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color.lua
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color.lua
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-- The MIT License (MIT)
--
-- Copyright (c) 2022 Leon Heidelbach
--
-- Permission is hereby granted, free of charge, to any person obtaining a copy
-- of this software and associated documentation files (the "Software"), to deal
-- in the Software without restriction, including without limitation the rights
-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-- copies of the Software, and to permit persons to whom the Software is
-- furnished to do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be included in all
-- copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-- SOFTWARE.
local M = {}
-- Convert a hex color value to RGB
-- @param hex: The hex color value
-- @return r: Red (0-255)
-- @return g: Green (0-255)
-- @return b: Blue (0-255)
M.hex2rgb = function(hex)
local hash = string.sub(hex, 1, 1) == "#"
if string.len(hex) ~= (7 - (hash and 0 or 1)) then
return nil
end
local r = tonumber(hex:sub(2 - (hash and 0 or 1), 3 - (hash and 0 or 1)), 16)
local g = tonumber(hex:sub(4 - (hash and 0 or 1), 5 - (hash and 0 or 1)), 16)
local b = tonumber(hex:sub(6 - (hash and 0 or 1), 7 - (hash and 0 or 1)), 16)
return r, g, b
end
-- Convert an RGB color value to hex
-- @param r: Red (0-255)
-- @param g: Green (0-255)
-- @param b: Blue (0-255)
-- @return The hexadecimal string representation of the color
M.rgb2hex = function(r, g, b)
return string.format("#%02x%02x%02x", math.floor(r), math.floor(g), math.floor(b))
end
-- Helper function to convert a HSL color value to RGB
-- Not to be used directly, use M.hsl2rgb instead
M.hsl2rgb_helper = function(p, q, a)
if a < 0 then
a = a + 6
end
if a >= 6 then
a = a - 6
end
if a < 1 then
return (q - p) * a + p
elseif a < 3 then
return q
elseif a < 4 then
return (q - p) * (4 - a) + p
else
return p
end
end
-- Convert a HSL color value to RGB
-- @param h: Hue (0-360)
-- @param s: Saturation (0-1)
-- @param l: Lightness (0-1)
-- @return r: Red (0-255)
-- @return g: Green (0-255)
-- @return b: Blue (0-255)
M.hsl2rgb = function(h, s, l)
local t1, t2, r, g, b
h = h / 60
if l <= 0.5 then
t2 = l * (s + 1)
else
t2 = l + s - (l * s)
end
t1 = l * 2 - t2
r = M.hsl2rgb_helper(t1, t2, h + 2) * 255
g = M.hsl2rgb_helper(t1, t2, h) * 255
b = M.hsl2rgb_helper(t1, t2, h - 2) * 255
return r, g, b
end
-- Convert an RGB color value to HSL
-- @param r Red (0-255)
-- @param g Green (0-255)
-- @param b Blue (0-255)
-- @return h Hue (0-360)
-- @return s Saturation (0-1)
-- @return l Lightness (0-1)
M.rgb2hsl = function(r, g, b)
local min, max, l, s, maxcolor, h
r, g, b = r / 255, g / 255, b / 255
min = math.min(r, g, b)
max = math.max(r, g, b)
maxcolor = 1 + (max == b and 2 or (max == g and 1 or 0))
if maxcolor == 1 then
h = (g - b) / (max - min)
elseif maxcolor == 2 then
h = 2 + (b - r) / (max - min)
elseif maxcolor == 3 then
h = 4 + (r - g) / (max - min)
end
if not rawequal(type(h), "number") then
h = 0
end
h = h * 60
if h < 0 then
h = h + 360
end
l = (min + max) / 2
if min == max then
s = 0
else
if l < 0.5 then
s = (max - min) / (max + min)
else
s = (max - min) / (2 - max - min)
end
end
return h, s, l
end
-- Convert a hex color value to HSL
-- @param hex: The hex color value
-- @param h: Hue (0-360)
-- @param s: Saturation (0-1)
-- @param l: Lightness (0-1)
M.hex2hsl = function(hex)
local r, g, b = M.hex2rgb(hex)
return M.rgb2hsl(r, g, b)
end
-- Convert a HSL color value to hex
-- @param h: Hue (0-360)
-- @param s: Saturation (0-1)
-- @param l: Lightness (0-1)
-- @returns hex color value
M.hsl2hex = function(h, s, l)
local r, g, b = M.hsl2rgb(h, s, l)
return M.rgb2hex(r, g, b)
end
-- Change the hue of a color by a given amount
-- @param hex The hex color value
-- @param amount The amount to change the hue.
-- Negative values decrease the hue, positive values increase it.
-- @return The hex color value
M.change_hex_hue = function(hex, percent)
local h, s, l = M.hex2hsl(hex)
h = h + (percent / 100)
if h > 360 then
h = 360
end
if h < 0 then
h = 0
end
return M.hsl2hex(h, s, l)
end
-- Desaturate or saturate a color by a given percentage
-- @param hex The hex color value
-- @param percent The percentage to desaturate or saturate the color.
-- Negative values desaturate the color, positive values saturate it
-- @return The hex color value
M.change_hex_saturation = function(hex, percent)
local h, s, l = M.hex2hsl(hex)
s = s + (percent / 100)
if s > 1 then
s = 1
end
if s < 0 then
s = 0
end
return M.hsl2hex(h, s, l)
end
-- Lighten or darken a color by a given percentage
-- @param hex The hex color value
-- @param percent The percentage to lighten or darken the color.
-- Negative values darken the color, positive values lighten it
-- @return The hex color value
M.change_hex_lightness = function(hex, percent)
local h, s, l = M.hex2hsl(hex)
l = l + (percent / 100)
if l > 1 then
l = 1
end
if l < 0 then
l = 0
end
return M.hsl2hex(h, s, l)
end
-- Compute a gradient between two colors
-- @param hex1 The first hex color value
-- @param hex2 The second hex color value
-- @param steps The number of steps to compute
-- @return A table of hex color values
M.compute_gradient = function(hex1, hex2, steps)
local h1, s1, l1 = M.hex2hsl(hex1)
local h2, s2, l2 = M.hex2hsl(hex2)
local h, s, l
local h_step = (h2 - h1) / (steps - 1)
local s_step = (s2 - s1) / (steps - 1)
local l_step = (l2 - l1) / (steps - 1)
local gradient = {}
for i = 0, steps - 1 do
h = h1 + (h_step * i)
s = s1 + (s_step * i)
l = l1 + (l_step * i)
gradient[i + 1] = M.hsl2hex(h, s, l)
end
return gradient
end
return M