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author | Hester Gong <hestergong@gmail.com> | 2023-05-10 19:19:03 +0800 |
---|---|---|
committer | GitHub <noreply@github.com> | 2023-05-10 11:19:03 +0000 |
commit | ea7954f069bf8bcb87d520f8aab0a80b0768590d (patch) | |
tree | f5edc566c9dbafa3507ed8ef3ffaa32944f80797 /modules/util/color.go | |
parent | 0ca5adee16a9de0fb0bd410aa841eeeda3372e23 (diff) | |
download | gitea-ea7954f069bf8bcb87d520f8aab0a80b0768590d.tar.gz gitea-ea7954f069bf8bcb87d520f8aab0a80b0768590d.zip |
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>
Diffstat (limited to 'modules/util/color.go')
-rw-r--r-- | modules/util/color.go | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/modules/util/color.go b/modules/util/color.go new file mode 100644 index 0000000000..240b045c28 --- /dev/null +++ b/modules/util/color.go @@ -0,0 +1,65 @@ +// 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 +} |