js/reveal.js

   1 /*!
   2  * reveal.js
   3  * http://lab.hakim.se/reveal-js
   4  * MIT licensed
   5  *
   6  * Copyright (C) 2013 Hakim El Hattab, http://hakim.se
   7  */
   8 var Reveal = (function(){
   9
  10         'use strict';
  11
  12         var SLIDES_SELECTOR = '.reveal .slides section',
  13                 HORIZONTAL_SLIDES_SELECTOR = '.reveal .slides>section',
  14                 VERTICAL_SLIDES_SELECTOR = '.reveal .slides>section.present>section',
  15                 HOME_SLIDE_SELECTOR = '.reveal .slides>section:first-child',
  16
  17                 // Configurations defaults, can be overridden at initialization time
  18                 config = {
  19
  20                         // The "normal" size of the presentation, aspect ratio will be preserved
  21                         // when the presentation is scaled to fit different resolutions
  22                         width: 960,
  23                         height: 700,
  24
  25                         // Factor of the display size that should remain empty around the content
  26                         margin: 0.1,
  27
  28                         // Bounds for smallest/largest possible scale to apply to content
  29                         minScale: 0.2,
  30                         maxScale: 1.0,
  31
  32                         // Display controls in the bottom right corner
  33                         controls: true,
  34
  35                         // Display a presentation progress bar
  36                         progress: true,
  37
  38                         // Push each slide change to the browser history
  39                         history: false,
  40
  41                         // Enable keyboard shortcuts for navigation
  42                         keyboard: true,
  43
  44                         // Enable the slide overview mode
  45                         overview: true,
  46
  47                         // Vertical centring of slides
  48                         center: true,
  49
  50                         // Enables touch navigation on devices with touch input
  51                         touch: true,
  52
  53                         // Loop the presentation
  54                         loop: false,
  55
  56                         // Change the presentation direction to be RTL
  57                         rtl: false,
  58
  59                         // Number of milliseconds between automatically proceeding to the
  60                         // next slide, disabled when set to 0, this value can be overwritten
  61                         // by using a data-autoslide attribute on your slides
  62                         autoSlide: 0,
  63
  64                         // Enable slide navigation via mouse wheel
  65                         mouseWheel: false,
  66
  67                         // Apply a 3D roll to links on hover
  68                         rollingLinks: true,
  69
  70                         // Theme (see /css/theme)
  71                         theme: null,
  72
  73                         // Transition style
  74                         transition: 'default', // default/cube/page/concave/zoom/linear/fade/none
  75
  76                         // Script dependencies to load
  77                         dependencies: []
  78                 },
  79
  80                 // The current auto-slide duration
  81                 autoSlide = 0,
  82
  83                 // The horizontal and vertical index of the currently active slide
  84                 indexh = 0,
  85                 indexv = 0,
  86
  87                 // The previous and current slide HTML elements
  88                 previousSlide,
  89                 currentSlide,
  90
  91                 // Slides may hold a data-state attribute which we pick up and apply
  92                 // as a class to the body. This list contains the combined state of
  93                 // all current slides.
  94                 state = [],
  95
  96                 // The current scale of the presentation (see width/height config)
  97                 scale = 1,
  98
  99                 // Cached references to DOM elements
 100                 dom = {},
 101
 102                 // Detect support for CSS 3D transforms
 103                 supports3DTransforms =  'WebkitPerspective' in document.body.style ||
 104                                                                 'MozPerspective' in document.body.style ||
 105                                                                 'msPerspective' in document.body.style ||
 106                                                                 'OPerspective' in document.body.style ||
 107                                                                 'perspective' in document.body.style,
 108
 109                 // Detect support for CSS 2D transforms
 110                 supports2DTransforms =  'WebkitTransform' in document.body.style ||
 111                                                                 'MozTransform' in document.body.style ||
 112                                                                 'msTransform' in document.body.style ||
 113                                                                 'OTransform' in document.body.style ||
 114                                                                 'transform' in document.body.style,
 115
 116                 // Throttles mouse wheel navigation
 117                 mouseWheelTimeout = 0,
 118
 119                 // An interval used to automatically move on to the next slide
 120                 autoSlideTimeout = 0,
 121
 122                 // Delays updates to the URL due to a Chrome thumbnailer bug
 123                 writeURLTimeout = 0,
 124
 125                 // A delay used to activate the overview mode
 126                 activateOverviewTimeout = 0,
 127
 128                 // A delay used to deactivate the overview mode
 129                 deactivateOverviewTimeout = 0,
 130
 131                 // Flags if the interaction event listeners are bound
 132                 eventsAreBound = false,
 133
 134                 // Holds information about the currently ongoing touch input
 135                 touch = {
 136                         startX: 0,
 137                         startY: 0,
 138                         startSpan: 0,
 139                         startCount: 0,
 140                         handled: false,
 141                         threshold: 80
 142                 };
 143
 144         /**
 145          * Starts up the presentation if the client is capable.
 146          */
 147         function initialize( options ) {
 148
 149                 if( !supports2DTransforms && !supports3DTransforms ) {
 150                         document.body.setAttribute( 'class', 'no-transforms' );
 151
 152                         // If the browser doesn't support core features we won't be
 153                         // using JavaScript to control the presentation
 154                         return;
 155                 }
 156
 157                 // Force a layout when the whole page, incl fonts, has loaded
 158                 window.addEventListener( 'load', layout, false );
 159
 160                 // Copy options over to our config object
 161                 extend( config, options );
 162
 163                 // Hide the address bar in mobile browsers
 164                 hideAddressBar();
 165
 166                 // Loads the dependencies and continues to #start() once done
 167                 load();
 168
 169         }
 170
 171         /**
 172          * Finds and stores references to DOM elements which are
 173          * required by the presentation. If a required element is
 174          * not found, it is created.
