Multimodal

A plugin for Reveal.js to show content in modal windows.

Multimodal can be used as a lightbox or actual modal to showcase images, video or HTML content from wihin a presentation. It can be triggered from text links, images, or buttons, or automatically when a slide is shown.

• Demo
• Markdown demo

Basics

There are really only three steps:

1. Install Multimodal
2. Add the multimodal data-attributes to your links
3. Enjoy the modals

Installation

Regular installation

Copy the multimodal folder to the plugins folder of the reveal.js folder, like this: plugin/multimodal.

npm installation

This plugin is published to, and can be installed from, npm.

npm install reveal.js-multimodal

The Multimodal plugin folder can then be referenced from node_modules/reveal.js-multimodal/plugin/multimodal

Setup

JavaScript

There are two JavaScript files for Multimodal, a regular one, multimodal.js, and a module one, multimodal.esm.js. You only need one of them:

Regular

If you're not using ES modules, for example, to be able to run your presentation from the filesystem, you can add it like this:

<script type="text/javascript" src="dist/reveal.js"></script>
<script src="plugin/multimodal/multimodal.js"></script>
<script>
	Reveal.initialize({
		// ...
		plugins: [ Multimodal ]
	});
</script>

As a module

If you're using ES modules, you can add it like this:

<script type="module">
	// This will need a server
	import Reveal from './dist/reveal.esm.js';
	import Multimodal from './plugin/multimodal/multimodal.esm.js';
	Reveal.initialize({
		// ...
		plugins: [ Multimodal ]
	});
</script>

Styling

The styling of Multimodal is automatically inserted when the multimodal folder is manually (or automatically) copied to the Reveal.js plugin folder.

If you import reveal.js-multimodal from npm, you will need to import the CSS file yourself. Depending on your setup this can be something like this:

import 'reveal.js-multimodal/plugin/multimodal/multimodal.css';

Multimodal will detect if it runs in a module environment and will then not autoload the CSS. You can still set cssautoload to true if you like, but your bundler (Vite, Webpack) may not like that. In any of these cases, import the CSS file yourself.

If you want to change the Multimodal style, you can do a lot of that via the Reveal.js options. Or you can simply make your own style and use that stylesheet instead. Linking to your custom styles can be managed through the csspath option of Multimodal or through import when using modules.

Custom CSS

If and when you decide to create your own CSS file, make sure that you also include the following CSS variable, that is used by the plugin to avoid loading the CSS multiple times, and to avoid using the autoloading feature when using modules:

:root {
    --cssimported-multimodal: true;
}

Markup

It is easy to set up your HTML structure for Multimodal. To show a modal, it needs to be triggered from a trigger. A trigger needs at least a data-modal-type.

• From a data-modal-url in an anchor tag
• From an href attribute in an anchor tag
• From a data-modal-url in a button tag

<a href="#" data-modal-type="image" data-modal-url="assets/img/1.jpg">a data-modal-url</a>
<a href="assets/img/2.jpg" data-modal-type="image">an href attribute</a>
<a href="#" data-modal-type="image" data-modal-url="assets/img/3.jpg">a data-modal-url</a>

Content for an HTML modal usually sits on the slide it is opened from, where it should not be seen until the modal opens. Give it the mm-dialog class and the plugin keeps it out of sight:

<div class="mm-dialog" id="somehiddendiv">
  <h2>Example of HTML content</h2>
</div>

For Markdown markup, check the Markdown demo above. The same class goes in an element comment: <!-- .element: id="somehiddendiv" class="mm-dialog"-->

Note: If the modal-content is not valid or can’t be found, no modal will be opened. So make sure that the content you are linking to (an image, a video, a piece of HTML) is there where you expect it.

Modal behaviour

Modal size

• Content in modals will display at its original size, but is constrained to the maximum size of the modal.
• The maximum size of modals is the size to the viewport, minus the margin as set in the Reveal config.
• The minimum size of HTML modals is 100x100 pixels. This can be set in the config.

Navigation changes

• The arrow keys will close modals and go to the next slide
• The space bar or escape key will only close the modal
• A video modal uses the space bar to play and pause instead

In fullscreen, a browser normally uses the escape key to leave fullscreen, and the presentation never sees it. In Chrome and Edge, Multimodal asks for that key while a modal is open, so the first press closes the modal and the next one leaves fullscreen. Holding it down still leaves fullscreen straight away. This needs localhost or https. Safari and Firefox do not allow it, so there the first press leaves fullscreen and the second closes the modal.

Multimodal hands these keys to the modal through Reveal's keyboardCondition, which it sets when the presentation loads, and it keeps any keyboardCondition of your own. If you change keyboardCondition later with Reveal.configure, then the modal no longer gets its keys.

Focus

When a modal opens, focus moves into it, and the rest of the presentation cannot be clicked or tabbed to until it closes. Focus then goes back to the element that had it, usually the trigger. If you style triggers on focus, then use :focus-visible, so that a trigger that was clicked does not keep its focus style.

Slide modals

To automatically open a modal when a slide is shown, add the data-modal-type and data-modal-url attributes to the section element.

<section data-modal-type="image" data-modal-url="assets/img/4.jpg">
  <h2>Slide modals</h2>
  <!-- Slide content here -->
</section>

Speaker view

In Speaker view (with the Reveal.js Notes plugin), opening any modal also opens it in the main window. It also works the other way around.

Scrolling a longer modal document is also repeated across the two windows, but that will only work for local content (on the page), not with iframes.

