mirror of
https://github.com/hakimel/reveal.js.git
synced 2025-10-28 20:36:13 +01:00
471 lines
15 KiB
JavaScript
471 lines
15 KiB
JavaScript
import { queryAll } from '../utils/util.js'
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import { colorToRgb, colorBrightness } from '../utils/color.js'
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/**
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* Creates and updates slide backgrounds.
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*/
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export default class Backgrounds {
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constructor( Reveal ) {
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this.Reveal = Reveal;
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}
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render() {
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this.element = document.createElement( 'div' );
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this.element.className = 'backgrounds';
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this.Reveal.getRevealElement().appendChild( this.element );
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}
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/**
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* Creates the slide background elements and appends them
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* to the background container. One element is created per
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* slide no matter if the given slide has visible background.
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*/
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create() {
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// Clear prior backgrounds
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this.element.innerHTML = '';
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this.element.classList.add( 'no-transition' );
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// Iterate over all horizontal slides
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this.Reveal.getHorizontalSlides().forEach( slideh => {
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let backgroundStack = this.createBackground( slideh, this.element );
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// Iterate over all vertical slides
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queryAll( slideh, 'section' ).forEach( slidev => {
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this.createBackground( slidev, backgroundStack );
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backgroundStack.classList.add( 'stack' );
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} );
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} );
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// Add parallax background if specified
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if( this.Reveal.getConfig().parallaxBackgroundImage ) {
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this.element.style.backgroundImage = 'url("' + this.Reveal.getConfig().parallaxBackgroundImage + '")';
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this.element.style.backgroundSize = this.Reveal.getConfig().parallaxBackgroundSize;
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this.element.style.backgroundRepeat = this.Reveal.getConfig().parallaxBackgroundRepeat;
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this.element.style.backgroundPosition = this.Reveal.getConfig().parallaxBackgroundPosition;
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// Make sure the below properties are set on the element - these properties are
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// needed for proper transitions to be set on the element via CSS. To remove
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// annoying background slide-in effect when the presentation starts, apply
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// these properties after short time delay
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setTimeout( () => {
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this.Reveal.getRevealElement().classList.add( 'has-parallax-background' );
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}, 1 );
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}
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else {
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this.element.style.backgroundImage = '';
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this.Reveal.getRevealElement().classList.remove( 'has-parallax-background' );
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}
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}
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/**
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* Creates a background for the given slide.
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*
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* @param {HTMLElement} slide
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* @param {HTMLElement} container The element that the background
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* should be appended to
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* @return {HTMLElement} New background div
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*/
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createBackground( slide, container ) {
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// Main slide background element
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let element = document.createElement( 'div' );
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element.className = 'slide-background ' + slide.className.replace( /present|past|future/, '' );
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// Inner background element that wraps images/videos/iframes
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let contentElement = document.createElement( 'div' );
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contentElement.className = 'slide-background-content';
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element.appendChild( contentElement );
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container.appendChild( element );
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slide.slideBackgroundElement = element;
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slide.slideBackgroundContentElement = contentElement;
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// Syncs the background to reflect all current background settings
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this.sync( slide );
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return element;
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}
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/**
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* Renders all of the visual properties of a slide background
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* based on the various background attributes.