 175          */
 176         function setupDOM() {
 177
 178                 // Cache references to key DOM elements
 179                 dom.theme = document.querySelector( '#theme' );
 180                 dom.wrapper = document.querySelector( '.reveal' );
 181                 dom.slides = document.querySelector( '.reveal .slides' );
 182
 183                 // Progress bar
 184                 if( !dom.wrapper.querySelector( '.progress' ) && config.progress ) {
 185                         var progressElement = document.createElement( 'div' );
 186                         progressElement.classList.add( 'progress' );
 187                         progressElement.innerHTML = '<span></span>';
 188                         dom.wrapper.appendChild( progressElement );
 189                 }
 190
 191                 // Arrow controls
 192                 if( !dom.wrapper.querySelector( '.controls' ) && config.controls ) {
 193                         var controlsElement = document.createElement( 'aside' );
 194                         controlsElement.classList.add( 'controls' );
 195                         controlsElement.innerHTML = '<div class="navigate-left"></div>' +
 196                                                                                 '<div class="navigate-right"></div>' +
 197                                                                                 '<div class="navigate-up"></div>' +
 198                                                                                 '<div class="navigate-down"></div>';
 199                         dom.wrapper.appendChild( controlsElement );
 200                 }
 201
 202                 // Presentation background element
 203                 if( !dom.wrapper.querySelector( '.state-background' ) ) {
 204                         var backgroundElement = document.createElement( 'div' );
 205                         backgroundElement.classList.add( 'state-background' );
 206                         dom.wrapper.appendChild( backgroundElement );
 207                 }
 208
 209                 // Overlay graphic which is displayed during the paused mode
 210                 if( !dom.wrapper.querySelector( '.pause-overlay' ) ) {
 211                         var pausedElement = document.createElement( 'div' );
 212                         pausedElement.classList.add( 'pause-overlay' );
 213                         dom.wrapper.appendChild( pausedElement );
 214                 }
 215
 216                 // Cache references to elements
 217                 dom.progress = document.querySelector( '.reveal .progress' );
 218                 dom.progressbar = document.querySelector( '.reveal .progress span' );
 219
 220                 if ( config.controls ) {
 221                         dom.controls = document.querySelector( '.reveal .controls' );
 222
 223                         // There can be multiple instances of controls throughout the page
 224                         dom.controlsLeft = toArray( document.querySelectorAll( '.navigate-left' ) );
 225                         dom.controlsRight = toArray( document.querySelectorAll( '.navigate-right' ) );
 226                         dom.controlsUp = toArray( document.querySelectorAll( '.navigate-up' ) );
 227                         dom.controlsDown = toArray( document.querySelectorAll( '.navigate-down' ) );
 228                         dom.controlsPrev = toArray( document.querySelectorAll( '.navigate-prev' ) );
 229                         dom.controlsNext = toArray( document.querySelectorAll( '.navigate-next' ) );
 230                 }
 231
 232         }
 233
 234         /**
 235          * Hides the address bar if we're on a mobile device.
 236          */
 237         function hideAddressBar() {
 238
 239                 if( /iphone|ipod|android/gi.test( navigator.userAgent ) && !/crios/gi.test( navigator.userAgent ) ) {
 240                         // Events that should trigger the address bar to hide
 241                         window.addEventListener( 'load', removeAddressBar, false );
 242                         window.addEventListener( 'orientationchange', removeAddressBar, false );
 243                 }
 244
 245         }
 246
 247         /**
 248          * Loads the dependencies of reveal.js. Dependencies are
 249          * defined via the configuration option 'dependencies'
 250          * and will be loaded prior to starting/binding reveal.js.
 251          * Some dependencies may have an 'async' flag, if so they
 252          * will load after reveal.js has been started up.
 253          */
 254         function load() {
 255
 256                 var scripts = [],
 257                         scriptsAsync = [];
 258
 259                 for( var i = 0, len = config.dependencies.length; i < len; i++ ) {
 260                         var s = config.dependencies[i];
 261
 262                         // Load if there's no condition or the condition is truthy
 263                         if( !s.condition || s.condition() ) {
 264                                 if( s.async ) {
 265                                         scriptsAsync.push( s.src );
 266                                 }
 267                                 else {
 268                                         scripts.push( s.src );
 269                                 }
 270
 271                                 // Extension may contain callback functions
 272                                 if( typeof s.callback === 'function' ) {
 273                                         head.ready( s.src.match( /([\w\d_\-]*)\.?js$|[^\\\/]*$/i )[0], s.callback );
 274                                 }
 275                         }
 276                 }
 277
 278                 // Called once synchronous scripts finish loading
 279                 function proceed() {
 280                         if( scriptsAsync.length ) {
 281                                 // Load asynchronous scripts
 282                                 head.js.apply( null, scriptsAsync );
 283                         }
 284
 285                         start();
 286                 }
 287
 288                 if( scripts.length ) {
 289                         head.ready( proceed );
 290
 291                         // Load synchronous scripts
 292                         head.js.apply( null, scripts );
 293                 }
 294                 else {
 295                         proceed();
 296                 }
 297
 298         }
 299
 300         /**
 301          * Starts up reveal.js by binding input events and navigating
 302          * to the current URL deeplink if there is one.
 303          */
 304         function start() {
 305
 306                 // Make sure we've got all the DOM elements we need
 307                 setupDOM();
 308
 309                 // Subscribe to input
 310                 addEventListeners();
 311
 312                 // Updates the presentation to match the current configuration values
 313                 configure();
 314
 315                 // Read the initial hash
 316                 readURL();
 317
 318                 // Notify listeners that the presentation is ready but use a 1ms
 319                 // timeout to ensure it's not fired synchronously after #initialize()
 320                 setTimeout( function() {
 321                         dispatchEvent( 'ready', {
 322                                 'indexh': indexh,
 323                                 'indexv': indexv,
 324                                 'currentSlide': currentSlide
 325                         } );
 326                 }, 1 );
 327
 328         }
 329
 330         /**
 331          * Applies the configuration settings from the config object.
 332          */
 333         function configure( options ) {
 334
 335                 dom.wrapper.classList.remove( config.transition );
 336
 337                 // New config options may be passed when this method
 338                 // is invoked through the API after initialization
 339                 if( typeof options === 'object' ) extend( config, options );
 340
 341                 // Force linear transition based on browser capabilities
 342                 if( supports3DTransforms === false ) config.transition = 'linear';
 343
 344                 dom.wrapper.classList.add( config.transition );
 345
 346                 if( dom.controls ) {
 347                         dom.controls.style.display = ( config.controls && dom.controls ) ? 'block' : 'none';
 348                 }
 349
 350                 if( dom.progress ) {
 351                         dom.progress.style.display = ( config.progress && dom.progress ) ? 'block' : 'none';
 352                 }
 353
 354                 if( config.rtl ) {
 355                         dom.wrapper.classList.add( 'rtl' );
 356                 }
 357                 else {
 358                         dom.wrapper.classList.remove( 'rtl' );
 359                 }
 360
 361                 if( config.center ) {
 362                         dom.wrapper.classList.add( 'center' );
 363                 }
 364                 else {
 365                         dom.wrapper.classList.remove( 'center' );
 366                 }
 367
 368                 if( config.mouseWheel ) {
 369                         document.addEventListener( 'DOMMouseScroll', onDocumentMouseScroll, false ); // FF
 370                         document.addEventListener( 'mousewheel', onDocumentMouseScroll, false );
 371                 }
 372                 else {
 373                         document.removeEventListener( 'DOMMouseScroll', onDocumentMouseScroll, false ); // FF
 374                         document.removeEventListener( 'mousewheel', onDocumentMouseScroll, false );
 375                 }
 376
 377                 // 3D links
 378                 if( config.rollingLinks ) {
 379                         enable3DLinks();
 380                 }
 381                 else {
 382                         disable3DLinks();
 383                 }
 384
 385                 // Load the theme in the config, if it's not already loaded
 386                 if( config.theme && dom.theme ) {
 387                         var themeURL = dom.theme.getAttribute( 'href' );
 388                         var themeFinder = /[^\/]*?(?=\.css)/;
 389                         var themeName = themeURL.match(themeFinder)[0];
 390
 391                         if(  config.theme !== themeName ) {
 392                                 themeURL = themeURL.replace(themeFinder, config.theme);
 393                                 dom.theme.setAttribute( 'href', themeURL );
 394                         }
 395                 }
 396
 397                 // Force a layout to make sure the current config is accounted for
 398                 layout();
 399
 400                 // Reflect the current autoSlide value
 401                 autoSlide = config.autoSlide;
 402
 403                 // Start auto-sliding if it's enabled
 404                 cueAutoSlide();
 405
 406         }
 407
 408         /**
 409          * Binds all event listeners.
