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0001-2865.mp4

melpa package melpa stable package Non-GNU ELPA

Present Org Documents 🦄

  • Per-heading configurable behavior
  • Nested or independent child slides
  • Header with breadcrumbs generated from document keywords
  • Actions that consume typical org data in smart ways

Fully Programmable ✨

  • Script steps in your presentation with Org babel blocks
  • Incorporate anything Emacs does into a presentation
  • Convenient API for quickly writing reliable custom actions for reuse

Status 💹

Version 0.5.5 👷 Subscribe to Positron's YouTube for updates and related demonstrations.

  • Still pre-1.0. See the version 1.0 feature roadmap.
  • Expect markup to become easier as affiliated keywords are adopted. Will attempt to not break options that currently work. See release notes when updating.
  • Accepting PR's and issue reports. Read the manual section on hacking
  • Some behaviors may be advertised as working already when they are only 90% implemented. I have no idea what you want. File issues.

Installation

;; From MELPA or ELPA
(use-package dslide)

;; package-vc
(package-vc-install
 '(dslide
   :url "https://github.com/positron-solutions/dslide.git"))

;; using elpaca's with explicit recipe
(use-package dslide
    :elpaca (dslide :host github
                    :repo "positron-solutions/dslide"))

;; straight with explicit recipe
(use-package dslide
    :straight (dslide :type git :host github
                      :repo "positron-solutions/dslide"))

;; or use manual load-path & require, you brave yak shaver

Try It Out

With just defaults, run dslide-deck-start on your existing documents. You can load the examples in the ./test/demo.org file to see a showcase of configuration behavior.

The default keymap uses arrow keys. Left and right are dslide-deck-forward and dslide-deck-backward. Up is dslide-deck-start and will show the contents. Down is dslide-deck-stop and will stop the slide show.

Features

Simple User Interface

Fully programmable sequences behind a two-button presentation interface:

  • dslide-deck-forward
  • dslide-deck-backward

Contents Navigation

Call dslide-contents to show a contents overview. Calling dslide-deck-forward and dslide-deck-backward in the contents can quickly move through headings. Call dslide-deck-start again to resume the presentation from that point.

Narrate While Presenting

Check out dslide-deck-develop. You can see your hidden comments and the approximate progress indications. Babel actions will highlight blocks as they execute, showing you what just happened.

Hide Markup

By default, the dslide-action-hide-markup action is configured in dslide-default-actions. Looks clean out of the box. Commented and :noslide: or :noexport: headings are filtered. Todos and tags are hidden.

Independent Buffer State

The actual display is done in an indirect buffer. Your hooks and customizations for presentation will not pollute your editing buffer. Dirty state will not pile up in your presentation buffer, greatly increasing reliability even if your custom Elisp scripting is sloppy 💩.

Table of Contents

Creating

Making an org document into a presentation.

Actions

By default, you just get one slide per heading, a header, and some animation. This is not very exciting. You need to add actions to slides to consume their section content in a more engaging way.

There are two kinds of actions:

  • Slide actions: mostly responsible for narrowing to a slide and then handling the child headings, either inline or as separate slides
  • Section actions: work on the content in the heading's section.

To browse all actions, because they are all EIEIO classes, you can use eieio-browse and see the actions descend from dslide-action.

+--dslide-stateful-sequence
     +--dslide-action
          +--dslide-action-propertize
          +--dslide-action-image
          +--dslide-action-babel
          +--dslide-action-item-reveal
          +--dslide-action-hide-markup
          +--dslide-slide-action
               +--dslide-slide-action-every-child
               +--dslide-slide-action-inline
               +--dslide-slide-action-child
               +--dslide-slide-action-flat

Adding Actions

By default, every slide has two actions, configurable in dslide-default-actions:

  • dslide-action-propertize for adding text properties to arbitrary elements
  • dslide-action-hide-markup to hide keywords, todo states, and tags, allowing you to have these things in your source without them cluttering the presentation

Non-default actions must be added to a slide using the slide's property drawer. Actions that work by recognizing org elements by type are perhaps a bit dangerous to leave on all the time.

