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Yay Emacs: Using elisp: links in Org Mode to note the time and display messages on stream

| yay-emacs, org

I like adding chapters to my videos so that people can jump to sections. I can figure out the sections by reading the transcript, adding NOTE comments, and extracting the times for those with my-youtube-copy-chapters. It could be nice to capture the times on the fly. org-timer could let me insert relative timestamps, but I think it might need some tweaking to synchronize that with when the stream starts according to YouTube. I've set up a capture, too, so I can take notes with timestamps.

It turns out that I don't have a lot of mental bandwidth when I'm on stream, so it's hard to remember keyboard shortcuts. (Maybe if I practise using the hydra I set up…) Fortunately, Org Mode's elisp: link type makes it easy to set up executable shortcuts. For example, I can add links like [[elisp:my-stream-message-link][TODO]] to my livestream plans like this:

Figure 1: Shortcuts with elisp: links

I can then click on the links or use C-c C-o (org-open-link-at-point) to run the function. When I follow the TODO link in the first item, Emacs displays a clock and a message based on the rest of the line after the link.

Figure 2: Displaying a clock and a message

In the background, the code also sets the description of the link to the wall-clock time.

Figure 3: Link description updated with the time

If I start the livestream with a clock displayed on screen, I can use that to translate wall-clock times to relative time offsets. I'll probably figure out some Elisp to translate the times automatically at some point, maybe based on something like org-timer-change-times-in-region.

I figured it might be fun to add a QR code automatically if we detect a URL, taking advantage of that qrencode package I started playing around with.

Figure 4: With a QR code

You can also use elisp: links for more complicated Emacs Lisp functions, like this: elisp:(progn ... ...).

Here's the code that makes it happen. It's based on emacsconf-stream.el.

(defvar my-stream-message-buffer "*Yay Emacs*")
(defvar my-stream-message-timer nil)

(defun my-stream-message-link ()
    (when (and (derived-mode-p 'org-mode)
               (eq (org-element-type (org-element-context)) 'link))
      (goto-char (org-element-end (org-element-context)))
      (my-stream-message (org-export-string-as (buffer-substring (point) (line-end-position)) 'ascii t)))))
(defun my-stream-update-todo-description-with-time ()
  (when (and (derived-mode-p 'org-mode)
             (eq (org-element-type (org-element-context)) 'link))
    (my-org-update-link-description (format-time-string "%-I:%M:%S %p"))))

(defun my-stream-message (&optional message)
  (interactive "MMessage: ")
  ;; update the description of the link at point to be the current time, if any
  (switch-to-buffer (get-buffer-create my-stream-message-buffer))
  (when (string= message "") (setq message nil))
  (face-remap-add-relative 'default :height 200)
   "Yay Emacs! - Sacha Chua (\n"
    'stream-time (lambda () (format-time-string "%Y-%m-%d %H:%M:%S %Z (%z)")))
  ;; has a URL? Let's QR encode it!
  (when-let ((url (save-excursion
                    (when (re-search-backward ffap-url-regexp nil t)
    (insert (propertize (qrencode url) 'face '(:height 50)) "\n"))
  (insert  "\\n")
  (when (timerp my-stream-message-timer) (cancel-timer my-stream-message-timer))
  (setq my-stream-message-timer (run-at-time t 1 #'my-stream-update-time))
  (goto-char (point-min)))

(defun my-stream-update-time ()
  "Update the displayed time."
  (if (get-buffer my-stream-message-buffer)
      (when (get-buffer-window my-stream-message-buffer)
        (with-current-buffer my-stream-message-buffer
            (goto-char (point-min))
            (let (match)
              (while (setq match (text-property-search-forward 'stream-time))
                (goto-char (prop-match-beginning match))
                 (prop-match-beginning match)
                 (prop-match-end match)
                 (list 'display
                       (funcall (get-text-property
                                 (prop-match-beginning match)
                (goto-char (prop-match-end match)))))))
    (when (timerp my-stream-message-timer)
      (cancel-timer my-stream-message-timer))))

Let's see if that makes it easy enough for me to remember to actually do it!

View org source for this post

Running the current Org Mode Babel Javascript block from Emacs using Spookfox

| emacs, org, spookfox

I often want to send Javascript from Emacs to the web browser. It's handy for testing code snippets or working with data on pages that require Javascript or authentication. I could start Google Chrome or Mozilla Firefox with their remote debugging protocols, copy the websocket URLs, and talk to the browser through something like Puppeteer, but it's so much easier to use the Spookfox extension for Mozilla to execute code in the active tab. spookfox-js-injection-eval-in-active-tab lets you evaluate Javascript and get the results back in Emacs Lisp.

I wanted to be able to execute code even more easily. This code lets me add a :spookfox t parameter to Org Babel Javascript blocks so that I can run the block in my Firefox active tab. For example, if I have (spookfox-init) set up, Spookfox connected, and in my active tab, I can use it with the following code:

#+begin_src js :eval never-export :spookfox t :exports results
[...document.querySelectorAll('.post > h2')].slice(0,5).map((o) => '- ' + o.textContent.trim().replace(/[ \n]+/g, ' ') + '\n').join('')
  • Mario Jason Braganza: Updated to Emacs 29.2
  • Irreal: Zamansky: Learning Elisp #16
  • Tim Heaney: Lisp syntax
  • Erik L. Arneson: Many Posts of Interest for January 2024
  • William Denton: Basic citations in Org (Part 4)

Evaluating a Javascript block with :spookfox t

To do this, we wrap some advice around the org-babel-execute:js function that's called by org-babel-execute-src-block.

(defun my-org-babel-execute:js-spookfox (old-fn body params)
  "Maybe execute Spookfox."
  (if (assq :spookfox params)
       body t)
    (funcall old-fn body params)))
(with-eval-after-load 'ob-js
  (advice-add 'org-babel-execute:js :around #'my-org-babel-execute:js-spookfox))

I can also run the block in Spookfox without adding the parameter if I make an interactive function:

(defun my-spookfox-eval-org-block ()
  (let ((block (org-element-context)))
    (when (and (eq (org-element-type block) 'src-block)
               (string= (org-element-property :language block) "js"))
       (nth 2 (org-src--contents-area block))

I can add that as an Embark context action:

(with-eval-after-load 'embark-org
  (define-key embark-org-src-block-map "f" #'my-spookfox-eval-org-block))

In Javascript buffers, I want the ability to send the current line, region, or buffer too, just like nodejs-repl does.