 410          */
 411         function addEventListeners() {
 412
 413                 eventsAreBound = true;
 414
 415                 window.addEventListener( 'hashchange', onWindowHashChange, false );
 416                 window.addEventListener( 'resize', onWindowResize, false );
 417
 418                 if( config.touch ) {
 419                         dom.wrapper.addEventListener( 'touchstart', onTouchStart, false );
 420                         dom.wrapper.addEventListener( 'touchmove', onTouchMove, false );
 421                         dom.wrapper.addEventListener( 'touchend', onTouchEnd, false );
 422
 423                         // Support pointer-style touch interaction as well
 424                         if( window.navigator.msPointerEnabled ) {
 425                                 dom.wrapper.addEventListener( 'MSPointerDown', onPointerDown, false );
 426                                 dom.wrapper.addEventListener( 'MSPointerMove', onPointerMove, false );
 427                                 dom.wrapper.addEventListener( 'MSPointerUp', onPointerUp, false );
 428                         }
 429                 }
 430
 431                 if( config.keyboard ) {
 432                         document.addEventListener( 'keydown', onDocumentKeyDown, false );
 433                 }
 434
 435                 if ( config.progress && dom.progress ) {
 436                         dom.progress.addEventListener( 'click', onProgressClicked, false );
 437                 }
 438
 439                 if ( config.controls && dom.controls ) {
 440                         [ 'touchstart', 'click' ].forEach( function( eventName ) {
 441                                 dom.controlsLeft.forEach( function( el ) { el.addEventListener( eventName, onNavigateLeftClicked, false ); } );
 442                                 dom.controlsRight.forEach( function( el ) { el.addEventListener( eventName, onNavigateRightClicked, false ); } );
 443                                 dom.controlsUp.forEach( function( el ) { el.addEventListener( eventName, onNavigateUpClicked, false ); } );
 444                                 dom.controlsDown.forEach( function( el ) { el.addEventListener( eventName, onNavigateDownClicked, false ); } );
 445                                 dom.controlsPrev.forEach( function( el ) { el.addEventListener( eventName, onNavigatePrevClicked, false ); } );
 446                                 dom.controlsNext.forEach( function( el ) { el.addEventListener( eventName, onNavigateNextClicked, false ); } );
 447                         } );
 448                 }
 449
 450         }
 451
 452         /**
 453          * Unbinds all event listeners.
 454          */
 455         function removeEventListeners() {
 456
 457                 eventsAreBound = false;
 458
 459                 document.removeEventListener( 'keydown', onDocumentKeyDown, false );
 460                 window.removeEventListener( 'hashchange', onWindowHashChange, false );
 461                 window.removeEventListener( 'resize', onWindowResize, false );
 462
 463                 if( config.touch ) {
 464                         dom.wrapper.removeEventListener( 'touchstart', onTouchStart, false );
 465                         dom.wrapper.removeEventListener( 'touchmove', onTouchMove, false );
 466                         dom.wrapper.removeEventListener( 'touchend', onTouchEnd, false );
 467
 468                         if( window.navigator.msPointerEnabled ) {
 469                                 dom.wrapper.removeEventListener( 'MSPointerDown', onPointerDown, false );
 470                                 dom.wrapper.removeEventListener( 'MSPointerMove', onPointerMove, false );
 471                                 dom.wrapper.removeEventListener( 'MSPointerUp', onPointerUp, false );
 472                         }
 473                 }
 474
 475                 if ( config.progress && dom.progress ) {
 476                         dom.progress.removeEventListener( 'click', onProgressClicked, false );
 477                 }
 478
 479                 if ( config.controls && dom.controls ) {
 480                         [ 'touchstart', 'click' ].forEach( function( eventName ) {
 481                                 dom.controlsLeft.forEach( function( el ) { el.removeEventListener( eventName, onNavigateLeftClicked, false ); } );
 482                                 dom.controlsRight.forEach( function( el ) { el.removeEventListener( eventName, onNavigateRightClicked, false ); } );
 483                                 dom.controlsUp.forEach( function( el ) { el.removeEventListener( eventName, onNavigateUpClicked, false ); } );
 484                                 dom.controlsDown.forEach( function( el ) { el.removeEventListener( eventName, onNavigateDownClicked, false ); } );
 485                                 dom.controlsPrev.forEach( function( el ) { el.removeEventListener( eventName, onNavigatePrevClicked, false ); } );
 486                                 dom.controlsNext.forEach( function( el ) { el.removeEventListener( eventName, onNavigateNextClicked, false ); } );
 487                         } );
 488                 }
 489
 490         }
 491
 492         /**
 493          * Extend object a with the properties of object b.
 494          * If there's a conflict, object b takes precedence.
 495          */
 496         function extend( a, b ) {
 497
 498                 for( var i in b ) {
 499                         a[ i ] = b[ i ];
 500                 }
 501
 502         }
 503
 504         /**
 505          * Converts the target object to an array.
 506          */
 507         function toArray( o ) {
 508
 509                 return Array.prototype.slice.call( o );
 510
 511         }
 512
 513         /**
 514          * Measures the distance in pixels between point a
 515          * and point b.
 516          *
 517          * @param {Object} a point with x/y properties
 518          * @param {Object} b point with x/y properties
 519          */
 520         function distanceBetween( a, b ) {
 521
 522                 var dx = a.x - b.x,
 523                         dy = a.y - b.y;
 524
 525                 return Math.sqrt( dx*dx + dy*dy );
 526
 527         }
 528
 529         /**
 530          * Causes the address bar to hide on mobile devices,
 531          * more vertical space ftw.
 532          */
 533         function removeAddressBar() {
 534
 535                 if( window.orientation === 0 ) {
 536                         document.documentElement.style.overflow = 'scroll';
 537                         document.body.style.height = '120%';
 538                 }
 539                 else {
 540                         document.documentElement.style.overflow = '';
 541                         document.body.style.height = '100%';
 542                 }
 543
 544                 setTimeout( function() {
 545                         window.scrollTo( 0, 1 );
 546                 }, 10 );
 547
 548         }
 549
 550         /**
 551          * Dispatches an event of the specified type from the
 552          * reveal DOM element.
 553          */
 554         function dispatchEvent( type, properties ) {
 555
 556                 var event = document.createEvent( "HTMLEvents", 1, 2 );
 557                 event.initEvent( type, true, true );
 558                 extend( event, properties );
 559                 dom.wrapper.dispatchEvent( event );
 560
 561         }
 562
 563         /**
 564          * Wrap all links in 3D goodness.