  • DSLIDE_SLIDE_ACTION: Usually narrows to the slide and creates children from child headings. Lifecycle encloses the section actions.
  • DSLIDE_ACTIONS: Most commonly used. You can list multiple actions. Each one will step through its forward and backward steps.

Regular Org Mode markup is used to add actions to headings. See more examples in the [[./test]] directory.

* Full Screen Images
:PROPERTIES:
:DSLIDE_ACTIONS: dslide-action-images
:END:
#+attr_html: :width 50%
[[./images/emacsen4.jpeg]] [[./images/before-google3.jpeg]]

Action Arguments

Many actions understand arguments, allowing tuning of similar behaviors from the same class.

To view an action's arguments, call describe-symbol on it. Any slot definition usually has the same :initarg and will be understood when added as a plist-style argument.

Configuring the slot is done by adding plist-style properties after the class name:

:PROPERTIES:
:DSLIDE_ACTIONS: dslide-action-item-reveal :inline t
:END:

You can also use "property+" syntax to add to a property, and these accept plist arguments too:

:PROPERTIES:
:DSLIDE_ACTIONS: dslide-action-babel
:DSLIDE_ACTIONS+: dslide-action-images :full-frame t
:END:

🚧 The current plist read implementation splits the string rather than using read-string and is therefore not smart enough to parse lists as arguments. However dslide-action-propertize demonstrates doing this correctly and shows that it will be possible if needed.

Annotating Elements

Some actions, such as dslide-action-propertize, can't decide which elements to operate on or what to do with those elements. You can add some meta data to an element using an affiliated keyword.

⚠️ If you are extending an action and want to create your own affiliated keyword, they must start with attr or else the org element parser will not consider them affiliated and that property will not be set on the element!

* Fancy Text
:PROPERTIES:
:DSLIDE_ACTIONS: dslide-action-propertize
:END:
Add text properties to an element using the =attr_dslide_propertize= affiliated keyword.  No quoting is required.  Lists will be interpreted as such.

#+attr_dslide_propertize: face (:background "#ddddff" :foreground "#000000" :weight bold :height 2.0)
This is some fancy text

Babel Scripting

You can write custom scripts into your presentation as Org Babel blocks. These can be executed with the dslide-action-babel action.

In the future the babel action may become a default, using the #+attr_dslide_babel affiliated keyword or :noeval to decide a block should not be executed. As of this version of dslide, either add dslide-action-babel to your dslide-default-actions or add it to the actions list via the property drawer.

* My Heading With Babel Blocks
:PROPERTIES:
:DSLIDE_ACTIONS: dslide-action-babel
:END:
#+begin_src elisp
  (message "Good job!")
#+end_src

By default blocks only execute going forward, one block per step. You need to label your blocks with lifecycle methods if you want to perform setup (forward and backward) and teardown. See the dslide-action-babel class and examples in ./test/demo.org.

The #+attr_dslide: affiliated keyword is used to configure which methods will run the block. Block labels that are understood:

  • begin and end are run when the slide is instantiated, going forward and backward respectively. You can have several blocks with these methods, and they will be run from top-to-bottom always, making it easier to re-use code usually.

  • final is called to clean up when no progress can be made or if the presentation is stopped.

  • forward and backward are self-explanatory. Position your backward blocks above any block that they undo

  • both runs either direction. It will not repeat in place when reversing. Use separate forward and backward blocks for that 💡

These methods follow the naming and behavior of dslide's stateful sequence interface. The babel action is basically delegating stateful sequence calls into the blocks of your org document.

The babel action also understands regular babel options such as :exports and :results. Exports none will make the block invisible. Results controls whether results will be printed into the buffer or not.

