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-rw-r--r--vendor/golang.org/x/image/vector/raster_fixed.go327
1 files changed, 0 insertions, 327 deletions
diff --git a/vendor/golang.org/x/image/vector/raster_fixed.go b/vendor/golang.org/x/image/vector/raster_fixed.go
deleted file mode 100644
index 5b0fe7a..0000000
--- a/vendor/golang.org/x/image/vector/raster_fixed.go
+++ /dev/null
@@ -1,327 +0,0 @@
-// Copyright 2016 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 vector
-
-// This file contains a fixed point math implementation of the vector
-// graphics rasterizer.
-
-const (
- // ϕ is the number of binary digits after the fixed point.
- //
- // For example, if ϕ == 10 (and int1ϕ is based on the int32 type) then we
- // are using 22.10 fixed point math.
- //
- // When changing this number, also change the assembly code (search for ϕ
- // in the .s files).
- ϕ = 9
-
- fxOne int1ϕ = 1 << ϕ
- fxOneAndAHalf int1ϕ = 1<<ϕ + 1<<(ϕ-1)
- fxOneMinusIota int1ϕ = 1<<ϕ - 1 // Used for rounding up.
-)
-
-// int1ϕ is a signed fixed-point number with 1*ϕ binary digits after the fixed
-// point.
-type int1ϕ int32
-
-// int2ϕ is a signed fixed-point number with 2*ϕ binary digits after the fixed
-// point.
-//
-// The Rasterizer's bufU32 field, nominally of type []uint32 (since that slice
-// is also used by other code), can be thought of as a []int2ϕ during the
-// fixedLineTo method. Lines of code that are actually like:
-// buf[i] += uint32(etc) // buf has type []uint32.
-// can be thought of as
-// buf[i] += int2ϕ(etc) // buf has type []int2ϕ.
-type int2ϕ int32
-
-func fixedMax(x, y int1ϕ) int1ϕ {
- if x > y {
- return x
- }
- return y
-}
-
-func fixedMin(x, y int1ϕ) int1ϕ {
- if x < y {
- return x
- }
- return y
-}
-
-func fixedFloor(x int1ϕ) int32 { return int32(x >> ϕ) }
-func fixedCeil(x int1ϕ) int32 { return int32((x + fxOneMinusIota) >> ϕ) }
-
-func (z *Rasterizer) fixedLineTo(bx, by float32) {
- ax, ay := z.penX, z.penY
- z.penX, z.penY = bx, by
- dir := int1ϕ(1)
- if ay > by {
- dir, ax, ay, bx, by = -1, bx, by, ax, ay
- }
- // Horizontal line segments yield no change in coverage. Almost horizontal
- // segments would yield some change, in ideal math, but the computation
- // further below, involving 1 / (by - ay), is unstable in fixed point math,
- // so we treat the segment as if it was perfectly horizontal.
- if by-ay <= 0.000001 {
- return
- }
- dxdy := (bx - ax) / (by - ay)
-
- ayϕ := int1ϕ(ay * float32(fxOne))
- byϕ := int1ϕ(by * float32(fxOne))
-
- x := int1ϕ(ax * float32(fxOne))
- y := fixedFloor(ayϕ)
- yMax := fixedCeil(byϕ)
- if yMax > int32(z.size.Y) {
- yMax = int32(z.size.Y)
- }
- width := int32(z.size.X)
-
- for ; y < yMax; y++ {
- dy := fixedMin(int1ϕ(y+1)<<ϕ, byϕ) - fixedMax(int1ϕ(y)<<ϕ, ayϕ)
- xNext := x + int1ϕ(float32(dy)*dxdy)
- if y < 0 {
- x = xNext
- continue
- }
- buf := z.bufU32[y*width:]
- d := dy * dir // d ranges up to ±1<<(1*ϕ).
- x0, x1 := x, xNext
- if x > xNext {
- x0, x1 = x1, x0
- }
- x0i := fixedFloor(x0)
- x0Floor := int1ϕ(x0i) << ϕ
- x1i := fixedCeil(x1)
- x1Ceil := int1ϕ(x1i) << ϕ
-
- if x1i <= x0i+1 {
- xmf := (x+xNext)>>1 - x0Floor
- if i := clamp(x0i+0, width); i < uint(len(buf)) {
- buf[i] += uint32(d * (fxOne - xmf))
- }
- if i := clamp(x0i+1, width); i < uint(len(buf)) {
- buf[i] += uint32(d * xmf)
- }
- } else {
- oneOverS := x1 - x0
- twoOverS := 2 * oneOverS
- x0f := x0 - x0Floor
- oneMinusX0f := fxOne - x0f
- oneMinusX0fSquared := oneMinusX0f * oneMinusX0f
- x1f := x1 - x1Ceil + fxOne
- x1fSquared := x1f * x1f
-
- // These next two variables are unused, as rounding errors are
- // minimized when we delay the division by oneOverS for as long as
- // possible. These lines of code (and the "In ideal math" comments
- // below) are commented out instead of deleted in order to aid the
- // comparison with the floating point version of the rasterizer.
