Updating golang dependancies (#4075)

3 files changed, 457 insertions, 0 deletions

diff --git a/vendor/golang.org/x/image/vector/raster_floating.go b/vendor/golang.org/x/image/vector/raster_floating.go
new file mode 100644
index 000000000..d03936a1e
--- /dev/null
+++ b/vendor/golang.org/x/image/vector/raster_floating.go
@@ -0,0 +1,153 @@
+// 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 floating point math implementation of the vector
+// graphics rasterizer.
+
+import (
+	"math"
+
+	"golang.org/x/image/math/f32"
+)
+
+func floatingMax(x, y float32) float32 {
+	if x > y {
+		return x
+	}
+	return y
+}
+
+func floatingMin(x, y float32) float32 {
+	if x < y {
+		return x
+	}
+	return y
+}
+
+func floatingFloor(x float32) int32 { return int32(math.Floor(float64(x))) }
+func floatingCeil(x float32) int32  { return int32(math.Ceil(float64(x))) }
+
+func (z *Rasterizer) floatingLineTo(b f32.Vec2) {
+	a := z.pen
+	z.pen = b
+	dir := float32(1)
+	if a[1] > b[1] {
+		dir, a, b = -1, b, a
+	}
+	// 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 / (b[1] - a[1]), is unstable in floating
+	// point math, so we treat the segment as if it was perfectly horizontal.
+	if b[1]-a[1] <= 0.000001 {
+		return
+	}
+	dxdy := (b[0] - a[0]) / (b[1] - a[1])
+
+	x := a[0]
+	y := floatingFloor(a[1])
+	yMax := floatingCeil(b[1])
+	if yMax > int32(z.size.Y) {
+		yMax = int32(z.size.Y)
+	}
+	width := int32(z.size.X)
+
+	for ; y < yMax; y++ {
+		dy := floatingMin(float32(y+1), b[1]) - floatingMax(float32(y), a[1])
+		xNext := x + dy*dxdy
+		if y < 0 {
+			x = xNext
+			continue
+		}
+		buf := z.area[y*width:]
+		d := dy * dir
+		x0, x1 := x, xNext
+		if x > xNext {
+			x0, x1 = x1, x0
+		}
+		x0i := floatingFloor(x0)
+		x0Floor := float32(x0i)
+		x1i := floatingCeil(x1)
+		x1Ceil := float32(x1i)
+
+		if x1i <= x0i+1 {
+			xmf := 0.5*(x+xNext) - x0Floor
+			if i := clamp(x0i+0, width); i < uint(len(buf)) {
+				buf[i] += d - d*xmf
+			}
+			if i := clamp(x0i+1, width); i < uint(len(buf)) {
+				buf[i] += d * xmf
+			}
+		} else {
+			s := 1 / (x1 - x0)
+			x0f := x0 - x0Floor
+			oneMinusX0f := 1 - x0f
+			a0 := 0.5 * s * oneMinusX0f * oneMinusX0f
+			x1f := x1 - x1Ceil + 1
+			am := 0.5 * s * x1f * x1f
+
+			if i := clamp(x0i, width); i < uint(len(buf)) {
+				buf[i] += d * a0
+			}
+
+			if x1i == x0i+2 {
+				if i := clamp(x0i+1, width); i < uint(len(buf)) {
+					buf[i] += d * (1 - a0 - am)
+				}
+			} else {
+				a1 := s * (1.5 - x0f)
+				if i := clamp(x0i+1, width); i < uint(len(buf)) {
+					buf[i] += d * (a1 - a0)
+				}
+				dTimesS := d * s
+				for xi := x0i + 2; xi < x1i-1; xi++ {
+					if i := clamp(xi, width); i < uint(len(buf)) {
+						buf[i] += dTimesS
+					}
+				}
+				a2 := a1 + s*float32(x1i-x0i-3)
+				if i := clamp(x1i-1, width); i < uint(len(buf)) {
+					buf[i] += d * (1 - a2 - am)
+				}
+			}
+
+			if i := clamp(x1i, width); i < uint(len(buf)) {
+				buf[i] += d * am
+			}
+		}
+
+		x = xNext
+	}
+}
+
+func floatingAccumulate(dst []uint8, src []float32) {
+	// almost256 scales a floating point value in the range [0, 1] to a uint8
+	// value in the range [0x00, 0xff].
