js/controllers/printview.js
import { SLIDES_SELECTOR } from '../utils/constants.js'
import { queryAll, createStyleSheet } from '../utils/util.js'
/**
* Setups up our presentation for printing/exporting to PDF.
*/
export default class PrintView {
constructor( Reveal ) {
this.Reveal = Reveal;
}
/**
* Configures the presentation for printing to a static
* PDF.
*/
async activate() {
const config = this.Reveal.getConfig();
const slides = queryAll( this.Reveal.getRevealElement(), SLIDES_SELECTOR )
// Compute slide numbers now, before we start duplicating slides
const injectPageNumbers = config.slideNumber && /all|print/i.test( config.showSlideNumber );
const slideSize = this.Reveal.getComputedSlideSize( window.innerWidth, window.innerHeight );
// Dimensions of the PDF pages
const pageWidth = Math.floor( slideSize.width * ( 1 + config.margin ) ),
pageHeight = Math.floor( slideSize.height * ( 1 + config.margin ) );
// Dimensions of slides within the pages
const slideWidth = slideSize.width,
slideHeight = slideSize.height;
await new Promise( requestAnimationFrame );
// Let the browser know what page size we want to print
createStyleSheet( '@page{size:'+ pageWidth +'px '+ pageHeight +'px; margin: 0px;}' );
// Limit the size of certain elements to the dimensions of the slide
createStyleSheet( '.reveal section>img, .reveal section>video, .reveal section>iframe{max-width: '+ slideWidth +'px; max-height:'+ slideHeight +'px}' );
document.documentElement.classList.add( 'reveal-print', 'print-pdf' );
document.body.style.width = pageWidth + 'px';
document.body.style.height = pageHeight + 'px';
const viewportElement = this.Reveal.getViewportElement();
let presentationBackground;
if( viewportElement ) {
const viewportStyles = window.getComputedStyle( viewportElement );
if( viewportStyles && viewportStyles.background ) {
presentationBackground = viewportStyles.background;
}
}
// Make sure stretch elements fit on slide
await new Promise( requestAnimationFrame );
this.Reveal.layoutSlideContents( slideWidth, slideHeight );
// Batch scrollHeight access to prevent layout thrashing
await new Promise( requestAnimationFrame );
const slideScrollHeights = slides.map( slide => slide.scrollHeight );
const pages = [];
const pageContainer = slides[0].parentNode;
let slideNumber = 1;
// Slide and slide background layout
slides.forEach( function( slide, index ) {
// Vertical stacks are not centred since their section
// children will be
if( slide.classList.contains( 'stack' ) === false ) {
// Center the slide inside of the page, giving the slide some margin
let left = ( pageWidth - slideWidth ) / 2;
let top = ( pageHeight - slideHeight ) / 2;
const contentHeight = slideScrollHeights[ index ];
let numberOfPages = Math.max( Math.ceil( contentHeight / pageHeight ), 1 );
// Adhere to configured pages per slide limit
numberOfPages = Math.min( numberOfPages, config.pdfMaxPagesPerSlide );
// Center slides vertically
if( numberOfPages === 1 && config.center || slide.classList.contains( 'center' ) ) {
top = Math.max( ( pageHeight - contentHeight ) / 2, 0 );
}
// Wrap the slide in a page element and hide its overflow
// so that no page ever flows onto another
const page = document.createElement( 'div' );
pages.push( page );
page.className = 'pdf-page';
page.style.height = ( ( pageHeight + config.pdfPageHeightOffset ) * numberOfPages ) + 'px';
// Copy the presentation-wide background to each individual
// page when printing
if( presentationBackground ) {
page.style.background = presentationBackground;
}
page.appendChild( slide );
// Position the slide inside of the page
slide.style.left = left + 'px';
slide.style.top = top + 'px';
slide.style.width = slideWidth + 'px';
this.Reveal.slideContent.layout( slide );
if( slide.slideBackgroundElement ) {
page.insertBefore( slide.slideBackgroundElement, slide );
}
// Inject notes if `showNotes` is enabled
if( config.showNotes ) {
// Are there notes for this slide?
const notes = this.Reveal.getSlideNotes( slide );
if( notes ) {
const notesSpacing = 8;
const notesLayout = typeof config.showNotes === 'string' ? config.showNotes : 'inline';
const notesElement = document.createElement( 'div' );
notesElement.classList.add( 'speaker-notes' );
notesElement.classList.add( 'speaker-notes-pdf' );
notesElement.setAttribute( 'data-layout', notesLayout );
notesElement.innerHTML = notes;
if( notesLayout === 'separate-page' ) {
pages.push( notesElement );
}
else {
notesElement.style.left = notesSpacing + 'px';
notesElement.style.bottom = notesSpacing + 'px';
notesElement.style.width = ( pageWidth - notesSpacing*2 ) + 'px';
page.appendChild( notesElement );
}
}
}
// Inject page numbers if `slideNumbers` are enabled
if( injectPageNumbers ) {
const numberElement = document.createElement( 'div' );
numberElement.classList.add( 'slide-number' );
numberElement.classList.add( 'slide-number-pdf' );
numberElement.innerHTML = slideNumber++;
page.appendChild( numberElement );
}
// Copy page and show fragments one after another
if( config.pdfSeparateFragments ) {
// Each fragment 'group' is an array containing one or more
// fragments. Multiple fragments that appear at the same time
// are part of the same group.
const fragmentGroups = this.Reveal.fragments.sort( page.querySelectorAll( '.fragment' ), true );
let previousFragmentStep;
fragmentGroups.forEach( function( fragments, index ) {
// Remove 'current-fragment' from the previous group
if( previousFragmentStep ) {
previousFragmentStep.forEach( function( fragment ) {
fragment.classList.remove( 'current-fragment' );
} );
}
// Show the fragments for the current index
fragments.forEach( function( fragment ) {
fragment.classList.add( 'visible', 'current-fragment' );
}, this );
// Create a separate page for the current fragment state
const clonedPage = page.cloneNode( true );
// Inject unique page numbers for fragments
if( injectPageNumbers ) {
const numberElement = clonedPage.querySelector( '.slide-number-pdf' );
const fragmentNumber = index + 1;
numberElement.innerHTML += '.' + fragmentNumber;
}
pages.push( clonedPage );
previousFragmentStep = fragments;
}, this );
// Reset the first/original page so that all fragments are hidden
fragmentGroups.forEach( function( fragments ) {
fragments.forEach( function( fragment ) {
fragment.classList.remove( 'visible', 'current-fragment' );
} );
} );
}
// Show all fragments
else {
queryAll( page, '.fragment:not(.fade-out)' ).forEach( function( fragment ) {
fragment.classList.add( 'visible' );
} );
}
}
}, this );
await new Promise( requestAnimationFrame );
pages.forEach( page => pageContainer.appendChild( page ) );
// Re-run JS-based content layout after the slide is added to page DOM
this.Reveal.slideContent.layout( this.Reveal.getSlidesElement() );
// Notify subscribers that the PDF layout is good to go
this.Reveal.dispatchEvent({ type: 'pdf-ready' });
viewportElement.classList.remove( 'loading-scroll-mode' );
}
/**
* Checks if the print mode is/should be activated.
*/
isActive() {
return this.Reveal.getConfig().view === 'print';
}
}