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color.go
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color.go
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package starpack
import (
"fmt"
"image/color"
"math"
"sort"
colorful "github.com/lucasb-eyer/go-colorful"
)
type ColorMerge func([]colorful.Color) colorful.Color
func AverageColor(colors []colorful.Color) colorful.Color {
var h, c, l float64
for i := range colors {
currH, currC, currL := colors[i].Hcl()
h += currH
c += currC
l += currL
}
count := float64(len(colors))
return colorful.Hcl(h/count, c/count, l/count).Clamped()
}
func BrightestColor(colors []colorful.Color) colorful.Color {
brightestValue := -1.0
brightestColor := 0
for i := range colors {
_, _, v := colors[i].Hsv()
if brightestValue < v {
brightestColor = i
brightestValue = v
}
}
return colors[brightestColor]
}
func ContrastColor(colors []colorful.Color) colorful.Color {
brightestValue := -1.0
brightestColor := 0
for i := range colors {
_, _, v := colors[i].Hsv()
if brightestValue < v {
brightestColor = i
brightestValue = v
}
}
// Find darkest color instead
if brightestValue < 0.2 {
darkestValue := 1.0
darkestColor := 0
for i := range colors {
_, _, v := colors[i].Hsv()
if darkestValue > v {
darkestColor = i
darkestValue = v
}
}
return colors[darkestColor]
}
return colors[brightestColor]
}
func MedianColor(colors []colorful.Color) colorful.Color {
c := len(colors)
if c == 1 {
return colors[0]
}
l := make([]float64, c)
a := make([]float64, c)
b := make([]float64, c)
for i := range colors {
l[i], a[i], b[i] = colors[i].Lab()
}
// How do I order colors? By luminoscence?
sort.Slice(colors, func(i, j int) bool {
return l[i] < l[j]
})
if c%2 == 1 {
return colorful.Lab(l[c/2], a[c/2], b[c/2])
}
i := int(math.Floor(float64(c) / 2.0))
return colorful.Lab((l[i]+l[i-1])/2.0, (a[i]+a[i-1])/2.0, (b[i]+b[i-1])/2.0).Clamped()
}
func rgbaToColorful(c color.Color) colorful.Color {
res, _ := colorful.MakeColor(c)
return res.Clamped()
}
func distance(c1, c2 colorful.Color) float64 {
d := c1.DistanceCIEDE2000(c2)
if math.IsNaN(d) {
fmt.Printf("%s + %s = %#v\n", c1.Hex(), c2.Hex(), d)
panic("Color distance is NaN")
}
if d < -1.0 {
return -1.0
}
if d > 1.0 {
return 1.0
}
return d
}