Imported Upstream version 2011.01.12upstream/2011.01.12

1 files changed, 116 insertions, 91 deletions

diff --git a/src/pkg/exp/draw/draw.go b/src/pkg/exp/draw/draw.go
index 415dd99ac..1d0729d92 100644
--- a/src/pkg/exp/draw/draw.go
+++ b/src/pkg/exp/draw/draw.go
@@ -8,8 +8,6 @@
 // and the X Render extension.
 package draw
 
-// BUG(rsc): This is a toy library and not ready for production use.
-
 import "image"
 
 // m is the maximum color value returned by image.Color.RGBA.
@@ -34,22 +32,22 @@ type Image interface {
 }
 
 // Draw calls DrawMask with a nil mask and an Over op.
-func Draw(dst Image, r Rectangle, src image.Image, sp Point) {
-	DrawMask(dst, r, src, sp, nil, ZP, Over)
+func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
+	DrawMask(dst, r, src, sp, nil, image.ZP, Over)
 }
 
 // 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.
-// The implementation is simple and slow.
-// TODO(nigeltao): Optimize this.
-func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Image, mp Point, op Op) {
-	dx, dy := src.Width()-sp.X, src.Height()-sp.Y
+func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) {
+	sb := src.Bounds()
+	dx, dy := sb.Max.X-sp.X, sb.Max.Y-sp.Y
 	if mask != nil {
-		if dx > mask.Width()-mp.X {
-			dx = mask.Width() - mp.X
+		mb := mask.Bounds()
+		if dx > mb.Max.X-mp.X {
+			dx = mb.Max.X - mp.X
 		}
-		if dy > mask.Height()-mp.Y {
-			dy = mask.Height() - mp.Y
+		if dy > mb.Max.Y-mp.Y {
+			dy = mb.Max.Y - mp.Y
 		}
 	}
 	if r.Dx() > dx {
@@ -58,45 +56,38 @@ func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Imag
 	if r.Dy() > dy {
 		r.Max.Y = r.Min.Y + dy
 	}
-
-	// TODO(nigeltao): Clip r to dst's bounding box, and handle the case when sp or mp has negative X or Y.
-	// TODO(nigeltao): Ensure that r is well formed, i.e. r.Max.X >= r.Min.X and likewise for Y.
+	r = r.Intersect(dst.Bounds())
+	if r.Empty() {
+		return
+	}
 
 	// 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 op == Over {
 			if mask == nil {
-				if src0, ok := src.(image.ColorImage); ok {
+				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
-					}
+					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)
 					return
 				}
 			}
 		} else {
 			if mask == nil {
-				if src0, ok := src.(image.ColorImage); ok {
+				if src0, ok := src.(*image.ColorImage); ok {
 					drawFillSrc(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 {
-						drawCopySrc(dst0, r, src0, sp)
-						return
-					}
+					drawCopySrc(dst0, r, src0, sp)
+					return
 				}
 			}
 		}
@@ -158,66 +149,96 @@ func DrawMask(dst Image, r Rectangle, src image.Image, sp Point, mask image.Imag
 	}
 }
 
