63 lines
1.2 KiB
Go
63 lines
1.2 KiB
Go
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package img
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import (
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"errors"
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"image/color"
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"regexp"
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)
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var hexColorRE = regexp.MustCompile(`^#?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})?$`)
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func HexColor(s string) (color.RGBA, error) {
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match := hexColorRE.FindStringSubmatch(s)
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if match == nil {
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return color.RGBA{}, errors.New("invalid color format")
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}
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values, err := HexToInts(match[1:]...)
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if err != nil {
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return color.RGBA{}, err
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}
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a := 255
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if len(match[4]) > 0 {
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a = values[3]
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}
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return color.RGBA{R: uint8(values[0]), G: uint8(values[1]), B: uint8(values[2]), A: uint8(a)}, nil
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}
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func MustHexColor(s string) color.RGBA {
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color, err := HexColor(s)
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if err != nil {
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panic(err)
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}
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return color
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}
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func HexToInt(s string) (int, error) {
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var i int
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for _, c := range s {
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i *= 16
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if c >= '0' && c <= '9' {
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i += int(c - '0')
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} else if c >= 'A' && c <= 'F' {
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i += int(c - 'A' + 10)
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} else if c >= 'a' && c <= 'f' {
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i += int(c - 'a' + 10)
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} else {
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return 0, errors.New("hex digit not supported")
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}
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}
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return i, nil
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}
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func HexToInts(s ...string) ([]int, error) {
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ints := make([]int, len(s))
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for i, s := range s {
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value, err := HexToInt(s)
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if err != nil {
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return nil, err
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}
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ints[i] = value
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}
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return ints, nil
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}
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