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*
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* @param {HTMLElement} slide
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*/
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sync( slide ) {
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const element = slide.slideBackgroundElement,
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contentElement = slide.slideBackgroundContentElement;
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const data = {
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background: slide.getAttribute( 'data-background' ),
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backgroundSize: slide.getAttribute( 'data-background-size' ),
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backgroundImage: slide.getAttribute( 'data-background-image' ),
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backgroundVideo: slide.getAttribute( 'data-background-video' ),
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backgroundIframe: slide.getAttribute( 'data-background-iframe' ),
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backgroundColor: slide.getAttribute( 'data-background-color' ),
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backgroundGradient: slide.getAttribute( 'data-background-gradient' ),
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backgroundRepeat: slide.getAttribute( 'data-background-repeat' ),
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backgroundPosition: slide.getAttribute( 'data-background-position' ),
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backgroundTransition: slide.getAttribute( 'data-background-transition' ),
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backgroundOpacity: slide.getAttribute( 'data-background-opacity' ),
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};
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const dataPreload = slide.hasAttribute( 'data-preload' );
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// Reset the prior background state in case this is not the
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// initial sync
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slide.classList.remove( 'has-dark-background' );
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slide.classList.remove( 'has-light-background' );
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element.removeAttribute( 'data-loaded' );
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element.removeAttribute( 'data-background-hash' );
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element.removeAttribute( 'data-background-size' );
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element.removeAttribute( 'data-background-transition' );
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element.style.backgroundColor = '';
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contentElement.style.backgroundSize = '';
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contentElement.style.backgroundRepeat = '';
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contentElement.style.backgroundPosition = '';
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contentElement.style.backgroundImage = '';
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contentElement.style.opacity = '';
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contentElement.innerHTML = '';
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if( data.background ) {
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// Auto-wrap image urls in url(...)
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if( /^(http|file|\/\/)/gi.test( data.background ) || /\.(svg|png|jpg|jpeg|gif|bmp|webp)([?#\s]|$)/gi.test( data.background ) ) {
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slide.setAttribute( 'data-background-image', data.background );
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}
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else {
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element.style.background = data.background;
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}
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}
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// Create a hash for this combination of background settings.
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// This is used to determine when two slide backgrounds are
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// the same.
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if( data.background || data.backgroundColor || data.backgroundGradient || data.backgroundImage || data.backgroundVideo || data.backgroundIframe ) {
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element.setAttribute( 'data-background-hash', data.background +
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data.backgroundSize +
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data.backgroundImage +
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data.backgroundVideo +
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data.backgroundIframe +
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data.backgroundColor +
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data.backgroundGradient +
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data.backgroundRepeat +
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data.backgroundPosition +
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data.backgroundTransition +
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data.backgroundOpacity );
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}
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// Additional and optional background properties
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if( data.backgroundSize ) element.setAttribute( 'data-background-size', data.backgroundSize );
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if( data.backgroundColor ) element.style.backgroundColor = data.backgroundColor;
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if( data.backgroundGradient ) element.style.backgroundImage = data.backgroundGradient;
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if( data.backgroundTransition ) element.setAttribute( 'data-background-transition', data.backgroundTransition );
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if( dataPreload ) element.setAttribute( 'data-preload', '' );
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// Background image options are set on the content wrapper
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if( data.backgroundSize ) contentElement.style.backgroundSize = data.backgroundSize;
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if( data.backgroundRepeat ) contentElement.style.backgroundRepeat = data.backgroundRepeat;
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if( data.backgroundPosition ) contentElement.style.backgroundPosition = data.backgroundPosition;
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if( data.backgroundOpacity ) contentElement.style.opacity = data.backgroundOpacity;
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const contrastClass = this.getContrastClass( slide );
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if( typeof contrastClass === 'string' ) {
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slide.classList.add( contrastClass );
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}
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}
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/**
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* Returns a class name that can be applied to a slide to indicate
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* if it has a light or dark background.