Step Callbacks

See dslide-push-step for inserting arbitrary callbacks that can function as steps. Unless your action performs state tracking to decide when to consume dslide-deck-forward and dslide-deck-backward itself, a callback may be easier. Using dslide-push-step is also one way to optionally add a step callback from a babel block.

Hiding Markup

Dslide uses a lot of markup that would not look good in a presentation. It also filters it by default using dslide-action-hide-markup. You can adjust the types using dslide-hide-markup-types

Hiding Todos and Tags

dslide-action-hide-markup will also hide todos and tags. You can modifiy this with dslide-hide-todo and dslide-hide-tags.

Filtering Headings

  • Any heading with COMMENT directly after the stars will be skipped
  • Any heading with the :noslide: or :noexport: tags will be skipped

Use this when your headings are work-in-progress and you run out of time on Friday before the feature demo meeting. Have some content that is only not used in presentations? Use :noslide:.

To change the filtering from what is done by dslide-built-in-filter, customize dslide-default-filter or set DSLIDE_FILTER (possibly implemented 🤡, file an issue!).

Header Keywords

If dslide-header is configured, the keywords for the document title, email, and author etc will be used to generate an okay header.

#+,#+title:	Domain Specific sLIDEs
#+author:	Positron
#+email:	[email protected]

You can try customizing with dslide-header-email and similar variables or just set dslide-header-fun to complete replace the header with your own device.

Breadcrumbs

Whenever dslide-breadcrumb-separator is non-nil, breadcrumbs will be rendered in the heading, displaying parent headings so the audience an track context.

Because breadcrumb text comes from your headings, you may want to set a face on them to prevent various heading faces from leaking into the breadcrumbs.

File Local Variables

Don't forget that if you need a customize variable only set in a particular presentation, you can use file local variables. Not every setting needs a keyword or babel block integration.

# Local Variables:
# dslide-header: nil
# End:

Presenting

How to control and view your presentation.

Two Button Interface

Presentations tend to be organized into a scripted linear sequence. We want to control the entire presentation sequence mostly with two buttons, forwards and backwards.

The controllers for presenting usually have very few buttons. Dslide was designed with this usage pattern in mind and can mostly be controlled by two commands.

  • dslide-deck-forward

  • dslide-deck-backward

Many controllers also have a "play" button or similar. It's recommended to map this to dslide-deck-start.

🚧 It is intended to overload dslide-deck-start further to implement "secondary" actions that can be triggered non-linearly.

There is likely no good place to bind dslide-deck-stop, but it's not critical. You can do everything with just three buttons.

Contents Interface

Navigate your presentation faster when answering questions. The contents interface is a view of top-level headings. It overloads the presentation controls to navigate.

To enter the contents, call dslide-deck-start when a presentation is already active.

  • dslide-deck-start will resume the presentation at that heading
  • dslide-deck-stop will similarly exit the contents view
  • dslide-deck-forward and dslide-deck-backward move between top level headings.

Narrating

The presentation you see is a cloned [indirect buffer](info:elisp#Indirect Buffers) of your org mode buffer. The Elisp state and overlays are independent. There are two key advantages:

  • Any state you create in the presentation (besides buffer text and text properties!) will not pollute the org mode buffer you are editing
  • We can display the source for the presentation simultaneously, making one pretty while leaving the other to show us what is hidden

dslide-deck-develop will attempt to display both the presentation and source simultaneously. Whenever the source is visible, highlights will be applied to indicate where the presentation is at. This is especially helpful for including presentation notes in comments, which are hidden by default.

To leave a comment for yourself in the presentation source, just add a comment block or comment line:

# This is also a comment

#+begin_comment
This is a comment that only I can see while presenting, only when I look at my base buffer while sharing another frame.
#+end_comment

You can also switch a window to the base buffer manually. That's almost all dslide-deck-develop does.

Cursor Visibility

By default, the cursor is hidden in the presentation buffer using dslide-cursor-hide. You can call dslide-cursor-restore if you need it.

