Change Emacs Mode-Line color based on major-mode

Question

I like to see if there is a way to change the mode-link foreground and background color base on the major-mode,

I was thinking to add the logic in the

(add-hook 'after-change-major-mode-hook

But, I do not have all the emacs lisp experience to make such change. Here is the logic:

switch major-mode:
case "emacs-lisp-mode":
  (set-face-foreground 'mode-line "ivory")
  (set-face-background 'mode-line "DarkOrange2")
case "ruby-mode":
  (set-face-foreground 'mode-line "white")
  (set-face-background 'mode-line "red")
...
default:
  (set-face-foreground 'mode-line "black")
  (set-face-background 'mode-line "white")
end switch

Many thanks in advance!.

Answer 1

You probably want something like:

(add-hook 'emacs-lisp-mode-hook
          (lambda ()
            (face-remap-add-relative
             'mode-line '((:foreground "ivory" :background "DarkOrange2") mode-line))))

You might want to use face-remap for the mode-line-inactive face as well.

Answer 2

"The logic" you are talking about is something like this:

(add-hook 'after-change-major-mode-hook 'my-set-mode-line-colors)
(defvar my-mode-line-colors
  '((emacs-lisp-mode :foreground "ivory" :background "DarkOrange2")
    (ruby-mode :foreground "white" :background "red")))
(defun my-set-mode-line-colors ()
  (face-remap-add-relative
   'mode-line (list (or (cdr (assq major-mode my-mode-line-colors))
                        '(:foreground "black" :background "white"))
                    'mode-line)))

Alternatively, you can do that from mode-specific hooks, as suggested by Stefan.