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// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package images
import (
"encoding/hex"
"image/color"
"strings"
"github.com/pkg/errors"
)
// AddColorToPalette adds c as the first color in p if not already there.
// Note that it does no additional checks, so callers must make sure
// that the palette is valid for the relevant format.
func AddColorToPalette(c color.Color, p color.Palette) color.Palette {
var found bool
for _, cc := range p {
if c == cc {
found = true
break
}
}
if !found {
p = append(color.Palette{c}, p...)
}
return p
}
// ReplaceColorInPalette will replace the color in palette p closest to c in Euclidean
// R,G,B,A space with c.
func ReplaceColorInPalette(c color.Color, p color.Palette) {
p[p.Index(c)] = c
}
func hexStringToColor(s string) (color.Color, error) {
s = strings.TrimPrefix(s, "#")
if len(s) != 3 && len(s) != 6 {
return nil, errors.Errorf("invalid color code: %q", s)
}
s = strings.ToLower(s)
if len(s) == 3 {
var v string
for _, r := range s {
v += string(r) + string(r)
}
s = v
}
// Standard colors.
if s == "ffffff" {
return color.White, nil
}
if s == "000000" {
return color.Black, nil
}
// Set Alfa to white.
s += "ff"
b, err := hex.DecodeString(s)
if err != nil {
return nil, err
}
return color.RGBA{b[0], b[1], b[2], b[3]}, nil
}
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