palette

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
}

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
}

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)
}

type HSVA struct {
	H, S, V, A float64
}

type Hue float64

type Palette interface {
	Colors() []color.Color
}