+	//
+	// 255 is too small. Floating point math accumulates rounding errors, so a
+	// fully covered src value that would in ideal math be float32(1) might be
+	// float32(1-ε), and uint8(255 * (1-ε)) would be 0xfe instead of 0xff. The
+	// uint8 conversion rounds to zero, not to nearest.
+	//
+	// 256 is too big. If we multiplied by 256, below, then a fully covered src
+	// value of float32(1) would translate to uint8(256 * 1), which can be 0x00
+	// instead of the maximal value 0xff.
+	//
+	// math.Float32bits(almost256) is 0x437fffff.
+	const almost256 = 255.99998
+
+	acc := float32(0)
+	for i, v := range src {
+		acc += v
+		a := acc
+		if a < 0 {
+			a = -a
+		}
+		if a > 1 {
+			a = 1
+		}
+		dst[i] = uint8(almost256 * a)
+	}
+}
diff --git a/vendor/golang.org/x/image/vector/vector.go b/vendor/golang.org/x/image/vector/vector.go
new file mode 100644
index 000000000..218e76489
--- /dev/null
+++ b/vendor/golang.org/x/image/vector/vector.go
@@ -0,0 +1,228 @@
+// 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 provides a rasterizer for 2-D vector graphics.
+package vector // import "golang.org/x/image/vector"
+
+// The rasterizer's design follows
+// https://medium.com/@raphlinus/inside-the-fastest-font-renderer-in-the-world-75ae5270c445
+//
+// Proof of concept code is in
+// https://github.com/google/font-go
+//
+// See also:
+// http://nothings.org/gamedev/rasterize/
+// http://projects.tuxee.net/cl-vectors/section-the-cl-aa-algorithm
+// https://people.gnome.org/~mathieu/libart/internals.html#INTERNALS-SCANLINE
+
+import (
+	"image"
+	"image/draw"
+	"math"
+
+	"golang.org/x/image/math/f32"
+)
+
+func midPoint(p, q f32.Vec2) f32.Vec2 {
+	return f32.Vec2{
+		(p[0] + q[0]) * 0.5,
+		(p[1] + q[1]) * 0.5,
+	}
+}
+
+func lerp(t float32, p, q f32.Vec2) f32.Vec2 {
+	return f32.Vec2{
+		p[0] + t*(q[0]-p[0]),
+		p[1] + t*(q[1]-p[1]),
+	}
+}
+
+func clamp(i, width int32) uint {
+	if i < 0 {
+		return 0
+	}
+	if i < width {
+		return uint(i)
+	}
+	return uint(width)
+}
+
+// NewRasterizer returns a new Rasterizer whose rendered mask image is bounded
+// by the given width and height.
+func NewRasterizer(w, h int) *Rasterizer {
+	return &Rasterizer{
+		area: make([]float32, w*h),
+		size: image.Point{w, h},
+	}
+}
+
+// Raster is a 2-D vector graphics rasterizer.
+type Rasterizer struct {
+	area  []float32
+	size  image.Point
+	first f32.Vec2
+	pen   f32.Vec2
+
+	// DrawOp is the operator used for the Draw method.
+	//
+	// The zero value is draw.Over.
+	DrawOp draw.Op
+
+	// TODO: an exported field equivalent to the mask point in the
+	// draw.DrawMask function in the stdlib image/draw package?
+}
+
+// Reset resets a Rasterizer as if it was just returned by NewRasterizer.
+//
+// This includes setting z.DrawOp to draw.Over.
+func (z *Rasterizer) Reset(w, h int) {
+	if n := w * h; n > cap(z.area) {
+		z.area = make([]float32, n)
+	} else {
+		z.area = z.area[:n]
+		for i := range z.area {
+			z.area[i] = 0
+		}
+	}
+	z.size = image.Point{w, h}
+	z.first = f32.Vec2{}
+	z.pen = f32.Vec2{}
+	z.DrawOp = draw.Over
+}
+
+// Size returns the width and height passed to NewRasterizer or Reset.
