ff5f50c52c
Update to current version of Go library. Update testsuite for removed types. * go-lang.c (go_langhook_init): Omit float_type_size when calling go_create_gogo. * go-c.h: Update declaration of go_create_gogo. From-SVN: r169098
364 lines
10 KiB
Go
364 lines
10 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package draw provides basic graphics and drawing primitives,
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// in the style of the Plan 9 graphics library
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// (see http://plan9.bell-labs.com/magic/man2html/2/draw)
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// and the X Render extension.
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package draw
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import "image"
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// m is the maximum color value returned by image.Color.RGBA.
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const m = 1<<16 - 1
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// A Porter-Duff compositing operator.
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type Op int
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const (
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// Over specifies ``(src in mask) over dst''.
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Over Op = iota
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// Src specifies ``src in mask''.
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Src
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)
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var zeroColor image.Color = image.AlphaColor{0}
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// A draw.Image is an image.Image with a Set method to change a single pixel.
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type Image interface {
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image.Image
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Set(x, y int, c image.Color)
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}
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// Draw calls DrawMask with a nil mask and an Over op.
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func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
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DrawMask(dst, r, src, sp, nil, image.ZP, Over)
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}
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// DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r
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// in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque.
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func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) {
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sb := src.Bounds()
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dx, dy := sb.Max.X-sp.X, sb.Max.Y-sp.Y
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if mask != nil {
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mb := mask.Bounds()
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if dx > mb.Max.X-mp.X {
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dx = mb.Max.X - mp.X
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}
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if dy > mb.Max.Y-mp.Y {
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dy = mb.Max.Y - mp.Y
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}
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}
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if r.Dx() > dx {
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r.Max.X = r.Min.X + dx
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}
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if r.Dy() > dy {
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r.Max.Y = r.Min.Y + dy
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}
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r = r.Intersect(dst.Bounds())
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if r.Empty() {
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return
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}
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// Fast paths for special cases. If none of them apply, then we fall back to a general but slow implementation.
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if dst0, ok := dst.(*image.RGBA); ok {
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if op == Over {
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if mask == nil {
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if src0, ok := src.(*image.ColorImage); ok {
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drawFillOver(dst0, r, src0)
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return
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}
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if src0, ok := src.(*image.RGBA); ok {
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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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drawGlyphOver(dst0, r, src0, mask0, mp)
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return
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}
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}
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} else {
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if mask == nil {
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if src0, ok := src.(*image.ColorImage); ok {
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drawFillSrc(dst0, r, src0)
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return
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}
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if src0, ok := src.(*image.RGBA); ok {
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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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drawRGBA(dst0, r, src, sp, mask, mp, op)
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return
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}
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x0, x1, dx := r.Min.X, r.Max.X, 1
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y0, y1, dy := r.Min.Y, r.Max.Y, 1
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if image.Image(dst) == src && r.Overlaps(r.Add(sp.Sub(r.Min))) {
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// Rectangles overlap: process backward?
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if sp.Y < r.Min.Y || sp.Y == r.Min.Y && sp.X < r.Min.X {
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x0, x1, dx = x1-1, x0-1, -1
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y0, y1, dy = y1-1, y0-1, -1
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}
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}
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var out *image.RGBA64Color
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sy := sp.Y + y0 - r.Min.Y
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my := mp.Y + y0 - r.Min.Y
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for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
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sx := sp.X + x0 - r.Min.X
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mx := mp.X + x0 - r.Min.X
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for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
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ma := uint32(m)
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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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switch {
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case ma == 0:
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if op == Over {
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// No-op.
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} else {
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dst.Set(x, y, zeroColor)
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}
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case ma == m && op == Src:
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dst.Set(x, y, src.At(sx, sy))
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default:
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sr, sg, sb, sa := src.At(sx, sy).RGBA()
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if out == nil {
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out = new(image.RGBA64Color)
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}
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if op == Over {
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dr, dg, db, da := dst.At(x, y).RGBA()
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a := m - (sa * ma / m)
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out.R = uint16((dr*a + sr*ma) / m)
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out.G = uint16((dg*a + sg*ma) / m)
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out.B = uint16((db*a + sb*ma) / m)
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out.A = uint16((da*a + sa*ma) / m)
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} else {
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out.R = uint16(sr * ma / m)
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out.G = uint16(sg * ma / m)
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out.B = uint16(sb * ma / m)
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out.A = uint16(sa * ma / m)
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}
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dst.Set(x, y, out)
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}
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}
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}
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}
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func drawFillOver(dst *image.RGBA, r image.Rectangle, src *image.ColorImage) {
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cr, cg, cb, ca := src.RGBA()
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// The 0x101 is here for the same reason as in drawRGBA.