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*
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* @param {*} slide
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*
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* @returns {string|null}
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*/
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getContrastClass( slide ) {
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const element = slide.slideBackgroundElement;
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// If this slide has a background color, we add a class that
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// signals if it is light or dark. If the slide has no background
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// color, no class will be added
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let contrastColor = slide.getAttribute( 'data-background-color' );
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// If no bg color was found, or it cannot be converted by colorToRgb, check the computed background
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if( !contrastColor || !colorToRgb( contrastColor ) ) {
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let computedBackgroundStyle = window.getComputedStyle( element );
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if( computedBackgroundStyle && computedBackgroundStyle.backgroundColor ) {
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contrastColor = computedBackgroundStyle.backgroundColor;
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}
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}
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if( contrastColor ) {
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const rgb = colorToRgb( contrastColor );
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// Ignore fully transparent backgrounds. Some browsers return
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// rgba(0,0,0,0) when reading the computed background color of
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// an element with no background
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if( rgb && rgb.a !== 0 ) {
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if( colorBrightness( contrastColor ) < 128 ) {
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return 'has-dark-background';
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}
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else {
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return 'has-light-background';
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}
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}
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}
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return null;
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}
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/**
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* Bubble the 'has-light-background'/'has-dark-background' classes.
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*/
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bubbleSlideContrastClassToElement( slide, target ) {
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[ 'has-light-background', 'has-dark-background' ].forEach( classToBubble => {
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if( slide.classList.contains( classToBubble ) ) {
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target.classList.add( classToBubble );
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}
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else {
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target.classList.remove( classToBubble );
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}
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}, this );
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}
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/**
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* Updates the background elements to reflect the current
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* slide.
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*
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* @param {boolean} includeAll If true, the backgrounds of
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* all vertical slides (not just the present) will be updated.
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*/
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update( includeAll = false ) {
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let config = this.Reveal.getConfig();
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let currentSlide = this.Reveal.getCurrentSlide();
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let indices = this.Reveal.getIndices();
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let currentBackground = null;
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// Reverse past/future classes when in RTL mode
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let horizontalPast = config.rtl ? 'future' : 'past',
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horizontalFuture = config.rtl ? 'past' : 'future';
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// Update the classes of all backgrounds to match the
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// states of their slides (past/present/future)
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Array.from( this.element.childNodes ).forEach( ( backgroundh, h ) => {
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backgroundh.classList.remove( 'past', 'present', 'future' );
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if( h < indices.h ) {
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backgroundh.classList.add( horizontalPast );
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}
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else if ( h > indices.h ) {
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backgroundh.classList.add( horizontalFuture );
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}
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else {
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backgroundh.classList.add( 'present' );
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// Store a reference to the current background element
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currentBackground = backgroundh;
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}
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if( includeAll || h === indices.h ) {
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queryAll( backgroundh, '.slide-background' ).forEach( ( backgroundv, v ) => {
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backgroundv.classList.remove( 'past', 'present', 'future' );
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const indexv = typeof indices.v === 'number' ? indices.v : 0;
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if( v < indexv ) {
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backgroundv.classList.add( 'past' );
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}
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else if ( v > indexv ) {
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backgroundv.classList.add( 'future' );
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}
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else {
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backgroundv.classList.add( 'present' );
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// Only if this is the present horizontal and vertical slide
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if( h === indices.h ) currentBackground = backgroundv;
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}
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} );
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}
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} );
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// The previous background may refer to a DOM element that has
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// been removed after a presentation is synced & bgs are recreated
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if( this.previousBackground && !this.previousBackground.closest( 'body' ) ) {
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this.previousBackground = null;
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}
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if( currentBackground && this.previousBackground ) {
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// Don't transition between identical backgrounds. This
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// prevents unwanted flicker.