(defun my-spookfox-send-region (start end)
  (interactive "r")
  (spookfox-js-injection-eval-in-active-tab (buffer-substring start end) t))

(defun my-spookfox-send-buffer ()
  (my-spookfox-send-region (point-min) (point-max)))

(defun my-spookfox-send-line ()
  (my-spookfox-send-region (line-beginning-position) (line-end-position)))

(defun my-spookfox-send-last-expression ()
  (my-spookfox-send-region (save-excursion (nodejs-repl--beginning-of-expression)) (point)))

(defvar-keymap my-js-spookfox-minor-mode-map
  :doc "Send parts of the buffer to Spookfox."
  "C-x C-e" 'my-spookfox-send-last-expression
  "C-c C-j" 'my-spookfox-send-line
  "C-c C-r" 'my-spookfox-send-region
  "C-c C-c" 'my-spookfox-send-buffer)

(define-minor-mode my-js-spookfox-minor-mode "Send code to Spookfox.")

I usually edit Javascript files with js2-mode, so I can use my-js-spookfox-minor-mode in addition to that.

I can turn the minor mode on automatically for :spookfox t source blocks. There's no org-babel-edit-prep:js yet, I think, so we need to define it instead of advising it.

(defun org-babel-edit-prep:js (info)
  (when (assq :spookfox (nth 2 info))
    (my-js-spookfox-minor-mode 1)))

Let's try it out by sending the last line repeatedly:

Sending the current line

I used to do this kind of interaction with Skewer, which also has some extra stuff for evaluating CSS and HTML. Skewer hasn't been updated in a while, but maybe I should also check that out again to see if I can get it working.

Anyway, now it's just a little bit easier to tinker with Javascript!

View org source for this post
This is part of my Emacs configuration.

Org Mode custom link: copy to clipboard

| emacs, org

I have a tiny corporation for my consulting. I do all of my own paperwork. I have lots of notes in Org Mode for infrequent tasks like the tax-related paperwork I do once a year. My notes include checklists, links, and Org Babel blocks for calculations. I often need to copy standard text (ex: the name of the company) or parts of the output of my Org Babel blocks (ex: tax collected) so that I can fill in web forms on the Canada Revenue Agency website.

This little snippet makes it easy to copy text for pasting. It defines a custom Org link that starts with copy:. When I follow the link by clicking on it or using C-c C-o (org-open-at-point), it copies the text to the kill ring (which is what Emacs calls the clipboard) so that I can paste it anywhere. For example, [[copy:Hello world]] becomes a link to copy "Hello world". Copying means never having to worry about typos or accidentally selecting only part of the text.

(use-package org
   :follow (lambda (link) (kill-new link))
   :export (lambda (_ desc &rest _) desc)))

I can use these links as part of my checklist so that I can quickly fill in things like my business name and other details. I can put sensitive information like my social insurance number in a GPG-encrypted file. (Just set up your GPG keys and end a filename with .gpg, and Emacs will take care of transparently encrypting and decrypting the file.)

I can also export those links as part of my Org Babel output. For example, the following code calculates the numbers I need to fill in a T5 form for the other-than-eligible dividends that I issue myself according to the T5 instructions from the CRA.

(let* ((box-10 1234) ; fake number for demo
       (box-11 (* 1.15 box-10))
       (box-12 (* 0.090301 box-11)))
  `((box-10 ,(format "[[copy:%.2f][%.2f]]" box-10 box-10))
    (box-11 ,(format "[[copy:%.2f][%.2f]]" box-11 box-11))
    (box-12 ,(format "[[copy:%.2f][%.2f]]" box-12 box-12))))
box-10 1234.00
box-11 1419.10
box-12 128.15

On my computer, the numbers become links that I can click and copy. Another little shortcut thanks to Emacs and Org Mode!

View org source for this post
This is part of my Emacs configuration.

Animating SVG topic maps with Inkscape, Emacs, FFmpeg, and Reveal.js

| emacs, drawing, org, ffmpeg, video

tldr (2167 words): I can make animating presentation maps easier by writing my own functions for the Emacs text editor. In this post, I show how I can animate an SVG element by element. I can also add IDs to the path and use CSS to build up an SVG with temporary highlighting in a Reveal.js presentation.

Text from the sketch
  • PNG: Inkscape: trace
  • Supernote (e-ink)
  • iPad: Adobe Fresco

Convert PDF to SVG with Inkscape (Cairo option) or pdftocairo)

  • PNG / Supernote PDF: Combined shapes. Process
    1. Break apart, fracture overlaps
    2. Recombine
    3. Set IDs
    4. Sort paths -> Animation style 1
  • Adobe Fresco: individual elements in order; landscape feels natural

Animation styles

  • Animation style 1: Display elements one after another
  • Animation style 2: Display elements one after another, and also show/hide highlights
    • Table: slide ID, IDs to add, temporary highlights -> Reveal.js: CSS with transitions

Ideas for next steps:

  • Explore graphviz & other diagramming tools
  • Frame-by-frame SVGs
    • on include
    • write to files
  • FFmpeg crossfade
  • Recording Reveal.js presentations
  • Use OCR results?

I often have a hard time organizing my thoughts into a linear sequence. Sketches are nice because they let me jump around and still show the connections between ideas. For presentations, I'd like to walk people through these sketches by highlighting different areas. For example, I might highlight the current topic or show the previous topics that are connected to the current one. Of course, this is something Emacs can help with. Before we dive into it, here are quick previews of the kinds of animation I'm talking about:

Figure 1: Animation style 1: based on drawing order

Animation style 2: building up a map with temporary highlights

Getting the sketches: PDFs are not all the same

Let's start with getting the sketches. I usually export my sketches as PNGs from my Supernote A5X. But if I know that I'm going to animate a sketch, I can export it as a PDF. I've recently been experimenting with Adobe Fresco on the iPad, which can also export to PDF. The PDF I get from Fresco is easier to animate, but I prefer to draw on the Supernote because it's an e-ink device (and because the kiddo usually uses the iPad).

