First step to add support for transparency

basis.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

bench_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

builder.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

builder_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

catmull_rom.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

example_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad_test
 
 import (

gimp.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

gimp_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

gradient.go

@@ -4,35 +4,23 @@ import (
 	"image/color"
 	"math"
 
-	"github.com/lucasb-eyer/go-colorful"
+	"github.com/mazznoer/csscolorparser"
 )
 
 type BlendMode int
 
 const (
-	BlendHcl BlendMode = iota
-	BlendHsv
-	BlendLab
+	BlendRgb BlendMode = iota
 	BlendLinearRgb
-	BlendLuv
-	BlendRgb
 	BlendOklab
 )
 
 func (b BlendMode) String() string {
 	switch b {
-	case BlendHcl:
-		return "BlendHcl"
-	case BlendHsv:
-		return "BlendHsv"
-	case BlendLab:
-		return "BlendLab"
-	case BlendLinearRgb:
-		return "BlendLinearRgb"
-	case BlendLuv:
-		return "BlendLuv"
 	case BlendRgb:
 		return "BlendRgb"
+	case BlendLinearRgb:
+		return "BlendLinearRgb"
 	case BlendOklab:
 		return "BlendOklab"
 	}
@@ -59,9 +47,14 @@ func (i Interpolation) String() string {
 	return ""
 }
 
+type Color = csscolorparser.Color
+
+var LinearRgb = csscolorparser.FromLinearRGB
+var Oklab = csscolorparser.FromOklab
+
 type gradientBase interface {
 	// Get color at certain position
-	At(float64) colorful.Color
+	At(float64) Color
 }
 
 type Gradient struct {
@@ -71,29 +64,29 @@ type Gradient struct {
 }
 
 // Get color at certain position
-func (g Gradient) At(t float64) colorful.Color {
+func (g Gradient) At(t float64) Color {
 	return g.grad.At(t)
 }
 
 // Get color at certain position
-func (g Gradient) RepeatAt(t float64) colorful.Color {
+func (g Gradient) RepeatAt(t float64) Color {
 	t = norm(t, g.dmin, g.dmax)
 	return g.grad.At(g.dmin + modulo(t, 1)*(g.dmax-g.dmin))
 }
 
 // Get color at certain position
-func (g Gradient) ReflectAt(t float64) colorful.Color {
+func (g Gradient) ReflectAt(t float64) Color {
 	t = norm(t, g.dmin, g.dmax)
 	return g.grad.At(g.dmin + math.Abs(modulo(1+t, 2)-1)*(g.dmax-g.dmin))
 }
 
 // Get n colors evenly spaced across gradient
-func (g Gradient) ColorfulColors(count uint) []colorful.Color {
+func (g Gradient) ColorfulColors(count uint) []Color {
 	d := g.dmax - g.dmin
 	l := float64(count) - 1
-	colors := make([]colorful.Color, count)
+	colors := make([]Color, count)
 	for i := range colors {
-		colors[i] = g.grad.At(g.dmin + (float64(i)*d)/l).Clamped()
+		colors[i] = g.grad.At(g.dmin + (float64(i)*d)/l) //.Clamped()
 	}
 	return colors
 }
@@ -114,7 +107,7 @@ func (g Gradient) Domain() (float64, float64) {
 
 // Return a new hard-edge gradient
 func (g Gradient) Sharp(segment uint, smoothness float64) Gradient {
-	colors := []colorful.Color{}
+	colors := []Color{}
 	if segment >= 2 {
 		colors = g.ColorfulColors(segment)
 	} else {
@@ -125,9 +118,9 @@ func (g Gradient) Sharp(segment uint, smoothness float64) Gradient {
 }
 
 type zeroGradient struct {
-	color colorful.Color
+	color Color
 }
 
-func (zg zeroGradient) At(t float64) colorful.Color {
+func (zg zeroGradient) At(t float64) Color {
 	return zg.color
 }

gradient_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

linear.go

@@ -2,21 +2,19 @@ package colorgrad
 
 import (
 	"math"
-
-	"github.com/lucasb-eyer/go-colorful"
 )
 
 type linearGradient struct {
-	colors     [][3]float64
+	colors     [][4]float64
 	pos        []float64
 	dmin       float64
 	dmax       float64
 	mode       BlendMode
-	firstColor colorful.Color
-	lastColor  colorful.Color
+	firstColor Color
+	lastColor  Color
 }
 
