Function: erc-nicks--get-contrast

erc-nicks--get-contrast is a byte-compiled function defined in erc-nicks.el.gz.

Signature

(erc-nicks--get-contrast FG &optional BG)

Documentation

Return a float between 1 and 21 for colors FG and BG.

If FG or BG are floats, interpret them as luminance values.

Source Code

;; Defined in /usr/src/emacs/lisp/erc/erc-nicks.el.gz
(defun erc-nicks--get-contrast (fg &optional bg)
  "Return a float between 1 and 21 for colors FG and BG.
If FG or BG are floats, interpret them as luminance values."
  (let* ((lum-fg (if (numberp fg) fg (erc-nicks--get-luminance fg)))
         (lum-bg (if bg
                     (if (numberp bg) bg (erc-nicks--get-luminance bg))
                   (or erc-nicks--bg-luminance
                       (setq erc-nicks--bg-luminance
                             (erc-nicks--get-luminance erc-nicks-bg-color))))))
    (when (< lum-fg lum-bg) (cl-rotatef lum-fg lum-bg))
    (/ (+ 0.05 lum-fg) (+ 0.05 lum-bg))))