67 lines
1.7 KiB
Go
67 lines
1.7 KiB
Go
|
package zntg
|
||
|
|
|
||
|
|
import (
|
||
|
|
"errors"
|
||
|
|
"image/color"
|
||
|
|
"regexp"
|
||
|
|
)
|
||
|
|
|
||
|
|
var hexColorRE = regexp.MustCompile(`^#?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})?$`)
|
||
|
|
|
||
|
|
// HexColor parses hexadecimal string s and returns the RGBA color. Accepted are 3 or 4 components (R, G, B, A) following an optional hash character '#'.
|
||
|
|
func HexColor(s string) (color.RGBA, error) {
|
||
|
|
match := hexColorRE.FindStringSubmatch(s)
|
||
|
|
if match == nil {
|
||
|
|
return color.RGBA{}, errors.New("invalid color format")
|
||
|
|
}
|
||
|
|
values, err := HexToInts(match[1:]...)
|
||
|
|
if err != nil {
|
||
|
|
return color.RGBA{}, err
|
||
|
|
}
|
||
|
|
a := 255
|
||
|
|
if len(match[4]) > 0 {
|
||
|
|
a = values[3]
|
||
|
|
}
|
||
|
|
return color.RGBA{R: uint8(values[0]), G: uint8(values[1]), B: uint8(values[2]), A: uint8(a)}, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// HexToInt tries to convert a string with hexadecimal characters to an integer.
|
||
|
|
func HexToInt(s string) (int, error) {
|
||
|
|
var i int
|
||
|
|
for _, c := range s {
|
||
|
|
i *= 16
|
||
|
|
if c >= '0' && c <= '9' {
|
||
|
|
i += int(c - '0')
|
||
|
|
} else if c >= 'A' && c <= 'F' {
|
||
|
|
i += int(c - 'A' + 10)
|
||
|
|
} else if c >= 'a' && c <= 'f' {
|
||
|
|
i += int(c - 'a' + 10)
|
||
|
|
} else {
|
||
|
|
return 0, errors.New("hex digit not supported")
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return i, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// HexToInts tries to convert multiple strings with hexadecimal characters to a slice of integers.
|
||
|
|
func HexToInts(s ...string) ([]int, error) {
|
||
|
|
ints := make([]int, len(s))
|
||
|
|
for i, s := range s {
|
||
|
|
value, err := HexToInt(s)
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
ints[i] = value
|
||
|
|
}
|
||
|
|
return ints, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// MustHexColor parses hexadecimal string s and returns the RGBA color. If the conversion fails it panics.
|
||
|
|
func MustHexColor(s string) color.RGBA {
|
||
|
|
color, err := HexColor(s)
|
||
|
|
if err != nil {
|
||
|
|
panic(err)
|
||
|
|
}
|
||
|
|
return color
|
||
|
|
}
|