From e1e8d058a33f7566f9c565d04b0d8b56f9645c35 Mon Sep 17 00:00:00 2001 From: Dimitri Sokolyuk Date: Wed, 25 Apr 2018 09:28:54 +0200 Subject: add vendor --- vendor/golang.org/x/image/vector/vector.go | 472 +++++++++++++++++++++++++++++ 1 file changed, 472 insertions(+) create mode 100644 vendor/golang.org/x/image/vector/vector.go (limited to 'vendor/golang.org/x/image/vector/vector.go') 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 0000000..852a4f8 --- /dev/null +++ b/vendor/golang.org/x/image/vector/vector.go @@ -0,0 +1,472 @@ +// 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. + +//go:generate go run gen.go +//go:generate asmfmt -w acc_amd64.s + +// asmfmt is https://github.com/klauspost/asmfmt + +// 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/color" + "image/draw" + "math" +) + +// floatingPointMathThreshold is the width or height above which the rasterizer +// chooses to used floating point math instead of fixed point math. +// +// Both implementations of line segmentation rasterization (see raster_fixed.go +// and raster_floating.go) implement the same algorithm (in ideal, infinite +// precision math) but they perform differently in practice. The fixed point +// math version is roughtly 1.25x faster (on GOARCH=amd64) on the benchmarks, +// but at sufficiently large scales, the computations will overflow and hence +// show rendering artifacts. The floating point math version has more +// consistent quality over larger scales, but it is significantly slower. +// +// This constant determines when to use the faster implementation and when to +// use the better quality implementation. +// +// The rationale for this particular value is that TestRasterizePolygon in +// vector_test.go checks the rendering quality of polygon edges at various +// angles, inscribed in a circle of diameter 512. It may be that a higher value +// would still produce acceptable quality, but 512 seems to work. +const floatingPointMathThreshold = 512 + +func lerp(t, px, py, qx, qy float32) (x, y float32) { + return px + t*(qx-px), py + t*(qy-py) +} + +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 { + z := &Rasterizer{} + z.Reset(w, h) + return z +} + +// Raster is a 2-D vector graphics rasterizer. +// +// The zero value is usable, in that it is a Rasterizer whose rendered mask +// image has zero width and zero height. Call Reset to change its bounds. +type Rasterizer struct { + // bufXxx are buffers of float32 or uint32 values, holding either the + // individual or cumulative area values. + // + // We don't actually need both values at any given time, and to conserve + // memory, the integration of the individual to the cumulative could modify + // the buffer in place. In other words, we could use a single buffer, say + // of type []uint32, and add some math.Float32bits and math.Float32frombits + // calls to satisfy the compiler's type checking. As of Go 1.7, though, + // there is a performance penalty between: + // bufF32[i] += x + // and + // bufU32[i] = math.Float32bits(x + math.Float32frombits(bufU32[i])) + // + // See golang.org/issue/17220 for some discussion. + bufF32 []float32 + bufU32 []uint32 + + useFloatingPointMath bool + + size image.Point + firstX float32 + firstY float32 + penX float32 + penY float32 + + // 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) { + z.size = image.Point{w, h} + z.firstX = 0 + z.firstY = 0 + z.penX = 0 + z.penY = 0 + z.DrawOp = draw.Over + + z.setUseFloatingPointMath(w > floatingPointMathThreshold || h > floatingPointMathThreshold) +} + +func (z *Rasterizer) setUseFloatingPointMath(b bool) { + z.useFloatingPointMath = b + + // Make z.bufF32 or z.bufU32 large enough to hold width * height samples. + if z.useFloatingPointMath { + if n := z.size.X * z.size.Y; n > cap(z.bufF32) { + z.bufF32 = make([]float32, n) + } else { + z.bufF32 = z.bufF32[:n] + for i := range z.bufF32 { + z.bufF32[i] = 0 + } + } + } else { + if n := z.size.X * z.size.Y; n > cap(z.bufU32) { + z.bufU32 = make([]uint32, n) + } else { + z.bufU32 = z.bufU32[:n] + for i := range z.bufU32 { + z.bufU32[i] = 0 + } + } + } +} + +// 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() (x, y float32) { + return z.penX, z.penY +} + +// ClosePath closes the current path. +func (z *Rasterizer) ClosePath() { + z.LineTo(z.firstX, z.firstY) +} + +// MoveTo starts a new path and moves the pen to (ax, ay). +// +// The coordinates are allowed to be out of the Rasterizer's bounds. +func (z *Rasterizer) MoveTo(ax, ay float32) { + z.firstX = ax + z.firstY = ay + z.penX = ax + z.penY = ay +} + +// LineTo adds a line segment, from the pen to (bx, by), and moves the pen to +// (bx, by). +// +// The coordinates are allowed to be out of the Rasterizer's bounds. +func (z *Rasterizer) LineTo(bx, by float32) { + if z.useFloatingPointMath { + z.floatingLineTo(bx, by) + } else { + z.fixedLineTo(bx, by) + } +} + +// QuadTo adds a quadratic Bézier segment, from the pen via (bx, by) to (cx, +// cy), and moves the pen to (cx, cy). +// +// The coordinates are allowed to be out of the Rasterizer's bounds. +func (z *Rasterizer) QuadTo(bx, by, cx, cy float32) { + ax, ay := z.penX, z.penY + devsq := devSquared(ax, ay, bx, by, cx, cy) + 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 + abx, aby := lerp(t, ax, ay, bx, by) + bcx, bcy := lerp(t, bx, by, cx, cy) + z.LineTo(lerp(t, abx, aby, bcx, bcy)) + } + } + z.LineTo(cx, cy) +} + +// CubeTo adds a cubic Bézier segment, from the pen via (bx, by) and (cx, cy) +// to (dx, dy), and moves the pen to (dx, dy). +// +// The coordinates are allowed to be out of the Rasterizer's bounds. +func (z *Rasterizer) CubeTo(bx, by, cx, cy, dx, dy float32) { + ax, ay := z.penX, z.penY + devsq := devSquared(ax, ay, bx, by, dx, dy) + if devsqAlt := devSquared(ax, ay, cx, cy, dx, dy); 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 + abx, aby := lerp(t, ax, ay, bx, by) + bcx, bcy := lerp(t, bx, by, cx, cy) + cdx, cdy := lerp(t, cx, cy, dx, dy) + abcx, abcy := lerp(t, abx, aby, bcx, bcy) + bcdx, bcdy := lerp(t, bcx, bcy, cdx, cdy) + z.LineTo(lerp(t, abcx, abcy, bcdx, bcdy)) + } + } + z.LineTo(dx, dy) +} + +// devSquared returns a measure of how curvy the sequence (ax, ay) to (bx, by) +// to (cx, cy) 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(ax, ay, bx, by, cx, cy float32) float32 { + devx := ax - 2*bx + cx + devy := ay - 2*by + cy + 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) { + // TODO: adjust r and sp (and mp?) if src.Bounds() doesn't contain + // r.Add(sp.Sub(r.Min)). + + if src, ok := src.