If I start with a PNG, I could use Inkscape to trace the PNG and turn it into an SVG. I think Inkscape uses autotrace behind the scenes. I don't usually put my highlights on a separate layer, so autotrace will make odd shapes.

It's a lot easier if you start off with vector graphics in the first place. I can export a vector PDF from the SuperNote A5X and either import it into Inkscape using the Cairo option or use the command-line pdftocairo tool.

I've been looking into using Adobe Fresco, which is a free app available for the iPad. Fresco's PDF export can be converted to an SVG using Inkscape or PDF to Cairo. What I like about the output of this app is that it gives me individual elements as their own paths and they're listed in order of drawing. This makes it really easy to animate by just going through the paths in order.

Animation style 1: displaying paths in order

Here's a sample SVG file that pdfcairo creates from an Adobe Fresco PDF export:

pdftocairo -svg ~/Downloads/subed-audio.pdf ~/Downloads/subed-audio.svg
Sample SVG

Adobe Fresco also includes built-in time-lapse, but since I often like to move things around or tidy things up, it's easier to just work with the final image, export it as a PDF, and convert it to an SVG.

I can make a very simple animation by setting the opacity of all the paths to 0, then looping through the elements to set the opacity back to 1 and write that version of the SVG to a separate file. From how-can-i-generate-png-frames-that-step-through-the-highlights:

my-animate-svg-paths: Add one path at a time. Save the resulting SVGs to OUTPUT-DIR.
(defun my-animate-svg-paths (filename output-dir)
  "Add one path at a time. Save the resulting SVGs to OUTPUT-DIR."
  (unless (file-directory-p output-dir)
    (make-directory output-dir t))
  (let* ((dom (xml-parse-file filename))
         (paths (seq-filter (lambda (e) (dom-attr e 'style))
                            (dom-by-tag dom 'path)))
         (total (length paths))
         (frame-num (length paths))
    (dolist (elem paths)
      (dom-set-attribute elem 'style
                          (dom-attr elem 'style)
    (with-temp-file (expand-file-name (format "frame-%03d.svg" (1+ frame-num)) output-dir)
      (xml-print dom))
    (dolist (elem paths)
      (dom-set-attribute elem 'style
                          (dom-attr elem 'style)
    (dolist (elem paths)
      (with-temp-file (expand-file-name
                       (format "frame-%03d.svg"
                               (- total frame-num))
        (message "%03d" frame-num)
        (dom-set-attribute elem 'style
                           (concat (dom-attr elem 'style)
        (push (list (format "frame-%03d.svg"
                            (1+ (- total frame-num)))
                    (dom-attr elem 'id))
        (setq frame-num (1- frame-num))
        (xml-print dom)))
    (reverse result)))

Here's how I call it:

(my-animate-svg-paths "~/Downloads/subed-audio.svg" "/tmp/subed-audio/frames" t)

Then I can use FFmpeg to combine all of those frames into a video:

ffmpeg -i frame-%03d.svg -vf palettegen -y palette.png
ffmpeg -framerate 30 -i frame-%03d.svg -i palette.png -lavfi "paletteuse" -loop 0 -y animation-loop.gif
Figure 2: Animating SVG paths based on drawing order

Neither Supernote nor Adobe Fresco give me the original stroke information. These are filled shapes, so I can't animate something drawing it. But having different elements appear in sequence is fine for my purposes. If you happen to know how to get stroke information out of Supernote .note files or of an iPad app that exports nice single-line SVGs that have stroke direction, I would love to hear about it.

Identifying paths from Supernote sketches

When I export a PDF from Supernote and convert it to an SVG, each color is a combined shape with all the elements. If I want to animate parts of the image, I have to break it up and recombine selected elements (Inkscape's Ctrl-k shortcut) so that the holes in shapes are properly handled. This is a bit of a tedious process and it usually ends up with elements in a pretty random order. Since I have to reorder elements by hand, I don't really want to animate the sketch letter-by-letter. Instead, I combine them into larger chunks like topics or paragraphs.

The following code takes the PDF, converts it to an SVG, recolours highlights, and then breaks up paths into elements:

my-sketch-convert-pdf-and-break-up-paths: Convert PDF to SVG and break up paths.
(defun my-sketch-convert-pdf-and-break-up-paths (pdf-file &optional rotate)
  "Convert PDF to SVG and break up paths."
  (interactive (list (read-file-name
                      (format "PDF (%s): "
                              (my-latest-file "~/Dropbox/Supernote/EXPORT/" "pdf"))
                      (my-latest-file "~/Dropbox/Supernote/EXPORT/" "pdf")
                      (lambda (s) (string-match "pdf" s)))))
  (unless (file-exists-p (concat (file-name-sans-extension pdf-file) ".svg"))
    (call-process "pdftocairo" nil nil nil "-svg" (expand-file-name pdf-file)
                  (expand-file-name (concat (file-name-sans-extension pdf-file) ".svg"))))
  (let ((dom (xml-parse-file (expand-file-name (concat (file-name-sans-extension pdf-file) ".svg"))))
    (setq highlights (dom-node 'g '((id . "highlights"))))
    (dom-append-child dom highlights)
    (dolist (path (dom-by-tag dom 'path))
      ;;  recolor and move
      (unless (string-match (regexp-quote "rgb(0%,0%,0%)") (or (dom-attr path 'style) ""))
        (dom-remove-node dom path)
        (dom-append-child highlights path)
         path 'style
          (regexp-quote "rgb(78.822327%,78.822327%,78.822327%)")
          (or (dom-attr path 'style) ""))))
      (let ((parent (dom-parent dom path)))
        ;; break apart
        (when (dom-attr path 'd)
          (dolist (part (split-string (dom-attr path 'd) "M " t " +"))
             (dom-node 'path `((style . ,(dom-attr path 'style))
                               (d . ,(concat "M " part))))))
          (dom-remove-node dom path))))
    ;; remove the use
    (dolist (use (dom-by-tag dom 'use))
      (dom-remove-node dom use))
    (dolist (use (dom-by-tag dom 'image))
      (dom-remove-node dom use))
    ;; move the first g down
    (let ((g (car (dom-by-id dom "surface1"))))
      (setf (cddar dom)
            (seq-remove (lambda (o)
                          (and (listp o) (string= (dom-attr o 'id) "surface1")))
                        (dom-children dom)))
      (dom-append-child dom g)
      (when rotate
        (let* ((old-width (dom-attr dom 'width))
               (old-height (dom-attr dom 'height))
               (view-box (mapcar 'string-to-number (split-string (dom-attr dom 'viewBox))))
               (rotate (format "rotate(90) translate(0 %s)" (- (elt view-box 3)))))
          (dom-set-attribute dom 'width old-height)
          (dom-set-attribute dom 'height old-width)
          (dom-set-attribute dom 'viewBox (format "0 0 %d %d" (elt view-box 3) (elt view-box 2)))
          (dom-set-attribute highlights 'transform rotate)
          (dom-set-attribute g 'transform rotate))))
    (with-temp-file (expand-file-name (concat (file-name-sans-extension pdf-file) "-split.svg"))
      (svg-print (car dom)))))

