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package colors
import (
"fmt"
"math"
"regexp"
"strconv"
"strings"
)
const (
rgbString = "rgb(%d,%d,%d)"
rgbCaptureRegexString = "^rgb\\(\\s*(0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])\\s*,\\s*(0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])\\s*,\\s*(0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])\\s*\\)$"
rgbCaptureRegexPercentString = "^rgb\\(\\s*(0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%\\s*,\\s*(0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%\\s*,\\s*(0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%\\s*\\)$"
)
var (
rgbCaptureRegex = regexp.MustCompile(rgbCaptureRegexString)
rgbCapturePercentRegex = regexp.MustCompile(rgbCaptureRegexPercentString)
)
// RGBColor represents an RGB color
type RGBColor struct {
R uint8
G uint8
B uint8
}
// ParseRGB validates an parses the provided string into an RGBColor object
// supports both RGB 255 and RGB as percentages
func ParseRGB(s string) (*RGBColor, error) {
s = strings.ToLower(s)
var isPercent bool
vals := rgbCaptureRegex.FindAllStringSubmatch(s, -1)
if vals == nil || len(vals) == 0 || len(vals[0]) == 0 {
vals = rgbCapturePercentRegex.FindAllStringSubmatch(s, -1)
if vals == nil || len(vals) == 0 || len(vals[0]) == 0 {
return nil, ErrBadColor
}
isPercent = true
}
r, _ := strconv.ParseUint(vals[0][1], 10, 8)
g, _ := strconv.ParseUint(vals[0][2], 10, 8)
b, _ := strconv.ParseUint(vals[0][3], 10, 8)
if isPercent {
r = uint64(math.Floor(float64(r)/100*255 + .5))
g = uint64(math.Floor(float64(g)/100*255 + .5))
b = uint64(math.Floor(float64(b)/100*255 + .5))
}
return &RGBColor{R: uint8(r), G: uint8(g), B: uint8(b)}, nil
}
// RGB validates and returns a new RGBColor object from the provided r, g, b values
func RGB(r, g, b uint8) (*RGBColor, error) {
return &RGBColor{R: r, G: g, B: b}, nil
}
// String returns the string representation on the RGBColor
func (c *RGBColor) String() string {
return fmt.Sprintf(rgbString, c.R, c.G, c.B)
}
// ToHEX converts the RGBColor to a HEXColor
func (c *RGBColor) ToHEX() *HEXColor {
return &HEXColor{hex: fmt.Sprintf("#%02x%02x%02x", c.R, c.G, c.B)}
}
// ToRGB converts the RGBColor to an RGBColor
// it's here to satisfy the Color interface
func (c *RGBColor) ToRGB() *RGBColor {
return c
}
// ToRGBA converts the RGBColor to an RGBAColor
func (c *RGBColor) ToRGBA() *RGBAColor {
return &RGBAColor{R: c.R, G: c.G, B: c.B, A: 1}
}
// IsLight returns whether the color is perceived to be a light color
func (c *RGBColor) IsLight() bool {
r := float64(c.R)
g := float64(c.G)
b := float64(c.B)
hsp := math.Sqrt(0.299*math.Pow(r, 2) + 0.587*math.Pow(g, 2) + 0.114*math.Pow(b, 2))
return hsp > 130
}
// IsDark returns whether the color is perceived to be a dark color
func (c *RGBColor) IsDark() bool {
return !c.IsLight()
}
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