fixed dependencies

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

@@ -0,0 +1,188 @@
+// 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 ©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 provides basic color palette handling.
+package palette // import "gonum.org/v1/plot/palette"
+
+import (
+	"errors"
+	"image/color"
+	"math"
+)
+
+// Palette is a collection of colors ordered into a palette.
+type Palette interface {
+	Colors() []color.Color
+}
+
+// DivergingPalette is a collection of colors ordered into a palette with
+// a critical class or break in the middle of the color range.
+type DivergingPalette interface {
+	Palette
+
+	// CriticalIndex returns the indices of the lightest
+	// (median) color or colors in the DivergingPalette.
+	// The low and high index values will be equal when
+	// there is a single median color.
+	CriticalIndex() (low, high int)
+}
+
+// A ColorMap maps scalar values to colors.
+type ColorMap interface {
+	// At returns the color associated with the given value.
+	// If the value is not between Max() and Min(), an error is returned.
+	At(float64) (color.Color, error)
+
+	// Max returns the current maximum value of the ColorMap.
+	Max() float64
+
+	// SetMax sets the maximum value of the ColorMap.
+	SetMax(float64)
+
+	// Min returns the current minimum value of the ColorMap.
+	Min() float64
+
+	// SetMin sets the minimum value of the ColorMap.
+	SetMin(float64)
+
+	// Alpha returns the opacity value of the ColorMap.
+	Alpha() float64
+
+	// SetAlpha sets the opacity value of the ColorMap. Zero is transparent
+	// and one is completely opaque. The default value of alpha should be
+	// expected to be one. The function should be expected to panic
+	// if alpha is not between zero and one.
+	SetAlpha(float64)
+
+	// Palette creates a Palette with the specified number of colors
+	// from the ColorMap.
+	Palette(colors int) Palette
+}
+
+// DivergingColorMap maps scalar values to colors that diverge
+// from a central value.
+type DivergingColorMap interface {
+	ColorMap
+
+	// SetConvergePoint sets the value where the diverging colors
+	// should meet. The default value should be expected to be
+	// (Min() + Max()) / 2. It should be expected that calling either
+	// SetMax() or SetMin() will set a new default value, so for a
+	// custom convergence point this function should be called after
+	// SetMax() and SetMin(). The function should be expected to panic
+	// if the value is not between Min() and Max().
+	SetConvergePoint(float64)
+
+	// ConvergePoint returns the value where the diverging colors meet.
+	ConvergePoint() float64
+}
+
+// Hue represents a hue in HSV color space. Valid Hues are within [0, 1].
+type Hue float64
+
+const (
+	Red Hue = Hue(iota) / 6
+	Yellow
+	Green
+	Cyan
+	Blue
+	Magenta
+)
+
+var (
+	// ErrOverflow is the error returned by ColorMaps when the specified
+	// value is greater than the maximum value.
+	ErrOverflow = errors.New("palette: specified value > maximum")
+
+	// ErrUnderflow is the error returned by ColorMaps when the specified
+	// value is less than the minimum value.
+	ErrUnderflow = errors.New("palette: specified value < minimum")
+
+	// ErrNaN is the error returned by ColorMaps when the specified
+	// value is NaN.
+	ErrNaN = errors.New("palette: specified value == NaN")
+)
+
+// Complement returns the complementary hue of a Hue.
+func (h Hue) Complement() Hue { return Hue(math.Mod(float64(h+0.5), 1)) }
+
+type palette []color.Color
+
+func (p palette) Colors() []color.Color { return p }
+
+type divergingPalette []color.Color
+
+func (p divergingPalette) Colors() []color.Color { return p }
+
+func (d divergingPalette) CriticalIndex() (low, high int) {
+	l := len(d)
+	return (l - 1) / 2, l / 2
+}
+
+// Rainbow returns a rainbow palette with the specified number of colors, saturation
+// value and alpha, and hues in the specified range.
+func Rainbow(colors int, start, end Hue, sat, val, alpha float64) Palette {
+	p := make(palette, colors)
+	hd := float64(end-start) / float64(colors-1)
+	c := HSVA{V: val, S: sat, A: alpha}
+	for i := range p {
+		c.H = float64(start) + float64(i)*hd
+		p[i] = color.NRGBAModel.Convert(c)
+	}
+
+	return p
+}
+
+// Heat returns a red to yellow palette with the specified number of colors and alpha.
+func Heat(colors int, alpha float64) Palette {
+	p := make(palette, colors)
+	j := colors / 4
+	i := colors - j
+
+	hd := float64(Yellow-Red) / float64(i-1)
+	c := HSVA{V: 1, S: 1, A: alpha}
+	for k := range p[:i] {
+		c.H = float64(Red) + float64(k)*hd
+		p[k] = color.NRGBAModel.Convert(c)
+	}
+	if j == 0 {
+		return p
+	}
+
+	c.H = float64(Yellow)
+	start, end := 1-1/(2*float64(j)), 1/(2*float64(j))
+	c.S = start
+	sd := (end - start) / float64(j-1)
+	for k := range p[i:] {
+		c.S = start + float64(k)*sd
+		p[k+i] = color.NRGBAModel.Convert(c)
+	}
+
+	return p
+}
+
+// Radial return a diverging palette across the specified range, through white and with
+// the specified alpha.
+func Radial(colors int, start, end Hue, alpha float64) DivergingPalette {
+	p := make(divergingPalette, colors)
+	h := colors / 2
+	c := HSVA{V: 1, A: alpha}
+	ds := 0.5 / float64(h)
+	for i := range p[:h] {
+		c.H = float64(start)
+		c.S = 0.5 - float64(i)*ds
+		p[i] = color.NRGBAModel.Convert(c)
+		c.H = float64(end)
+		p[len(p)-1-i] = color.NRGBAModel.Convert(c)
+	}
+	if colors%2 != 0 {
+		p[colors/2] = color.NRGBA{0xff, 0xff, 0xff, byte(math.MaxUint8 * alpha)}
+	}
+
+	return p
+}