feat: color conversion utilities for (hsv, rgb, and hex)

exp/color/conversion.go

@@ -0,0 +1,145 @@
+package color
+
+import (
+	"fmt"
+	"image/color"
+	"math"
+)
+
+// Color is convenience type that wraps an RGBA color with additional methods
+// for converion.
+type Color struct {
+	v color.RGBA
+}
+
+// RGBA returns the RGBA values of the color.
+func (c Color) RGBA() (r, g, b, a uint32) {
+	return c.v.RGBA()
+}
+
+// Hex returns the hex value of the color as a string.
+func (c Color) Hex() string {
+	return ColorToHex(c)
+}
+
+// HSV returns the HSV values of the color.
+func (c Color) HSV() (h, s, v float64) {
+	return ColorToHSV(c)
+}
+
+// FromHSV sets the color from HSV values.
+func (c Color) FromHSV(h, s, v float64) {
+	c.v = HSVToRGBA(h, s, v)
+}
+
+// FromRGB sets the color from RGB values.
+func (c Color) FromRGB(r, g, b uint8) {
+	c.v.R = r
+	c.v.G = g
+	c.v.B = b
+	c.v.A = 255
+}
+
+// ColorToHex converts a color to a hex string.
+func ColorToHex(c color.Color) string {
+	r, g, b, _ := c.RGBA()
+	return fmt.Sprintf("#%02X%02X%02X", r, g, b)
+}
+
+// HSVToRGBA converts HSV values to an RGBA color. HSV values should be in the
+// ranges [0, 360], [0, 1], and [0, 1] respectively.
+func HSVToRGBA(h, s, v float64) color.RGBA {
+	h = math.Mod(h, 360)            // Ensure h is in the range [0, 360]
+	s = math.Max(0, math.Min(1, s)) // Clamp s to [0, 1]
+	v = math.Max(0, math.Min(1, v)) // Clamp v to [0, 1]
+
+	c := v * s
+	x := c * (1 - math.Abs(math.Mod(h/60, 2)-1))
+	m := v - c
+
+	var r, g, b float64
+
+	switch {
+	case h < 60:
+		r, g, b = c, x, 0
+	case h < 120:
+		r, g, b = x, c, 0
+	case h < 180:
+		r, g, b = 0, c, x
+	case h < 240:
+		r, g, b = 0, x, c
+	case h < 300:
+		r, g, b = x, 0, c
+	default:
+		r, g, b = c, 0, x
+	}
+
+	r = math.Round((r + m) * 255)
+	g = math.Round((g + m) * 255)
+	b = math.Round((b + m) * 255)
+
+	return color.RGBA{
+		R: uint8(r),
+		G: uint8(g),
+		B: uint8(b),
+		A: 255, // Full opacity
+	}
+}
+
+// ColorToHSV converts a color to HSV.
+//
+// A few things to note:
+//
+//   - Due to rounding errors, we mayget a slightly different color when
+//     converting back to RGB.
+//   - The hue will be rounded to the nearest degree, while the saturation and
+//     value will be rounded to two decimal places.
+func ColorToHSV(c color.Color) (h, s, v float64) {
+	r, g, b, _ := c.RGBA()
+
+	// Convert from uint32 (0-MaxUint32) to float64 (0-1).
+	rf := float64(r) / float64(0xFFFF)
+	gf := float64(g) / float64(0xFFFF)
+	bf := float64(b) / float64(0xFFFF)
+
+	minimum := math.Min(rf, math.Min(gf, bf))
+	maximum := math.Max(rf, math.Max(gf, bf))
+
+	v = maximum
+	delta := maximum - minimum
+
+	if maximum == 0 {
+		// Black.
+		s = 0
+		h = 0
+		return
+	}
+
+	s = delta / maximum
+
+	if delta == 0 {
+		// Gray.
+		h = 0
+		return
+	}
+
+	switch maximum {
+	case rf:
+		h = (gf - bf) / delta
+		if gf < bf {
+			h += 6
+		}
+	case gf:
+		h = 2 + (bf-rf)/delta
+	case bf:
+		h = 4 + (rf-gf)/delta
+	}
+
+	h *= 60
+
+	h = math.Round(h)           // Round to nearest degree.
+	s = math.Round(s*100) / 100 // Round to two decimal places.
+	v = math.Round(v*100) / 100 // Round to two decimal places.
+
+	return
+}

