA(image.Rect(0, 0, 100, 100))
+ mask0 := image.NewRGBA(image.Rect(0, 0, 100, 100))
+ for _, c := range clipTests {
+ dst := dst0.SubImage(c.dr).(*image.RGBA)
+ src := src0.SubImage(c.sr).(*image.RGBA)
+ var mask image.Image
+ if !c.nilMask {
+ mask = mask0.SubImage(c.mr)
+ }
+ r, sp, mp := c.r, c.sp, c.mp
+ clip(dst, &r, src, &sp, mask, &mp)
+
+ // Check that the actual results equal the expected results.
+ if !c.r0.Eq(r) {
+ t.Errorf("%s: clip rectangle want %v got %v", c.desc, c.r0, r)
+ continue
+ }
+ if !c.sp0.Eq(sp) {
+ t.Errorf("%s: sp want %v got %v", c.desc, c.sp0, sp)
+ continue
+ }
+ if !c.nilMask {
+ if !c.mp0.Eq(mp) {
+ t.Errorf("%s: mp want %v got %v", c.desc, c.mp0, mp)
+ continue
+ }
+ }
+
+ // Check that the clipped rectangle is contained by the dst / src / mask
+ // rectangles, in their respective co-ordinate spaces.
+ if !r.In(c.dr) {
+ t.Errorf("%s: c.dr %v does not contain r %v", c.desc, c.dr, r)
+ }
+ // sr is r translated into src's co-ordinate space.
+ sr := r.Add(c.sp.Sub(c.dr.Min))
+ if !sr.In(c.sr) {
+ t.Errorf("%s: c.sr %v does not contain sr %v", c.desc, c.sr, sr)
+ }
+ if !c.nilMask {
+ // mr is r translated into mask's co-ordinate space.
+ mr := r.Add(c.mp.Sub(c.dr.Min))
+ if !mr.In(c.mr) {
+ t.Errorf("%s: c.mr %v does not contain mr %v", c.desc, c.mr, mr)
+ }
+ }
+ }
+}
diff --git a/src/image/draw/draw.go b/src/image/draw/draw.go
new file mode 100644
index 000000000..661230e7c
--- /dev/null
+++ b/src/image/draw/draw.go
@@ -0,0 +1,673 @@
+// 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{}
+ }
+ }
+ }
+}
diff --git a/src/image/draw/draw_test.go b/src/image/draw/draw_test.go
new file mode 100644
index 000000000..0dd7fbd47
--- /dev/null
+++ b/src/image/draw/draw_test.go
@@ -0,0 +1,429 @@
+// Copyright 2010 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
+
+import (
+ "image"
+ "image/color"
+ "image/png"
+ "os"
+ "testing"
+)
+
+func eq(c0, c1 color.Color) bool {
+ r0, g0, b0, a0 := c0.RGBA()
+ r1, g1, b1, a1 := c1.RGBA()
+ return r0 == r1 && g0 == g1 && b0 == b1 && a0 == a1
+}
+
+func fillBlue(alpha int) image.Image {
+ return image.NewUniform(color.RGBA{0, 0, uint8(alpha), uint8(alpha)})
+}
+
+func fillAlpha(alpha int) image.Image {
+ return image.NewUniform(color.Alpha{uint8(alpha)})
+}
+
+func vgradGreen(alpha int) image.Image {
+ m := image.NewRGBA(image.Rect(0, 0, 16, 16))
+ for y := 0; y < 16; y++ {
+ for x := 0; x < 16; x++ {
+ m.Set(x, y, color.RGBA{0, uint8(y * alpha / 15), 0, uint8(alpha)})
+ }
+ }
+ return m
+}
+
+func vgradAlpha(alpha int) image.Image {
+ m := image.NewAlpha(image.Rect(0, 0, 16, 16))
+ for y := 0; y < 16; y++ {
+ for x := 0; x < 16; x++ {
+ m.Set(x, y, color.Alpha{uint8(y * alpha / 15)})
+ }
+ }
+ return m
+}
+
+func vgradGreenNRGBA(alpha int) image.Image {
+ m := image.NewNRGBA(image.Rect(0, 0, 16, 16))
+ for y := 0; y < 16; y++ {
+ for x := 0; x < 16; x++ {
+ m.Set(x, y, color.RGBA{0, uint8(y * 0x11), 0, uint8(alpha)})
+ }
+ }
+ return m
+}
+
+func vgradCr() image.Image {
+ m := &image.YCbCr{
+ Y: make([]byte, 16*16),
+ Cb: make([]byte, 16*16),
+ Cr: make([]byte, 16*16),
+ YStride: 16,
+ CStride: 16,
+ SubsampleRatio: image.YCbCrSubsampleRatio444,
+ Rect: image.Rect(0, 0, 16, 16),
+ }
+ for y := 0; y < 16; y++ {
+ for x := 0; x < 16; x++ {
+ m.Cr[y*m.CStride+x] = uint8(y * 0x11)
+ }
+ }
+ return m
+}
+
+func hgradRed(alpha int) Image {
+ m := image.NewRGBA(image.Rect(0, 0, 16, 16))
+ for y := 0; y < 16; y++ {
+ for x := 0; x < 16; x++ {
+ m.Set(x, y, color.RGBA{uint8(x * alpha / 15), 0, 0, uint8(alpha)})
+ }
+ }
+ return m
+}
+
+func gradYellow(alpha int) Image {
+ m := image.NewRGBA(image.Rect(0, 0, 16, 16))
+ for y := 0; y < 16; y++ {
+ for x := 0; x < 16; x++ {
+ m.Set(x, y, color.RGBA{uint8(x * alpha / 15), uint8(y * alpha / 15), 0, uint8(alpha)})
+ }
+ }
+ return m
+}
+
+type drawTest struct {
+ desc string
+ src image.Image
+ mask image.Image
+ op Op
+ expected color.Color
+}
+
+var drawTests = []drawTest{
+ // Uniform mask (0% opaque).
