Initial Commit

lua/skift/utils/hsl.lua

@@ -0,0 +1,71 @@
+-- https://github.com/EmmanuelOga/columns/blob/master/utils/color.lua
+
+local M = {}
+
+--- Converts an HSL color value to RGB. Conversion formula
+--- adapted from http://en.wikipedia.org/wiki/HSL_color_space.
+--- Assumes h, s, and l are contained in the set [0, 1] and
+--- returns r, g, and b in the set [0, 255].
+---
+--- @param h number      The hue
+--- @param s number      The saturation
+--- @param l number      The lightness
+--- @return number, number, number     # The RGB representation
+function M.hslToRgb(h, s, l)
+    --- @type number, number, number
+    local r, g, b
+
+    if s == 0 then
+        r, g, b = l, l, l -- achromatic
+    else
+        --- @param p number
+        --- @param q number
+        --- @param t number
+        local function hue2rgb(p, q, t)
+            if t < 0 then
+                t = t + 1
+            end
+            if t > 1 then
+                t = t - 1
+            end
+            if t < 1 / 6 then
+                return p + (q - p) * 6 * t
+            end
+            if t < 1 / 2 then
+                return q
+            end
+            if t < 2 / 3 then
+                return p + (q - p) * (2 / 3 - t) * 6
+            end
+            return p
+        end
+
+        --- @type number
+        local q
+        if l < 0.5 then
+            q = l * (1 + s)
+        else
+            q = l + s - l * s
+        end
+        local p = 2 * l - q
+
+        r = hue2rgb(p, q, h + 1 / 3)
+        g = hue2rgb(p, q, h)
+        b = hue2rgb(p, q, h - 1 / 3)
+    end
+
+    return r * 255, g * 255, b * 255
+end
+
+--- Converts an HSL color value to RGB in Hex representation.
+--- @param  h number   The hue
+--- @param  s number   The saturation
+--- @param  l number   The lightness
+--- @return   string   # The hex representation
+function M.hslToHex(h, s, l)
+    local r, g, b = M.hslToRgb(h / 360, s / 100, l / 100)
+
+    return string.format("#%02x%02x%02x", r, g, b)
+end
+
+return M