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exp/draw: fast path for drawing overlapping image.RGBAs.
R=r, nigeltao CC=golang-dev https://golang.org/cl/2145045
This commit is contained in:
Nigel Tao
parent
d660d4a6d0
commit
5801928817
@ -74,12 +74,8 @@ func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mas
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return
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}
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if src0, ok := src.(*image.RGBA); ok {
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if dst0 == src0 && r.Overlaps(r.Add(sp.Sub(r.Min))) {
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// TODO(nigeltao): Implement a fast path for the overlapping case.
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} else {
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drawCopyOver(dst0, r, src0, sp)
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return
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}
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drawCopyOver(dst0, r, src0, sp)
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return
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}
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} else if mask0, ok := mask.(*image.Alpha); ok {
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if src0, ok := src.(image.ColorImage); ok {
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@ -94,12 +90,8 @@ func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mas
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return
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}
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if src0, ok := src.(*image.RGBA); ok {
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if dst0 == src0 && r.Overlaps(r.Add(sp.Sub(r.Min))) {
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// TODO(nigeltao): Implement a fast path for the overlapping case.
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} else {
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drawCopySrc(dst0, r, src0, sp)
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return
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}
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drawCopySrc(dst0, r, src0, sp)
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return
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}
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}
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}
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@ -181,18 +173,42 @@ func drawFillOver(dst *image.RGBA, r image.Rectangle, src image.ColorImage) {
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}
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func drawCopyOver(dst *image.RGBA, r image.Rectangle, src *image.RGBA, sp image.Point) {
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x0, x1 := r.Min.X, r.Max.X
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y0, y1 := r.Min.Y, r.Max.Y
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for y, sy := y0, sp.Y; y != y1; y, sy = y+1, sy+1 {
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dbase := y * dst.Stride
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dpix := dst.Pix[dbase+x0 : dbase+x1]
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sbase := sy * src.Stride
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spix := src.Pix[sbase+sp.X:]
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for i, rgba := range dpix {
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dx0, dx1 := r.Min.X, r.Max.X
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dy0, dy1 := r.Min.Y, r.Max.Y
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nrows := dy1 - dy0
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sx0, sx1 := sp.X, sp.X+dx1-dx0
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d0 := dy0*dst.Stride + dx0
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d1 := dy0*dst.Stride + dx1
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s0 := sp.Y*src.Stride + sx0
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s1 := sp.Y*src.Stride + sx1
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var (
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ddelta, sdelta int
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i0, i1, idelta int
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)
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if r.Min.Y < sp.Y || r.Min.Y == sp.Y && r.Min.X <= sp.X {
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ddelta = dst.Stride
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sdelta = src.Stride
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i0, i1, idelta = 0, d1-d0, +1
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} else {
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// If the source start point is higher than the destination start point, or equal height but to the left,
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// then we compose the rows in right-to-left, bottom-up order instead of left-to-right, top-down.
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d0 += (nrows - 1) * dst.Stride
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d1 += (nrows - 1) * dst.Stride
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s0 += (nrows - 1) * src.Stride
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s1 += (nrows - 1) * src.Stride
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ddelta = -dst.Stride
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sdelta = -src.Stride
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i0, i1, idelta = d1-d0-1, -1, -1
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}
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for ; nrows > 0; nrows-- {
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dpix := dst.Pix[d0:d1]
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spix := src.Pix[s0:s1]
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for i := i0; i != i1; i += idelta {
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// For unknown reasons, even though both dpix[i] and spix[i] are
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// image.RGBAColors, on an x86 CPU it seems fastest to call RGBA
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// for the source but to do it manually for the destination.
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sr, sg, sb, sa := spix[i].RGBA()
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rgba := dpix[i]
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dr := uint32(rgba.R)
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dg := uint32(rgba.G)
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db := uint32(rgba.B)
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@ -205,6 +221,10 @@ func drawCopyOver(dst *image.RGBA, r image.Rectangle, src *image.RGBA, sp image.
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da = (da*a)/m + sa
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dpix[i] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
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}
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d0 += ddelta
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d1 += ddelta
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s0 += sdelta
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s1 += sdelta
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}
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}
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@ -265,17 +285,33 @@ func drawFillSrc(dst *image.RGBA, r image.Rectangle, src image.ColorImage) {
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func drawCopySrc(dst *image.RGBA, r image.Rectangle, src *image.RGBA, sp image.Point) {
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dx0, dx1 := r.Min.X, r.Max.X
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dy0, dy1 := r.Min.Y, r.Max.Y
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nrows := dy1 - dy0
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sx0, sx1 := sp.X, sp.X+dx1-dx0
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d0 := dy0*dst.Stride + dx0
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d1 := dy0*dst.Stride + dx1
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s0 := sp.Y*dst.Stride + sx0
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s1 := sp.Y*dst.Stride + sx1
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for y := dy0; y < dy1; y++ {
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s0 := sp.Y*src.Stride + sx0
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s1 := sp.Y*src.Stride + sx1
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var ddelta, sdelta int
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if r.Min.Y <= sp.Y {
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ddelta = dst.Stride
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sdelta = src.Stride
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} else {
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// If the source start point is higher than the destination start point, then we compose the rows
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// in bottom-up order instead of top-down. Unlike the drawCopyOver function, we don't have to
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// check the x co-ordinates because the built-in copy function can handle overlapping slices.