 565          */
 566         function enable3DLinks() {
 567
 568                 if( supports3DTransforms && !( 'msPerspective' in document.body.style ) ) {
 569                         var anchors = document.querySelectorAll( SLIDES_SELECTOR + ' a:not(.image)' );
 570
 571                         for( var i = 0, len = anchors.length; i < len; i++ ) {
 572                                 var anchor = anchors[i];
 573
 574                                 if( anchor.textContent && !anchor.querySelector( '*' ) && ( !anchor.className || !anchor.classList.contains( anchor, 'roll' ) ) ) {
 575                                         var span = document.createElement('span');
 576                                         span.setAttribute('data-title', anchor.text);
 577                                         span.innerHTML = anchor.innerHTML;
 578
 579                                         anchor.classList.add( 'roll' );
 580                                         anchor.innerHTML = '';
 581                                         anchor.appendChild(span);
 582                                 }
 583                         }
 584                 }
 585
 586         }
 587
 588         /**
 589          * Unwrap all 3D links.
 590          */
 591         function disable3DLinks() {
 592
 593                 var anchors = document.querySelectorAll( SLIDES_SELECTOR + ' a.roll' );
 594
 595                 for( var i = 0, len = anchors.length; i < len; i++ ) {
 596                         var anchor = anchors[i];
 597                         var span = anchor.querySelector( 'span' );
 598
 599                         if( span ) {
 600                                 anchor.classList.remove( 'roll' );
 601                                 anchor.innerHTML = span.innerHTML;
 602                         }
 603                 }
 604
 605         }
 606
 607         /**
 608          * Return a sorted fragments list, ordered by an increasing
 609          * "data-fragment-index" attribute.
 610          *
 611          * Fragments will be revealed in the order that they are returned by
 612          * this function, so you can use the index attributes to control the
 613          * order of fragment appearance.
 614          *
 615          * To maintain a sensible default fragment order, fragments are presumed
 616          * to be passed in document order. This function adds a "fragment-index"
 617          * attribute to each node if such an attribute is not already present,
 618          * and sets that attribute to an integer value which is the position of
 619          * the fragment within the fragments list.
 620          */
 621         function sortFragments( fragments ) {
 622
 623                 var a = toArray( fragments );
 624
 625                 a.forEach( function( el, idx ) {
 626                         if( !el.hasAttribute( 'data-fragment-index' ) ) {
 627                                 el.setAttribute( 'data-fragment-index', idx );
 628                         }
 629                 } );
 630
 631                 a.sort( function( l, r ) {
 632                         return l.getAttribute( 'data-fragment-index' ) - r.getAttribute( 'data-fragment-index');
 633                 } );
 634
 635                 return a
 636
 637         }
 638
 639         /**
 640          * Applies JavaScript-controlled layout rules to the
 641          * presentation.
 642          */
 643         function layout() {
 644
 645                 if( dom.wrapper ) {
 646
 647                         // Available space to scale within
 648                         var availableWidth = dom.wrapper.offsetWidth,
 649                                 availableHeight = dom.wrapper.offsetHeight;
 650
 651                         // Reduce available space by margin
 652                         availableWidth -= ( availableHeight * config.margin );
 653                         availableHeight -= ( availableHeight * config.margin );
 654
 655                         // Dimensions of the content
 656                         var slideWidth = config.width,
 657                                 slideHeight = config.height;
 658
 659                         // Slide width may be a percentage of available width
 660                         if( typeof slideWidth === 'string' && /%$/.test( slideWidth ) ) {
 661                                 slideWidth = parseInt( slideWidth, 10 ) / 100 * availableWidth;
 662                         }
 663
 664                         // Slide height may be a percentage of available height
 665                         if( typeof slideHeight === 'string' && /%$/.test( slideHeight ) ) {
 666                                 slideHeight = parseInt( slideHeight, 10 ) / 100 * availableHeight;
 667                         }
 668
 669                         dom.slides.style.width = slideWidth + 'px';
 670                         dom.slides.style.height = slideHeight + 'px';
 671
 672                         // Determine scale of content to fit within available space
 673                         scale = Math.min( availableWidth / slideWidth, availableHeight / slideHeight );
 674
 675                         // Respect max/min scale settings
 676                         scale = Math.max( scale, config.minScale );
 677                         scale = Math.min( scale, config.maxScale );
 678
 679                         // Prefer applying scale via zoom since Chrome blurs scaled content
 680                         // with nested transforms
 681                         if( typeof dom.slides.style.zoom !== 'undefined' && !navigator.userAgent.match( /(iphone|ipod|ipad|android)/gi ) ) {
 682                                 dom.slides.style.zoom = scale;
 683                         }
 684                         // Apply scale transform as a fallback
 685                         else {
 686                                 var transform = 'translate(-50%, -50%) scale('+ scale +') translate(50%, 50%)';
 687
 688                                 dom.slides.style.WebkitTransform = transform;
 689                                 dom.slides.style.MozTransform = transform;
 690                                 dom.slides.style.msTransform = transform;
 691                                 dom.slides.style.OTransform = transform;
 692                                 dom.slides.style.transform = transform;
 693                         }
 694
 695                         // Select all slides, vertical and horizontal
 696                         var slides = toArray( document.querySelectorAll( SLIDES_SELECTOR ) );
 697
 698                         for( var i = 0, len = slides.length; i < len; i++ ) {
 699                                 var slide = slides[ i ];
 700
 701                                 // Don't bother updating invisible slides
 702                                 if( slide.style.display === 'none' ) {
 703                                         continue;
 704                                 }
 705
 706                                 if( config.center ) {
 707                                         // Vertical stacks are not centred since their section
 708                                         // children will be
 709                                         if( slide.classList.contains( 'stack' ) ) {
 710                                                 slide.style.top = 0;
 711                                         }
 712                                         else {
 713                                                 slide.style.top = Math.max( - ( slide.offsetHeight / 2 ) - 20, -slideHeight / 2 ) + 'px';
 714                                         }
 715                                 }
 716                                 else {
 717                                         slide.style.top = '';
 718                                 }
 719
 720                         }
 721
 722                 }
 723
 724         }
 725
 726         /**
 727          * Stores the vertical index of a stack so that the same
 728          * vertical slide can be selected when navigating to and
 729          * from the stack.
 730          *
 731          * @param {HTMLElement} stack The vertical stack element
 732          * @param {int} v Index to memorize
 733          */
 734         function setPreviousVerticalIndex( stack, v ) {
 735
 736                 if( typeof stack === 'object' && typeof stack.setAttribute === 'function' ) {
 737                         stack.setAttribute( 'data-previous-indexv', v || 0 );
 738                 }
 739
 740         }
 741
 742         /**
 743          * Retrieves the vertical index which was stored using
 744          * #setPreviousVerticalIndex() or 0 if no previous index
 745          * exists.
 746          *
 747          * @param {HTMLElement} stack The vertical stack element
 748          */
 749         function getPreviousVerticalIndex( stack ) {
 750
 751                 if( typeof stack === 'object' && typeof stack.setAttribute === 'function' && stack.classList.contains( 'stack' ) ) {
 752                         return parseInt( stack.getAttribute( 'data-previous-indexv' ) || 0, 10 );
 753                 }
 754
 755                 return 0;
 756
 757         }
 758
 759         /**
 760          * Displays the overview of slides (quick nav) by
 761          * scaling down and arranging all slide elements.
