6543/go-hexcolor
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no regex - it's faster

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This commit is contained in:
6543 2020-09-10 22:18:29 +02:00
parent d25019851f
commit c32969ffb1
Signed by: 6543
GPG Key ID: A1CA74D27FD13271
1 changed files with 14 additions and 38 deletions
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52
hexcolor.go
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@ -3,7 +3,6 @@ package go_hexcolor
import (
"fmt"
"image/color"
"regexp"
"strconv"
"strings"
)
@ -14,35 +13,20 @@ type HexColor struct {
hex string
}

// The compiled regular expression used to test the validity of a color statement
var (
hexDefault *regexp.Regexp
hexShort *regexp.Regexp
)

// The raw regular expression string used for testing the validity
const (
hexDefaultRaw string = `[0-9a-f]{6}`
hexShortRaw string = `[0-9a-f]{3}`
)

func init() {
hexDefault = regexp.MustCompile("^" + hexDefaultRaw + "$")
hexShort = regexp.MustCompile("^" + hexShortRaw + "$")
}

// NewHexColor convert string into a HexColor
func NewHexColor(hc string) (*HexColor, error) {
c := &HexColor{original: hc}
hc = strings.TrimLeft(strings.ToLower(hc), "#")

if hexDefault.MatchString(hc) {
c.hex = hc
return c, nil
}
if hexShort.MatchString(hc) {
c.hex = hc[:1] + hc[:1] + hc[1:][:1] + hc[1:][:1] + hc[2:] + hc[2:]
return c, nil
if _, err := strconv.ParseUint(hc, 16, 24); err == nil {
if len(hc) == 6 {
c.hex = hc
return c, nil
}
if len(hc) == 3 {
c.hex = hc[:1] + hc[:1] + hc[1:][:1] + hc[1:][:1] + hc[2:] + hc[2:]
return c, nil
}
}

// handle named colors
@ -63,22 +47,14 @@ func (c *HexColor) ToRGBA() (*color.RGBA, error) {
if c == nil {
return nil, nil
}
rr, err := strconv.ParseUint(c.hex[:2], 16, 8)
if err != nil {
return nil, err
}
gg, err := strconv.ParseUint(c.hex[2:][:2], 16, 8)
if err != nil {
return nil, err
}
bb, err := strconv.ParseUint(c.hex[4:], 16, 8)
if err != nil {
var r, g, b uint8
if _, err := fmt.Sscanf(c.hex, "%2x%2x%2x", &r, &g, &b); err != nil {
return nil, err
}
return &color.RGBA{
R: uint8(rr),
G: uint8(gg),
B: uint8(bb),
R: r,
G: g,
B: b,
A: 0xff,
}, nil
}