plugin/notes/plugin.js
import speakerViewHTML from './speaker-view.html'
import { marked } from 'marked';
/**
* Handles opening of and synchronization with the reveal.js
* notes window.
*
* Handshake process:
* 1. This window posts 'connect' to notes window
* - Includes URL of presentation to show
* 2. Notes window responds with 'connected' when it is available
* 3. This window proceeds to send the current presentation state
* to the notes window
*/
const Plugin = () => {
let connectInterval;
let speakerWindow = null;
let deck;
/**
* Opens a new speaker view window.
*/
function openSpeakerWindow() {
// If a window is already open, focus it
if( speakerWindow && !speakerWindow.closed ) {
speakerWindow.focus();
}
else {
speakerWindow = window.open( 'about:blank', 'reveal.js - Notes', 'width=1100,height=700' );
speakerWindow.marked = marked;
speakerWindow.document.write( speakerViewHTML );
if( !speakerWindow ) {
alert( 'Speaker view popup failed to open. Please make sure popups are allowed and reopen the speaker view.' );
return;
}
connect();
}
}
/**
* Reconnect with an existing speaker view window.
*/
function reconnectSpeakerWindow( reconnectWindow ) {
if( speakerWindow && !speakerWindow.closed ) {
speakerWindow.focus();
}
else {
speakerWindow = reconnectWindow;
window.addEventListener( 'message', onPostMessage );
onConnected();
}
}
/**
* Connect to the notes window through a postmessage handshake.
* Using postmessage enables us to work in situations where the
* origins differ, such as a presentation being opened from the
* file system.
*/
function connect() {
const presentationURL = deck.getConfig().url;
const url = typeof presentationURL === 'string' ? presentationURL :
window.location.protocol + '//' + window.location.host + window.location.pathname + window.location.search;
// Keep trying to connect until we get a 'connected' message back
connectInterval = setInterval( function() {
speakerWindow.postMessage( JSON.stringify( {
namespace: 'reveal-notes',
type: 'connect',
state: deck.getState(),
url
} ), '*' );
}, 500 );
window.addEventListener( 'message', onPostMessage );
}
/**
* Calls the specified Reveal.js method with the provided argument
* and then pushes the result to the notes frame.
*/
function callRevealApi( methodName, methodArguments, callId ) {
let result = deck[methodName].apply( deck, methodArguments );
speakerWindow.postMessage( JSON.stringify( {
namespace: 'reveal-notes',
type: 'return',
result,
callId
} ), '*' );
}
/**
* Posts the current slide data to the notes window.
*/
function post( event ) {
let slideElement = deck.getCurrentSlide(),
notesElements = slideElement.querySelectorAll( 'aside.notes' ),
fragmentElement = slideElement.querySelector( '.current-fragment' );
let messageData = {
namespace: 'reveal-notes',
type: 'state',
notes: '',
markdown: false,
whitespace: 'normal',
state: deck.getState()
};
// Look for notes defined in a slide attribute
if( slideElement.hasAttribute( 'data-notes' ) ) {
messageData.notes = slideElement.getAttribute( 'data-notes' );
messageData.whitespace = 'pre-wrap';
}
// Look for notes defined in a fragment
if( fragmentElement ) {
let fragmentNotes = fragmentElement.querySelector( 'aside.notes' );
if( fragmentNotes ) {
messageData.notes = fragmentNotes.innerHTML;
messageData.markdown = typeof fragmentNotes.getAttribute( 'data-markdown' ) === 'string';
// Ignore other slide notes
notesElements = null;
}
else if( fragmentElement.hasAttribute( 'data-notes' ) ) {
messageData.notes = fragmentElement.getAttribute( 'data-notes' );
messageData.whitespace = 'pre-wrap';
// In case there are slide notes
notesElements = null;
}
}
// Look for notes defined in an aside element
if( notesElements && notesElements.length ) {
// Ignore notes inside of fragments since those are shown
// individually when stepping through fragments
notesElements = Array.from( notesElements ).filter( notesElement => notesElement.closest( '.fragment' ) === null );
messageData.notes = notesElements.map( notesElement => notesElement.innerHTML ).join( '\n' );
messageData.markdown = notesElements[0] && typeof notesElements[0].getAttribute( 'data-markdown' ) === 'string';
}
speakerWindow.postMessage( JSON.stringify( messageData ), '*' );
}
/**
* Check if the given event is from the same origin as the
* current window.
*/
function isSameOriginEvent( event ) {
try {
return window.location.origin === event.source.location.origin;
}
catch ( error ) {
return false;
}
}
function onPostMessage( event ) {
// Only allow same-origin messages
// (added 12/5/22 as a XSS safeguard)
if( isSameOriginEvent( event ) ) {
try {
let data = JSON.parse( event.data );
if( data && data.namespace === 'reveal-notes' && data.type === 'connected' ) {
clearInterval( connectInterval );
onConnected();
}
else if( data && data.namespace === 'reveal-notes' && data.type === 'call' ) {
callRevealApi( data.methodName, data.arguments, data.callId );
}
} catch (e) {}
}
}
/**
* Called once we have established a connection to the notes
* window.
*/
function onConnected() {
// Monitor events that trigger a change in state
deck.on( 'slidechanged', post );
deck.on( 'fragmentshown', post );
deck.on( 'fragmenthidden', post );
deck.on( 'overviewhidden', post );
deck.on( 'overviewshown', post );
deck.on( 'paused', post );
deck.on( 'resumed', post );
// Post the initial state
post();
}
return {
id: 'notes',
init: function( reveal ) {
deck = reveal;
if( !/receiver/i.test( window.location.search ) ) {
// If the there's a 'notes' query set, open directly
if( window.location.search.match( /(\?|\&)notes/gi ) !== null ) {
openSpeakerWindow();
}
else {
// Keep listening for speaker view hearbeats. If we receive a
// heartbeat from an orphaned window, reconnect it. This ensures
// that we remain connected to the notes even if the presentation
// is reloaded.
window.addEventListener( 'message', event => {
if( !speakerWindow && typeof event.data === 'string' ) {
let data;
try {
data = JSON.parse( event.data );
}
catch( error ) {}
if( data && data.namespace === 'reveal-notes' && data.type === 'heartbeat' ) {
reconnectSpeakerWindow( event.source );
}
}
});
}
// Open the notes when the 's' key is hit
deck.addKeyBinding({keyCode: 83, key: 'S', description: 'Speaker notes view'}, function() {
openSpeakerWindow();
} );
}
},
open: openSpeakerWindow
};
};
export default Plugin;