exp/color/conversion_test.go

@@ -0,0 +1,65 @@
+package color
+
+import (
+	"image/color"
+	"testing"
+)
+
+func TestColorToHex(t *testing.T) {
+	for i, test := range []struct {
+		c    color.Color
+		want string
+	}{
+		{color.RGBA{0, 0, 0, 255}, "#000000"},
+		{color.RGBA{255, 255, 255, 255}, "#FFFFFF"},
+		{color.RGBA{255, 0, 0, 255}, "#FF0000"},
+		{color.RGBA{0, 255, 0, 255}, "#00FF00"},
+		{color.RGBA{0, 0, 255, 255}, "#0000FF"},
+		{color.RGBA{107, 80, 255, 255}, "#6B50FF"},
+	} {
+		got := ColorToHex(test.c)
+		if got != test.want {
+			t.Errorf("Test %d: ColorToHex(%v)\nGot:  %v\nWant: %v", i, test.c, got, test.want)
+		}
+	}
+}
+
+func TestHSVToRGBA(t *testing.T) {
+	for i, test := range []struct {
+		h, s, v float64
+		want    color.RGBA
+	}{
+		{0, 0, 0, color.RGBA{0, 0, 0, 255}},
+		{0, 0, 1, color.RGBA{255, 255, 255, 255}},
+		{0, 1, 1, color.RGBA{255, 0, 0, 255}},
+		{120, 1, 1, color.RGBA{0, 255, 0, 255}},
+		{240, 1, 1, color.RGBA{0, 0, 255, 255}},
+		{249, 0.69, 1, color.RGBA{105, 79, 255, 255}},
+	} {
+		got := HSVToRGBA(test.h, test.s, test.v)
+		if got != test.want {
+			t.Errorf("Test %d: HSVToRGBA(%v, %v, %v)\nGot:  %v\nWant: %v", i, test.h, test.s, test.v, got, test.want)
+		}
+	}
+}
+
+func TestColorToHSV(t *testing.T) {
+	for i, test := range []struct {
+		c    color.Color
+		want struct {
+			h, s, v float64
+		}
+	}{
+		{color.RGBA{0, 0, 0, 255}, struct{ h, s, v float64 }{0, 0, 0}},
+		{color.RGBA{255, 255, 255, 255}, struct{ h, s, v float64 }{0, 0, 1}},
+		{color.RGBA{255, 0, 0, 255}, struct{ h, s, v float64 }{0, 1, 1}},
+		{color.RGBA{0, 255, 0, 255}, struct{ h, s, v float64 }{120, 1, 1}},
+		{color.RGBA{0, 0, 255, 255}, struct{ h, s, v float64 }{240, 1, 1}},
+		{color.RGBA{105, 79, 255, 255}, struct{ h, s, v float64 }{249, 0.69, 1}},
+	} {
+		h, s, v := ColorToHSV(test.c)
+		if h != test.want.h || s != test.want.s || v != test.want.v {
+			t.Errorf("Test %d: ColorToHSV(%v)\nGot:  %v\nWant: %v", i, test.c, struct{ h, s, v float64 }{h, s, v}, test.want)
+		}
+	}
+}

exp/color/go.mod

@@ -0,0 +1,3 @@
+module github.com/charmbracelet/x/exp/color
+
+go 1.18

go.work

@@ -8,6 +8,7 @@ use (
 	./editor
 	./errors
 	./examples
+	./exp/color
 	./exp/golden
 	./exp/higherorder
 	./exp/maps

go.work.sum

@@ -1,4 +1,3 @@
-github.com/charmbracelet/bubbletea v1.1.1/go.mod h1:9Ogk0HrdbHolIKHdjfFpyXJmiCzGwy+FesYkZr7hYU4=
 github.com/charmbracelet/harmonica v0.2.0/go.mod h1:KSri/1RMQOZLbw7AHqgcBycp8pgJnQMYYT8QZRqZ1Ao=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
@@ -11,6 +10,5 @@ golang.org/x/mod v0.17.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.25.0/go.mod h1:JkAGAh7GEvH74S6FOH42FLoXpXbE/aqXSrIQjXgsiwM=
 golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/telemetry v0.0.0-20240228155512-f48c80bd79b2/go.mod h1:TeRTkGYfJXctD9OcfyVLyj2J3IxLnKwHJR8f4D8a3YE=
-golang.org/x/term v0.23.0/go.mod h1:DgV24QBUrK6jhZXl+20l6UWznPlwAHm1Q1mGHtydmSk=
 golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
 golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d/go.mod h1:aiJjzUbINMkxbQROHiO6hDPo2LHcIPhhQsa9DLh0yGk=