fixed dependencies

vendor/gonum.org/v1/plot/palette/hsva.go

@@ -0,0 +1,116 @@
+// Copyright ©2015 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Copyright ©2011-2013 The bíogo Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package palette
+
+import (
+	"image/color"
+	"math"
+)
+
+// HSVA represents a Hue/Saturation/Value/Alpha color.
+// H, S, V and A are valid within [0, 1].
+type HSVA struct {
+	H, S, V, A float64
+}
+
+// HSVAModel converts any color.Color to an HSVA color.
+var HSVAModel = color.ModelFunc(hsvaModel)
+
+func hsvaModel(c color.Color) color.Color {
+	if _, ok := c.(HSVA); ok {
+		return c
+	}
+	return rgbaToHsva(c.RGBA())
+}
+
+// Convert r, g, b, a to HSVA
+func rgbaToHsva(r, g, b, a uint32) HSVA {
+	red := float64(r)
+	blue := float64(b)
+	green := float64(g)
+
+	max := math.Max(red, green)
+	max = math.Max(max, blue)
+	min := math.Min(red, green)
+	min = math.Min(min, blue)
+	chroma := max - min
+
+	var hue float64
+	switch {
+	case chroma == 0:
+		// This should really be math.NaN() since we have a 0 length vector,
+		// but 0 seems to be the convention and it may simplify imports in
+		// dependent packages.
+		hue = 0
+	case max == red:
+		hue = math.Mod((green-blue)/chroma, 6)
+	case max == green:
+		hue = (blue-red)/chroma + 2
+	case max == blue:
+		hue = (red-green)/chroma + 4
+	}
+
+	hue /= 6
+
+	var s float64
+	if chroma != 0 {
+		s = chroma / max
+	}
+
+	return HSVA{
+		H: math.Mod(math.Mod(hue, 1)+1, 1),
+		S: s,
+		V: max / math.MaxUint16,
+		A: float64(a) / math.MaxUint16,
+	}
+}
+
+// RGBA allows HSVAColor to satisfy the color.Color interface.
+func (c HSVA) RGBA() (r, g, b, a uint32) {
+	var red, green, blue float64
+
+	a = uint32(math.MaxUint16 * c.A)
+
+	if c.V == 0 {
+		return
+	}
+
+	if c.S == 0 {
+		r, g, b = uint32(math.MaxUint16*c.V), uint32(math.MaxUint16*c.V), uint32(math.MaxUint16*c.V)
+		return
+	}
+
+	chroma := c.V * c.S
+	m := c.V - chroma
+
+	if !math.IsNaN(c.H) {
+		hue := math.Mod(c.H, 1) * 6
+		x := chroma * (1 - math.Abs(math.Mod(hue, 2)-1))
+		switch math.Floor(hue) {
+		case 0:
+			red, green = chroma, x
+		case 1:
+			red, green = x, chroma
+		case 2:
+			green, blue = chroma, x
+		case 3:
+			green, blue = x, chroma
+		case 4:
+			red, blue = x, chroma
+		case 5:
+			red, blue = chroma, x
+		}
+	} else {
+		red, green, blue = 0, 0, 0
+	}
+
+	r, g, b = uint32(math.MaxUint16*(red+m)), uint32(math.MaxUint16*(green+m)), uint32(math.MaxUint16*(blue+m))
+
+	return
+}