+func (z *Rasterizer) Size() image.Point {
+	return z.size
+}
+
+// Bounds returns the rectangle from (0, 0) to the width and height passed to
+// NewRasterizer or Reset.
+func (z *Rasterizer) Bounds() image.Rectangle {
+	return image.Rectangle{Max: z.size}
+}
+
+// Pen returns the location of the path-drawing pen: the last argument to the
+// most recent XxxTo call.
+func (z *Rasterizer) Pen() f32.Vec2 {
+	return z.pen
+}
+
+// ClosePath closes the current path.
+func (z *Rasterizer) ClosePath() {
+	z.LineTo(z.first)
+}
+
+// MoveTo starts a new path and moves the pen to a.
+//
+// The coordinates are allowed to be out of the Rasterizer's bounds.
+func (z *Rasterizer) MoveTo(a f32.Vec2) {
+	z.first = a
+	z.pen = a
+}
+
+// LineTo adds a line segment, from the pen to b, and moves the pen to b.
+//
+// The coordinates are allowed to be out of the Rasterizer's bounds.
+func (z *Rasterizer) LineTo(b f32.Vec2) {
+	// TODO: add a fixed point math implementation.
+	z.floatingLineTo(b)
+}
+
+// QuadTo adds a quadratic Bézier segment, from the pen via b to c, and moves
+// the pen to c.
+//
+// The coordinates are allowed to be out of the Rasterizer's bounds.
+func (z *Rasterizer) QuadTo(b, c f32.Vec2) {
+	a := z.pen
+	devsq := devSquared(a, b, c)
+	if devsq >= 0.333 {
+		const tol = 3
+		n := 1 + int(math.Sqrt(math.Sqrt(tol*float64(devsq))))
+		t, nInv := float32(0), 1/float32(n)
+		for i := 0; i < n-1; i++ {
+			t += nInv
+			ab := lerp(t, a, b)
+			bc := lerp(t, b, c)
+			z.LineTo(lerp(t, ab, bc))
+		}
+	}
+	z.LineTo(c)
+}
+
+// CubeTo adds a cubic Bézier segment, from the pen via b and c to d, and moves
+// the pen to d.
+//
+// The coordinates are allowed to be out of the Rasterizer's bounds.
+func (z *Rasterizer) CubeTo(b, c, d f32.Vec2) {
+	a := z.pen
+	devsq := devSquared(a, b, d)
+	if devsqAlt := devSquared(a, c, d); devsq < devsqAlt {
+		devsq = devsqAlt
+	}
+	if devsq >= 0.333 {
+		const tol = 3
+		n := 1 + int(math.Sqrt(math.Sqrt(tol*float64(devsq))))
+		t, nInv := float32(0), 1/float32(n)
+		for i := 0; i < n-1; i++ {
+			t += nInv
+			ab := lerp(t, a, b)
+			bc := lerp(t, b, c)
+			cd := lerp(t, c, d)
+			abc := lerp(t, ab, bc)
+			bcd := lerp(t, bc, cd)
+			z.LineTo(lerp(t, abc, bcd))
+		}
+	}
+	z.LineTo(d)
+}
+
+// devSquared returns a measure of how curvy the sequnce a to b to c is. It
+// determines how many line segments will approximate a Bézier curve segment.
+//
+// http://lists.nongnu.org/archive/html/freetype-devel/2016-08/msg00080.html
+// gives the rationale for this evenly spaced heuristic instead of a recursive
+// de Casteljau approach:
+//
+// The reason for the subdivision by n is that I expect the "flatness"
+// computation to be semi-expensive (it's done once rather than on each
+// potential subdivision) and also because you'll often get fewer subdivisions.
+// Taking a circular arc as a simplifying assumption (ie a spherical cow),
+// where I get n, a recursive approach would get 2^⌈lg n⌉, which, if I haven't
+// made any horrible mistakes, is expected to be 33% more in the limit.