Configuring

Be sure to check M-x customize-group dslide to see all declared custom variables. All of the variables are configured to recommended defaults except hooks, which would depend on other packages usually.

Many settings can be configured at:

  • global level through customize variables
  • document level through keywords
  • slide level through the property drawer

Binding

You likely want to start the mode via dslide-deck-start. Once the mode starts, it creates an indirect buffer to display the slides and then calls dslide-deck-start-function once the mode is active and everything is initialized, so you can customize startup behavior.

All commands begin with dslide-deck 💡

(keymap-set org-mode-map "<f5>" #'dslide-deck-start)

Once the global minor mode, dslide-mode is active, additional bindings in dslide-mode-map are active in every buffer so that you can integrate other buffers into your presentation. (Tracking which buffers are part of a presentation is still a topic under consideration 🚧)

Secondary Commands 🚧

Because you might want to play a video or take a branch in the presentation and then exit that branch, the plan is to overload the dslide-deck-start binding within presentations to enter / exit these branches.

Hooks

Beware of using the normal dslide-mode-hook 😱 because it runs in the base buffer ⚠️. If you use that hook to remap faces or add a bunch of styling, state will be copied to the indirect buffer but then linger in your base buffer. Instead, use dslide-start-hook. 💡

  • dslide-start-hook is run in the indirect buffer after it is set it. This is what you want.

  • dslide-stop-hook is run in the base buffer because the indirect buffer is already dead.

  • dslide-contents-hook is run after switching to contents. It runs in the slide buffer.

  • dslide-narrow-hook is run after narrowing, usually after a slide is started

  • dslide-after-last-slide-hook is run when the user tries to go forward but there are no more slides. You can use this to implement a final feedback before quitting or add dslide-deck-stop to exit without feedback.

    Another option is to use dslide-push-step to push a callback that will only run when called going forward.

(defun my-stop-if-forward ()
  (dslide-push-step (lambda (direction)
                  (when (eq direction 'forward)
                    ;; Be sure to return t or the callback won't count as a
                    ;; step and the hook will run again.
                    (prog1 t (dslide-deck-stop))))))

(setq dslide-after-last-slide-hook #'my-stop-if-forward)

Per-Slide Actions

💡 If you want to do something on each slide or specific slides, before using hooks, instead consider using actions.

See the dslide-action-hide-markup which is by default added to dslide-default-actions and hides markup on every slide. The lifecycle of actions and their methods for obtaining the current slide's heading make them very good for per-slide behavior.

Steezing Org

This is not unique to dslide, but if you want more professional looking results, you will likely need to make your org a bit prettier.

The setup used for the Positron's YouTube demos is not much more complex than this well-documented setup by System Crafters. Also see Prot's further documentation on customizing org mode faces and fonts.

In short, use:

  • org-modern
  • org-appear
  • nerd-icons for more cheesy (Emacs logo)
  • And set the faces for org headings and document title.

Don't forget built-in emoji-search and searching insert-char.

Positron is cheating and also apply custom line-spacing and line-height. While Psionic maintains a custom org-modern, using custom spacing everywhere fights with visual-line-mode currently.

Extending

Creating new actions or replacing dslide classes.

Creating Actions

Actions are the right choice when you need custom behavior that you want to re-use. Actions can be configured with arguments. They implement the stateful sequence lifecycle. For one-off solutions, you probably just want a babel block.

First choose your action type:

  • Override dslide-action to create an action that works mainly on a heading's section content.

  • Override dslide-slide-action to create a slide action. Your action will control the display of the slide and its children, usually controlling the narrow state and adding or removing overlays from children.

Override methods as appropriate, configure a heading to use your action, and you're done. Some actions, such as dslide-action-propertize only work when some of the section data is annotated.

A Custom Action

The dslide-section-next and dslide-section-previous method documentation are very helpful behavior for quickly writing custom actions. They advance the action's :marker forwards and backwards to the next matching element and return that element so we can do something with it.