Figure 3: Image after splitting up into elements

You can see how the spaces inside letters like "o" end up being black. Selecting and combining those paths fixes that.

Combining paths in Inkscape

If there were shapes that were touching, then I need to draw lines and fracture the shapes in order to break them apart.

Fracturing shapes and checking the highlights

The end result should be an SVG with the different chunks that I might want to animate, but I need to identify the paths first. You can assign object IDs in Inkscape, but this is a bit of an annoying process since I haven't figured out a keyboard-friendly way to set object IDs. I usually find it easier to just set up an Autokey shortcut (or AutoHotkey in Windows) to click on the ID text box so that I can type something in.

Autokey script for clicking
import time
x, y = mouse.get_location()
# Use the coordinates of the ID text field on your screen; xev can help
mouse.click_absolute(3152, 639, 1)
mouse.move_cursor(x, y)

Then I can select each element, press the shortcut key, and type an ID into the textbox. I might use "t-…" to indicate the text for a map section, "h-…" to indicate a highlight, and arrows by specifying their start and end.

Setting IDs in Inkscape

To simplify things, I wrote a function in Emacs that will go through the different groups that I've made, show each path in a different color and with a reasonable guess at a bounding box, and prompt me for an ID. This way, I can quickly assign IDs to all of the paths. The completion is mostly there to make sure I don't accidentally reuse an ID, although it can try to combine paths if I specify the ID. It saves the paths after each change so that I can start and stop as needed. Identifying paths in Emacs is usually much nicer than identifying them in Inkscape.

Identifying paths inside Emacs

my-svg-identify-paths: Prompt for IDs for each path in FILENAME.
(defun my-svg-identify-paths (filename)
  "Prompt for IDs for each path in FILENAME."
  (interactive (list (read-file-name "SVG: " nil nil
                                     (lambda (f) (string-match "\\.svg$" f)))))
  (let* ((dom (car (xml-parse-file filename)))
         (paths (dom-by-tag dom 'path))
         (vertico-count 3)
         (ids (seq-keep (lambda (path)
                          (unless (string-match "path[0-9]+" (or (dom-attr path 'id) "path0"))
                            (dom-attr path 'id)))
         (edges (window-inside-pixel-edges (get-buffer-window)))
    (my-svg-display "*image*" dom nil t)
    (dolist (path paths)
      (when (string-match "path[0-9]+" (or (dom-attr path 'id) "path0"))
        ;; display the image with an outline
              (my-svg-display "*image*" dom (dom-attr path 'id) t)
              (setq id (completing-read
                        (format "ID (%s): " (dom-attr path 'id))
              ;; already exists, merge with existing element
              (if-let ((old (dom-by-id dom id)))
                     (concat (dom-attr (dom-by-id dom id) 'd)
                             " "
                             ;; change relative to absolute
                             (replace-regexp-in-string "^m" "M"
                                                       (dom-attr path 'd))))
                    (dom-remove-node dom path)
                    (setq id nil))
                (dom-set-attribute path 'id id)
                (add-to-list 'ids id))))
        ;; save the image just in case we get interrupted halfway through
        (with-temp-file filename
          (svg-print dom))))))

Sorting and animating the paths by IDs

Then I can animate SVGs by specifying the IDs. I can reorder the paths in the SVG itself so that I can animate it group by group, like the way that the Adobe Fresco SVGs were animated element by element.

Reordering paths
(my-svg-reorder-paths "~/proj/2023-12-audio-workflow/map.svg"
                      '("t-start" "h-audio" "h-capture" "t-but" "t-mic" "h-mic"
                        "t-reviewing" "h-reviewing"
                        "t-words" "h-words" "t-workflow" "h-workflow"
                        "t-lapel" "h-lapel"
                        "mic-recorder" "t-recorder" "h-recorder"
                        "t-syncthing" "h-sync"
                        "t-keywords" "h-keywords" "t-keyword-types"
                        "t-lines" "h-lines"
                        "t-align" "h-align"
                        "t-org" "h-org" "t-todo" "h-todo" "h-linked"
                        "t-jump" "h-jump"
                        "t-waveform" "h-waveform"
                        "t-speech-recognition" "h-speech-recognition"
                        "t-ai" "h-ai"
(my-animate-svg-paths "~/proj/2023-12-audio-workflow/map-output.svg"
Table of filenames after reordering paths and animating the image
frame-001.svg t-start
frame-002.svg h-audio
frame-003.svg h-capture
frame-004.svg t-but
frame-005.svg t-mic
frame-006.svg h-mic
frame-007.svg t-reviewing
frame-008.svg h-reviewing
frame-009.svg t-words
frame-010.svg h-words
frame-011.svg t-workflow
frame-012.svg h-workflow
frame-013.svg t-lapel
frame-014.svg h-lapel
frame-015.svg mic-recorder
frame-016.svg t-recorder
frame-017.svg h-recorder
frame-018.svg t-syncthing
frame-019.svg h-sync
frame-020.svg t-keywords
frame-021.svg h-keywords
frame-022.svg t-keyword-types
frame-023.svg t-lines
frame-024.svg h-lines
frame-025.svg t-align
frame-026.svg h-align
frame-027.svg arrow
frame-028.svg t-org
frame-029.svg h-org
frame-030.svg t-todo
frame-031.svg h-todo
frame-032.svg h-linked
frame-033.svg t-jump
frame-034.svg h-jump
frame-035.svg t-waveform
frame-036.svg h-waveform
frame-037.svg t-someday
frame-038.svg h-sections
frame-039.svg t-speech-recognition
frame-040.svg h-speech-recognition
frame-041.svg t-ai
frame-042.svg h-ai
frame-043.svg t-summary
frame-044.svg extra

The table of filenames makes it easy to use specific frames as part of a presentation or video.