-func drawFillOver(dst *image.RGBA, r Rectangle, src image.ColorImage) {
+func drawFillOver(dst *image.RGBA, r image.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++ {
-		dpix := dst.Pixel[y]
-		for x := x0; x != x1; x++ {
-			rgba := dpix[x]
+		dbase := y * dst.Stride
+		dpix := dst.Pix[dbase+x0 : dbase+x1]
+		for i, rgba := range dpix {
 			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
-			dpix[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
+			dpix[i] = 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[sy]
-		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
+func drawCopyOver(dst *image.RGBA, r image.Rectangle, src *image.RGBA, sp image.Point) {
+	dx0, dx1 := r.Min.X, r.Max.X
+	dy0, dy1 := r.Min.Y, r.Max.Y
+	nrows := dy1 - dy0
+	sx0, sx1 := sp.X, sp.X+dx1-dx0
+	d0 := dy0*dst.Stride + dx0
+	d1 := dy0*dst.Stride + dx1
+	s0 := sp.Y*src.Stride + sx0
+	s1 := sp.Y*src.Stride + sx1
+	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, d1-d0, +1
+	} 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 += (nrows - 1) * dst.Stride
+		d1 += (nrows - 1) * dst.Stride
+		s0 += (nrows - 1) * src.Stride
+		s1 += (nrows - 1) * src.Stride
+		ddelta = -dst.Stride
+		sdelta = -src.Stride
+		i0, i1, idelta = d1-d0-1, -1, -1
+	}
+	for ; nrows > 0; nrows-- {
+		dpix := dst.Pix[d0:d1]
+		spix := src.Pix[s0:s1]
+		for i := i0; i != i1; i += idelta {
+			// For unknown reasons, even though both dpix[i] and spix[i] 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)
+			sr, sg, sb, sa := spix[i].RGBA()
+			rgba := dpix[i]
+			dr := uint32(rgba.R)
+			dg := uint32(rgba.G)
+			db := uint32(rgba.B)
+			da := uint32(rgba.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)}
+			dpix[i] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
 		}
+		d0 += ddelta
+		d1 += ddelta
+		s0 += sdelta
+		s1 += sdelta
 	}
 }
 
-func drawGlyphOver(dst *image.RGBA, r Rectangle, src image.ColorImage, mask *image.Alpha, mp Point) {
+func drawGlyphOver(dst *image.RGBA, r image.Rectangle, src *image.ColorImage, mask *image.Alpha, mp image.Point) {
 	x0, x1 := r.Min.X, r.Max.X
 	y0, y1 := r.Min.Y, r.Max.Y
 	cr, cg, cb, ca := src.RGBA()
 	for y, my := y0, mp.Y; y != y1; y, my = y+1, my+1 {
-		dpix := dst.Pixel[y]
-		mpix := mask.Pixel[my]
-		for x, mx := x0, mp.X; x != x1; x, mx = x+1, mx+1 {
-			ma := uint32(mpix[mx].A)
+		dbase := y * dst.Stride
+		dpix := dst.Pix[dbase+x0 : dbase+x1]
+		mbase := my * mask.Stride
+		mpix := mask.Pix[mbase+mp.X:]
+		for i, rgba := range dpix {
+			ma := uint32(mpix[i].A)
 			if ma == 0 {
 				continue
 			}
 			ma |= ma << 8
-			rgba := dpix[x]
 			dr := uint32(rgba.R)
 			dg := uint32(rgba.G)
 			db := uint32(rgba.B)
@@ -228,12 +249,12 @@ func drawGlyphOver(dst *image.RGBA, r Rectangle, src image.ColorImage, mask *ima
 			dg = (dg*a + cg*ma) / m
 			db = (db*a + cb*ma) / m
 			da = (da*a + ca*ma) / m
-			dpix[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
+			dpix[i] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
 		}
 	}
 }
 
-func drawFillSrc(dst *image.RGBA, r Rectangle, src image.ColorImage) {
+func drawFillSrc(dst *image.RGBA, r image.Rectangle, src *image.ColorImage) {
 	if r.Dy() < 1 {
 		return
 	}
@@ -244,26 +265,53 @@ func drawFillSrc(dst *image.RGBA, r Rectangle, src image.ColorImage) {
 	// then use the first row as the slice source for the remaining rows.
 	dx0, dx1 := r.Min.X, r.Max.X
 	dy0, dy1 := r.Min.Y, r.Max.Y
-	firstRow := dst.Pixel[dy0]
-	for x := dx0; x < dx1; x++ {
-		firstRow[x] = color
+	dbase := dy0 * dst.Stride
+	i0, i1 := dbase+dx0, dbase+dx1
+	firstRow := dst.Pix[i0:i1]
+	for i := range firstRow {
+		firstRow[i] = color
 	}
-	copySrc := firstRow[dx0:dx1]
 	for y := dy0 + 1; y < dy1; y++ {
-		copy(dst.Pixel[y][dx0:dx1], copySrc)
+		i0 += dst.Stride
+		i1 += dst.Stride
+		copy(dst.Pix[i0:i1], firstRow)
 	}
 }
 