Sound only comes out of the presentation window. A video modal plays muted in the speaker view, and an iframe that asks to autoplay is loaded there with YouTube and Vimeo's mute parameters. Any other player (which has no parameter we can rely on), is asked not to autoplay.

Events

There are 4 events that may help you do things in your modals: multimodal:show, multimodal:shown, multimodal:hide, and multimodal:hidden. Details are in event.detail. Use it like this:

deck.addEventListener("multimodal:shown", async (event) => {
  const triggerInfo = event.detail.trigger;
  console.log("Trigger type:", triggerInfo.dataset.modalType);
});

Override navigation

To prevent the user from accidentally navigating to another slide while the modal is open, you can add the data-modal-navblock attribute to the triggering element.

<a href="assets/img/3.jpg" data-modal-type="image" data-modal-navblock="true">Show modal</a>

Adjust styling

The modal is styled with CSS variables, which are controlled through the Reveal.js options (see Global options). Some of these options can also be set per trigger:

Overlay

Add a data-modal-overlaycolor attribute to the trigger to change the overlay color on a per-trigger basis.

<a href="#" data-modal-type="image" data-modal-url="assets/img/5.jpg" data-modal-overlaycolor="rgba(150, 50, 0, 0.5)">Show modal</a>

Background and padding

The background color and padding can be set with the data-modal-background and data-modal-padding attributes. When using SVG's, this may come in handy. Both attributes can also be globally set in the options.

<a href="#" data-modal-type="image" data-modal-background="gray" data-modal-padding="1em">
    <img class="small" src="assets/img/svgexample.svg" alt="Graph">
</a>

Passing extra classes

A triggering element can pass extra classes to the modal with data-modal-class.

<a href="#" data-modal-type="html" data-modal-url="#somehiddendiv" data-modal-class="special">Show modal</a>

<style>
    .special { --mm-bordercolor: red; }
    .special p, .special h2 { color: red; }
</style>

Global options

There are a few options that you can change from the Reveal.js options. The values below are default and do not need to be set if they are not changed.

Reveal.initialize({
  // ...
  multimodal: {
    background: {
      html: "var(--r-background-color)",
      iframe: "var(--r-background-color)",
      media: "white"
    },
    bordercolor: "white",
    borderwidth: "1px",
    closebuttonhtml: '',
    cssautoload: true,
    csspath: '',
    htmlminwidth: "100px",
    htmlminheight: "100px",
    overlaycolor: "rgba(0, 0, 0, 0.30)",
    padding: {
      html: "1em",
      iframe: "0",
      media: "0"
    },
    radius: "0.5em",
    scalecorrection: true,
    shadow: "0 0.5em 0.75em 0.5em rgba(0, 0, 0, 0.25)",
    slidemodalevent: "slidetransitionend",
    speed: 300,
    videoautoplay: true,
    videocontrols: true,
    videoautohide: true,
    zoom: true,
    zoomfrom: 0.90
  },
  plugins: [ Multimodal ]
});

1. background: This sets the standard background color of the modal. If the padding is set to 0 (default for images and video’s), you will not see it. HTML, iframe and media (images and video) are set separately.
   • html: This is set to "var(--r-background-color)", which is the standard background color of the presentation.
   • iframe: This is set to "var(--r-background-color)", which is the standard background color of the presentation.
   • media: This is set to "white".
2. bordercolor: Set to white by default. You can set this to any CSS color value.
3. borderwidth: Set to 1px by default. You can set this to any CSS border width value.
4. closebuttonhtml: Allows you to add your own HTML for the close button. Can be any HTML, for example <button class="mm-close" type="button" data-modal-close="">X</button>.
5. cssautoload: Multimodal loads its own stylesheet when this is on. If you bundle Multimodal, or import its CSS yourself, it works this out and does not load a second copy, so this normally does not need setting. If you do want it to autoload in a bundled deck, then setting it to true yourself turns it back on.
6. csspath: Multimodal will automatically load the styling of the plugin. If you want to customise the styling, you can link to your own CSS file here.
7. htmlminwidth: This sets the minimum width of the HTML modals. The default is 100 pixels.
8. htmlminheight: This sets the minimum height of the HTML modals. The default is 100 pixels.
9. overlaycolor : This sets the color of the overlay. Some people may call it a backdrop. The default is rgba(0, 0, 0, 0.30). That's like 30% black. You can use any CSS color here, but it’s best to use rgba for transparency.
10. padding: This sets the standard padding of modals. HTML, iframe and media (images and video) are set separately.
    • html: This is set to "1em", so that content inside a modal has some breathing space.
    • iframe: Set to "0" but can be changed.
    • media: Set to "0" but can be changed.
11. radius: This sets the radius of the dialog box.

• scalecorrection : This sets a scale correction, used in the border width and the close button. On small devices or screens, the border and close button may be too small. This option scales them back up.
• shadow: This sets the shadow around the dialog box. The default is 0 0.5em 0.75em 0.5em rgba(0, 0, 0, 0.25), which is a soft but dark shadow.
• slidemodalevent: This sets the event that triggers the modal on a slide, if that slide is set to show a modal.
• speed: This sets the speed of the modal opening and closing.
• videoautoplay : This sets the video to autoplay when opened.
• videocontrols : This sets the video to show controls when opened.
• videoautohide : This sets the modal to close when the video in it ends.
• zoom: This sets the modal to zoom in when opened.
• zoomfrom: This sets the starting zoom factor of the modal when it is opened. It then zooms to factor 1.

Like it?

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And if you want to show off what you made with it, please do :-)

License

MIT licensed

Copyright (C) 2024 Martijn De Jongh (Martino)