- //
- // a0 := ((oneMinusX0f * oneMinusX0f) >> 1) / oneOverS
- // am := ((x1f * x1f) >> 1) / oneOverS
-
- if i := clamp(x0i, width); i < uint(len(buf)) {
- // In ideal math: buf[i] += uint32(d * a0)
- D := oneMinusX0fSquared // D ranges up to ±1<<(2*ϕ).
- D *= d // D ranges up to ±1<<(3*ϕ).
- D /= twoOverS
- buf[i] += uint32(D)
- }
-
- if x1i == x0i+2 {
- if i := clamp(x0i+1, width); i < uint(len(buf)) {
- // In ideal math: buf[i] += uint32(d * (fxOne - a0 - am))
- //
- // (x1i == x0i+2) and (twoOverS == 2 * (x1 - x0)) implies
- // that twoOverS ranges up to +1<<(1*ϕ+2).
- D := twoOverS<<ϕ - oneMinusX0fSquared - x1fSquared // D ranges up to ±1<<(2*ϕ+2).
- D *= d // D ranges up to ±1<<(3*ϕ+2).
- D /= twoOverS
- buf[i] += uint32(D)
- }
- } else {
- // This is commented out for the same reason as a0 and am.
- //
- // a1 := ((fxOneAndAHalf - x0f) << ϕ) / oneOverS
-
- if i := clamp(x0i+1, width); i < uint(len(buf)) {
- // In ideal math:
- // buf[i] += uint32(d * (a1 - a0))
- // or equivalently (but better in non-ideal, integer math,
- // with respect to rounding errors),
- // buf[i] += uint32(A * d / twoOverS)
- // where
- // A = (a1 - a0) * twoOverS
- // = a1*twoOverS - a0*twoOverS
- // Noting that twoOverS/oneOverS equals 2, substituting for
- // a0 and then a1, given above, yields:
- // A = a1*twoOverS - oneMinusX0fSquared
- // = (fxOneAndAHalf-x0f)<<(ϕ+1) - oneMinusX0fSquared
- // = fxOneAndAHalf<<(ϕ+1) - x0f<<(ϕ+1) - oneMinusX0fSquared
- //
- // This is a positive number minus two non-negative
- // numbers. For an upper bound on A, the positive number is
- // P = fxOneAndAHalf<<(ϕ+1)
- // < (2*fxOne)<<(ϕ+1)
- // = fxOne<<(ϕ+2)
- // = 1<<(2*ϕ+2)
- //
- // For a lower bound on A, the two non-negative numbers are
- // N = x0f<<(ϕ+1) + oneMinusX0fSquared
- // ≤ x0f<<(ϕ+1) + fxOne*fxOne
- // = x0f<<(ϕ+1) + 1<<(2*ϕ)
- // < x0f<<(ϕ+1) + 1<<(2*ϕ+1)
- // ≤ fxOne<<(ϕ+1) + 1<<(2*ϕ+1)
- // = 1<<(2*ϕ+1) + 1<<(2*ϕ+1)
- // = 1<<(2*ϕ+2)
- //
- // Thus, A ranges up to ±1<<(2*ϕ+2). It is possible to
- // derive a tighter bound, but this bound is sufficient to
- // reason about overflow.
- D := (fxOneAndAHalf-x0f)<<(ϕ+1) - oneMinusX0fSquared // D ranges up to ±1<<(2*ϕ+2).
- D *= d // D ranges up to ±1<<(3*ϕ+2).
- D /= twoOverS
- buf[i] += uint32(D)
- }
- dTimesS := uint32((d << (2 * ϕ)) / oneOverS)
- for xi := x0i + 2; xi < x1i-1; xi++ {
- if i := clamp(xi, width); i < uint(len(buf)) {
- buf[i] += dTimesS
- }
- }
-
- // This is commented out for the same reason as a0 and am.
