Font changes inside words

Question

I want to have intra-word font changes in org mode -- eg. "Teacher vs teaching" -- works fine here in SE markdown. Doesn't in org.

There is this old question. Is it possible to combine two answers there? I want to use user81065's use of zero width space along with itsjeyd's suggestion to tweak org-emphasis-regexp-components. This is for org mode export in general. ie I'd rather avoid latex/html/odt specific methods (as some other answers suggest) and stick to pure org to work with any back-end.

Basically using zero width space shows as an ugly grey blob in odt export. Can we use the regexp-components to recognize the zero width space as a delimiter and then throw it away?

Answer 1

To get this

export the org snippet below after eval-ling the setup code.

(Note that both the setup code and org snippet have ZERO WIDTH SPACES and you CANNOT SEE these either in this stackexchange post or in your Emacs buffer. The fontification in Emacs buffer will give you a clue where the ZERO WIDTH SPACE characters are)

#+options: author:nil broken-links:nil c:nil creator:nil
#+title: Intra-word emphasis using Zero Width Spaces

Teach​*er* vs teach​*ing*

/Method/​-s and =Class=​es

- HiDPI :: *Hi*​gh *D*​ots *P*​er *I*​nch

#+begin_src emacs-lisp :exports results
  ;; Tell `whitespace-mode' that we are only interested
  ;; in ZERO WIDTH SPACE chars

  (custom-set-variables
   '(whitespace-display-mappings
     '((space-mark 8203
           [8857])))
   '(whitespace-space-regexp "\\(​+\\)")
   '(whitespace-style
     '(face spaces space-mark)))

  (custom-set-faces
   '(whitespace-space
     ((t
       (:background "yellow" :foreground "firebrick")))))

  ;; Put the `org' buffer in `whitespace-mode', so that we can 
  (whitespace-mode +1)

  ;; Use `C-x r i SPC' to insert ZERO WIDTH SPACE easily
  (set-register ?  "​")

  ;; Remove ZERO WIDTH SPACE from output
  (require 'ox)
  (add-to-list
   'org-export-filter-final-output-functions
   (defun my-org-export-filter-plain-text-functions
       (text backend _info)
     (replace-regexp-in-string "​" "" text t t)))

  ;; Report `org' version
  (format "Demo-ed with `Org-%s'" org-version)
#+end_src

---

Here I have extracted the setup emacs-lisp code separately

;; Tell `whitespace-mode' that we are only interested
;; in ZERO WIDTH SPACE chars
(custom-set-variables
 '(whitespace-display-mappings
   '((space-mark 8203
                 [8857])))
 '(whitespace-space-regexp "\\(​+\\)")
 '(whitespace-style
   '(face spaces space-mark)))

(custom-set-faces
 '(whitespace-space
   ((t
     (:background "yellow" :foreground "firebrick")))))

;; Put the `org' buffer in `whitespace-mode', so that we can 
(whitespace-mode +1)

;; Use `C-x r i SPC' to insert ZERO WIDTH SPACE easily
(set-register ?  "​")

;; Remove ZERO WIDTH SPACE from output
(require 'ox)
(add-to-list
 'org-export-filter-final-output-functions
 (defun my-org-export-filter-plain-text-functions
     (text backend _info)
   (replace-regexp-in-string "​" "" text t t)))

;; Report `org' version
(format "Demo-ed with `Org-%s'" org-version)