-func drawCopySrc(dst *image.RGBA, r Rectangle, src *image.RGBA, sp Point) {
+func drawCopySrc(dst *image.RGBA, r image.Rectangle, src *image.RGBA, sp image.Point) {
 	dx0, dx1 := r.Min.X, r.Max.X
 	dy0, dy1 := r.Min.Y, r.Max.Y
+	nrows := dy1 - dy0
 	sx0, sx1 := sp.X, sp.X+dx1-dx0
-	for y, sy := dy0, sp.Y; y < dy1; y, sy = y+1, sy+1 {
-		copy(dst.Pixel[y][dx0:dx1], src.Pixel[sy][sx0:sx1])
+	d0 := dy0*dst.Stride + dx0
+	d1 := dy0*dst.Stride + dx1
+	s0 := sp.Y*src.Stride + sx0
+	s1 := sp.Y*src.Stride + sx1
+	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 += (nrows - 1) * dst.Stride
+		d1 += (nrows - 1) * dst.Stride
+		s0 += (nrows - 1) * src.Stride
+		s1 += (nrows - 1) * src.Stride
+		ddelta = -dst.Stride
+		sdelta = -src.Stride
+	}
+	for ; nrows > 0; nrows-- {
+		copy(dst.Pix[d0:d1], src.Pix[s0:s1])
+		d0 += ddelta
+		d1 += ddelta
+		s0 += sdelta
+		s1 += sdelta
 	}
 }
 
-func drawRGBA(dst *image.RGBA, r Rectangle, src image.Image, sp Point, mask image.Image, mp Point, op Op) {
+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))) {
@@ -278,7 +326,7 @@ func drawRGBA(dst *image.RGBA, r Rectangle, src image.Image, sp Point, mask imag
 	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
-		dpix := dst.Pixel[y]
+		dpix := dst.Pix[y*dst.Stride : (y+1)*dst.Stride]
 		for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
 			ma := uint32(m)
 			if mask != nil {
@@ -313,26 +361,3 @@ func drawRGBA(dst *image.RGBA, r Rectangle, src image.Image, sp Point, mask imag
 		}
 	}
 }
-
-// Border aligns r.Min in dst with sp in src and then replaces pixels
-// in a w-pixel border around r in dst with the result of the Porter-Duff compositing
-// operation ``src over dst.''  If w is positive, the border extends w pixels inside r.
-// If w is negative, the border extends w pixels outside r.
-func Border(dst Image, r Rectangle, w int, src image.Image, sp Point) {
-	i := w
-	if i > 0 {
-		// inside r
-		Draw(dst, Rect(r.Min.X, r.Min.Y, r.Max.X, r.Min.Y+i), src, sp)                          // top
-		Draw(dst, Rect(r.Min.X, r.Min.Y+i, r.Min.X+i, r.Max.Y-i), src, sp.Add(Pt(0, i)))        // left
-		Draw(dst, Rect(r.Max.X-i, r.Min.Y+i, r.Max.X, r.Max.Y-i), src, sp.Add(Pt(r.Dx()-i, i))) // right
-		Draw(dst, Rect(r.Min.X, r.Max.Y-i, r.Max.X, r.Max.Y), src, sp.Add(Pt(0, r.Dy()-i)))     // bottom
-		return
-	}
-
-	// outside r;
-	i = -i
-	Draw(dst, Rect(r.Min.X-i, r.Min.Y-i, r.Max.X+i, r.Min.Y), src, sp.Add(Pt(-i, -i))) // top
-	Draw(dst, Rect(r.Min.X-i, r.Min.Y, r.Min.X, r.Max.Y), src, sp.Add(Pt(-i, 0)))      // left
-	Draw(dst, Rect(r.Max.X, r.Min.Y, r.Max.X+i, r.Max.Y), src, sp.Add(Pt(r.Dx(), 0)))  // right
-	Draw(dst, Rect(r.Min.X-i, r.Max.Y, r.Max.X+i, r.Max.Y+i), src, sp.Add(Pt(-i, 0)))  // bottom
-}