Use SVGs to replace text in Emacs

svg-text.el

;; Score out this text

(require 'svg)
(defun replace-text (start end)
  (let* ((str (buffer-substring start end))
	 (scale (cadr (assoc :height (assoc 'default face-remapping-alist))))
	 (family (face-attribute 'default :family))
	 (height (* (aref (font-info family) 2) (if scale scale 1)))
	 (ascent (* (aref (font-info family) 8) (if scale scale 1)))
	 (img (svg-create (car (window-text-pixel-size nil start end))
			  (line-pixel-height)
			  :font-size height
			  :font-family family)))
    (svg-text img str :y ascent :fill "red" :textLength "100%")
    (svg-line img 0 0 "100%" "100%" :stroke "currentColor")
    (svg-line img "100%" 0 0 "100%" :stroke "currentColor")

    (add-text-properties start end `(display
				     ,(svg-image img :ascent 'center :scale 1)
				     rear-nonsticky t))))

(replace-text 14 18)