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a := (m - ca) * 0x101
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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 := y0; y != y1; y++ {
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dbase := y * dst.Stride
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dpix := dst.Pix[dbase+x0 : dbase+x1]
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for i, rgba := range dpix {
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dr := (uint32(rgba.R)*a)/m + cr
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dg := (uint32(rgba.G)*a)/m + cg
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db := (uint32(rgba.B)*a)/m + cb
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da := (uint32(rgba.A)*a)/m + ca
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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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}
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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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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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da := uint32(rgba.A)
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// The 0x101 is here for the same reason as in drawRGBA.
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a := (m - sa) * 0x101
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dr = (dr*a)/m + sr
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dg = (dg*a)/m + sg
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db = (db*a)/m + sb
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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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func drawGlyphOver(dst *image.RGBA, r image.Rectangle, src *image.ColorImage, mask *image.Alpha, mp 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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cr, cg, cb, ca := src.RGBA()
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for y, my := y0, mp.Y; y != y1; y, my = y+1, my+1 {
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dbase := y * dst.Stride
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dpix := dst.Pix[dbase+x0 : dbase+x1]
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mbase := my * mask.Stride
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mpix := mask.Pix[mbase+mp.X:]
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for i, rgba := range dpix {
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ma := uint32(mpix[i].A)
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if ma == 0 {
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continue
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}
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ma |= ma << 8
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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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da := uint32(rgba.A)
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// The 0x101 is here for the same reason as in drawRGBA.
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a := (m - (ca * ma / m)) * 0x101
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dr = (dr*a + cr*ma) / m
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dg = (dg*a + cg*ma) / m
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db = (db*a + cb*ma) / m
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da = (da*a + ca*ma) / m
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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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}
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}
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func drawFillSrc(dst *image.RGBA, r image.Rectangle, src *image.ColorImage) {
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if r.Dy() < 1 {
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return
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}
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cr, cg, cb, ca := src.RGBA()
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color := image.RGBAColor{uint8(cr >> 8), uint8(cg >> 8), uint8(cb >> 8), uint8(ca >> 8)}
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// The built-in copy function is faster than a straightforward for loop to fill the destination with
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// the color, but copy requires a slice source. We therefore use a for loop to fill the first row, and
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// then use the first row as the slice source for the remaining rows.
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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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dbase := dy0 * dst.Stride
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i0, i1 := dbase+dx0, dbase+dx1
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firstRow := dst.Pix[i0:i1]
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for i := range firstRow {
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firstRow[i] = color
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}
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for y := dy0 + 1; y < dy1; y++ {
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i0 += dst.Stride
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i1 += dst.Stride
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copy(dst.Pix[i0:i1], firstRow)
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}
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}
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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*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 += 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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func drawRGBA(dst *image.RGBA, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) {
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x0, x1, dx := r.Min.X, r.Max.X, 1
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y0, y1, dy := r.Min.Y, r.Max.Y, 1
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if image.Image(dst) == src && r.Overlaps(r.Add(sp.Sub(r.Min))) {
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if sp.Y < r.Min.Y || sp.Y == r.Min.Y && sp.X < r.Min.X {
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x0, x1, dx = x1-1, x0-1, -1
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y0, y1, dy = y1-1, y0-1, -1
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}
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}
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sy := sp.Y + y0 - r.Min.Y
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my := mp.Y + y0 - r.Min.Y
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for y := y0; y != y1; y, sy, my = y+dy, sy+dy, my+dy {
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sx := sp.X + x0 - r.Min.X
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mx := mp.X + x0 - r.Min.X
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dpix := dst.Pix[y*dst.Stride : (y+1)*dst.Stride]
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for x := x0; x != x1; x, sx, mx = x+dx, sx+dx, mx+dx {
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ma := uint32(m)
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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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sr, sg, sb, sa := src.At(sx, sy).RGBA()
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var dr, dg, db, da uint32
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if op == Over {
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rgba := dpix[x]
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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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da = uint32(rgba.A)
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// dr, dg, db and da are all 8-bit color at the moment, ranging in [0,255].
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// We work in 16-bit color, and so would normally do:
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// dr |= dr << 8
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// and similarly for dg, db and da, but instead we multiply a
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// (which is a 16-bit color, ranging in [0,65535]) by 0x101.
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// This yields the same result, but is fewer arithmetic operations.
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a := (m - (sa * ma / m)) * 0x101
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dr = (dr*a + sr*ma) / m
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dg = (dg*a + sg*ma) / m
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db = (db*a + sb*ma) / m
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da = (da*a + sa*ma) / m
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} else {
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dr = sr * ma / m
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dg = sg * ma / m
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db = sb * ma / m
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da = sa * ma / m
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}
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dpix[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
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}
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}
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}
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