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package gg
import (
"math"
"github.com/golang/freetype/raster"
"golang.org/x/image/math/fixed"
)
func flattenPath(p raster.Path) [][]Point {
var result [][]Point
var path []Point
var cx, cy float64
for i := 0; i < len(p); {
switch p[i] {
case 0:
if len(path) > 0 {
result = append(result, path)
path = nil
}
x := unfix(p[i+1])
y := unfix(p[i+2])
path = append(path, Point{x, y})
cx, cy = x, y
i += 4
case 1:
x := unfix(p[i+1])
y := unfix(p[i+2])
path = append(path, Point{x, y})
cx, cy = x, y
i += 4
case 2:
x1 := unfix(p[i+1])
y1 := unfix(p[i+2])
x2 := unfix(p[i+3])
y2 := unfix(p[i+4])
points := QuadraticBezier(cx, cy, x1, y1, x2, y2)
path = append(path, points...)
cx, cy = x2, y2
i += 6
case 3:
x1 := unfix(p[i+1])
y1 := unfix(p[i+2])
x2 := unfix(p[i+3])
y2 := unfix(p[i+4])
x3 := unfix(p[i+5])
y3 := unfix(p[i+6])
points := CubicBezier(cx, cy, x1, y1, x2, y2, x3, y3)
path = append(path, points...)
cx, cy = x3, y3
i += 8
default:
panic("bad path")
}
}
if len(path) > 0 {
result = append(result, path)
}
return result
}
func dashPath(paths [][]Point, dashes []float64, offset float64) [][]Point {
var result [][]Point
if len(dashes) == 0 {
return paths
}
if len(dashes) == 1 {
dashes = append(dashes, dashes[0])
}
for _, path := range paths {
if len(path) < 2 {
continue
}
previous := path[0]
pathIndex := 1
dashIndex := 0
segmentLength := 0.0
// offset
if offset != 0 {
var totalLength float64
for _, dashLength := range dashes {
totalLength += dashLength
}
offset = math.Mod(offset, totalLength)
if offset < 0 {
offset += totalLength
}
for i, dashLength := range dashes {
offset -= dashLength
if offset < 0 {
dashIndex = i
segmentLength = dashLength + offset
break
}
}
}
var segment []Point
segment = append(segment, previous)
for pathIndex < len(path) {
dashLength := dashes[dashIndex]
point := path[pathIndex]
d := previous.Distance(point)
maxd := dashLength - segmentLength
if d > maxd {
t := maxd / d
p := previous.Interpolate(point, t)
segment = append(segment, p)
if dashIndex%2 == 0 && len(segment) > 1 {
result = append(result, segment)
}
segment = nil
segment = append(segment, p)
segmentLength = 0
previous = p
dashIndex = (dashIndex + 1) % len(dashes)
} else {
segment = append(segment, point)
previous = point
segmentLength += d
pathIndex++
}
}
if dashIndex%2 == 0 && len(segment) > 1 {
result = append(result, segment)
}
}
return result
}
func rasterPath(paths [][]Point) raster.Path {
var result raster.Path
for _, path := range paths {
var previous fixed.Point26_6
for i, point := range path {
f := point.Fixed()
if i == 0 {
result.Start(f)
} else {
dx := f.X - previous.X
dy := f.Y - previous.Y
if dx < 0 {
dx = -dx
}
if dy < 0 {
dy = -dy
}
if dx+dy > 8 {
// TODO: this is a hack for cases where two points are
// too close - causes rendering issues with joins / caps
result.Add1(f)
}
}
previous = f
}
}
return result
}
func dashed(path raster.Path, dashes []float64, offset float64) raster.Path {
return rasterPath(dashPath(flattenPath(path), dashes, offset))
}
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