+func devSquared(a, b, c f32.Vec2) float32 {
+	devx := a[0] - 2*b[0] + c[0]
+	devy := a[1] - 2*b[1] + c[1]
+	return devx*devx + devy*devy
+}
+
+// Draw implements the Drawer interface from the standard library's image/draw
+// package.
+//
+// The vector paths previously added via the XxxTo calls become the mask for
+// drawing src onto dst.
+func (z *Rasterizer) Draw(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point) {
+	if src, ok := src.(*image.Uniform); ok {
+		_, _, _, srcA := src.RGBA()
+		switch dst := dst.(type) {
+		case *image.Alpha:
+			// Fast path for glyph rendering.
+			if srcA == 0xffff && z.DrawOp == draw.Src {
+				z.rasterizeDstAlphaSrcOpaqueOpSrc(dst, r)
+				return
+			}
+		}
+	}
+	println("TODO: the general case")
+}
+
+func (z *Rasterizer) rasterizeDstAlphaSrcOpaqueOpSrc(dst *image.Alpha, r image.Rectangle) {
+	// TODO: add SIMD implementations.
+	// TODO: add a fixed point math implementation.
+	// TODO: non-zero vs even-odd winding?
+	if r == dst.Bounds() && r == z.Bounds() {
+		floatingAccumulate(dst.Pix, z.area)
+		return
+	}
+	println("TODO: the general case")
+}
diff --git a/vendor/golang.org/x/image/vector/vector_test.go b/vendor/golang.org/x/image/vector/vector_test.go
new file mode 100644
index 000000000..3aa8c192f
--- /dev/null
+++ b/vendor/golang.org/x/image/vector/vector_test.go
@@ -0,0 +1,76 @@
+// 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
+
+// TODO: add tests for NaN and Inf coordinates.
+
+import (
+	"image"
+	"image/draw"
+	"image/png"
+	"os"
+	"testing"
+
+	"golang.org/x/image/math/f32"
+)
+
+// encodePNG is useful for manually debugging the tests.
+func encodePNG(dstFilename string, src image.Image) error {
+	f, err := os.Create(dstFilename)
+	if err != nil {
+		return err
+	}
+	encErr := png.Encode(f, src)
+	closeErr := f.Close()
+	if encErr != nil {
+		return encErr
+	}
+	return closeErr
+}
+
+func TestBasicPath(t *testing.T) {
+	want := []byte{
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe3, 0xaa, 0x3e, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfa, 0x5f, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x24, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xa1, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0x14, 0x00, 0x00,
+		0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x4a, 0x00, 0x00,
+		0x00, 0x00, 0xcc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x81, 0x00, 0x00,
+		0x00, 0x00, 0x66, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0xe4, 0xff, 0xff, 0xff, 0xb6, 0x00, 0x00,
+		0x00, 0x00, 0x0c, 0xf2, 0xff, 0xff, 0xfe, 0x9e, 0x15, 0x00, 0x15, 0x96, 0xff, 0xce, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x88, 0xfc, 0xe3, 0x43, 0x00, 0x00, 0x00, 0x00, 0x06, 0xcd, 0xdc, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x10, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x25, 0xde, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x56, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	}
+
+	z := NewRasterizer(16, 16)
+	z.MoveTo(f32.Vec2{2, 2})
+	z.LineTo(f32.Vec2{8, 2})
+	z.QuadTo(f32.Vec2{14, 2}, f32.Vec2{14, 14})
+	z.CubeTo(f32.Vec2{8, 2}, f32.Vec2{5, 20}, f32.Vec2{2, 8})
+	z.ClosePath()
+
+	dst := image.NewAlpha(z.Bounds())
+	z.DrawOp = draw.Src
+	z.Draw(dst, dst.Bounds(), image.Opaque, image.Point{})
+
+	got := dst.Pix
+	if len(got) != len(want) {
+		t.Fatalf("len(got)=%d and len(want)=%d differ", len(got), len(want))
+	}
+	for i := range got {
+		delta := int(got[i]) - int(want[i])
+		// The +/- 2 allows different implementations to give different
+		// rounding errors.
+		if delta < -2 || +2 < delta {
+			t.Errorf("i=%d: got %#02x, want %#02x", i, got[i], want[i])
+		}
+	}
+}