qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-22 01:14:40 -07:00
Code Releases Activity

draw.Draw fast paths for the Over operator.

Browse Source 
Time (us) to draw a 200x200 src onto an image.RGBA dst with the Over
operator. Each case was measured three separate times, and the sorted
times are reported.

Fill case (where src is an image.ColorImage):
Before:
7438, 7511, 7526
After:
3073, 3087, 3102

Copy case (where src is an image.RGBA):
Before:
9506, 9510, 9563
After:
5262, 5300, 5344

R=rsc
CC=golang-dev
https://golang.org/cl/1532041
This commit is contained in:
Nigel Tao 2010-06-03 17:19:00 -07:00
parent c2e9f0c562
commit 2006667931
1 changed files with 93 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

127
src/pkg/exp/draw/draw.go
View File

@ -12,6 +12,9 @@ package draw
import "image" import "image"
// m is the maximum color value returned by image.Color.RGBA.
const m = 1<<16 - 1
// A Porter-Duff compositing operator. // A Porter-Duff compositing operator.
type Op int type Op int
@ -62,7 +65,20 @@ func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Imag
// Fast paths for special cases. If none of them apply, then we fall back to a general but slow implementation. // Fast paths for special cases. If none of them apply, then we fall back to a general but slow implementation.
if dst0, ok := dst.(*image.RGBA); ok { if dst0, ok := dst.(*image.RGBA); ok {
if op == Over { if op == Over {
if mask0, ok := mask.(*image.Alpha); ok { if mask == nil {
if src0, ok := src.(image.ColorImage); ok {
drawFillOver(dst0, r, src0)
return
}
if src0, ok := src.(*image.RGBA); ok {
if dst0 == src0 && r.Overlaps(r.Add(sp.Sub(r.Min))) {
// TODO(nigeltao): Implement a fast path for the overlapping case.
} else {
drawCopyOver(dst0, r, src0, sp)
return
}
}
} else if mask0, ok := mask.(*image.Alpha); ok {
if src0, ok := src.(image.ColorImage); ok { if src0, ok := src.(image.ColorImage); ok {
drawGlyphOver(dst0, r, src0, mask0, mp) drawGlyphOver(dst0, r, src0, mask0, mp)
return return
@ -71,14 +87,14 @@ func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Imag
} else { } else {
if mask == nil { if mask == nil {
if src0, ok := src.(image.ColorImage); ok { if src0, ok := src.(image.ColorImage); ok {
drawFill(dst0, r, src0) drawFillSrc(dst0, r, src0)
return return
} }
if src0, ok := src.(*image.RGBA); ok { if src0, ok := src.(*image.RGBA); ok {
if dst0 == src0 && r.Overlaps(r.Add(sp.Sub(r.Min))) { if dst0 == src0 && r.Overlaps(r.Add(sp.Sub(r.Min))) {
// TODO(nigeltao): Implement a fast path for the overlapping case. // TODO(nigeltao): Implement a fast path for the overlapping case.
} else { } else {
drawCopy(dst0, r, src0, sp) drawCopySrc(dst0, r, src0, sp)
return return
} }
} }
@ -105,8 +121,7 @@ func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Imag
sx := sp.X + x0 - r.Min.X sx := sp.X + x0 - r.Min.X
mx := mp.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 { for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
const M = 1<<16 - 1 ma := uint32(m)
ma := uint32(M)
if mask != nil { if mask != nil {
_, _, _, ma = mask.At(mx, my).RGBA() _, _, _, ma = mask.At(mx, my).RGBA()
} }
@ -117,7 +132,7 @@ func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Imag
} else { } else {
dst.Set(x, y, zeroColor) dst.Set(x, y, zeroColor)
} }
case ma == M && op == Src: case ma == m && op == Src:
dst.Set(x, y, src.At(sx, sy)) dst.Set(x, y, src.At(sx, sy))
default: default:
sr, sg, sb, sa := src.At(sx, sy).RGBA() sr, sg, sb, sa := src.At(sx, sy).RGBA()
@ -126,16 +141,16 @@ func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Imag
} }
if op == Over { if op == Over {
dr, dg, db, da := dst.At(x, y).RGBA() dr, dg, db, da := dst.At(x, y).RGBA()
a := M - (sa * ma / M) a := m - (sa * ma / m)
out.R = uint16((dr*a + sr*ma) / M) out.R = uint16((dr*a + sr*ma) / m)
out.G = uint16((dg*a + sg*ma) / M) out.G = uint16((dg*a + sg*ma) / m)
out.B = uint16((db*a + sb*ma) / M) out.B = uint16((db*a + sb*ma) / m)
out.A = uint16((da*a + sa*ma) / M) out.A = uint16((da*a + sa*ma) / m)
} else { } else {
out.R = uint16(sr * ma / M) out.R = uint16(sr * ma / m)
out.G = uint16(sg * ma / M) out.G = uint16(sg * ma / m)
out.B = uint16(sb * ma / M) out.B = uint16(sb * ma / m)
out.A = uint16(sa * ma / M) out.A = uint16(sa * ma / m)
} }
dst.Set(x, y, out) dst.Set(x, y, out)
} }
@ -143,6 +158,52 @@ func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Imag
} }
} }
func drawFillOver(dst *image.RGBA, r Rectangle, src image.ColorImage) {
