fastpastebin/vendor/github.com/alecthomas/chroma/colour.go

165 lines
4.5 KiB
Go

package chroma
import (
"fmt"
"math"
"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",
// Aliases without the "ansi" prefix, because...why?
"#black": "000000",
"#darkred": "7f0000",
"#darkgreen": "007f00",
"#brown": "7f7fe0",
"#darkblue": "00007f",
"#purple": "7f007f",
"#teal": "007f7f",
"#lightgray": "e5e5e5",
// Normal
"#darkgray": "555555",
"#red": "ff0000",
"#green": "00ff00",
"#yellow": "ffff00",
"#blue": "0000ff",
"#fuchsia": "ff00ff",
"#turquoise": "00ffff",
"#white": "ffffff",
}
// Colour represents an RGB colour.
type Colour int32
// NewColour creates a Colour directly from RGB values.
func NewColour(r, g, b uint8) Colour {
return ParseColour(fmt.Sprintf("%02x%02x%02x", r, g, b))
}
// Distance between this colour and another.
//
// This uses the approach described here (https://www.compuphase.com/cmetric.htm).
// This is not as accurate as LAB, et. al. but is *vastly* simpler and sufficient for our needs.
func (c Colour) Distance(e2 Colour) float64 {
ar, ag, ab := int64(c.Red()), int64(c.Green()), int64(c.Blue())
br, bg, bb := int64(e2.Red()), int64(e2.Green()), int64(e2.Blue())
rmean := (ar + br) / 2
r := ar - br
g := ag - bg
b := ab - bb
return math.Sqrt(float64((((512 + rmean) * r * r) >> 8) + 4*g*g + (((767 - rmean) * b * b) >> 8)))
}
// Brighten returns a copy of this colour with its brightness adjusted.
//
// If factor is negative, the colour is darkened.
//
// Uses approach described here (http://www.pvladov.com/2012/09/make-color-lighter-or-darker.html).
func (c Colour) Brighten(factor float64) Colour {
r := float64(c.Red())
g := float64(c.Green())
b := float64(c.Blue())
if factor < 0 {
factor++
r *= factor
g *= factor
b *= factor
} else {
r = (255-r)*factor + r
g = (255-g)*factor + g
b = (255-b)*factor + b
}
return NewColour(uint8(r), uint8(g), uint8(b))
}
// BrightenOrDarken brightens a colour if it is < 0.5 brighteness or darkens if > 0.5 brightness.
func (c Colour) BrightenOrDarken(factor float64) Colour {
if c.Brightness() < 0.5 {
return c.Brighten(factor)
}
return c.Brighten(-factor)
}
// Brightness of the colour (roughly) in the range 0.0 to 1.0
func (c Colour) Brightness() float64 {
return (float64(c.Red()) + float64(c.Green()) + float64(c.Blue())) / 255.0 / 3.0
}
// ParseColour in the forms #rgb, #rrggbb, #ansi<colour>, or #<colour>.
// Will return an "unset" colour if invalid.
func ParseColour(colour string) Colour {
colour = normaliseColour(colour)
n, err := strconv.ParseUint(colour, 16, 32)
if err != nil {
return 0
}
return Colour(n + 1)
}
// MustParseColour is like ParseColour except it panics if the colour is invalid.
//
// Will panic if colour is in an invalid format.
func MustParseColour(colour string) Colour {
parsed := ParseColour(colour)
if !parsed.IsSet() {
panic(fmt.Errorf("invalid colour %q", colour))
}
return parsed
}
// IsSet returns true if the colour is set.
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) }
// 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
}