Emacs: Convert CSS Color, RGB to HSL 🚀

By Xah Lee. Date: . Last updated: .

Command to Convert RGB Color to HSL

Here's a command that convert CSS RGB hexadecimal syntax to HSL.

put this in your Emacs Init File:

(defun xah-css-normalize-number-scale (Val RangeMax)
  "Scale Val from range [0, RangeMax] to [0, 1]
The arguments can be int or float.
Return value is float.

URL `http://xahlee.info/emacs/emacs/emacs_css_color_rgb_to_hsl.html'
Version: 2016-07-19 2024-03-24"
  (/ (float Val) (float RangeMax)))

(defun xah-css-convert-color-hex-to-vec (Rrggbb)
  "Convert color Rrggbb from 6-digit RGB string to a elisp vector [r g b], where the values are from 0 to 1.
e.g. 00ffcc becomes [0.0 1.0 0.8]

Note: arguments is a string and must NOT start with #.

URL `http://xahlee.info/emacs/emacs/emacs_css_color_rgb_to_hsl.html'
Version: 2016-07-19 2023-05-13 2024-03-24"
   (xah-css-normalize-number-scale (string-to-number (substring Rrggbb 0 2) 16) 255)
   (xah-css-normalize-number-scale (string-to-number (substring Rrggbb 2 4) 16) 255)
   (xah-css-normalize-number-scale (string-to-number (substring Rrggbb 4) 16) 255)))

(defun xah-css-hex-to-hsl-color (HexStr)
  "Convert HexStr color to CSS HSL format.
Return a string. e.g. ffefd5 becomes hsl(37,100%,91%)
Note: The input string must NOT start with #.

URL `http://xahlee.info/emacs/emacs/emacs_css_color_rgb_to_hsl.html'
Version: 2016-07-19 2023-05-13 2024-03-24"
  (let* (
         (xcolorVec (xah-css-convert-color-hex-to-vec HexStr))
         (xR (elt xcolorVec 0))
         (xG (elt xcolorVec 1))
         (xB (elt xcolorVec 2))
         (xhsl (color-rgb-to-hsl xR xG xB))
         (xH (elt xhsl 0))
         (xS (elt xhsl 1))
         (xL (elt xhsl 2)))
    (format "hsl(%d,%d%%,%d%%)" (* xH 360) (* xS 100) (* xL 100))))

(defun xah-css-hex-color-to-hsl ()
  "Convert color spec under cursor from CSS 6-digit RGB to CSS HSL format.
 e.g. #ffefd5 becomes hsl(37,100%,91%)

URL `http://xahlee.info/emacs/emacs/emacs_css_color_rgb_to_hsl.html'
Version: 2016-07-19 2024-03-24"
  (let (xp1 xp2 xcurrentWord)
    (seq-setq (xp1 xp2) (xah-get-pos-of-glyphs))
    (setq xcurrentWord (buffer-substring-no-properties xp1 xp2))
    (if (string-match "[a-fA-F0-9]\\{6\\}" xcurrentWord)
          (delete-region xp1 xp2)
          (when (eq (char-before) ?#)
            (delete-char -1))
          (insert (xah-css-hex-to-hsl-color xcurrentWord)))
        (user-error "The current word 「%s」 is not of the form #rrggbb." xcurrentWord)))))

requires package Emacs: xah-get-thing.el

Emacs, CSS Color Topics