Here is the result as a video:

(let ((compile-media-output-video-width 1280)
      (compile-media-output-video-height 720))
   (directory-files "~/proj/2023-12-audio-workflow/frames/" t "\\.svg$")
   (expand-file-name "~/proj/2023-12-audio-workflow/frames/animation.webm")

Animation of SVG by paths

The way it works is that the my-svg-reorder-paths function removes and readds elements following the list of IDs specified, so everything's ready to go for step-by-step animation. Here's the code:

my-svg-reorder-paths: Sort paths in FILENAME.
(defun my-svg-reorder-paths (filename &optional ids output-filename)
  "Sort paths in FILENAME."
  (interactive (list (read-file-name "SVG: " nil nil (lambda (f) (string-match "\\.svg$" f)))
                     nil (read-file-name "Output: ")))
  (let* ((dom (car (xml-parse-file filename)))
         (paths (dom-by-tag dom 'path))
         (parent (dom-parent dom (car paths)))
          (nreverse (seq-keep (lambda (path)
                                (unless (string-match "path[0-9]+" (or (dom-attr path 'id) "path0"))
                                  (dom-attr path 'id)))
    (when (called-interactively-p)
      (while ids-left
        (my-svg-display "*image*" dom (car ids-left))
        (let ((current (completing-read
                        (format "ID (%s): "
                                (car ids-left))
                        ids-left nil nil nil nil (car ids-left)))
          (add-to-list 'ids current)
          (setq ids-left (seq-remove (lambda (o) (string= o current)) ids-left)))))
    (if ids ;; reorganize under the first path's parent
          (dolist (id ids)
            (if-let ((node (car (dom-by-id dom id))))
                  (dom-remove-node dom node)
                  (dom-append-child parent node))
              (message "Could not find %s" id)))
          (with-temp-file (or output-filename filename)
            (svg-print dom))))
    (nreverse (seq-keep (lambda (path)
                          (unless (string-match "path[0-9]+" (or (dom-attr path 'id) "path0"))
                            (dom-attr path 'id)))
                        (dom-by-tag dom 'path)))))

Animation style 2: Building up a map with temporary highlights

I can also use CSS rules to transition between opacity values for more complex animations. For my EmacsConf 2023 presentation, I wanted to make a self-paced, narrated presentation so that people could follow hyperlinks, read the source code, and explore. I wanted to include a map so that I could try to make sense of everything. For this map, I wanted to highlight the previous sections that were connected to the topic for the current section.

I used a custom Org link to include the full contents of the SVG instead of just including it with an img tag.

#+ATTR_HTML: :class r-stretch
my-include:~/proj/emacsconf-2023-emacsconf/map.svg?wrap=export html

my-include-export: Export PATH to FORMAT using the specified wrap parameter.
(defun my-include-export (path _ format _)
  "Export PATH to FORMAT using the specified wrap parameter."
  (let (params body start end)
    (when (string-match "^\\(.*+?\\)\\(?:::\\|\\?\\)\\(.*+\\)" path)
      (setq params (save-match-data (org-protocol-convert-query-to-plist (match-string 2 path)))
            path (match-string 1 path)))
      (insert-file-contents-literally path)
      (when (string-match "\\.org$" path)
      (if (plist-get params :name)
          (when (org-babel-find-named-block (plist-get params :name))
            (goto-char (org-babel-find-named-block (plist-get params :name)))
            (let ((block (org-element-context)))
              (setq start (org-element-begin block)
                    end (org-element-end block))))
        (goto-char (point-min))
        (when (plist-get params :from-regexp)
          (re-search-forward (url-unhex-string (plist-get params :from-regexp)))
          (goto-char (match-beginning 0)))
        (setq start (point))
        (setq end (point-max))
        (when (plist-get params :to-regexp)
          (re-search-forward (url-unhex-string (plist-get params :to-regexp)))
          (setq end (match-beginning 0))))
      (setq body (buffer-substring start end)))
      (when (plist-get params :wrap)
        (let* ((wrap (plist-get params :wrap))
               block args)
          (when (string-match "\\<\\(\\S-+\\)\\( +.*\\)?" wrap)
            (setq block (match-string 1 wrap))
            (setq args (match-string 2 wrap))
            (setq body (format "#+BEGIN_%s%s\n%s\n#+END_%s\n"
                               block (or args "")
      (when (plist-get params :summary)
        (setq body (format "#+begin_my_details %s\n%s\n#+end_my_details\n"
                           (plist-get params :summary)
      (insert body)
      (org-export-as format nil nil t))))

I wanted to be able to specify the entire sequence using a table in the Org Mode source for my presentation. Each row had the slide ID, a list of highlights in the form prev1,prev2;current, and a comma-separated list of elements to add to the full-opacity view.

