dotfiles/emacs-lisp/org_mode.org

:PROPERTIES:
:ID:       986ca7a5-d225-49bb-9e35-f2dffafe8aee
:END:
#+title: Org Mode
#+filetags: emacs-load

# SPDX-FileCopyrightText: 2022 Richard Brežák <richard@brezak.sk>
#
# SPDX-License-Identifier: LGPL-3.0-or-later

I used to respect the 80 column limit, but why waste all the space when it can be dynamic. In this way all of the available screen space is utilized.

#+BEGIN_SRC emacs-lisp :results none
  (add-hook 'org-mode-hook 'visual-line-mode)
#+END_SRC

Enable /"fake"/ indentation in =org-mode=, in other words, add indentation using overlays, but on disk the buffer is not indented.

#+BEGIN_SRC emacs-lisp :results none
  (add-hook 'org-mode-hook 'org-indent-mode)
#+END_SRC

Increase the size of headings, in my personal opinion this makes the headings stand out a bit more and therefore easier to read.

#+BEGIN_SRC emacs-lisp :results none
  (custom-set-faces
   '(org-level-1 ((t (:inherit outline-1 :height 1.25))))
   '(org-level-2 ((t (:inherit outline-2 :height 1.2))))
   '(org-level-3 ((t (:inherit outline-3 :height 1.15))))
   '(org-level-4 ((t (:inherit outline-4 :height 1.10))))
   '(org-level-5 ((t (:inherit outline-5 :height 1.05)))))
#+END_SRC

Disable element cache for now, it freaks out all the damn time. God forbid I make a tiny syntax error...

#+begin_src emacs-lisp
  (setq org-element-use-cache nil)
#+end_src

#+begin_src emacs-lisp
  (setf org-blank-before-new-entry '((heading . t) (plain-list-item . nil)))
#+end_src

* Org Mark Ring

To go back to the previous mark, very useful with [[id:18476d68-cccb-48f4-aa77-caefe213d8bd][Org Roam]].

#+BEGIN_SRC emacs-lisp :results none
  (general-def org-mode-map "C-c b" 'org-mark-ring-goto)
#+END_SRC

* Babel

Enable =tangle on save=, big thanks to Diego Zamboni for his amazing booklet about /[[https://leanpub.com/lit-config/read][Literate Configuration]]/.

#+BEGIN_SRC emacs-lisp :results none
   (add-hook 'org-mode-hook
             (lambda () (add-hook 'after-save-hook #'org-babel-tangle :append :local)))
#+END_SRC

After executing a source code block with =org-babel=, redisplay inline images, this speeds up the REPL-like workflow a lot.

#+BEGIN_SRC emacs-lisp :results none
  (add-hook 'org-babel-after-execute-hook 'org-redisplay-inline-images)
#+END_SRC

Enable additional babel languages.

#+BEGIN_SRC emacs-lisp :results none
  (org-babel-do-load-languages
   'org-babel-load-languages
   (cl-map 'list (lambda (lang) `(,lang . t))
           '(python R shell dot latex plantuml)))
#+END_SRC

* Latex

For previews, create SVGs and not PNGs or something, use the ~dvisvgm-lua~ command.

#+BEGIN_SRC emacs-lisp :results none
  (setq org-preview-latex-default-process 'dvisvgm)
#+END_SRC

Actually define ~dvisvgm-lua~.

#+begin_src emacs-lisp :results none
  (add-to-list
   'org-preview-latex-process-alist
   '(dvisvgm-lua
     :programs ("dvilualatex" "dvisvgm")
     :description "dvi > svg"
     :message "you need to install the programs: latex and dvisvgm."
     :image-input-type "dvi"
     :image-output-type "svg"
     :image-size-adjust (1.7 . 1.5)
     :latex-compiler ("dvilualatex -interaction nonstopmode -output-directory %o %f")
     :image-converter ("dvisvgm %f -n -b min -c %S -o %O")))
#+end_src

Adjust size of LaTeX previews.

#+BEGIN_SRC emacs-lisp :results none
  (pcase (system-name)
    ("heater" (setq org-format-latex-options (plist-put org-format-latex-options :scale 1.75)))
    ("omen" (setq org-format-latex-options (plist-put org-format-latex-options :scale 0.8))))
#+END_SRC

To support non-breakable whitespace, create a new ~org-entity~.

#+begin_src emacs-lisp
  (add-to-list 'org-entities
        '("space" "~" nil "&nbsp;" " " " " " "))
#+end_src

Enable fontification for inline LaTeX blocks which convieniently also makes in fixed-width.

#+begin_src emacs-lisp
  (setq org-highlight-latex-and-related '(native script entities))
#+end_src


** Sliced Previews

Normally a LaTeX preview is just one huge image which makes Emacs really jumpy and makes writing prose a really unpleasant experience. With these two functions, that's fixed. They work using mainly text properties (overlays are still involved but only one per preview, max two) so it should be fast still.

#+begin_src emacs-lisp
  ;;; -*- lexical-binding: t; -*-

  (defadvice org-clear-latex-preview (after org-prop-img--org-clear-later-preview (beg end) activate)
    (save-excursion
      (goto-char beg)
      (with-silent-modifications
        (put-text-property beg end 'read-only nil)
        (put-text-property beg end 'display nil)
        (put-text-property beg end 'line-height nil))
      (font-lock-fontify-region beg end)))

  (defun org--make-preview-overlay (beg end image &optional imagetype)
    "Build an overlay between BEG and END using IMAGE file.
  Argument IMAGETYPE is the extension of the displayed image,
  as a string.  It defaults to \"png\"."
    (let* ((imagetype (or (intern imagetype) 'png))
           (image-spec (list 'image :type imagetype :file image :relief 0 :ascent 'center))
           (ov (make-overlay beg end)))
      (overlay-put ov 'org-overlay-type 'org-latex-overlay)
      (overlay-put ov
                   'modification-hooks
                   (list (lambda (&rest _args)
                           (org-clear-latex-preview beg end))))
      (if (> (count-lines beg end) 1)
          (let ((image-height (cdr (image-size image-spec t)))

                (y 0)
                (endm (make-marker)))
            (set-marker endm end)
            (save-excursion
              (goto-char beg)
              (while (and (<= (point) endm) (< y image-height))
                (let* ((dy (line-pixel-height)))

                  ;; loop through and check for empty lines, those will break rendering
                  (when (= (line-beginning-position) (line-end-position))
                    (goto-char (line-beginning-position))
                    (insert "%")
                    (forward-char -1))

                  (when (> (* dy 2) (- image-height y))
                      (setq dy (- image-height y)))

                  (with-silent-modifications
                    ;; place the image property on the current line
                    (put-text-property (line-beginning-position) (line-end-position)
                                       'display
                                       (list
                                        (list 'slice
                                              0 y 1.0 dy)
                                        image-spec))
                    ;; ;; remove any fontification face so the images don't get colored
                    ;; (put-text-property (line-beginning-position) (line-end-position)
                    ;;                    'face
                    ;;                    nil)
                  )

                  (forward-line 1)
                  (setq y (+ y dy))))
              (if (not (> (point) endm))
                  (let ((ov (make-overlay (- (point) 1) endm)))

                    (overlay-put ov 'org-overlay-type 'org-latex-overlay)
                    (overlay-put ov 'evaporate t)
                    (overlay-put ov 'invisible t))))
            (set-marker endm nil))
        (with-silent-modifications
          (put-text-property beg end
                             'display
                             (list image-spec))))
      (font-lock-fontify-region beg end)
      (with-silent-modifications
        (put-text-property beg end 'line-height t))))
#+end_src