+ {"nop", vgradGreen(255), fillAlpha(0), Over, color.RGBA{136, 0, 0, 255}},
+ {"clear", vgradGreen(255), fillAlpha(0), Src, color.RGBA{0, 0, 0, 0}},
+ // Uniform mask (100%, 75%, nil) and uniform source.
+ // At (x, y) == (8, 8):
+ // The destination pixel is {136, 0, 0, 255}.
+ // The source pixel is {0, 0, 90, 90}.
+ {"fill", fillBlue(90), fillAlpha(255), Over, color.RGBA{88, 0, 90, 255}},
+ {"fillSrc", fillBlue(90), fillAlpha(255), Src, color.RGBA{0, 0, 90, 90}},
+ {"fillAlpha", fillBlue(90), fillAlpha(192), Over, color.RGBA{100, 0, 68, 255}},
+ {"fillAlphaSrc", fillBlue(90), fillAlpha(192), Src, color.RGBA{0, 0, 68, 68}},
+ {"fillNil", fillBlue(90), nil, Over, color.RGBA{88, 0, 90, 255}},
+ {"fillNilSrc", fillBlue(90), nil, Src, color.RGBA{0, 0, 90, 90}},
+ // Uniform mask (100%, 75%, nil) and variable source.
+ // At (x, y) == (8, 8):
+ // The destination pixel is {136, 0, 0, 255}.
+ // The source pixel is {0, 48, 0, 90}.
+ {"copy", vgradGreen(90), fillAlpha(255), Over, color.RGBA{88, 48, 0, 255}},
+ {"copySrc", vgradGreen(90), fillAlpha(255), Src, color.RGBA{0, 48, 0, 90}},
+ {"copyAlpha", vgradGreen(90), fillAlpha(192), Over, color.RGBA{100, 36, 0, 255}},
+ {"copyAlphaSrc", vgradGreen(90), fillAlpha(192), Src, color.RGBA{0, 36, 0, 68}},
+ {"copyNil", vgradGreen(90), nil, Over, color.RGBA{88, 48, 0, 255}},
+ {"copyNilSrc", vgradGreen(90), nil, Src, color.RGBA{0, 48, 0, 90}},
+ // Uniform mask (100%, 75%, nil) and variable NRGBA source.
+ // At (x, y) == (8, 8):
+ // The destination pixel is {136, 0, 0, 255}.
+ // The source pixel is {0, 136, 0, 90} in NRGBA-space, which is {0, 48, 0, 90} in RGBA-space.
+ // The result pixel is different than in the "copy*" test cases because of rounding errors.
+ {"nrgba", vgradGreenNRGBA(90), fillAlpha(255), Over, color.RGBA{88, 46, 0, 255}},
+ {"nrgbaSrc", vgradGreenNRGBA(90), fillAlpha(255), Src, color.RGBA{0, 46, 0, 90}},
+ {"nrgbaAlpha", vgradGreenNRGBA(90), fillAlpha(192), Over, color.RGBA{100, 34, 0, 255}},
+ {"nrgbaAlphaSrc", vgradGreenNRGBA(90), fillAlpha(192), Src, color.RGBA{0, 34, 0, 68}},
+ {"nrgbaNil", vgradGreenNRGBA(90), nil, Over, color.RGBA{88, 46, 0, 255}},
+ {"nrgbaNilSrc", vgradGreenNRGBA(90), nil, Src, color.RGBA{0, 46, 0, 90}},
+ // Uniform mask (100%, 75%, nil) and variable YCbCr source.
