mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-12-30 11:23:56 -05:00
ea7954f069
Close #24508 Main changes: As discussed in the issue 1. Change luminance calculation function to use [Relative Luminance](https://www.w3.org/WAI/GL/wiki/Relative_luminance) 2. Move the luminance related functions into color.go/color.js 3. Add tests for both the files (Not sure if test cases are too many now) Before (tests included by `UseLightTextOnBackground` are labels started with `##`): https://try.gitea.io/HesterG/testrepo/labels After: <img width="1307" alt="Screen Shot 2023-05-08 at 13 37 55" src="https://user-images.githubusercontent.com/17645053/236742562-fdfc3a4d-2fab-466b-9613-96f2bf96b4bc.png"> <img width="1289" alt="Screen Shot 2023-05-08 at 13 38 06" src="https://user-images.githubusercontent.com/17645053/236742570-022db68e-cec0-43bb-888a-fc54f5332cc3.png"> <img width="1299" alt="Screen Shot 2023-05-08 at 13 38 20" src="https://user-images.githubusercontent.com/17645053/236742572-9af1de45-fb7f-460b-828d-ba25fae20f51.png"> --------- Co-authored-by: silverwind <me@silverwind.io> Co-authored-by: Giteabot <teabot@gitea.io>
65 lines
2 KiB
Go
65 lines
2 KiB
Go
// Copyright 2023 The Gitea Authors. All rights reserved.
|
|
// SPDX-License-Identifier: MIT
|
|
package util
|
|
|
|
import (
|
|
"fmt"
|
|
"math"
|
|
"strconv"
|
|
"strings"
|
|
)
|
|
|
|
// Check similar implementation in web_src/js/utils/color.js and keep synchronization
|
|
|
|
// Return R, G, B values defined in reletive luminance
|
|
func getLuminanceRGB(channel float64) float64 {
|
|
sRGB := channel / 255
|
|
if sRGB <= 0.03928 {
|
|
return sRGB / 12.92
|
|
}
|
|
return math.Pow((sRGB+0.055)/1.055, 2.4)
|
|
}
|
|
|
|
// Get color as RGB values in 0..255 range from the hex color string (with or without #)
|
|
func HexToRBGColor(colorString string) (float64, float64, float64) {
|
|
hexString := colorString
|
|
if strings.HasPrefix(colorString, "#") {
|
|
hexString = colorString[1:]
|
|
}
|
|
// only support transfer of rgb, rgba, rrggbb and rrggbbaa
|
|
// if not in these formats, use default values 0, 0, 0
|
|
if len(hexString) != 3 && len(hexString) != 4 && len(hexString) != 6 && len(hexString) != 8 {
|
|
return 0, 0, 0
|
|
}
|
|
if len(hexString) == 3 || len(hexString) == 4 {
|
|
hexString = fmt.Sprintf("%c%c%c%c%c%c", hexString[0], hexString[0], hexString[1], hexString[1], hexString[2], hexString[2])
|
|
}
|
|
if len(hexString) == 8 {
|
|
hexString = hexString[0:6]
|
|
}
|
|
color, err := strconv.ParseUint(hexString, 16, 64)
|
|
if err != nil {
|
|
return 0, 0, 0
|
|
}
|
|
r := float64(uint8(0xFF & (uint32(color) >> 16)))
|
|
g := float64(uint8(0xFF & (uint32(color) >> 8)))
|
|
b := float64(uint8(0xFF & uint32(color)))
|
|
return r, g, b
|
|
}
|
|
|
|
// return luminance given RGB channels
|
|
// Reference from: https://www.w3.org/WAI/GL/wiki/Relative_luminance
|
|
func GetLuminance(r, g, b float64) float64 {
|
|
R := getLuminanceRGB(r)
|
|
G := getLuminanceRGB(g)
|
|
B := getLuminanceRGB(b)
|
|
luminance := 0.2126*R + 0.7152*G + 0.0722*B
|
|
return luminance
|
|
}
|
|
|
|
// Reference from: https://firsching.ch/github_labels.html
|
|
// In the future WCAG 3 APCA may be a better solution.
|
|
// Check if text should use light color based on RGB of background
|
|
func UseLightTextOnBackground(r, g, b float64) bool {
|
|
return GetLuminance(r, g, b) < 0.453
|
|
}
|