cr, cg, cb, ca := src.RGBA()
// The 0x101 is here for the same reason as in drawRGBA.
a := (m - ca) * 0x101
x0, x1 := r.Min.X, r.Max.X
y0, y1 := r.Min.Y, r.Max.Y
for y := y0; y != y1; y++ {
p := dst.Pixel[y]
for x := x0; x != x1; x++ {
rgba := p[x]
dr := (uint32(rgba.R)*a)/m + cr
dg := (uint32(rgba.G)*a)/m + cg
db := (uint32(rgba.B)*a)/m + cb
da := (uint32(rgba.A)*a)/m + ca
p[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
}
}
}
func drawCopyOver(dst *image.RGBA, r Rectangle, src *image.RGBA, sp Point) {
x0, x1 := r.Min.X, r.Max.X
y0, y1 := r.Min.Y, r.Max.Y
for y, sy := y0, sp.Y; y != y1; y, sy = y+1, sy+1 {
dpix := dst.Pixel[y]
spix := src.Pixel[y]
for x, sx := x0, sp.X; x != x1; x, sx = x+1, sx+1 {
// For unknown reasons, even though both dpix[x] and spix[sx] are
// image.RGBAColors, on an x86 CPU it seems fastest to call RGBA
// for the source but to do it manually for the destination.
sr, sg, sb, sa := spix[sx].RGBA()
drgba := dpix[x]
dr := uint32(drgba.R)
dg := uint32(drgba.G)
db := uint32(drgba.B)
da := uint32(drgba.A)
// The 0x101 is here for the same reason as in drawRGBA.
a := (m - sa) * 0x101
dr = (dr*a)/m + sr
dg = (dg*a)/m + sg
db = (db*a)/m + sb
da = (da*a)/m + sa
dpix[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
}
}
}
func drawGlyphOver(dst *image.RGBA, r Rectangle, src image.ColorImage, mask *image.Alpha, mp Point) { func drawGlyphOver(dst *image.RGBA, r Rectangle, src image.ColorImage, mask *image.Alpha, mp Point) {
x0, x1 := r.Min.X, r.Max.X x0, x1 := r.Min.X, r.Max.X
y0, y1 := r.Min.Y, r.Max.Y y0, y1 := r.Min.Y, r.Max.Y
@ -160,19 +221,18 @@ func drawGlyphOver(dst *image.RGBA, r Rectangle, src image.ColorImage, mask *ima
dg := uint32(rgba.G) dg := uint32(rgba.G)
db := uint32(rgba.B) db := uint32(rgba.B)
da := uint32(rgba.A) da := uint32(rgba.A)
const M = 1<<16 - 1
// The 0x101 is here for the same reason as in drawRGBA. // The 0x101 is here for the same reason as in drawRGBA.
a := (M - (ca * ma / M)) * 0x101 a := (m - (ca * ma / m)) * 0x101
dr = (dr*a + cr*ma) / M dr = (dr*a + cr*ma) / m
dg = (dg*a + cg*ma) / M dg = (dg*a + cg*ma) / m
db = (db*a + cb*ma) / M db = (db*a + cb*ma) / m
da = (da*a + ca*ma) / M da = (da*a + ca*ma) / m
p[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)} p[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
} }
} }
} }
func drawFill(dst *image.RGBA, r Rectangle, src image.ColorImage) { func drawFillSrc(dst *image.RGBA, r Rectangle, src image.ColorImage) {
if r.Dy() < 1 { if r.Dy() < 1 {
return return
} }
@ -193,7 +253,7 @@ func drawFill(dst *image.RGBA, r Rectangle, src image.ColorImage) {
} }
} }
func drawCopy(dst *image.RGBA, r Rectangle, src *image.RGBA, sp Point) { func drawCopySrc(dst *image.RGBA, r Rectangle, src *image.RGBA, sp Point) {
dx0, dx1 := r.Min.X, r.Max.X dx0, dx1 := r.Min.X, r.Max.X
dy0, dy1 := r.Min.Y, r.Max.Y dy0, dy1 := r.Min.Y, r.Max.Y
sx0, sx1 := sp.X, sp.X+dx1-dx0 sx0, sx1 := sp.X, sp.X+dx1-dx0
@ -219,8 +279,7 @@ func drawRGBA(dst *image.RGBA, r Rectangle, src image.Image, sp Point, mask imag
mx := mp.X + x0 - r.Min.X mx := mp.X + x0 - r.Min.X
p := dst.Pixel[y] p := dst.Pixel[y]
for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx { for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
const M = 1<<16 - 1 ma := uint32(m)
ma := uint32(M)
if mask != nil { if mask != nil {
_, _, _, ma = mask.At(mx, my).RGBA() _, _, _, ma = mask.At(mx, my).RGBA()
} }
@ -238,16 +297,16 @@ func drawRGBA(dst *image.RGBA, r Rectangle, src image.Image, sp Point, mask imag
// and similarly for dg, db and da, but instead we multiply a // and similarly for dg, db and da, but instead we multiply a
// (which is a 16-bit color, ranging in [0,65535]) by 0x101. // (which is a 16-bit color, ranging in [0,65535]) by 0x101.
// This yields the same result, but is fewer arithmetic operations. // This yields the same result, but is fewer arithmetic operations.
a := (M - (sa * ma / M)) * 0x101 a := (m - (sa * ma / m)) * 0x101
dr = (dr*a + sr*ma) / M dr = (dr*a + sr*ma) / m
dg = (dg*a + sg*ma) / M dg = (dg*a + sg*ma) / m
db = (db*a + sb*ma) / M db = (db*a + sb*ma) / m
da = (da*a + sa*ma) / M da = (da*a + sa*ma) / m
} else { } else {
dr = sr * ma / M dr = sr * ma / m
dg = sg * ma / M dg = sg * ma / m
db = sb * ma / M db = sb * ma / m
da = sa * ma / M da = sa * ma / m
} }
p[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)} p[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
} }