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a4028112e3
Which returns the most dominant colors of an image using a simple histogram method. Fixes #10307
91 lines
2.1 KiB
Go
91 lines
2.1 KiB
Go
// Copyright 2019 The Hugo Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package images
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import (
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"encoding/hex"
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"fmt"
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"image/color"
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"strings"
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)
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// AddColorToPalette adds c as the first color in p if not already there.
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// Note that it does no additional checks, so callers must make sure
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// that the palette is valid for the relevant format.
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func AddColorToPalette(c color.Color, p color.Palette) color.Palette {
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var found bool
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for _, cc := range p {
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if c == cc {
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found = true
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break
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}
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}
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if !found {
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p = append(color.Palette{c}, p...)
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}
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return p
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}
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// ReplaceColorInPalette will replace the color in palette p closest to c in Euclidean
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// R,G,B,A space with c.
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func ReplaceColorInPalette(c color.Color, p color.Palette) {
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p[p.Index(c)] = c
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}
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// ColorToHexString converts a color to a hex string.
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func ColorToHexString(c color.Color) string {
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r, g, b, a := c.RGBA()
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rgba := color.RGBA{uint8(r), uint8(g), uint8(b), uint8(a)}
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return fmt.Sprintf("#%.2x%.2x%.2x", rgba.R, rgba.G, rgba.B)
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}
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func hexStringToColor(s string) (color.Color, error) {
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s = strings.TrimPrefix(s, "#")
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if len(s) != 3 && len(s) != 6 {
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return nil, fmt.Errorf("invalid color code: %q", s)
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}
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s = strings.ToLower(s)
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if len(s) == 3 {
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var v string
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for _, r := range s {
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v += string(r) + string(r)
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}
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s = v
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}
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// Standard colors.
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if s == "ffffff" {
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return color.White, nil
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}
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if s == "000000" {
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return color.Black, nil
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}
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// Set Alfa to white.
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s += "ff"
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b, err := hex.DecodeString(s)
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if err != nil {
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return nil, err
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}
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return color.RGBA{b[0], b[1], b[2], b[3]}, nil
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}
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