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-rw-r--r--modules/util/color.go42
1 files changed, 17 insertions, 25 deletions
diff --git a/modules/util/color.go b/modules/util/color.go
index 240b045c28..9c520dce78 100644
--- a/modules/util/color.go
+++ b/modules/util/color.go
@@ -4,22 +4,10 @@ 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
@@ -47,19 +35,23 @@ func HexToRBGColor(colorString string) (float64, float64, float64) {
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
+// Returns relative luminance for a SRGB color - https://en.wikipedia.org/wiki/Relative_luminance
+// Keep this in sync with web_src/js/utils/color.js
+func GetRelativeLuminance(color string) float64 {
+ r, g, b := HexToRBGColor(color)
+ return (0.2126729*r + 0.7151522*g + 0.0721750*b) / 255
}
-// 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
+func UseLightText(backgroundColor string) bool {
+ return GetRelativeLuminance(backgroundColor) < 0.453
+}
+
+// Given a background color, returns a black or white foreground color that the highest
+// contrast ratio. In the future, the APCA contrast function, or CSS `contrast-color` will be better.
+// https://github.com/color-js/color.js/blob/eb7b53f7a13bb716ec8b28c7a56f052cd599acd9/src/contrast/APCA.js#L42
+func ContrastColor(backgroundColor string) string {
+ if UseLightText(backgroundColor) {
+ return "#fff"
+ }
+ return "#000"
}