first commit

lua/avante/diff/colors.lua

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+local M = {}
+
+local bit = require("bit")
+local rshift, band = bit.rshift, bit.band
+
+--- Returns a table containing the RGB values encoded inside 24 least
+--- significant bits of the number @rgb_24bit
+---
+--@param rgb_24bit (number) 24-bit RGB value
+--@returns (table) with keys 'r', 'g', 'b' in [0,255]
+local function decode_24bit_rgb(rgb_24bit)
+  vim.validate({ rgb_24bit = { rgb_24bit, "n", true } })
+  local r = band(rshift(rgb_24bit, 16), 255)
+  local g = band(rshift(rgb_24bit, 8), 255)
+  local b = band(rgb_24bit, 255)
+  return { r = r, g = g, b = b }
+end
+
+local function alter(attr, percent)
+  return math.floor(attr * (100 + percent) / 100)
+end
+
+---@source https://stackoverflow.com/q/5560248
+---@see: https://stackoverflow.com/a/37797380
+---Darken a specified hex color
+---@param color string
+---@param percent number
+---@return string
+function M.shade_color(color, percent)
+  local rgb = decode_24bit_rgb(color)
+  if not rgb.r or not rgb.g or not rgb.b then
+    return "NONE"
+  end
+  local r, g, b = alter(rgb.r, percent), alter(rgb.g, percent), alter(rgb.b, percent)
+  r, g, b = math.min(r, 255), math.min(g, 255), math.min(b, 255)
+  return string.format("#%02x%02x%02x", r, g, b)
+end
+
+return M