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let previousBackgroundHash = this.previousBackground.getAttribute( 'data-background-hash' );
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let currentBackgroundHash = currentBackground.getAttribute( 'data-background-hash' );
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if( currentBackgroundHash && currentBackgroundHash === previousBackgroundHash && currentBackground !== this.previousBackground ) {
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this.element.classList.add( 'no-transition' );
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// If multiple slides have the same background video, carry
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// the <video> element forward so that it plays continuously
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// across multiple slides
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const currentVideo = currentBackground.querySelector( 'video' );
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const previousVideo = this.previousBackground.querySelector( 'video' );
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if( currentVideo && previousVideo ) {
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const currentVideoParent = currentVideo.parentNode;
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const previousVideoParent = previousVideo.parentNode;
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// Swap the two videos
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previousVideoParent.appendChild( currentVideo );
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currentVideoParent.appendChild( previousVideo );
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}
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}
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}
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const backgroundChanged = currentBackground !== this.previousBackground;
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// Stop content inside of previous backgrounds
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if( backgroundChanged && this.previousBackground ) {
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this.Reveal.slideContent.stopEmbeddedContent( this.previousBackground, { unloadIframes: !this.Reveal.slideContent.shouldPreload( this.previousBackground ) } );
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}
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// Start content in the current background
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if( backgroundChanged && currentBackground ) {
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this.Reveal.slideContent.startEmbeddedContent( currentBackground );
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let currentBackgroundContent = currentBackground.querySelector( '.slide-background-content' );
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if( currentBackgroundContent ) {
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let backgroundImageURL = currentBackgroundContent.style.backgroundImage || '';
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// Restart GIFs (doesn't work in Firefox)
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if( /\.gif/i.test( backgroundImageURL ) ) {
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currentBackgroundContent.style.backgroundImage = '';
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window.getComputedStyle( currentBackgroundContent ).opacity;
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currentBackgroundContent.style.backgroundImage = backgroundImageURL;
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}
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}
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this.previousBackground = currentBackground;
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}
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// If there's a background brightness flag for this slide,
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// bubble it to the .reveal container
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if( currentSlide ) {
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this.bubbleSlideContrastClassToElement( currentSlide, this.Reveal.getRevealElement() );
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}
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// Allow the first background to apply without transition
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setTimeout( () => {
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this.element.classList.remove( 'no-transition' );
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}, 10 );
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}
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/**
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* Updates the position of the parallax background based
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* on the current slide index.
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*/
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updateParallax() {
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let indices = this.Reveal.getIndices();
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if( this.Reveal.getConfig().parallaxBackgroundImage ) {
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let horizontalSlides = this.Reveal.getHorizontalSlides(),
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verticalSlides = this.Reveal.getVerticalSlides();
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let backgroundSize = this.element.style.backgroundSize.split( ' ' ),
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backgroundWidth, backgroundHeight;
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if( backgroundSize.length === 1 ) {
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backgroundWidth = backgroundHeight = parseInt( backgroundSize[0], 10 );
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}
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else {
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backgroundWidth = parseInt( backgroundSize[0], 10 );
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backgroundHeight = parseInt( backgroundSize[1], 10 );
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}
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let slideWidth = this.element.offsetWidth,
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horizontalSlideCount = horizontalSlides.length,
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horizontalOffsetMultiplier,
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horizontalOffset;
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if( typeof this.Reveal.getConfig().parallaxBackgroundHorizontal === 'number' ) {
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horizontalOffsetMultiplier = this.Reveal.getConfig().parallaxBackgroundHorizontal;
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}
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else {
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horizontalOffsetMultiplier = horizontalSlideCount > 1 ? ( backgroundWidth - slideWidth ) / ( horizontalSlideCount-1 ) : 0;
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}
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horizontalOffset = horizontalOffsetMultiplier * indices.h * -1;
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let slideHeight = this.element.offsetHeight,
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verticalSlideCount = verticalSlides.length,
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verticalOffsetMultiplier,
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verticalOffset;
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if( typeof this.Reveal.getConfig().parallaxBackgroundVertical === 'number' ) {
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verticalOffsetMultiplier = this.Reveal.getConfig().parallaxBackgroundVertical;
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}
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else {
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verticalOffsetMultiplier = ( backgroundHeight - slideHeight ) / ( verticalSlideCount-1 );
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}
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verticalOffset = verticalSlideCount > 0 ? verticalOffsetMultiplier * indices.v : 0;
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this.element.style.backgroundPosition = horizontalOffset + 'px ' + -verticalOffset + 'px';
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}
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}
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destroy() {
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this.element.remove();
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}
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}
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