Slide Highlight Additional elements
props-map h-email;h-properties t-email,email-properties,t-properties
file-prefixes h-properties;h-filename t-filename,properties-filename
renaming h-filename;h-renaming t-renaming,filename-renaming
shell-scripts h-renaming;h-shell-scripts renaming-shell-scripts,t-shell-scripts
availability h-properties;h-timezone t-timezone,properties-timezone
schedule h-timezone;h-schedule t-schedule,timezone-schedule
emailing-speakers h-timezone,h-mail-merge;h-emailing-speakers schedule-emailing-speakers,t-emailing-speakers
template h-properties;h-template t-template,properties-template
wiki h-template;h-wiki t-wiki,template-wiki,schedule-wiki
pad h-template;h-pad template-pad,t-pad
mail-merge h-template;h-mail-merge t-mail-merge,template-mail-merge,schedule-mail-merge,emailing-speakers-mail-merge
bbb h-bbb t-bbb
checkin h-mail-merge;h-checkin t-checkin,bbb-checkin
redirect h-bbb;h-redirect t-redirect,bbb-redirect
shortcuts h-email;h-shortcuts t-shortcuts,email-shortcuts
logbook h-shortcuts;h-logbook shortcuts-logbook,t-logbook
captions h-captions t-captions,captions-wiki
tramp h-captions;h-tramp t-tramp,captions-tramp
crontab h-tramp;h-crontab tramp-crontab,bbb-crontab,t-crontab
transitions h-crontab;h-transitions shell-scripts-transitions,t-transitions,shortcuts-transitions,transitions-crontab
irc h-transitions;h-irc t-irc,transitions-irc

Reveal.js adds a "current" class to the slide, so I can use that as a trigger for the transition. I have a bit of Emacs Lisp code that generates some very messy CSS, in which I specify the ID of the slide, followed by all of the elements that need their opacity set to 1, and also specifying the highlights that will be shown in an animated way.

my-reveal-svg-progression-css: Make the CSS.
(defun my-reveal-svg-progression-css (map-progression &optional highlight-duration)
  "Make the CSS.
map-progression should be a list of lists with the following format:
((\"slide-id\" \"prev1,prev2;cur1\" \"id-to-add1,id-to-add2\") ...)."
  (setq highlight-duration (or highlight-duration 2))
  (let (full)
      (lambda (slide)
        (setq full (append (split-string (elt slide 2) ",") full))
        (format "#slide-%s.present path { opacity: 0.2 }
%s { opacity: 1 !important }
                (car slide)
                (mapconcat (lambda (id) (format "#slide-%s.present #%s" (car slide) id))
                           ", ")
                (my-reveal-svg-highlight-different-colors slide)))
I call it from my Org file like this:

#+NAME: progression-css
#+begin_src emacs-lisp :exports code :var map-progression=progression :var highlight-duration=2 :results silent
(my-reveal-svg-progression-css map-progression highlight-duration)

Here's an excerpt showing the kind of code it makes:

<style>#slide-props-map.present path { opacity: 0.2 }
#slide-props-map.present #t-email, #slide-props-map.present #email-properties, #slide-props-map.present #t-properties { opacity: 1 !important }
#slide-props-map.present #h-email { fill: #c6c6c6; opacity: 1 !important; transition: fill 0.5s; transition-delay: 0.0s }#slide-props-map.present #h-properties { fill: #f6f396; opacity: 1 !important; transition: fill 0.5s; transition-delay: 0.5s }
#slide-file-prefixes.present path { opacity: 0.2 }
#slide-file-prefixes.present #t-filename, #slide-file-prefixes.present #properties-filename, #slide-file-prefixes.present #t-email, #slide-file-prefixes.present #email-properties, #slide-file-prefixes.present #t-properties { opacity: 1 !important }
#slide-file-prefixes.present #h-properties { fill: #c6c6c6; opacity: 1 !important; transition: fill 0.5s; transition-delay: 0.0s }#slide-file-prefixes.present #h-filename { fill: #f6f396; opacity: 1 !important; transition: fill 0.5s; transition-delay: 0.5s }

Since it's automatically generated, I don't have to worry about it once I've gotten it to work. It's all hidden in a results drawer. So this CSS highlights specific parts of the SVG with a transition, and the highlight changes over the course of a second or two. It highlights the previous names and then the current one. The topics I'd already discussed would be in black, and the topics that I had yet to discuss would be in very light gray. This could give people a sense of the progress through the presentation.

Code for making the CSS
(defun my-reveal-svg-animation (slide)
    (lambda (step-ids i)
      (format "%s { fill: #f6f396; transition: fill %ds; transition-delay: %ds }"
               (lambda (id) (format "#slide-%s.present #%s" (car slide) id))
               (split-string step-ids ",")
               ", ")
              (* i highlight-duration)))
    (split-string (elt slide 1) ";"))

(defun my-reveal-svg-highlight-different-colors (slide)
  (let* ((colors '("#f6f396" "#c6c6c6")) ; reverse
         (steps (split-string (elt slide 1) ";"))
         (step-length 0.5))
      (lambda (step-ids i)
        (format "%s { fill: %s; opacity: 1 !important; transition: fill %.1fs; transition-delay: %.1fs }"
                 (lambda (id) (format "#slide-%s.present #%s" (car slide) id))
                 (split-string step-ids ",")
                 ", ")
                (elt colors (- (length steps) i 1))
                (* i 0.5)))

(defun my-reveal-svg-progression-css (map-progression &optional highlight-duration)
  "Make the CSS.
map-progression should be a list of lists with the following format:
((\"slide-id\" \"prev1,prev2;cur1\" \"id-to-add1,id-to-add2\") ...)."
  (setq highlight-duration (or highlight-duration 2))
  (let (full)
      (lambda (slide)
        (setq full (append (split-string (elt slide 2) ",") full))
        (format "#slide-%s.present path { opacity: 0.2 }
%s { opacity: 1 !important }
                (car slide)
                (mapconcat (lambda (id) (format "#slide-%s.present #%s" (car slide) id))
                           ", ")
                (my-reveal-svg-highlight-different-colors slide)))

As a result, as I go through my presentation, the image appears to build up incrementally, which is the effect that I was going for. I can test this by exporting only my map slides:

  (goto-char (org-babel-find-named-block "progression-css"))
(let ((org-tags-exclude-from-inheritance "map")
      (org-export-select-tags '("map")))