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d0 += (nrows - 1) * dst.Stride
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d1 += (nrows - 1) * dst.Stride
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s0 += (nrows - 1) * src.Stride
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s1 += (nrows - 1) * src.Stride
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ddelta = -dst.Stride
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sdelta = -src.Stride
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}
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for ; nrows > 0; nrows-- {
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copy(dst.Pix[d0:d1], src.Pix[s0:s1])
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d0 += dst.Stride
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d1 += dst.Stride
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s0 += src.Stride
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s1 += src.Stride
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d0 += ddelta
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d1 += ddelta
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s0 += sdelta
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s1 += sdelta
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}
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}
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@ -53,6 +53,16 @@ func hgradRed(alpha int) Image {
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return m
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}
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func gradYellow(alpha int) Image {
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m := image.NewRGBA(16, 16)
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for y := 0; y < 16; y++ {
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for x := 0; x < 16; x++ {
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m.Set(x, y, image.RGBAColor{uint8(x * alpha / 15), uint8(y * alpha / 15), 0, uint8(alpha)})
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}
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}
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return m
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}
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type drawTest struct {
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desc string
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src image.Image
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@ -94,24 +104,31 @@ var drawTests = []drawTest{
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drawTest{"genericSrc", fillBlue(255), vgradAlpha(192), Src, image.RGBAColor{0, 0, 102, 102}},
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}
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func makeGolden(dst image.Image, t drawTest) image.Image {
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func makeGolden(dst, src, mask image.Image, op Op) image.Image {
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// Since golden is a newly allocated image, we don't have to check if the
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// input source and mask images and the output golden image overlap.
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b := dst.Bounds()
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golden := image.NewRGBA(b.Dx(), b.Dy())
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sx0 := src.Bounds().Min.X - b.Min.X
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sy0 := src.Bounds().Min.Y - b.Min.Y
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var mx0, my0 int
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if mask != nil {
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mx0 = mask.Bounds().Min.X - b.Min.X
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my0 = mask.Bounds().Min.Y - b.Min.Y
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}
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golden := image.NewRGBA(b.Max.X, b.Max.Y)
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for y := b.Min.Y; y < b.Max.Y; y++ {
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my, sy := y, y
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my, sy := my0+y, sy0+y
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for x := b.Min.X; x < b.Max.X; x++ {
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mx, sx := x, x
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mx, sx := mx0+x, sx0+x
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const M = 1<<16 - 1
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var dr, dg, db, da uint32
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if t.op == Over {
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if op == Over {
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dr, dg, db, da = dst.At(x, y).RGBA()
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}
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sr, sg, sb, sa := t.src.At(sx, sy).RGBA()
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sr, sg, sb, sa := src.At(sx, sy).RGBA()
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ma := uint32(M)
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if t.mask != nil {
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_, _, _, ma = t.mask.At(mx, my).RGBA()
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if mask != nil {
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_, _, _, ma = mask.At(mx, my).RGBA()
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}
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a := M - (sa * ma / M)
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golden.Set(x, y, image.RGBA64Color{
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@ -122,6 +139,7 @@ func makeGolden(dst image.Image, t drawTest) image.Image {
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})
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}
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}
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golden.Rect = b
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return golden
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}
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@ -130,14 +148,14 @@ loop:
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for _, test := range drawTests {
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dst := hgradRed(255)
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// Draw the (src, mask, op) onto a copy of dst using a slow but obviously correct implementation.
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golden := makeGolden(dst, test.src, test.mask, test.op)
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b := dst.Bounds()
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golden := makeGolden(dst, test)
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if !b.Eq(golden.Bounds()) {
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t.Errorf("draw %s: bounds %v versus %v", test.desc, dst.Bounds(), golden.Bounds())
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continue
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}
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// Draw the same combination onto the actual dst using the optimized DrawMask implementation.
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DrawMask(dst, image.Rect(b.Min.X, b.Min.Y, b.Max.X, b.Max.Y), test.src, image.ZP, test.mask, image.ZP, test.op)
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DrawMask(dst, b, test.src, image.ZP, test.mask, image.ZP, test.op)
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// Check that the resultant pixel at (8, 8) matches what we expect
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// (the expected value can be verified by hand).
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if !eq(dst.At(8, 8), test.expected) {
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@ -156,6 +174,45 @@ loop:
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}
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}
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func TestDrawOverlap(t *testing.T) {
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for _, op := range []Op{Over, Src} {
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for yoff := -2; yoff <= 2; yoff++ {
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loop:
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for xoff := -2; xoff <= 2; xoff++ {
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m := gradYellow(127).(*image.RGBA)
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dst := &image.RGBA{
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Pix: m.Pix,
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Stride: m.Stride,
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Rect: image.Rect(5, 5, 10, 10),
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}
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src := &image.RGBA{
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Pix: m.Pix,
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Stride: m.Stride,
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Rect: image.Rect(5+xoff, 5+yoff, 10+xoff, 10+yoff),
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}
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// Draw the (src, mask, op) onto a copy of dst using a slow but obviously correct implementation.
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golden := makeGolden(dst, src, nil, op)
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b := dst.Bounds()
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if !b.Eq(golden.Bounds()) {
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t.Errorf("drawOverlap xoff=%d,yoff=%d: bounds %v versus %v", xoff, yoff, dst.Bounds(), golden.Bounds())
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continue
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}
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// Draw the same combination onto the actual dst using the optimized DrawMask implementation.
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DrawMask(dst, b, src, src.Bounds().Min, nil, image.ZP, op)
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// Check that the resultant dst image matches the golden output.
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for y := b.Min.Y; y < b.Max.Y; y++ {
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for x := b.Min.X; x < b.Max.X; x++ {
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if !eq(dst.At(x, y), golden.At(x, y)) {
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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))
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continue loop
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}
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}
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}
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}
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}
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}
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}
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// TestIssue836 verifies http://code.google.com/p/go/issues/detail?id=836.
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func TestIssue836(t *testing.T) {
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a := image.NewRGBA(1, 1)
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