  • declare a class
  • override a few methods
  • now you too can paint the paragraphs red

Example code:

(defclass dslide-action-red-paragraphs (dslide-action)
  ((overlays :initform nil))
  "Paint the paragraphs red, one by one.")

;; Default no-op `dslide-begin' is sufficient

;; Default implementation of `dslide-end', which just plays forward to the end,
;; is well-behaved with this class.

;; Remove any remaining overlays when calling final.
(cl-defmethod dslide-final :after ((obj dslide-action-red-paragraphs))
  (mapc #'delete-overlay (oref obj overlays)))

;; Find the next paragraph and add an overlay if it exists
(cl-defmethod dslide-forward ((obj dslide-action-red-paragraphs))
  (when-let ((paragraph (dslide-section-next obj 'paragraph)))
    (let* ((beg (org-element-property :begin paragraph))
           (end (org-element-property :end paragraph))
           (new-overlay (make-overlay beg end)))
      (overlay-put new-overlay 'face 'error)
      (push new-overlay (oref obj overlays))
      ;; Return non-nil to indicate progress was made.  This also informs the
      ;; highlight when following the slides in the base buffer.
      beg)))

(cl-defmethod dslide-backward ((obj dslide-action-red-paragraphs))
  (when-let* ((overlay (pop (oref obj overlays))))
    (delete-overlay overlay)
    ;; If there is a preceding overlay, move to its beginning else move to the
    ;; beginning of the heading.
    (if-let ((overlay (car (oref obj overlays))))
        (dslide-marker obj (overlay-start overlay))
      (dslide-marker obj (org-element-property :begin (dslide-heading obj))))))

Default Classes

The deck and slide class as well as actions can be sub-classed. Use the existing sub-classes of actions as example code for writing other classes. See the eieio#Top manual for explanation of OOP in Elisp.

  • Action: Creating new action subclasses are an efficient way to perform similar operations on typical kinds of org data.

  • Slide: Slides can be configured extensively by changing their actions. However, for more vertical cooperation between slides or cooperation among actions, extended slides could be useful.

  • Deck: If the core methods of the deck are insufficient, extension is another option besides advice, hooks, and modifying the source.

    If you suspect you might need to sub-class the dslide-slide or dslide-deck, please file an issue because your use case is probably interesting.

Hacking

This section provides really high-level summary of the code's major design choices to prepare for diving into source.

Objects & Ownership

Org mode uses trees. Presentations are linear sequences. We can either traverse the tree or flatten it. Dslide chose to traverse. This design allowed implementing features such as dslide-slide-action-each-child. The children of such a parent slide exist simultaneously. A consequence of the choice not to flatten is that parents own their children. The lifecycle of a parent always encompasses its child.

  • The deck object is the root of all functionality and many commands delegate through it
  • The deck owns slides, which own actions
  • Slide actions may further own child slides

Life Cycles

Owning an object also means out-living it. This is important to understanding the sequence of events. The methods used for the lifecycle are part of dslide's Stateful Sequence. Every lifecyle starts with dslide-begin or dslide-end (depending on whether we go forward or backward) and ends with dslide-final.

The state of the slide out-lives the state of its slide action. The slide action out-lives both child slides and section actions. Child slides and section actions life cycles may overlap.

The child and section actions orders can vary depending on the slide action's choices. There may be multiple children alive at one time. The children may complete after, before, or at the same time as the section actions.

Going forward:

  1. slide dslide-begin
  2. slide action dslide-begin
  3. section actions + child slides dslide-begin
  4. section actions + child slides dslide-final
  5. slide action dslide-final
  6. slide dslide-final

Going backward:

  1. slide dslide-end
  2. slide action dslide-end
  3. child slides + section actions dslide-end
  4. child slides + section actions dslide-final
  5. slide action dslide-final
  6. slide dslide-final

Stateful Sequence

Presentations are supposed to be linear sequences. We want to traverse the sequence, performing the steps, entirely by calling dslide-forward and dslide-backward.