+ // At (x, y) == (8, 8):
+ // The destination pixel is {136, 0, 0, 255}.
+ // The source pixel is {0, 0, 136} in YCbCr-space, which is {11, 38, 0, 255} in RGB-space.
+ {"ycbcr", vgradCr(), fillAlpha(255), Over, color.RGBA{11, 38, 0, 255}},
+ {"ycbcrSrc", vgradCr(), fillAlpha(255), Src, color.RGBA{11, 38, 0, 255}},
+ {"ycbcrAlpha", vgradCr(), fillAlpha(192), Over, color.RGBA{42, 28, 0, 255}},
+ {"ycbcrAlphaSrc", vgradCr(), fillAlpha(192), Src, color.RGBA{8, 28, 0, 192}},
+ {"ycbcrNil", vgradCr(), nil, Over, color.RGBA{11, 38, 0, 255}},
+ {"ycbcrNilSrc", vgradCr(), nil, Src, color.RGBA{11, 38, 0, 255}},
+ // Variable mask and variable source.
+ // At (x, y) == (8, 8):
+ // The destination pixel is {136, 0, 0, 255}.
+ // The source pixel is {0, 0, 255, 255}.
+ // The mask pixel's alpha is 102, or 40%.
+ {"generic", fillBlue(255), vgradAlpha(192), Over, color.RGBA{81, 0, 102, 255}},
+ {"genericSrc", fillBlue(255), vgradAlpha(192), Src, color.RGBA{0, 0, 102, 102}},
+}
+
+func makeGolden(dst image.Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) image.Image {
+ // Since golden is a newly allocated image, we don't have to check if the
+ // input source and mask images and the output golden image overlap.
+ b := dst.Bounds()
+ sb := src.Bounds()
+ mb := image.Rect(-1e9, -1e9, 1e9, 1e9)
+ if mask != nil {
+ mb = mask.Bounds()
+ }
+ golden := image.NewRGBA(image.Rect(0, 0, b.Max.X, b.Max.Y))
+ for y := r.Min.Y; y < r.Max.Y; y++ {
+ sy := y + sp.Y - r.Min.Y
+ my := y + mp.Y - r.Min.Y
+ for x := r.Min.X; x < r.Max.X; x++ {
+ if !(image.Pt(x, y).In(b)) {
+ continue
+ }
+ sx := x + sp.X - r.Min.X
+ if !(image.Pt(sx, sy).In(sb)) {
+ continue
+ }
+ mx := x + mp.X - r.Min.X
+ if !(image.Pt(mx, my).In(mb)) {
+ continue
+ }
+
+ const M = 1<<16 - 1
+ var dr, dg, db, da uint32
+ if op == Over {
+ dr, dg, db, da = dst.At(x, y).RGBA()
+ }
+ sr, sg, sb, sa := src.At(sx, sy).RGBA()
+ ma := uint32(M)
+ if mask != nil {
+ _, _, _, ma = mask.At(mx, my).RGBA()
+ }
+ a := M - (sa * ma / M)
+ golden.Set(x, y, color.RGBA64{
+ uint16((dr*a + sr*ma) / M),
+ uint16((dg*a + sg*ma) / M),
+ uint16((db*a + sb*ma) / M),
+ uint16((da*a + sa*ma) / M),
+ })
+ }
+ }
+ return golden.SubImage(b)
+}
+
+func TestDraw(t *testing.T) {
+ rr := []image.Rectangle{
+ image.Rect(0, 0, 0, 0),
+ image.Rect(0, 0, 16, 16),
+ image.Rect(3, 5, 12, 10),
+ image.Rect(0, 0, 9, 9),
+ image.Rect(8, 8, 16, 16),
+ image.Rect(8, 0, 9, 16),
+ image.Rect(0, 8, 16, 9),
+ image.Rect(8, 8, 9, 9),
+ image.Rect(8, 8, 8, 8),
+ }
+ for _, r := range rr {
+ loop:
+ for _, test := range drawTests {
+ dst := hgradRed(255).(*image.RGBA).SubImage(r).(Image)
+ // Draw the (src, mask, op) onto a copy of dst using a slow but obviously correct implementation.
+ golden := makeGolden(dst, image.Rect(0, 0, 16, 16), test.src, image.ZP, test.mask, image.ZP, test.op)
+ b := dst.Bounds()
+ if !b.Eq(golden.Bounds()) {
+ t.Errorf("draw %v %s: bounds %v versus %v", r, test.desc, dst.Bounds(), golden.Bounds())
+ continue
+ }
+ // Draw the same combination onto the actual dst using the optimized DrawMask implementation.
