chroma/styles/colour.go

package styles

import (
	"fmt"
	"strconv"
	"strings"
)

// ANSI2RGB maps ANSI colour names, as supported by Chroma, to hex RGB values.
var ANSI2RGB = map[string]string{
	"#ansiblack":     "000000",
	"#ansidarkred":   "7f0000",
	"#ansidarkgreen": "007f00",
	"#ansibrown":     "7f7fe0",
	"#ansidarkblue":  "00007f",
	"#ansipurple":    "7f007f",
	"#ansiteal":      "007f7f",
	"#ansilightgray": "e5e5e5",
	// Normal
	"#ansidarkgray":  "555555",
	"#ansired":       "ff0000",
	"#ansigreen":     "00ff00",
	"#ansiyellow":    "ffff00",
	"#ansiblue":      "0000ff",
	"#ansifuchsia":   "ff00ff",
	"#ansiturquoise": "00ffff",
	"#ansiwhite":     "ffffff",
}

// Colour represents an RGB colour.
type Colour int32

// ParseColour in the forms #rgb, #rrggbb, or #ansi<colour>. Will panic
// if colour is in an invalid format.
func ParseColour(colour string) Colour {
	colour = normaliseColour(colour)
	n, err := strconv.ParseUint(colour, 16, 32)
	if err != nil {
		panic(err)
	}
	return Colour(n + 1)
}

func (c Colour) IsSet() bool { return c != 0 }

func (c Colour) String() string   { return fmt.Sprintf("#%06x", int(c-1)) }
func (c Colour) GoString() string { return fmt.Sprintf("Colour(0x%06x)", int(c-1)) }

// Red component of colour.
func (c Colour) Red() uint8 { return uint8(((c - 1) >> 16) & 0xff) }

// Green component of colour.
func (c Colour) Green() uint8 { return uint8(((c - 1) >> 8) & 0xff) }

// Blue component of colour.
func (c Colour) Blue() uint8 { return uint8((c - 1) & 0xff) }

// Distance squared between two colours.
func (c Colour) Distance(other Colour) int {
	rd := int(c.Red() - other.Red())
	gd := int(c.Green() - other.Green())
	bd := int(c.Blue() - other.Blue())
	return rd*rd + gd*gd + bd*bd
}

// Colours is an orderable set of colours.
type Colours []Colour

func (c Colours) Len() int           { return len(c) }
func (c Colours) Swap(i, j int)      { c[i], c[j] = c[j], c[i] }
func (c Colours) Less(i, j int) bool { return c[i] < c[j] }

// Convert colours to #rrggbb.
func normaliseColour(colour string) string {
	if ansi, ok := ANSI2RGB[colour]; ok {
		return ansi
	}
	if strings.HasPrefix(colour, "#") {
		colour = colour[1:]
		if len(colour) == 3 {
			return colour[0:1] + colour[0:1] + colour[1:2] + colour[1:2] + colour[2:3] + colour[2:3]
		}
	}
	return colour
}