Separating colour and positioning functioning

[Christopher Dimech <dimech@gmx.com>]

Have written a minor mode with part of the the code below and want to
modify tex-typeface-crucible so that the colour scheme is enabled when
the minor-mode is on.

Then one can apply supinf as an option

(defface colour-tex-cruc
  '( (default :inherit bold)
     ( ((class color) (min-colors 88) (background light))
       :foreground "#FF0000" )
     ( ((class color) (min-colors 88) (background dark))
       :foreground "#FF0000")
     (t :inherit font-lock-builtin-face) )
  "Typeface for tex keywords.")

(defconst crucible-tex-keywords
  `( (,(rx "\\" word-start (group (or "alpha" "beta")) word-end)
     (1 'colour-tex-cruc)) )
  "Fontification for letters and symbols.")

(defun supinf-disable-cruc (beg end)
  "Set typeface for text between BEG and END."
  (font-lock-default-unfontify-region beg end)
  (while (< beg end)
    (let ((next (next-single-property-change beg 'display nil end))
	  (prop (get-text-property beg 'display)))
      (if (and (eq (car-safe prop) 'raise)
	       (member (car-safe (cdr prop)) crucible-supinf-vshift)
	       (null (cddr prop)))
	  (put-text-property beg next 'display nil))
      (setq beg next))))

(defun tex-typeface-crucible ()
  "Font-lock setup for mathematical symbols."
  (font-lock-flush (point-min) (point-max))
  (if crucible-supinf-enable
      (progn
        (font-lock-add-keywords nil crucible-tex-keywords t)
        (font-lock-add-keywords nil supinf-font-lock-cruc t))
    (font-lock-remove-keywords nil crucible-tex-keywords)
    (supinf-disable-cruc (point-min) (point-max)))
  (font-lock-flush (point-min) (point-max)))