-func (lg linearGradient) At(t float64) colorful.Color {
+func (lg linearGradient) At(t float64) Color {
 	if t <= lg.dmin {
 		return lg.firstColor
 	}
@@ -26,7 +24,7 @@ func (lg linearGradient) At(t float64) colorful.Color {
 	}
 
 	if math.IsNaN(t) {
-		return colorful.Color{R: 0, G: 0, B: 0}
+		return Color{R: 0, G: 0, B: 0, A: 0}
 	}
 
 	low := 0
@@ -48,32 +46,21 @@ func (lg linearGradient) At(t float64) colorful.Color {
 	p1 := lg.pos[low-1]
 	p2 := lg.pos[low]
 	t = (t - p1) / (p2 - p1)
-	x, y, z := linearInterpolate(lg.colors[low-1], lg.colors[low], t)
+	a, b, c, d := linearInterpolate(lg.colors[low-1], lg.colors[low], t)
 
 	switch lg.mode {
-	case BlendHcl:
-		hue := interpAngle(lg.colors[low-1][0], lg.colors[low][0], t)
-		return colorful.Hcl(hue, y, z).Clamped()
-	case BlendHsv:
-		hue := interpAngle(lg.colors[low-1][0], lg.colors[low][0], t)
-		return colorful.Hsv(hue, y, z)
-	case BlendLab:
-		return colorful.Lab(x, y, z).Clamped()
-	case BlendLinearRgb:
-		return colorful.LinearRgb(x, y, z)
-	case BlendLuv:
-		return colorful.Luv(x, y, z).Clamped()
 	case BlendRgb:
-		return colorful.Color{R: x, G: y, B: z}
+		return Color{R: a, G: b, B: c, A: d}
+	case BlendLinearRgb:
+		return LinearRgb(a, b, c, d)
 	case BlendOklab:
-		a, b, c := oklabToLrgb(x, y, z)
-		return colorful.LinearRgb(a, b, c).Clamped()
+		return Oklab(a, b, c, d) //.Clamped()
 	}
 
-	return colorful.Color{R: 0, G: 0, B: 0}
+	return Color{R: 0, G: 0, B: 0, A: 0}
 }
 
-func newLinearGradient(colors []colorful.Color, pos []float64, mode BlendMode) Gradient {
+func newLinearGradient(colors []Color, pos []float64, mode BlendMode) Gradient {
 	gradbase := linearGradient{
 		colors:     convertColors(colors, mode),
 		pos:        pos,
@@ -90,41 +77,3 @@ func newLinearGradient(colors []colorful.Color, pos []float64, mode BlendMode) G
 		dmax: pos[len(pos)-1],
 	}
 }
-
-func convertColors(colorsIn []colorful.Color, mode BlendMode) [][3]float64 {
-	colors := make([][3]float64, len(colorsIn))
-	for i, col := range colorsIn {
-		var c1, c2, c3 float64
-		switch mode {
-		case BlendLinearRgb:
-			c1, c2, c3 = col.LinearRgb()
-		case BlendLab:
-			c1, c2, c3 = col.Lab()
-		case BlendLuv:
-			c1, c2, c3 = col.Luv()
-		case BlendHcl:
-			c1, c2, c3 = col.Hcl()
-		case BlendHsv:
-			c1, c2, c3 = col.Hsv()
-		case BlendOklab:
-			lr, lg, lb := col.LinearRgb()
-			c1, c2, c3 = lrgbToOklab(lr, lg, lb)
-		case BlendRgb:
-			c1, c2, c3 = col.R, col.G, col.B
-		}
-		colors[i] = [3]float64{c1, c2, c3}
-	}
-	return colors
-}
-
-func linearInterpolate(a, b [3]float64, t float64) (x, y, z float64) {
-	x = a[0] + t*(b[0]-a[0])
-	y = a[1] + t*(b[1]-a[1])
-	z = a[2] + t*(b[2]-a[2])
-	return
-}
-
-func interpAngle(a, b, t float64) float64 {
-	delta := math.Mod(((math.Mod(b-a, 360))+540), 360) - 180
-	return math.Mod((a + t*delta + 360), 360)
-}

preset.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

preset_fn.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

preset_fn_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

preset_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

sharp.go

@@ -2,19 +2,17 @@ package colorgrad
 
 import (
 	"math"
-
-	"github.com/lucasb-eyer/go-colorful"
 )
 
 type sharpGradient struct {
-	colors []colorful.Color
+	colors []Color
 	pos    []float64
 	last   int
 	dmin   float64
 	dmax   float64
 }
 
-func (sg sharpGradient) At(t float64) colorful.Color {
+func (sg sharpGradient) At(t float64) Color {
 	if t <= sg.dmin {
 		return sg.colors[0]
 	}
@@ -24,7 +22,7 @@ func (sg sharpGradient) At(t float64) colorful.Color {
 	}
 
 	if math.IsNaN(t) {
-		return colorful.Color{R: 0, G: 0, B: 0}
+		return Color{R: 0, G: 0, B: 0, A: 0}
 	}
 
 	low := 0
@@ -54,12 +52,12 @@ func (sg sharpGradient) At(t float64) colorful.Color {
 	t = (t - p1) / (p2 - p1)
 	a := sg.colors[i]
 	b := sg.colors[low]
-	return a.BlendRgb(b, t)
+	return blendRgb(a, b, t)
 }
 
-func newSharpGradient(colorsIn []colorful.Color, dmin, dmax float64, smoothness float64) Gradient {
+func newSharpGradient(colorsIn []Color, dmin, dmax float64, smoothness float64) Gradient {
 	n := len(colorsIn)
-	colors := make([]colorful.Color, n*2)
+	colors := make([]Color, n*2)
 	i := 0
 	for _, c := range colorsIn {
 		colors[i] = c

sharp_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (

spline_test.go

@@ -1,3 +1,4 @@
+//go:build ignore
 package colorgrad
 
 import (