+ DrawMask(dst, image.Rect(0, 0, 16, 16), test.src, image.ZP, test.mask, image.ZP, test.op)
+ if image.Pt(8, 8).In(r) {
+ // Check that the resultant pixel at (8, 8) matches what we expect
+ // (the expected value can be verified by hand).
+ if !eq(dst.At(8, 8), test.expected) {
+ t.Errorf("draw %v %s: at (8, 8) %v versus %v", r, test.desc, dst.At(8, 8), test.expected)
+ continue
+ }
+ }
+ // Check that the resultant dst image matches the golden output.
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ for x := b.Min.X; x < b.Max.X; x++ {
+ if !eq(dst.At(x, y), golden.At(x, y)) {
+ t.Errorf("draw %v %s: at (%d, %d), %v versus golden %v", r, test.desc, x, y, dst.At(x, y), golden.At(x, y))
+ continue loop
+ }
+ }
+ }
+ }
+ }
+}
+
+func TestDrawOverlap(t *testing.T) {
+ for _, op := range []Op{Over, Src} {
+ for yoff := -2; yoff <= 2; yoff++ {
+ loop:
+ for xoff := -2; xoff <= 2; xoff++ {
+ m := gradYellow(127).(*image.RGBA)
+ dst := m.SubImage(image.Rect(5, 5, 10, 10)).(*image.RGBA)
+ src := m.SubImage(image.Rect(5+xoff, 5+yoff, 10+xoff, 10+yoff)).(*image.RGBA)
+ b := dst.Bounds()
+ // Draw the (src, mask, op) onto a copy of dst using a slow but obviously correct implementation.
+ golden := makeGolden(dst, b, src, src.Bounds().Min, nil, image.ZP, op)
+ if !b.Eq(golden.Bounds()) {
+ t.Errorf("drawOverlap xoff=%d,yoff=%d: bounds %v versus %v", xoff, yoff, dst.Bounds(), golden.Bounds())
+ continue
+ }
+ // Draw the same combination onto the actual dst using the optimized DrawMask implementation.
+ DrawMask(dst, b, src, src.Bounds().Min, nil, image.ZP, op)
+ // Check that the resultant dst image matches the golden output.
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ for x := b.Min.X; x < b.Max.X; x++ {
+ if !eq(dst.At(x, y), golden.At(x, y)) {
+ t.Errorf("drawOverlap xoff=%d,yoff=%d: at (%d, %d), %v versus golden %v", xoff, yoff, x, y, dst.At(x, y), golden.At(x, y))
+ continue loop
+ }
+ }
+ }
+ }
+ }
+ }
+}
+
+// TestNonZeroSrcPt checks drawing with a non-zero src point parameter.
+func TestNonZeroSrcPt(t *testing.T) {
+ a := image.NewRGBA(image.Rect(0, 0, 1, 1))
+ b := image.NewRGBA(image.Rect(0, 0, 2, 2))
+ b.Set(0, 0, color.RGBA{0, 0, 0, 5})
+ b.Set(1, 0, color.RGBA{0, 0, 5, 5})
+ b.Set(0, 1, color.RGBA{0, 5, 0, 5})
+ b.Set(1, 1, color.RGBA{5, 0, 0, 5})
+ Draw(a, image.Rect(0, 0, 1, 1), b, image.Pt(1, 1), Over)
+ if !eq(color.RGBA{5, 0, 0, 5}, a.At(0, 0)) {
+ t.Errorf("non-zero src pt: want %v got %v", color.RGBA{5, 0, 0, 5}, a.At(0, 0))
+ }
+}
+
+func TestFill(t *testing.T) {
+ rr := []image.Rectangle{
+ image.Rect(0, 0, 0, 0),
+ image.Rect(0, 0, 40, 30),
+ image.Rect(10, 0, 40, 30),
+ image.Rect(0, 20, 40, 30),
+ image.Rect(10, 20, 40, 30),
+ image.Rect(10, 20, 15, 25),
+ image.Rect(10, 0, 35, 30),
+ image.Rect(0, 15, 40, 16),
+ image.Rect(24, 24, 25, 25),
+ image.Rect(23, 23, 26, 26),
+ image.Rect(22, 22, 27, 27),
+ image.Rect(21, 21, 28, 28),
+ image.Rect(20, 20, 29, 29),
+ }
+ for _, r := range rr {
+ m := image.NewRGBA(image.Rect(0, 0, 40, 30)).SubImage(r).(*image.RGBA)
+ b := m.Bounds()
+ c := color.RGBA{11, 0, 0, 255}
+ src := &image.Uniform{C: c}
+ check := func(desc string) {
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ for x := b.Min.X; x < b.Max.X; x++ {
+ if !eq(c, m.At(x, y)) {
+ t.Errorf("%s fill: at (%d, %d), sub-image bounds=%v: want %v got %v", desc, x, y, r, c, m.At(x, y))
+ return
+ }
+ }
+ }
+ }
+ // Draw 1 pixel at a time.
