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package color
import (
"github.com/lucasb-eyer/go-colorful"
"math"
)
const eps = 0.0001
const epsSquare = eps * eps
type Gamut struct {
Red XY `json:"red"`
Green XY `json:"green"`
Blue XY `json:"blue"`
}
func (cg *Gamut) side(x1, y1, x2, y2, x, y float64) float64 {
return (y2-y1)*(x-x1) + (-x2+x1)*(y-y1)
}
func (cg *Gamut) naiveContains(color XY) bool {
x, y := color.X, color.Y
x1, y1 := cg.Red.X, cg.Red.Y
x2, y2 := cg.Green.X, cg.Green.Y
x3, y3 := cg.Blue.X, cg.Blue.Y
checkSide1 := cg.side(x1, y1, x2, y2, x, y) < 0
checkSide2 := cg.side(x2, y2, x3, y3, x, y) < 0
checkSide3 := cg.side(x3, y3, x1, y1, x, y) < 0
return checkSide1 && checkSide2 && checkSide3
}
func (cg *Gamut) getBounds() (xMin, xMax, yMin, yMax float64) {
x1, y1 := cg.Red.X, cg.Red.Y
x2, y2 := cg.Green.X, cg.Green.Y
x3, y3 := cg.Blue.X, cg.Blue.Y
xMin = math.Min(x1, math.Min(x2, x3)) - eps
xMax = math.Max(x1, math.Max(x2, x3)) + eps
yMin = math.Min(y1, math.Min(y2, y3)) - eps
yMax = math.Max(y1, math.Max(y2, y3)) + eps
return
}
func (cg *Gamut) isInBounds(color XY) bool {
x, y := color.X, color.Y
xMin, xMax, yMin, yMax := cg.getBounds()
return !(x < xMin || xMax < x || y < yMin || yMax < y)
}
func (cg *Gamut) distanceSquarePointToSegment(x1, y1, x2, y2, x, y float64) float64 {
sqLength1 := (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1)
dotProduct := ((x-x1)*(x2-x1) + (y-y1)*(y2-y1)) / sqLength1
if dotProduct < 0 {
return (x-x1)*(x-x1) + (y-y1)*(y-y1)
} else if dotProduct <= 1 {
sqLength2 := (x1-x)*(x1-x) + (y1-y)*(y1-y)
return sqLength2 - dotProduct*dotProduct*sqLength1
} else {
return (x-x2)*(x-x2) + (y-y2)*(y-y2)
}
}
func (cg *Gamut) atTheEdge(color XY) bool {
x, y := color.X, color.Y
x1, y1 := cg.Red.X, cg.Red.Y
x2, y2 := cg.Green.X, cg.Green.Y
x3, y3 := cg.Blue.X, cg.Blue.Y
if cg.distanceSquarePointToSegment(x1, y1, x2, y2, x, y) <= epsSquare {
return true
}
if cg.distanceSquarePointToSegment(x2, y2, x3, y3, x, y) <= epsSquare {
return true
}
if cg.distanceSquarePointToSegment(x3, y3, x1, y1, x, y) <= epsSquare {
return true
}
return false
}
func (cg *Gamut) Contains(color XY) bool {
if cg == nil {
return true
}
return cg.isInBounds(color) && (cg.naiveContains(color) || cg.atTheEdge(color))
}
func (cg *Gamut) Conform(color XY) XY {
if cg.Contains(color) {
return color
}
var best *XY
xMin, xMax, yMin, yMax := cg.getBounds()
for x := xMin; x < xMax; x += 0.001 {
for y := yMin; y < yMax; y += 0.001 {
color2 := XY{X: x, Y: y}
if cg.Contains(color2) {
if best == nil || color.DistanceTo(color2) < color.DistanceTo(*best) {
best = &color2
}
}
}
}
if best == nil {
centerX := (cg.Red.X + cg.Green.X + cg.Blue.X) / 3
centerY := (cg.Red.Y + cg.Green.Y + cg.Blue.Y) / 3
stepX := (centerX - color.X) / 5000
stepY := (centerY - color.Y) / 5000
for !cg.Contains(color) {
color.X += stepX
color.Y += stepY
}
return color
}
for x := best.X - 0.001; x < best.X+0.001; x += 0.0002 {
for y := best.Y - 0.001; y < best.Y+0.001; y += 0.0002 {
color2 := XY{X: x, Y: y}
if cg.atTheEdge(color2) {
if best == nil || color.DistanceTo(color2) < color.DistanceTo(*best) {
best = &color2
}
}
}
}
for x := best.X - 0.0001; x < best.X+0.0001; x += 0.00003 {
for y := best.Y - 0.0001; y < best.Y+0.0001; y += 0.00003 {
color2 := XY{X: x, Y: y}
if cg.atTheEdge(color2) {
if best == nil || color.DistanceTo(color2) < color.DistanceTo(*best) {
best = &color2
}
}
}
}
return *best
}
type XY struct {
X float64 `json:"x"`
Y float64 `json:"y"`
}
func (xy XY) ToRGB() RGB {
h, s, _ := colorful.Xyy(xy.X, xy.Y, 0.5).Hsv()
c := colorful.Hsv(h, s, 1)
return RGB{Red: c.R, Green: c.G, Blue: c.B}
}
func (xy XY) ToHS() HueSat {
h, s, _ := colorful.Xyy(xy.X, xy.Y, 0.5).Hsv()
return HueSat{Hue: h, Sat: s}
}
func (xy XY) DistanceTo(other XY) float64 {
return math.Sqrt(math.Pow(xy.X-other.X, 2) + math.Pow(xy.Y-other.Y, 2))
}
func (xy XY) Round() XY {
return XY{
X: math.Round(xy.X*10000) / 10000,
Y: math.Round(xy.Y*10000) / 10000,
}
}