If all sequences were idempotent, we would only implement dslide-forward and dslide-backward. However, sequences often require setup and teardown before carrying out a single step. This is the "stateful" part.

Implementing this without explicit setup methods crammed too much behavior into dslide-forward and dslide-backward while also requiring them to decide if they were attempting to make progress or just performing setup. It was annoying when building actions.

Setup and teardown can happen in both directions, so there is dslide-begin and dslide-end. The latter commonly calls the former and then advances the state to the end, but some more optimal setups are possible and already in use.

Slides may be disposed of after they no longer make progress. To allow intended cleanup to happen at the right moment, the parent calls dslide-final. This can be called at any time after dslide-end or dslide-begin.

The return values for these methods matter! See flow control.

Flow Control

Decks, slides, and actions implement the dslide-stateful-sequence interface. On each call to dslide-deck-forward or dslide-deck-backward, the deck receives the first call to its dslide-forward method. First, the deck will check for any step callbacks. (These may be added with dslide-push-step in actions or babel blocks.) If there are no step callbacks, the deck delegates dslide-forward to the slide. The slide may delegate down to an action, which may then further delegate to a child slide and so on. Eventually, an action will implement the step.

The return value tells the parent if progress was made. In the most basic case, each delegate will try all of its actions until one returns non-nil. The delegate returns the first non-nil result. If the delegate returns nil, it means it was unable to make progress, and so the caller will instead try its own next action. The deck will find a root level sibling and hydrate it using dslide--make-slide. A child action would find the next child and hydrate that.

The moment of calling dslide-final can vary depending on the situation. If there is only one slide at a time, dslide-final is usually called right after the child returns nil. If the child is one of several, such as with dslide-slide-action-inline, then only after all children complete will they have their dslide-final called. If the presentation is quit early or the contents are opened, dslide-final is also called, possibly before all steps are complete.

Whenever all slides and actions return nil all the way back up to the deck, it looks for a next or previous top-level heading to make into a slide. If none is found, it indicates that the user is at the beginning or end of the presentation.

The deck object and slide actions frequently create new children from org headings. They call their dslide-begin or dslide-end methods right after that. If these methods don't indicate progress, the dslide-forward or dslide-back method will be called.

Instantiating Slides

Slides are created by calling dslide--make-slide with an org element for a heading. This function interprets the class name and arguments for the new slide and instantiates the object.

The default classes and actions can be configured at the document or customize level. Set the DSLIDE_DECK_CLASS and DSLIDE_SLIDE_CLASS as well as other properties that work at the heading level. The order of precedence (Not fully implemented 🚧):

  • Property definition of the current heading
  • Property definition in the document
  • Customize variable

dslide--make-slide will look in order for the highest precedence setting and then instantiate the class with that value in the slot.

Display

How various visual effects are achieved.

Hiding

The slide buffer, being an indirect clone of the base buffer, does not have independent text properties. For this reason, overlays are typically used to hide content.

Most things that are hidden could be once again revealed. This is typically accomplished by mutating or deleting the overlay.

Animation

There are currently two animation types, peel and slide-in:

  • Peel uses an overlay that is removed from the content one character at a time. In order to preserve the flow of the obscured contents, such as when doing inline reveal with content after the reveal, the overlay must either match the background color or use the display property.
  • Slide-in uses an overlay with a :before-string text property to insert a newline in order to use the :line-height property to slowly remove padding with a timer.

Peel is the default when an action or slide's :inline property is non-nil. If multiple actions try to slide in at once, the result will not be good. This is visible when combining dslide-slide-action-every-child and dslide-action-item-reveal

Full Screen Images

These are just image buffers with the mode line turned off.

Element Mapping

Org's Element API is the foundation on top of which dslide is built. It's documentation is not currently in a manual. Here's the web link: Org Element API docs. By using the element parser, we can avoid the issues that plague regex based implementations. (The trade-off is more garbage generation.)