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ for x := b.Min.X; x < b.Max.X; x++ {
+ DrawMask(m, image.Rect(x, y, x+1, y+1), src, image.ZP, nil, image.ZP, Src)
+ }
+ }
+ check("pixel")
+ // Draw 1 row at a time.
+ c = color.RGBA{0, 22, 0, 255}
+ src = &image.Uniform{C: c}
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ DrawMask(m, image.Rect(b.Min.X, y, b.Max.X, y+1), src, image.ZP, nil, image.ZP, Src)
+ }
+ check("row")
+ // Draw 1 column at a time.
+ c = color.RGBA{0, 0, 33, 255}
+ src = &image.Uniform{C: c}
+ for x := b.Min.X; x < b.Max.X; x++ {
+ DrawMask(m, image.Rect(x, b.Min.Y, x+1, b.Max.Y), src, image.ZP, nil, image.ZP, Src)
+ }
+ check("column")
+ // Draw the whole image at once.
+ c = color.RGBA{44, 55, 66, 77}
+ src = &image.Uniform{C: c}
+ DrawMask(m, b, src, image.ZP, nil, image.ZP, Src)
+ check("whole")
+ }
+}
+
+// TestFloydSteinbergCheckerboard tests that the result of Floyd-Steinberg
+// error diffusion of a uniform 50% gray source image with a black-and-white
+// palette is a checkerboard pattern.
+func TestFloydSteinbergCheckerboard(t *testing.T) {
+ b := image.Rect(0, 0, 640, 480)
+ // We can't represent 50% exactly, but 0x7fff / 0xffff is close enough.
+ src := &image.Uniform{color.Gray16{0x7fff}}
+ dst := image.NewPaletted(b, color.Palette{color.Black, color.White})
+ FloydSteinberg.Draw(dst, b, src, image.Point{})
+ nErr := 0
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ for x := b.Min.X; x < b.Max.X; x++ {
+ got := dst.Pix[dst.PixOffset(x, y)]
+ want := uint8(x+y) % 2
+ if got != want {
+ t.Errorf("at (%d, %d): got %d, want %d", x, y, got, want)
+ if nErr++; nErr == 10 {
+ t.Fatal("there may be more errors")
+ }
+ }
+ }
+ }
+}
+
+// embeddedPaletted is an Image that behaves like an *image.Paletted but whose
+// type is not *image.Paletted.
+type embeddedPaletted struct {
+ *image.Paletted
+}
+
+// TestPaletted tests that the drawPaletted function behaves the same
+// regardless of whether dst is an *image.Paletted.
+func TestPaletted(t *testing.T) {
+ f, err := os.Open("../testdata/video-001.png")
+ if err != nil {
+ t.Fatalf("open: %v", err)
+ }
+ defer f.Close()
+ src, err := png.Decode(f)
+ if err != nil {
+ t.Fatalf("decode: %v", err)
+ }
+ b := src.Bounds()
+
+ cgaPalette := color.Palette{
+ color.RGBA{0x00, 0x00, 0x00, 0xff},
+ color.RGBA{0x55, 0xff, 0xff, 0xff},
+ color.RGBA{0xff, 0x55, 0xff, 0xff},
+ color.RGBA{0xff, 0xff, 0xff, 0xff},
+ }
+ drawers := map[string]Drawer{
+ "src": Src,
+ "floyd-steinberg": FloydSteinberg,
+ }
+
+loop:
+ for dName, d := range drawers {
+ dst0 := image.NewPaletted(b, cgaPalette)
+ dst1 := image.NewPaletted(b, cgaPalette)
+ d.Draw(dst0, b, src, image.Point{})
+ d.Draw(embeddedPaletted{dst1}, b, src, image.Point{})
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ for x := b.Min.X; x < b.Max.X; x++ {
+ if !eq(dst0.At(x, y), dst1.At(x, y)) {
+ t.Errorf("%s: at (%d, %d), %v versus %v",
+ dName, x, y, dst0.At(x, y), dst1.At(x, y))
+ continue loop
+ }
+ }
+ }
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-30 04:01:08 +0000