 762          *
 763          * Experimental feature, might be dropped if perf
 764          * can't be improved.
 765          */
 766         function activateOverview() {
 767
 768                 // Only proceed if enabled in config
 769                 if( config.overview ) {
 770
 771                         // Don't auto-slide while in overview mode
 772                         cancelAutoSlide();
 773
 774                         var wasActive = dom.wrapper.classList.contains( 'overview' );
 775
 776                         dom.wrapper.classList.add( 'overview' );
 777                         dom.wrapper.classList.remove( 'exit-overview' );
 778
 779                         clearTimeout( activateOverviewTimeout );
 780                         clearTimeout( deactivateOverviewTimeout );
 781
 782                         // Not the pretties solution, but need to let the overview
 783                         // class apply first so that slides are measured accurately
 784                         // before we can position them
 785                         activateOverviewTimeout = setTimeout( function(){
 786
 787                                 var horizontalSlides = document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR );
 788
 789                                 for( var i = 0, len1 = horizontalSlides.length; i < len1; i++ ) {
 790                                         var hslide = horizontalSlides[i],
 791                                                 htransform = 'translateZ(-2500px) translate(' + ( ( i - indexh ) * 105 ) + '%, 0%)';
 792
 793                                         hslide.setAttribute( 'data-index-h', i );
 794                                         hslide.style.display = 'block';
 795                                         hslide.style.WebkitTransform = htransform;
 796                                         hslide.style.MozTransform = htransform;
 797                                         hslide.style.msTransform = htransform;
 798                                         hslide.style.OTransform = htransform;
 799                                         hslide.style.transform = htransform;
 800
 801                                         if( hslide.classList.contains( 'stack' ) ) {
 802
 803                                                 var verticalSlides = hslide.querySelectorAll( 'section' );
 804
 805                                                 for( var j = 0, len2 = verticalSlides.length; j < len2; j++ ) {
 806                                                         var verticalIndex = i === indexh ? indexv : getPreviousVerticalIndex( hslide );
 807
 808                                                         var vslide = verticalSlides[j],
 809                                                                 vtransform = 'translate(0%, ' + ( ( j - verticalIndex ) * 105 ) + '%)';
 810
 811                                                         vslide.setAttribute( 'data-index-h', i );
 812                                                         vslide.setAttribute( 'data-index-v', j );
 813                                                         vslide.style.display = 'block';
 814                                                         vslide.style.WebkitTransform = vtransform;
 815                                                         vslide.style.MozTransform = vtransform;
 816                                                         vslide.style.msTransform = vtransform;
 817                                                         vslide.style.OTransform = vtransform;
 818                                                         vslide.style.transform = vtransform;
 819
 820                                                         // Navigate to this slide on click
 821                                                         vslide.addEventListener( 'click', onOverviewSlideClicked, true );
 822                                                 }
 823
 824                                         }
 825                                         else {
 826
 827                                                 // Navigate to this slide on click
 828                                                 hslide.addEventListener( 'click', onOverviewSlideClicked, true );
 829
 830                                         }
 831                                 }
 832
 833                                 layout();
 834
 835                                 if( !wasActive ) {
 836                                         // Notify observers of the overview showing
 837                                         dispatchEvent( 'overviewshown', {
 838                                                 'indexh': indexh,
 839                                                 'indexv': indexv,
 840                                                 'currentSlide': currentSlide
 841                                         } );
 842                                 }
 843
 844                         }, 10 );
 845
 846                 }
 847
 848         }
 849
 850         /**
 851          * Exits the slide overview and enters the currently
 852          * active slide.
 853          */
 854         function deactivateOverview() {
 855
 856                 // Only proceed if enabled in config
 857                 if( config.overview ) {
 858
 859                         clearTimeout( activateOverviewTimeout );
 860                         clearTimeout( deactivateOverviewTimeout );
 861
 862                         dom.wrapper.classList.remove( 'overview' );
 863
 864                         // Temporarily add a class so that transitions can do different things
 865                         // depending on whether they are exiting/entering overview, or just
 866                         // moving from slide to slide
 867                         dom.wrapper.classList.add( 'exit-overview' );
 868
 869                         deactivateOverviewTimeout = setTimeout( function () {
 870                                 dom.wrapper.classList.remove( 'exit-overview' );
 871                         }, 10);
 872
 873                         // Select all slides
 874                         var slides = toArray( document.querySelectorAll( SLIDES_SELECTOR ) );
 875
 876                         for( var i = 0, len = slides.length; i < len; i++ ) {
 877                                 var element = slides[i];
 878
 879                                 element.style.display = '';
 880
 881                                 // Resets all transforms to use the external styles
 882                                 element.style.WebkitTransform = '';
 883                                 element.style.MozTransform = '';
 884                                 element.style.msTransform = '';
 885                                 element.style.OTransform = '';
 886                                 element.style.transform = '';
 887
 888                                 element.removeEventListener( 'click', onOverviewSlideClicked, true );
 889                         }
 890
 891                         slide( indexh, indexv );
 892
 893                         cueAutoSlide();
 894
 895                         // Notify observers of the overview hiding
 896                         dispatchEvent( 'overviewhidden', {
 897                                 'indexh': indexh,
 898                                 'indexv': indexv,
 899                                 'currentSlide': currentSlide
 900                         } );
 901
 902                 }
 903         }
 904
 905         /**
 906          * Toggles the slide overview mode on and off.
 907          *
 908          * @param {Boolean} override Optional flag which overrides the
 909          * toggle logic and forcibly sets the desired state. True means
 910          * overview is open, false means it's closed.
 911          */
 912         function toggleOverview( override ) {
 913
 914                 if( typeof override === 'boolean' ) {
 915                         override ? activateOverview() : deactivateOverview();
 916                 }
 917                 else {
 918                         isOverview() ? deactivateOverview() : activateOverview();
 919                 }
 920
 921         }
 922
 923         /**
 924          * Checks if the overview is currently active.
 925          *
 926          * @return {Boolean} true if the overview is active,
 927          * false otherwise
 928          */
 929         function isOverview() {
 930
 931                 return dom.wrapper.classList.contains( 'overview' );
 932
 933         }
 934
 935         /**
 936          * Handling the fullscreen functionality via the fullscreen API
 937          *
 938          * @see http://fullscreen.spec.whatwg.org/
 939          * @see https://developer.mozilla.org/en-US/docs/DOM/Using_fullscreen_mode
 940          */
 941         function enterFullscreen() {
 942
 943                 var element = document.body;
 944
 945                 // Check which implementation is available
 946                 var requestMethod = element.requestFullScreen ||
 947                                                         element.webkitRequestFullScreen ||
 948                                                         element.mozRequestFullScreen ||
 949                                                         element.msRequestFullScreen;
 950
 951                 if( requestMethod ) {
 952                         requestMethod.apply( element );
 953                 }
 954
 955         }
 956
 957         /**
 958          * Enters the paused mode which fades everything on screen to
 959          * black.