Very frequently, we parse a section of the document and map over elements or headings within. This allows us to treat the document or a part of it as a list. The mapping functions all eventually delegate to dslide--map which itself uses org-element-map, narrowed to the targeted region.

It is very common when writing actions to work on only the section or only the children. For this reason, some shortcuts to map the section or children exist. Some section actions such as dslide-action-hide-markup are almost entirely built on dslide-section-map.

Frequently we are looking for an element before or after a marker, so shortcuts exist for finding the next or previous element. Section actions typically use dslide-section-next and dslide-section-previous. Slide actions typically use dslide-child-next and dslide-child-previous to traverse the child headings.

Mapping and progress tracking are intimately related. Finding the previous or next element is implemented by mapping to find the element beginning before or after a certain point. Careful handling of markers and a consistent scheme for sensing progress enable markers in the buffer to act as progress cursors for a variety of actions.

Progress Tracking

Dslide's predecessor, org-tree-slide, frequently used the point to track state. This can be fragile and there is also only one point. To be more robust when the document is changing out from under us, dslide uses markers.

Slides keep a reference to the heading in their :begin slot and then retrieve it using org-element-at-point. Actions similarly use a marker in order to keep track of how much of the current heading they have already used. For convenience, dslide-section-next and dslide-section-previous are used to simultaneously find the next element and update the marker, eliminating silly mistakes like forgetting to update the marker.

There are two schemes in place for tracking progress:

  • When viewing a sequence of images, we reverse by going back to the previous image rather than re-showing the current image. This is the default progress scheme.
  • When showing and hiding elements, we reverse undoing the most recent work. This means hiding the most recently shown or showing the most recently hidden element. This is the scheme used when REVERSE-IN-PLACE is non-nil.

⚠️ This section is fiddly and tricky. Put on your smarty hat. 👷

Normal Progress

In short, find the element beginning after (before in reverse) the marker, move the marker to its beginning, and work on that element. If there is no next element, move as far as you can.

  • The heading always begins before the first element. We can reliably position before all elements by putting the marker at the beginning of the heading.
  • To go forward, we find the first element beginning after the marker and move the marker to its beginning. We work on that element. It will be skipped if we immediately go backward again.
  • If there is no next element, we move the marker to the end of the heading, which is after the beginning of the last element.
  • To go backward, we find the first element beginning before the marker and move the marker to its beginning. We work on that element. It will be skipped if we immediately go forward again.

Reverse In Place Progress

If doing work means the next reverse step should undo that work, you need reversing in place. We need to slightly tweak our rules to allow two states on each element. Since every element ends after it begins, we can reliably use the end and beginning positions to differentiate if we already used an element when going forwards or backwards.

A very deliberate design choice was to avoid needing to return more than one element from a mapping call. This means we always want to find the element we intend to work on e.g. we do not want to find the element to work on and then have to find the next element to update the marker.

  • To go forward, we find the first element beginning at or after the marker. We move the marker to the end of this element and work on this element.
  • To go backward, we find the first element ending at or before the marker. We move the marker to the beginning of this element and work on this element.
  • Going forward, begin at the beginning of the heading just like normal progress. The first element will not be skipped.
  • Going backward, begin at the end of the heading. This is at most the end of the last element, so it won't be skipped.

☢️ Before these two schemes were developed, some actions were easier to implement one way while others were easier the other way. There was much flip-flopping and radiation sickness from broken actions. Eventually it was realized that both schemes make perfect sense for the right problems.

⚠️ Org elements can and do overlap. Lists are one such challenge. List elements can all end at the same location. Naively calling org-element-at-point is a bad idea. See dslide-action-item-reveal for higher level interfaces.

If you need more states per element, this kind of implicit state tracking is insufficient and you will have to implement state-tracking. ⚠️ Don't use text properties to store state in buffer text since they will persist in the base buffer between presentation starts if not cleaned up.

