diff options
Diffstat (limited to 'modules/util/color.go')
-rw-r--r-- | modules/util/color.go | 42 |
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" } |