 960          */
 961         function pause() {
 962
 963                 var wasPaused = dom.wrapper.classList.contains( 'paused' );
 964
 965                 cancelAutoSlide();
 966                 dom.wrapper.classList.add( 'paused' );
 967
 968                 if( wasPaused === false ) {
 969                         dispatchEvent( 'paused' );
 970                 }
 971
 972         }
 973
 974         /**
 975          * Exits from the paused mode.
 976          */
 977         function resume() {
 978
 979                 var wasPaused = dom.wrapper.classList.contains( 'paused' );
 980
 981                 cueAutoSlide();
 982                 dom.wrapper.classList.remove( 'paused' );
 983
 984                 if( wasPaused ) {
 985                         dispatchEvent( 'resumed' );
 986                 }
 987
 988         }
 989
 990         /**
 991          * Toggles the paused mode on and off.
 992          */
 993         function togglePause() {
 994
 995                 if( isPaused() ) {
 996                         resume();
 997                 }
 998                 else {
 999                         pause();
1000                 }
1001
1002         }
1003
1004         /**
1005          * Checks if we are currently in the paused mode.
1006          */
1007         function isPaused() {
1008
1009                 return dom.wrapper.classList.contains( 'paused' );
1010
1011         }
1012
1013         /**
1014          * Steps from the current point in the presentation to the
1015          * slide which matches the specified horizontal and vertical
1016          * indices.
1017          *
1018          * @param {int} h Horizontal index of the target slide
1019          * @param {int} v Vertical index of the target slide
1020          * @param {int} f Optional index of a fragment within the
1021          * target slide to activate
1022          */
1023         function slide( h, v, f ) {
1024
1025                 // Remember where we were at before
1026                 previousSlide = currentSlide;
1027
1028                 // Query all horizontal slides in the deck
1029                 var horizontalSlides = document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR );
1030
1031                 // If no vertical index is specified and the upcoming slide is a
1032                 // stack, resume at its previous vertical index
1033                 if( v === undefined ) {
1034                         v = getPreviousVerticalIndex( horizontalSlides[ h ] );
1035                 }
1036
1037                 // If we were on a vertical stack, remember what vertical index
1038                 // it was on so we can resume at the same position when returning
1039                 if( previousSlide && previousSlide.parentNode && previousSlide.parentNode.classList.contains( 'stack' ) ) {
1040                         setPreviousVerticalIndex( previousSlide.parentNode, indexv );
1041                 }
1042
1043                 // Remember the state before this slide
1044                 var stateBefore = state.concat();
1045
1046                 // Reset the state array
1047                 state.length = 0;
1048
1049                 var indexhBefore = indexh,
1050                         indexvBefore = indexv;
1051
1052                 // Activate and transition to the new slide
1053                 indexh = updateSlides( HORIZONTAL_SLIDES_SELECTOR, h === undefined ? indexh : h );
1054                 indexv = updateSlides( VERTICAL_SLIDES_SELECTOR, v === undefined ? indexv : v );
1055
1056                 layout();
1057
1058                 // Apply the new state
1059                 stateLoop: for( var i = 0, len = state.length; i < len; i++ ) {
1060                         // Check if this state existed on the previous slide. If it
1061                         // did, we will avoid adding it repeatedly
1062                         for( var j = 0; j < stateBefore.length; j++ ) {
1063                                 if( stateBefore[j] === state[i] ) {
1064                                         stateBefore.splice( j, 1 );
1065                                         continue stateLoop;
1066                                 }
1067                         }
1068
1069                         document.documentElement.classList.add( state[i] );
1070
1071                         // Dispatch custom event matching the state's name
1072                         dispatchEvent( state[i] );
1073                 }
1074
1075                 // Clean up the remains of the previous state
1076                 while( stateBefore.length ) {
1077                         document.documentElement.classList.remove( stateBefore.pop() );
1078                 }
1079
1080                 // If the overview is active, re-activate it to update positions
1081                 if( isOverview() ) {
1082                         activateOverview();
1083                 }
1084
1085                 // Update the URL hash after a delay since updating it mid-transition
1086                 // is likely to cause visual lag
1087                 writeURL( 1500 );
1088
1089                 // Find the current horizontal slide and any possible vertical slides
1090                 // within it
1091                 var currentHorizontalSlide = horizontalSlides[ indexh ],
1092                         currentVerticalSlides = currentHorizontalSlide.querySelectorAll( 'section' );
1093
1094                 // Store references to the previous and current slides
1095                 currentSlide = currentVerticalSlides[ indexv ] || currentHorizontalSlide;
1096
1097
1098                 // Show fragment, if specified
1099                 if( typeof f !== 'undefined' ) {
1100                         var fragments = sortFragments( currentSlide.querySelectorAll( '.fragment' ) );
1101
1102                         toArray( fragments ).forEach( function( fragment, indexf ) {
1103                                 if( indexf < f ) {
1104                                         fragment.classList.add( 'visible' );
1105                                 }
1106                                 else {
1107                                         fragment.classList.remove( 'visible' );
1108                                 }
1109                         } );
1110                 }
1111
1112                 // Dispatch an event if the slide changed
1113                 if( indexh !== indexhBefore || indexv !== indexvBefore ) {
1114                         dispatchEvent( 'slidechanged', {
1115                                 'indexh': indexh,
1116                                 'indexv': indexv,
1117                                 'previousSlide': previousSlide,
1118                                 'currentSlide': currentSlide
1119                         } );
1120                 }
1121                 else {
1122                         // Ensure that the previous slide is never the same as the current
1123                         previousSlide = null;
1124                 }
1125
1126                 // Solves an edge case where the previous slide maintains the
1127                 // 'present' class when navigating between adjacent vertical
1128                 // stacks
1129                 if( previousSlide ) {
1130                         previousSlide.classList.remove( 'present' );
1131
1132                         // Reset all slides upon navigate to home
1133                         // Issue: #285
1134                         if ( document.querySelector( HOME_SLIDE_SELECTOR ).classList.contains( 'present' ) ) {
1135                                 // Launch async task
1136                                 setTimeout( function () {
1137                                         var slides = toArray( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.stack') ), i;
1138                                         for( i in slides ) {
1139                                                 if( slides[i] ) {
1140                                                         // Reset stack
1141                                                         setPreviousVerticalIndex( slides[i], 0 );
1142                                                 }
1143                                         }
1144                                 }, 0 );
1145                         }
1146                 }
1147
1148                 updateControls();
1149                 updateProgress();
1150
1151         }
1152
1153         /**
1154          * Updates one dimension of slides by showing the slide
1155          * with the specified index.
1156          *
1157          * @param {String} selector A CSS selector that will fetch
1158          * the group of slides we are working with
1159          * @param {Number} index The index of the slide that should be
1160          * shown
1161          *
1162          * @return {Number} The index of the slide that is now shown,
1163          * might differ from the passed in index if it was out of
1164          * bounds.
1165          */
1166         function updateSlides( selector, index ) {
1167
1168                 // Select all slides and convert the NodeList result to
1169                 // an array
1170                 var slides = toArray( document.querySelectorAll( selector ) ),
1171                         slidesLength = slides.length;
1172
1173                 if( slidesLength ) {
1174
1175                         // Should the index loop?