(*image.Uniform); ok { + srcR, srcG, srcB, srcA := src.RGBA() + switch dst := dst.(type) { + case *image.Alpha: + // Fast path for glyph rendering. + if srcA == 0xffff { + if z.DrawOp == draw.Over { + z.rasterizeDstAlphaSrcOpaqueOpOver(dst, r) + } else { + z.rasterizeDstAlphaSrcOpaqueOpSrc(dst, r) + } + return + } + case *image.RGBA: + if z.DrawOp == draw.Over { + z.rasterizeDstRGBASrcUniformOpOver(dst, r, srcR, srcG, srcB, srcA) + } else { + z.rasterizeDstRGBASrcUniformOpSrc(dst, r, srcR, srcG, srcB, srcA) + } + return + } + } + + if z.DrawOp == draw.Over { + z.rasterizeOpOver(dst, r, src, sp) + } else { + z.rasterizeOpSrc(dst, r, src, sp) + } +} + +func (z *Rasterizer) accumulateMask() { + if z.useFloatingPointMath { + if n := z.size.X * z.size.Y; n > cap(z.bufU32) { + z.bufU32 = make([]uint32, n) + } else { + z.bufU32 = z.bufU32[:n] + } + if haveFloatingAccumulateSIMD { + floatingAccumulateMaskSIMD(z.bufU32, z.bufF32) + } else { + floatingAccumulateMask(z.bufU32, z.bufF32) + } + } else { + if haveFixedAccumulateSIMD { + fixedAccumulateMaskSIMD(z.bufU32) + } else { + fixedAccumulateMask(z.bufU32) + } + } +} + +func (z *Rasterizer) rasterizeDstAlphaSrcOpaqueOpOver(dst *image.Alpha, r image.Rectangle) { + // TODO: non-zero vs even-odd winding? + if r == dst.Bounds() && r == z.Bounds() { + // We bypass the z.accumulateMask step and convert straight from + // z.bufF32 or z.bufU32 to dst.Pix. + if z.useFloatingPointMath { + if haveFloatingAccumulateSIMD { + floatingAccumulateOpOverSIMD(dst.Pix, z.bufF32) + } else { + floatingAccumulateOpOver(dst.Pix, z.bufF32) + } + } else { + if haveFixedAccumulateSIMD { + fixedAccumulateOpOverSIMD(dst.Pix, z.bufU32) + } else { + fixedAccumulateOpOver(dst.Pix, z.bufU32) + } + } + return + } + + z.accumulateMask() + pix := dst.Pix[dst.PixOffset(r.Min.X, r.Min.Y):] + for y, y1 := 0, r.Max.Y-r.Min.Y; y < y1; y++ { + for x, x1 := 0, r.Max.X-r.Min.X; x < x1; x++ { + ma := z.bufU32[y*z.size.X+x] + i := y*dst.Stride + x + + // This formula is like rasterizeOpOver's, simplified for the + // concrete dst type and opaque src assumption. + a := 0xffff - ma + pix[i] = uint8((uint32(pix[i])*0x101*a/0xffff + ma) >> 8) + } + } +} + +func (z *Rasterizer) rasterizeDstAlphaSrcOpaqueOpSrc(dst *image.Alpha, r image.Rectangle) { + // TODO: non-zero vs even-odd winding? + if r == dst.Bounds() && r == z.Bounds() { + // We bypass the z.accumulateMask step and convert straight from + // z.bufF32 or z.bufU32 to dst.Pix. + if z.useFloatingPointMath { + if haveFloatingAccumulateSIMD { + floatingAccumulateOpSrcSIMD(dst.Pix, z.bufF32) + } else { + floatingAccumulateOpSrc(dst.Pix, z.bufF32) + } + } else { + if haveFixedAccumulateSIMD { + fixedAccumulateOpSrcSIMD(dst.Pix, z.bufU32) + } else { + fixedAccumulateOpSrc(dst.Pix, z.bufU32) + } + } + return + } + + z.accumulateMask() + pix := dst.Pix[dst.PixOffset(r.Min.X, r.Min.Y):] + for y, y1 := 0, r.Max.Y-r.Min.Y; y < y1; y++ { + for x, x1 := 0, r.Max.X-r.Min.X; x < x1; x++ { + ma := z.bufU32[y*z.size.X+x] + + // This formula is like rasterizeOpSrc's, simplified for the + // concrete dst type and opaque src assumption. + pix[y*dst.Stride+x] = uint8(ma >> 8) + } + } +} + +func (z *Rasterizer) rasterizeDstRGBASrcUniformOpOver(dst *image.RGBA, r image.Rectangle, sr, sg, sb, sa uint32) { + z.accumulateMask() + pix := dst.Pix[dst.PixOffset(r.Min.X, r.Min.Y):] + for y, y1 := 0, r.Max.Y-r.Min.Y; y < y1; y++ { + for x, x1 := 0, r.Max.X-r.Min.X; x < x1; x++ { + ma := z.bufU32[y*z.size.X+x] + + // This formula is like rasterizeOpOver's, simplified for the + // concrete dst type and uniform src assumption. + a := 0xffff - (sa * ma / 0xffff) + i := y*dst.Stride + 4*x + pix[i+0] = uint8(((uint32(pix[i+0])*0x101*a + sr*ma) / 0xffff) >> 8) + pix[i+1] = uint8(((uint32(pix[i+1])*0x101*a + sg*ma) / 0xffff) >> 8) + pix[i+2] = uint8(((uint32(pix[i+2])*0x101*a + sb*ma) / 0xffff) >> 8) + pix[i+3] = uint8(((uint32(pix[i+3])*0x101*a + sa*ma) / 0xffff) >> 8) + } + } +} + +func (z *Rasterizer) rasterizeDstRGBASrcUniformOpSrc(dst *image.RGBA, r image.Rectangle, sr, sg, sb, sa uint32) { + z.accumulateMask() + pix := dst.Pix[dst.PixOffset(r.Min.X, r.Min.Y):] + for y, y1 := 0, r.Max.Y-r.Min.Y; y < y1; y++ { + for x, x1 := 0, r.Max.X-r.Min.X; x < x1; x++ { + ma := z.bufU32[y*z.size.X+x] + + // This formula is like rasterizeOpSrc's, simplified for the + // concrete dst type and uniform src assumption. + i := y*dst.Stride + 4*x + pix[i+0] = uint8((sr * ma / 0xffff) >> 8) + pix[i+1] = uint8((sg * ma / 0xffff) >> 8) + pix[i+2] = uint8((sb * ma / 0xffff) >> 8) + pix[i+3] = uint8((sa * ma / 0xffff) >> 8) + } + } +} + +func (z *Rasterizer) rasterizeOpOver(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point) { + z.accumulateMask() + out := color.RGBA64{} + outc := color.Color(&out) + for y, y1 := 0, r.Max.Y-r.Min.Y; y < y1; y++ { + for x, x1 := 0, r.Max.X-r.Min.X; x < x1; x++ { + sr, sg, sb, sa := src.At(sp.X+x, sp.Y+y).RGBA() + ma := z.bufU32[y*z.size.X+x] + + // This algorithm comes from the standard library's image/draw + // package. + dr, dg, db, da := dst.At(r.Min.X+x, r.Min.Y+y).RGBA() + a := 0xffff - (sa * ma / 0xffff) + out.R = uint16((dr*a + sr*ma) / 0xffff) + out.G = uint16((dg*a + sg*ma) / 0xffff) + out.B = uint16((db*a + sb*ma) / 0xffff) + out.A = uint16((da*a + sa*ma) / 0xffff) + + dst.Set(r.Min.X+x, r.Min.Y+y, outc) + } + } +} + +func (z *Rasterizer) rasterizeOpSrc(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point) { + z.accumulateMask() + out := color.RGBA64{} + outc := color.Color(&out) + for y, y1 := 0, r.Max.Y-r.Min.Y; y < y1; y++ { + for x, x1 := 0, r.Max.X-r.Min.X; x < x1; x++ { + sr, sg, sb, sa := src.At(sp.X+x, sp.Y+y).RGBA() + ma := z.bufU32[y*z.size.X+x] + + // This algorithm comes from the standard library's image/draw + // package. + out.R = uint16(sr * ma / 0xffff) + out.G = uint16(sg * ma / 0xffff) + out.B = uint16(sb * ma / 0xffff) + out.A = uint16(sa * ma / 0xffff) + + dst.Set(r.Min.X+x, r.Min.Y+y, outc) + } + } +} -- cgit v1.2.3