Face-based replacements

Question

I need to perform this kind of (query-)substitutions in LaTeX code:

"fig" --> "figure"

But I don't want to match text inside commands e.g. \label{fig:1} or \includegraphics[width=2cm]{fig/D.pdf}.

I figured out to use face properties to select the strings to be replaced and I wrote this piece of code

(goto-char (point-min)
(while (search-forward-regexp "\\<\\([Ff]ig\\)\\(s?\\)\\>\\.?" nil t)
  (save-excursion
    (let ((b (make-marker))
      (e (make-marker)))
      (set-marker b (match-beginning 0))
      (set-marker e (point))
      (goto-char b)
      (font-lock-fontify-buffer)
      (let* ((face 'query-replace)
         (bg (face-background face)))
    (set-face-background face "OliveDrab3")
    (unwind-protect
        (unless (or (string= (face-at-point) "font-lock-constant-face")
            (string= (face-at-point) "font-lock-builtin-face"))

          (perform-replace "\\<\\([Ff]ig\\)\\(s?\\)\\>\\.?"
                   "\\1ure\\2" t t nil 1 nil b e))
      (set-face-background face bg)))
)))

It works quite well but fails if I run it at the file opening. It seems that emacs needs to scan the buffer in some way I don't understand.

I tried to put (font-lock-fontify-buffer) at the beginning of the script but it doesn't work.

1 - How can I force emacs to fontify the whole buffer before running my code?

2 - Any (tested) idea to achieve the same result with some other technique?

Answer 1

I want to answer my own question because I've just found that the redisplay command seems to solve my problem. I want to share my solution:

(goto-char (point-min)
(while (search-forward-regexp "\\<\\([Ff]ig\\)\\(s?\\)\\>\\.?" nil t)
  (save-excursion
    (let ((b (make-marker))
      (e (make-marker)))
      (set-marker b (match-beginning 0))
      (set-marker e (point))
      (goto-char b)
      (redisplay t)
      (let* ((face 'query-replace)
         (bg (face-background face)))
    (set-face-background face "OliveDrab3")
    (unwind-protect
        (unless (or (string= (face-at-point) "font-lock-constant-face")
            (string= (face-at-point) "font-lock-builtin-face"))

          (perform-replace "\\<\\([Ff]ig\\)\\(s?\\)\\>\\.?"
                   "\\1ure\\2" t t nil 1 nil b e))
      (set-face-background face bg)))
)))

Any comment about it? Is it a bad idea?