Ideas for next steps

  • Graphviz, mermaid-js, and other diagramming tools can make SVGs. I should be able to adapt my code to animate those diagrams by adding other elements in addition to path. Then I'll be able to make diagrams even more easily.
  • Since SVGs can contain CSS, I could make an SVG equivalent of the CSS rules I used for the presentation, maybe calling a function with a Lisp expression that specifies the operations (ex: ("frame-001.svg" "h-foo" opacity 1)). Then I could write frames to SVGs.
  • FFmpeg has a crossfade filter. With a little bit of figuring out, I should be able to make the same kind of animation in a webm form that I can include in my regular videos instead of using Reveal.js and CSS transitions.
  • I've also been thinking about automating the recording of my Reveal.js presentations. For my EmacsConf talk, I opened my presentation, started the recording with the system audio and the screen, and then let it autoplay the presentation. I checked on it periodically to avoid the screensaver/energy saving things from kicking in and so that I could stop the recording when it's finished. If I want to make this take less work, one option is to use ffmpeg's "-t" argument to specify the expected duration of the presentation so that I don't have to manually stop it. I'm also thinking about using Puppeteer to open the presentation, check when it's fully loaded, and start the process to record it - maybe even polling to see whether it's finished. I haven't gotten around to it yet. Anyhow, those are some ideas to explore next time.
  • As for animation, I'm still curious about the possibility of finding a way to access the raw stroke information if it's even available from my Supernote A5X (difficult because it's a proprietary data format) or finding an app for the iPad that exports single line SVGs that use stroke information instead of fill. That would only be if I wanted to do those even fancier animations that look like the whole thing is being drawn for you. I was trying to figure out if I could green screen the Adobe Fresco timelapse videos so that even if I have a pre-sketch to figure out spacing and remind me what to draw, I can just export the finished elements. But there's too much anti-aliasing and I haven't figured out how to do it cleanly yet. Maybe some other day.
  • I use Google Cloud Vision's text detection engine to convert my handwriting to text. It can give me bounding polygons for words or paragraphs. I might be able to figure out which curves are entirely within a word's bounding polygon and combine those automatically.
  • It would be pretty cool if I could combine the words recognized by Google Cloud Vision with the word-level timestamps from speech recognition so that I could get word-synced sketchnote animations with maybe a little manual intervention.

Anyway, those are some workflows for animating sketches with Inkscape and Emacs. Yay Emacs!

View org source for this post

Using Embark and qrencode to show a QR code for the Org Mode link at point

Posted: - Modified: | emacs, org

[2024-01-12 Fri]: Added some code to display the QR code on the right side.

John Kitchin includes little QR codes in his videos. I thought that was a neat touch that makes it easier for people to jump to a link while they're watching. I'd like to make it easier to show QR codes too. The following code lets me show a QR code for the Org link at point. Since many of my links use custom Org link types that aren't that useful for people to scan, the code reuses the link resolution code from so that I can get the regular https: link.

(defun my-org-link-qr (url)
  "Display a QR code for URL in a buffer."
  (let ((buf (save-window-excursion (qrencode--encode-to-buffer (my-org-stored-link-as-url url)))))
    (display-buffer-in-side-window buf '((side . right)))))

(use-package qrencode
  (with-eval-after-load 'embark
    (define-key embark-org-link-map (kbd "q") #'my-org-link-qr)))
Figure 1: Screenshot of QR code for the link at point
View org source for this post
This is part of my Emacs configuration.

Using an Emacs Lisp macro to define quick custom Org Mode links to project files; plus URLs and search

| org, emacs, coding
  • [2024-01-12 Fri] Added embark action to copy the exported link URL.
  • [2024-01-11 Thu] Switched to using Github links since Codeberg's down.
  • [2024-01-11 Thu] Updated my-copy-link to just return the link if called from Emacs Lisp. Fix getting the properties.
  • [2024-01-08 Mon] Add tip from Omar about embark-around-action-hooks
  • [2024-01-08 Mon] Simplify code by using consult--grep-position

Summary (882 words): Emacs macros make it easy to define sets of related functions for custom Org links. This makes it easier to link to projects and export or copy the links to the files in the web-based repos. You can also use that information to consult-ripgrep across lots of projects.

I'd like to get better at writing notes while coding and at turning those notes into blog posts and videos. I want to be able to link to files in projects easily with the ability to complete, follow, and export links. For example, [[subed:subed.el]] should become subed.el, which opens the file if I'm in Emacs and exports a link if I'm publishing a post. I've been making custom link types using org-link-set-parameters. I think it's time to make a macro that defines that set of functions for me. Emacs Lisp macros are a great way to write code to write code.

(defvar my-project-web-base-list nil "Local path . web repo URLs for easy linking.")

(defmacro my-org-project-link (type file-path git-url)
     (defun ,(intern (format "my-org-%s-complete" type)) ()
       ,(format "Complete a file from %s." type)
       (concat ,type ":" (completing-read "File: "
                                          (projectile-project-files ,file-path))))
     (defun ,(intern (format "my-org-%s-follow" type)) (link _)
       ,(format "Open a file from %s." type)
     (defun ,(intern (format "my-org-%s-export" type)) (link desc format _)
       "Export link to file."
       (setq desc (or desc link))
       (when ,git-url
         (setq link (concat ,git-url (replace-regexp-in-string "^/" "" link))))
       (pcase format
         ((or 'html '11ty) (format "<a href=\"%s\">%s</a>"
                                   (or desc link)))
         ('md (if desc (format "[%s](%s)" desc link)
                (format "<%s>" link)))
         ('latex (format "\\href{%s}{%s}" link desc))
         ('texinfo (format "@uref{%s,%s}" link desc))
         ('ascii (format "%s (%s)" desc link))
         (_ (format "%s (%s)" desc link))))
     (with-eval-after-load 'org
        :complete (quote ,(intern (format "my-org-%s-complete" type)))
        :export (quote ,(intern (format "my-org-%s-export" type)))
        :follow (quote ,(intern (format "my-org-%s-follow" type))))
       (cl-pushnew (cons (expand-file-name ,file-path) ,git-url)
                   :test 'equal))))

Then I can define projects this way:

(my-org-project-link "subed"
                     ;; ""
(my-org-project-link "emacsconf-el"
(my-org-project-link "subed-record"
                     ;; ""
(my-org-project-link "compile-media"
                     ;; ""
(my-org-project-link "ox-11ty"

And I can complete them with the usual C-c C-l (org-insert-link) process:

Figure 1: Completing a custom link with org-insert-link

Sketches are handled by my Org Mode sketch links, but we can add them anyway.