Package Pairings

These are some packages that are likely to find use alongside dslide.

Org Modern

Bullets and many prettifications of common org markups. The markup that you don't hide looks better with org modern.

Org Appear

Never worry about turning on pretty links for a presentation. Edit them by just moving the point inside.

Master of Ceremonies

The master-of-ceremonies package is primarily used for its moc-focus command which isolates small snippets of buffer text to make fullscreen and pretty. You can save replay these snippets without having access to a source buffer.

Check the full commands by pressing h during focus. You can highlight a region, save an expression to playback a code snippet without the buffer open etc.

Open Broadcaster Software

Sacha Chua has written an OBS plugin integration helpful for video integration obs-websocket-el.

moom.el

The moom package contains some commands for resizing text and repositioning frames.

Contributing

  • Since you likely just need something to magically happen, the recommended option is to place a hamburger in the hamburger jar and file an issue.
  • If you do have time, excellent. Happy to support your PR's and provide context about the architecture and behavior.

Work In Progress 🚧

Open issues and give feedback on feature requests. Contributions welcome. See the 1.0 feature roadmap.

Affiliated Keyword

This is the future of dslide. Currently adding behavior to content can frequently require adding actions to the property drawer and then adding a keyword to the content. This lacks precision, is unintuitive, and is inconvenient. dslide-action-propertize shows the way. A dispatch system should find all dslide prefixed affiliated keywords and activate the actions with the configuration. This is faster and more concise. It only requires editing in one place rather than two.

The property drawer will remain in use because headings have slide behavior that doesn't make sense to adjust with affiliated keywords. For behavior affecting section elements or operating on objects within paragraphs, the affiliated keyword implementation is the right way.

Layout

The master-of-ceremonies package and its mc-focus command implement desirable behaviors such as filling the available space and padding the content to the center of the window. This behavior could easily be improved and adapted into an action.

Slide Action Precedence

When a slide is created in dslide-make-slide, it can obtain them from several places:

  • passed in arguments, as slide actions do to prevent children from trying to display themselves
  • properties, how slides are usually configured
  • customize variables that set the default actions.

The order of precedence and capability to override options is still pretty immature.

Secondary Commands

See the section about bindings for context. Video play or other situations where the presentation might branch should be supported by overloading the behavior of dslide-deck-start. I think this command will turn into dslide-deck-secondary in the dslide-mode-map.

Starting From Point

Since not many actions currently have implemented dslide-goto very accurately, playing from point is likely not that accurate. Progress updating in the base buffer is also currently only at the slide level of granularity.

Affiliated Buffers

There is no tracking whether a buffer is part of the presentation or not. How would a buffer become one? Should it be implicit? Without any sort of tracking, the consequence is that having a presentation open leaves the minor mode bindings hot. These commands do weird things when run from these situations, especially if running babel scripts, so some kind of first-class buffer affiliation seems necessary.

Non-Graphic Display

For terminals, the line-height based slide-in effect is not supported.

Improper Levels

Children with no parents or missing a level are currently not supported and likely cause bad behavior.

Counting Slides

Especially if slides launch sub-sequences, and they do it from Lisp, this is hard. Buffer slides and also slide actions make it somewhat ambiguous. Counting trees or tracking the point might be easier. A children method for sequences works as long as sequences actually implement it.

Non-Org Sequences

There's no concrete reason why presentations need to start with Org mode buffers. The deck object could have its org-specific functionality pushed down to an org-mode class. The only requirement is to be able to hydrate some stateful sequences, which may hydrate and call into sub-sequences, meaning anything is pretty trivially possible.

Acknowledgments

This package is a direct descendant of Takaaki ISHIKAWA's org-tree-slide package. Many of the ideas and some of the implementations were either inherited or inspired by ideas from that package. This package would not exist without the inspiration. Thanks to everyone who contributed on org-tree-slide.