Re: Fontify Hex colors

[Andreas Politz]

Sébastien Vauban <wxhgmqzgwmuf@spammotel.com> writes:

> Hi,
>
> I'd like to automatically get Hex colors fontified -- when opening my Emacs
> color-theme, an HTML/CSS file or a LaTeX class file with color definitions.
>
> To (try to) do so, I've added the following snippet of code into my `.emacs'
> file:
>
> #105099
> ;; #105099
> ;; this `#105099' is it
>
> (defun fontify-hex-colors (start end)
>   "Fontify Hex colors."
>   (interactive "r")
>   (save-restriction
>     (narrow-to-region start end)
>     (goto-char (point-min))
>     (while (search-forward-regexp
>             
> "\\(#[0-9A-Fa-f][0-9A-Fa-f][0-9A-Fa-f][0-9A-Fa-f][0-9A-Fa-f][0-9A-Fa-f]\\)"
>             nil t)
>       (put-text-property (match-beginning 0) (match-end 0)
>                          'font-lock-face (list :background (match-string 
> 1))))))
>
> Though, calling `M-x fontify-hex-colors' on that same region only highlights
> the first occurrence of the color code `#105099'. The two others get
> overridden by their normal color applied by the `emacs-lisp-mode'.
>
> The same appears in whatever mode that uses `font-lock'...
>
> Any idea how to go around this?
>
> Best regards,
>   Seb


I don't know exactly, why this doesn't work. But instead of working
against font-lock, why not let it work for you.

I also don't know if and how it would be possible to use dynamic faces
in regular font-lock keywords.  But you can use overlays combined with a
pseudo font-lock function.

(defun fontify-hex-colors (limit)
  (remove-overlays (point) limit 'fontify-hex-colors t)
  (while (re-search-forward "\\(#[[:xdigit:]]\\{6\\}\\)" limit t)
    (let ((ov (make-overlay (match-beginning 0)
                            (match-end 0))))
      (overlay-put ov 'face  (list :background (match-string 1)))
      (overlay-put ov 'fontify-hex-colors t)
      (overlay-put ov 'evaporate t)))
  ;; return nil telling font-lock not to fontify anything from this
  ;; function
  nil)

(font-lock-add-keywords nil
  '((fontify-hex-colors)))


I think this is safe, because fontifying always starts at bol, but I am
not shure about this either.

-ap