1176                         if( config.loop ) {
1177                                 index %= slidesLength;
1178
1179                                 if( index < 0 ) {
1180                                         index = slidesLength + index;
1181                                 }
1182                         }
1183
1184                         // Enforce max and minimum index bounds
1185                         index = Math.max( Math.min( index, slidesLength - 1 ), 0 );
1186
1187                         for( var i = 0; i < slidesLength; i++ ) {
1188                                 var element = slides[i];
1189
1190                                 // Optimization; hide all slides that are three or more steps
1191                                 // away from the present slide
1192                                 if( isOverview() === false ) {
1193                                         // The distance loops so that it measures 1 between the first
1194                                         // and last slides
1195                                         var distance = Math.abs( ( index - i ) % ( slidesLength - 3 ) ) || 0;
1196
1197                                         element.style.display = distance > 3 ? 'none' : 'block';
1198                                 }
1199
1200                                 slides[i].classList.remove( 'past' );
1201                                 slides[i].classList.remove( 'present' );
1202                                 slides[i].classList.remove( 'future' );
1203
1204                                 if( i < index ) {
1205                                         // Any element previous to index is given the 'past' class
1206                                         slides[i].classList.add( 'past' );
1207                                 }
1208                                 else if( i > index ) {
1209                                         // Any element subsequent to index is given the 'future' class
1210                                         slides[i].classList.add( 'future' );
1211                                 }
1212
1213                                 // If this element contains vertical slides
1214                                 if( element.querySelector( 'section' ) ) {
1215                                         slides[i].classList.add( 'stack' );
1216                                 }
1217                         }
1218
1219                         // Mark the current slide as present
1220                         slides[index].classList.add( 'present' );
1221
1222                         // If this slide has a state associated with it, add it
1223                         // onto the current state of the deck
1224                         var slideState = slides[index].getAttribute( 'data-state' );
1225                         if( slideState ) {
1226                                 state = state.concat( slideState.split( ' ' ) );
1227                         }
1228
1229                         // If this slide has a data-autoslide attribtue associated use this as
1230                         // autoSlide value otherwise use the global configured time
1231                         var slideAutoSlide = slides[index].getAttribute( 'data-autoslide' );
1232                         if( slideAutoSlide ) {
1233                                 autoSlide = parseInt( slideAutoSlide, 10 );
1234                         }
1235                         else {
1236                                 autoSlide = config.autoSlide;
1237                         }
1238
1239                 }
1240                 else {
1241                         // Since there are no slides we can't be anywhere beyond the
1242                         // zeroth index
1243                         index = 0;
1244                 }
1245
1246                 return index;
1247
1248         }
1249
1250         /**
1251          * Updates the progress bar to reflect the current slide.
1252          */
1253         function updateProgress() {
1254
1255                 // Update progress if enabled
1256                 if( config.progress && dom.progress ) {
1257
1258                         var horizontalSlides = toArray( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
1259
1260                         // The number of past and total slides
1261                         var totalCount = document.querySelectorAll( SLIDES_SELECTOR + ':not(.stack)' ).length;
1262                         var pastCount = 0;
1263
1264                         // Step through all slides and count the past ones
1265                         mainLoop: for( var i = 0; i < horizontalSlides.length; i++ ) {
1266
1267                                 var horizontalSlide = horizontalSlides[i];
1268                                 var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) );
1269
1270                                 for( var j = 0; j < verticalSlides.length; j++ ) {
1271
1272                                         // Stop as soon as we arrive at the present
1273                                         if( verticalSlides[j].classList.contains( 'present' ) ) {
1274                                                 break mainLoop;
1275                                         }
1276
1277                                         pastCount++;
1278
1279                                 }
1280
1281                                 // Stop as soon as we arrive at the present
1282                                 if( horizontalSlide.classList.contains( 'present' ) ) {
1283                                         break;
1284                                 }
1285
1286                                 // Don't count the wrapping section for vertical slides
1287                                 if( horizontalSlide.classList.contains( 'stack' ) === false ) {
1288                                         pastCount++;
1289                                 }
1290
1291                         }
1292
1293                         dom.progressbar.style.width = ( pastCount / ( totalCount - 1 ) ) * window.innerWidth + 'px';
1294
1295                 }
1296
1297         }
1298
1299         /**
1300          * Updates the state of all control/navigation arrows.
1301          */
1302         function updateControls() {
1303
1304                 if ( config.controls && dom.controls ) {
1305
1306                         var routes = availableRoutes();
1307
1308                         // Remove the 'enabled' class from all directions
1309                         dom.controlsLeft.concat( dom.controlsRight )
1310                                                         .concat( dom.controlsUp )
1311                                                         .concat( dom.controlsDown )
1312                                                         .concat( dom.controlsPrev )
1313                                                         .concat( dom.controlsNext ).forEach( function( node ) {
1314                                 node.classList.remove( 'enabled' );
1315                         } );
1316
1317                         // Add the 'enabled' class to the available routes
1318                         if( routes.left ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'enabled' );     } );
1319                         if( routes.right ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'enabled' ); } );
1320                         if( routes.up ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'enabled' ); } );
1321                         if( routes.down ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'enabled' ); } );
1322
1323                         // Prev/next buttons
1324                         if( routes.left || routes.up ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'enabled' ); } );
1325                         if( routes.right || routes.down ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'enabled' ); } );
1326
1327                 }
1328
1329         }
1330
1331         /**
1332          * Determine what available routes there are for navigation.
1333          *
1334          * @return {Object} containing four booleans: left/right/up/down
1335          */
1336         function availableRoutes() {
1337
1338                 var horizontalSlides = document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ),
1339                         verticalSlides = document.querySelectorAll( VERTICAL_SLIDES_SELECTOR );
1340
1341                 return {
1342                         left: indexh > 0 || config.loop,
1343                         right: indexh < horizontalSlides.length - 1 || config.loop,
1344                         up: indexv > 0,
1345                         down: indexv < verticalSlides.length - 1
1346                 };
1347
1348         }
1349
1350         /**
1351          * Reads the current URL (hash) and navigates accordingly.
1352          */
1353         function readURL() {
1354
1355                 var hash = window.location.hash;
1356
1357                 // Attempt to parse the hash as either an index or name
1358                 var bits = hash.slice( 2 ).split( '/' ),
1359                         name = hash.replace( /#|\//gi, '' );
1360
1361                 // If the first bit is invalid and there is a name we can
1362                 // assume that this is a named link
1363                 if( isNaN( parseInt( bits[0], 10 ) ) && name.length ) {
1364                         // Find the slide with the specified name
1365                         var element = document.querySelector( '#' + name );
1366
1367                         if( element ) {
1368                                 // Find the position of the named slide and navigate to it
1369                                 var indices = Reveal.getIndices( element );
1370                                 slide( indices.h, indices.v );
1371                         }
1372                         // If the slide doesn't exist, navigate to the current slide
1373                         else {
1374                                 slide( indexh, indexv );
1375                         }
1376                 }
1377                 else {
1378                         // Read the index components of the hash
1379                         var h = parseInt( bits[0], 10 ) || 0,
1380                                 v = parseInt( bits[1], 10 ) || 0;
1381
1382                         slide( h, v );
1383                 }
1384
1385         }
1386
1387         /**
1388          * Updates the page URL (hash) to reflect the current
1389          * state.