- //
- // a2 := a1 + (int1ϕ(x1i-x0i-3)<<(2*ϕ))/oneOverS
-
- if i := clamp(x1i-1, width); i < uint(len(buf)) {
- // In ideal math:
- // buf[i] += uint32(d * (fxOne - a2 - am))
- // or equivalently (but better in non-ideal, integer math,
- // with respect to rounding errors),
- // buf[i] += uint32(A * d / twoOverS)
- // where
- // A = (fxOne - a2 - am) * twoOverS
- // = twoOverS<<ϕ - a2*twoOverS - am*twoOverS
- // Noting that twoOverS/oneOverS equals 2, substituting for
- // am and then a2, given above, yields:
- // A = twoOverS<<ϕ - a2*twoOverS - x1f*x1f
- // = twoOverS<<ϕ - a1*twoOverS - (int1ϕ(x1i-x0i-3)<<(2*ϕ))*2 - x1f*x1f
- // = twoOverS<<ϕ - a1*twoOverS - int1ϕ(x1i-x0i-3)<<(2*ϕ+1) - x1f*x1f
- // Substituting for a1, given above, yields:
- // A = twoOverS<<ϕ - ((fxOneAndAHalf-x0f)<<ϕ)*2 - int1ϕ(x1i-x0i-3)<<(2*ϕ+1) - x1f*x1f
- // = twoOverS<<ϕ - (fxOneAndAHalf-x0f)<<(ϕ+1) - int1ϕ(x1i-x0i-3)<<(2*ϕ+1) - x1f*x1f
- // = B<<ϕ - x1f*x1f
- // where
- // B = twoOverS - (fxOneAndAHalf-x0f)<<1 - int1ϕ(x1i-x0i-3)<<(ϕ+1)
- // = (x1-x0)<<1 - (fxOneAndAHalf-x0f)<<1 - int1ϕ(x1i-x0i-3)<<(ϕ+1)
- //
- // Re-arranging the defintions given above:
- // x0Floor := int1ϕ(x0i) << ϕ
- // x0f := x0 - x0Floor
- // x1Ceil := int1ϕ(x1i) << ϕ
- // x1f := x1 - x1Ceil + fxOne
- // combined with fxOne = 1<<ϕ yields:
- // x0 = x0f + int1ϕ(x0i)<<ϕ
- // x1 = x1f + int1ϕ(x1i-1)<<ϕ
- // so that expanding (x1-x0) yields:
- // B = (x1f-x0f + int1ϕ(x1i-x0i-1)<<ϕ)<<1 - (fxOneAndAHalf-x0f)<<1 - int1ϕ(x1i-x0i-3)<<(ϕ+1)
- // = (x1f-x0f)<<1 + int1ϕ(x1i-x0i-1)<<(ϕ+1) - (fxOneAndAHalf-x0f)<<1 - int1ϕ(x1i-x0i-3)<<(ϕ+1)
- // A large part of the second and fourth terms cancel:
- // B = (x1f-x0f)<<1 - (fxOneAndAHalf-x0f)<<1 - int1ϕ(-2)<<(ϕ+1)
- // = (x1f-x0f)<<1 - (fxOneAndAHalf-x0f)<<1 + 1<<(ϕ+2)
- // = (x1f - fxOneAndAHalf)<<1 + 1<<(ϕ+2)
- // The first term, (x1f - fxOneAndAHalf)<<1, is a negative
- // number, bounded below by -fxOneAndAHalf<<1, which is
- // greater than -fxOne<<2, or -1<<(ϕ+2). Thus, B ranges up
- // to ±1<<(ϕ+2). One final simplification:
- // B = x1f<<1 + (1<<(ϕ+2) - fxOneAndAHalf<<1)
- const C = 1<<(ϕ+2) - fxOneAndAHalf<<1
- D := x1f<<1 + C // D ranges up to ±1<<(1*ϕ+2).
- D <<= ϕ // D ranges up to ±1<<(2*ϕ+2).
- D -= x1fSquared // D ranges up to ±1<<(2*ϕ+3).
- D *= d // D ranges up to ±1<<(3*ϕ+3).
- D /= twoOverS
- buf[i] += uint32(D)
- }
- }
-
- if i := clamp(x1i, width); i < uint(len(buf)) {
- // In ideal math: buf[i] += uint32(d * am)
- D := x1fSquared // D ranges up to ±1<<(2*ϕ).
- D *= d // D ranges up to ±1<<(3*ϕ).
- D /= twoOverS
- buf[i] += uint32(D)
- }
- }
-
- x = xNext
- }
-}
-
-func fixedAccumulateOpOver(dst []uint8, src []uint32) {
- // Sanity check that len(dst) >= len(src).
- if len(dst) < len(src) {
- return
- }
-
- acc := int2ϕ(0)
- for i, v := range src {
- acc += int2ϕ(v)
- a := acc
- if a < 0 {
- a = -a
- }
- a >>= 2*ϕ - 16
- if a > 0xffff {
- a = 0xffff
- }
- // This algorithm comes from the standard library's image/draw package.
- dstA := uint32(dst[i]) * 0x101
- maskA := uint32(a)
- outA := dstA*(0xffff-maskA)/0xffff + maskA
- dst[i] = uint8(outA >> 8)
- }
-}
-
-func fixedAccumulateOpSrc(dst []uint8, src []uint32) {
- // Sanity check that len(dst) >= len(src).
- if len(dst) < len(src) {
- return
- }
-
- acc := int2ϕ(0)
- for i, v := range src {
- acc += int2ϕ(v)
- a := acc
- if a < 0 {
- a = -a
- }
- a >>= 2*ϕ - 8
- if a > 0xff {
- a = 0xff
- }
- dst[i] = uint8(a)
- }
-}
-
-func fixedAccumulateMask(buf []uint32) {
- acc := int2ϕ(0)
- for i, v := range buf {
- acc += int2ϕ(v)
- a := acc
- if a < 0 {
- a = -a
- }
- a >>= 2*ϕ - 16
- if a > 0xffff {
- a = 0xffff
- }
- buf[i] = uint32(a)
- }
-}