(cl-pushnew (cons (expand-file-name "~/sync/sketches/") "")
            :test 'equal)

I've been really liking being able to refer to various emacsconf-el files by just selecting the link type and completing the filename, so maybe it'll be easier to write about lots of other stuff if I extend that to my other projects.

Quickly search my code

Since my-project-web-base-list is a list of projects I often think about or write about, I can also make something that searches through them. That way, I don't have to care about where my code is.

(defun my-consult-ripgrep-code ()
  (consult-ripgrep (mapcar 'car my-project-web-base-list)))

I can add .rgignore files in directories to tell ripgrep to ignore things like node_modules or *.json.

I also want to search my Emacs configuration at the same time, although links to my config are handled by my dotemacs link type so I'll leave the URL as nil. This is also the way I can handle other unpublished directories.

(cl-pushnew (cons (expand-file-name "~/sync/emacs/") nil)
            :test 'equal)
(cl-pushnew (cons (expand-file-name "~/proj/static-blog/_includes") nil)
            :test 'equal)
(cl-pushnew (cons (expand-file-name "~/bin") nil)
            :test 'equal)

Actually, let's throw my blog posts and Org files in there as well, since I often have code snippets. If it gets to be too much, I can always have different commands search different things.

(cl-pushnew (cons (expand-file-name "~/proj/static-blog/blog/") "")
            :test 'equal)
(cl-pushnew (cons (expand-file-name "~/sync/orgzly") nil)
            :test 'equal)
Figure 2: Using my-consult-ripgrep-code

I don't have anything bound to M-s c (code) yet, so let's try that.

(keymap-global-set "M-s c" #'my-consult-ripgrep-code)

At some point, it might be fun to get Embark set up so that I can grab a link to something right from the consult-ripgrep interface. In the meantime, I can always jump to it and get the link.

Tip from Omar: embark-around-action-hooks

[2024-01-07 Sun] I modified oantolin's suggestion from the comments to work with consult-ripgrep, since consult-ripgrep gives me consult-grep targets instead of consult-location:

(cl-defun embark-consult--at-location (&rest args &key target type run &allow-other-keys)
  "RUN action at the target location."
        (pcase type
          ('consult-location (consult--jump (consult--get-location target)))
          ('org-heading (org-goto-marker-or-bmk (get-text-property 0 'org-marker target)))
          ('consult-grep (consult--jump (consult--grep-position target)))
          ('file (find-file target)))
        (apply run args)))))

(cl-pushnew #'embark-consult--at-location (alist-get 'org-store-link embark-around-action-hooks))

I think I can use it with M-s c to search for the code, then C-. C-c l on the matching line, where C-c l is my regular keybinding for storing links. Thanks, Omar!

In general, I don't want to have to think about where something is on my laptop or where it's published on the Web, I just want to

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This is part of my Emacs configuration.

Using consult and org-ql to search my Org Mode agenda files and sort the results to prioritize heading matches

| emacs, org

I want to get better at looking in my Org files for something that I don't exactly remember. I might remember a few words from it but not in order, or I might remember some words from the body, or I might need to fiddle with the keywords until I find it.

I usually use C-u C-c C-w (org-refile with a prefix argument), counting on consult + orderless to let me just put in keywords in any order. This doesn't let me search the body, though.

org-ql seems like a great fit for this. It's fast and flexible, and might be useful for all sorts of queries.

I think by default org-ql matches against all of the text in the entry. You can scope the match to just the heading with a query like heading:your,text. I wanted to see all matches, prioritize heading matches so that they come first. I thought about saving the query by adding advice before org-ql-search and then adding a new comparator function, but that got a bit complicated, so I haven't figured that out yet. It was easier to figure out how to rewrite the query to use heading instead of rifle, do the more constrained query, and then append the other matches that weren't in the heading matches.

Also, I wanted something a little like helm-org-rifle's live previews. I've used helm before, but I was curious about getting it to work with consult.

Here's a quick demo of my-consult-org-ql-agenda-jump, which I've bound to M-s a. The top few tasks have org-ql in the heading, and they're followed by the rest of the matches. I think this might be handy.

Figure 1: Screencast of using my-consult-org-ql-agenda-jump
(defun my-consult-org-ql-agenda-jump ()
  "Search agenda files with preview."
  (let* ((marker (consult--read
                  :state (consult--jump-state)
                  :category 'consult-org-heading
                  :prompt "Heading: "
                  :sort nil
                  :lookup #'consult--lookup-candidate))
         (buffer (marker-buffer marker))
         (pos (marker-position marker)))
    ;; based on org-agenda-switch-to
    (unless buffer (user-error "Trying to switch to non-existent buffer"))
    (pop-to-buffer-same-window buffer)
    (goto-char pos)
    (when (derived-mode-p 'org-mode)
      (org-fold-show-context 'agenda)
      (run-hooks 'org-agenda-after-show-hook))))

(defun my-consult-org-ql-agenda-format (o)
   (org-ql-view--format-element o)
   'consult--candidate (org-element-property :org-hd-marker o)))

(defun my-consult-org-ql-agenda-match (string)
  "Return candidates that match STRING.
Sort heading matches first, followed by other matches.
Within those groups, sort by date and priority."
  (let* ((query (org-ql--query-string-to-sexp string))
         (sort '(date reverse priority))
         (heading-query (-tree-map (lambda (x) (if (eq x 'rifle) 'heading x)) query))
          (mapcar #'my-consult-org-ql-agenda-format
                  (org-ql-select 'org-agenda-files heading-query
                    :action 'element-with-markers
                    :sort sort)))
          (mapcar #'my-consult-org-ql-agenda-format
                  (org-ql-select 'org-agenda-files query
                    :action 'element-with-markers
                    :sort sort))))
     (seq-difference all-matches matched-heading))))

(use-package org-ql
  :bind ("M-s a" . my-consult-org-ql-agenda-jump))

Along the way, I learned how to use consult to complete using consult--dynamic-collection and add consult--candidate so that I can reuse consult--lookup-candidate and consult--jump-state. Neat!

Someday I'd like to figure out how to add a sorting function and sort by headers without having to reimplement the other sorts. In the meantime, this might be enough to help me get started.

This is part of my Emacs configuration.