Modify luminance calculation and extract related functions into single files (#24586)

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>
This commit is contained in:
Hester Gong 2023-05-10 19:19:03 +08:00 committed by GitHub
parent 0ca5adee16
commit ea7954f069
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10 changed files with 238 additions and 81 deletions

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@ -135,17 +135,3 @@ export function toAbsoluteUrl(url) {
return `${window.location.origin}${url}`;
}
// determine if light or dark text color should be used on a given background color
// NOTE: see models/issue_label.go for similar implementation
export function useLightTextOnBackground(backgroundColor) {
if (backgroundColor[0] === '#') {
backgroundColor = backgroundColor.substring(1);
}
// Perceived brightness from: https://www.w3.org/TR/AERT/#color-contrast
// In the future WCAG 3 APCA may be a better solution.
const r = parseInt(backgroundColor.substring(0, 2), 16);
const g = parseInt(backgroundColor.substring(2, 4), 16);
const b = parseInt(backgroundColor.substring(4, 6), 16);
const brightness = (0.299 * r + 0.587 * g + 0.114 * b) / 255;
return brightness < 0.35;
}