1390          *
1391          * @param {Number} delay The time in ms to wait before
1392          * writing the hash
1393          */
1394         function writeURL( delay ) {
1395
1396                 if( config.history ) {
1397
1398                         // Make sure there's never more than one timeout running
1399                         clearTimeout( writeURLTimeout );
1400
1401                         // If a delay is specified, timeout this call
1402                         if( typeof delay === 'number' ) {
1403                                 writeURLTimeout = setTimeout( writeURL, delay );
1404                         }
1405                         else {
1406                                 var url = '/';
1407
1408                                 // If the current slide has an ID, use that as a named link
1409                                 if( currentSlide && typeof currentSlide.getAttribute( 'id' ) === 'string' ) {
1410                                         url = '/' + currentSlide.getAttribute( 'id' );
1411                                 }
1412                                 // Otherwise use the /h/v index
1413                                 else {
1414                                         if( indexh > 0 || indexv > 0 ) url += indexh;
1415                                         if( indexv > 0 ) url += '/' + indexv;
1416                                 }
1417
1418                                 window.location.hash = url;
1419                         }
1420                 }
1421
1422         }
1423
1424         /**
1425          * Retrieves the h/v location of the current, or specified,
1426          * slide.
1427          *
1428          * @param {HTMLElement} slide If specified, the returned
1429          * index will be for this slide rather than the currently
1430          * active one
1431          *
1432          * @return {Object} { h: <int>, v: <int> }
1433          */
1434         function getIndices( slide ) {
1435
1436                 // By default, return the current indices
1437                 var h = indexh,
1438                         v = indexv;
1439
1440                 // If a slide is specified, return the indices of that slide
1441                 if( slide ) {
1442                         var isVertical = !!slide.parentNode.nodeName.match( /section/gi );
1443                         var slideh = isVertical ? slide.parentNode : slide;
1444
1445                         // Select all horizontal slides
1446                         var horizontalSlides = toArray( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
1447
1448                         // Now that we know which the horizontal slide is, get its index
1449                         h = Math.max( horizontalSlides.indexOf( slideh ), 0 );
1450
1451                         // If this is a vertical slide, grab the vertical index
1452                         if( isVertical ) {
1453                                 v = Math.max( toArray( slide.parentNode.querySelectorAll( 'section' ) ).indexOf( slide ), 0 );
1454                         }
1455                 }
1456
1457                 return { h: h, v: v };
1458
1459         }
1460
1461         /**
1462          * Navigate to the next slide fragment.
1463          *
1464          * @return {Boolean} true if there was a next fragment,
1465          * false otherwise
1466          */
1467         function nextFragment() {
1468
1469                 // Vertical slides:
1470                 if( document.querySelector( VERTICAL_SLIDES_SELECTOR + '.present' ) ) {
1471                         var verticalFragments = sortFragments( document.querySelectorAll( VERTICAL_SLIDES_SELECTOR + '.present .fragment:not(.visible)' ) );
1472
1473                         if( verticalFragments.length ) {
1474                                 verticalFragments[0].classList.add( 'visible' );
1475
1476                                 // Notify subscribers of the change
1477                                 dispatchEvent( 'fragmentshown', { fragment: verticalFragments[0] } );
1478                                 return true;
1479                         }
1480                 }
1481                 // Horizontal slides:
1482                 else {
1483                         var horizontalFragments = sortFragments( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.present .fragment:not(.visible)' ) );
1484
1485                         if( horizontalFragments.length ) {
1486                                 horizontalFragments[0].classList.add( 'visible' );
1487
1488                                 // Notify subscribers of the change
1489                                 dispatchEvent( 'fragmentshown', { fragment: horizontalFragments[0] } );
1490                                 return true;
1491                         }
1492                 }
1493
1494                 return false;
1495
1496         }
1497
1498         /**
1499          * Navigate to the previous slide fragment.
1500          *
1501          * @return {Boolean} true if there was a previous fragment,
1502          * false otherwise
1503          */
1504         function previousFragment() {
1505
1506                 // Vertical slides:
1507                 if( document.querySelector( VERTICAL_SLIDES_SELECTOR + '.present' ) ) {
1508                         var verticalFragments = sortFragments( document.querySelectorAll( VERTICAL_SLIDES_SELECTOR + '.present .fragment.visible' ) );
1509
1510                         if( verticalFragments.length ) {
1511                                 verticalFragments[ verticalFragments.length - 1 ].classList.remove( 'visible' );
1512
1513                                 // Notify subscribers of the change
1514                                 dispatchEvent( 'fragmenthidden', { fragment: verticalFragments[ verticalFragments.length - 1 ] } );
1515                                 return true;
1516                         }
1517                 }
1518                 // Horizontal slides:
1519                 else {
1520                         var horizontalFragments = sortFragments( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.present .fragment.visible' ) );
1521
1522                         if( horizontalFragments.length ) {
1523                                 horizontalFragments[ horizontalFragments.length - 1 ].classList.remove( 'visible' );
1524
1525                                 // Notify subscribers of the change
1526                                 dispatchEvent( 'fragmenthidden', { fragment: horizontalFragments[ horizontalFragments.length - 1 ] } );
1527                                 return true;
1528                         }
1529                 }
1530
1531                 return false;
1532
1533         }
1534
1535         /**
1536          * Cues a new automated slide if enabled in the config.
1537          */
1538         function cueAutoSlide() {
1539
1540                 clearTimeout( autoSlideTimeout );
1541
1542                 // Cue the next auto-slide if enabled
1543                 if( autoSlide && !isPaused() && !isOverview() ) {
1544                         autoSlideTimeout = setTimeout( navigateNext, autoSlide );
1545                 }
1546
1547         }
1548
1549         /**
1550          * Cancels any ongoing request to auto-slide.
1551          */
1552         function cancelAutoSlide() {
1553
1554                 clearTimeout( autoSlideTimeout );
1555
1556         }
1557
1558         function navigateLeft() {
1559
1560                 // Prioritize hiding fragments
1561                 if( availableRoutes().left && ( isOverview() || previousFragment() === false ) ) {
1562                         slide( indexh - 1 );
1563                 }
1564
1565         }
1566
1567         function navigateRight() {
1568
1569                 // Prioritize revealing fragments
1570                 if( availableRoutes().right && ( isOverview() || nextFragment() === false ) ) {
1571                         slide( indexh + 1 );
1572                 }
1573
1574         }
1575
1576         function navigateUp() {
1577
1578                 // Prioritize hiding fragments
1579                 if( availableRoutes().up && isOverview() || previousFragment() === false ) {
1580                         slide( indexh, indexv - 1 );
1581                 }
1582
1583         }
1584
1585         function navigateDown() {
1586
1587                 // Prioritize revealing fragments
1588                 if( availableRoutes().down && isOverview() || nextFragment() === false ) {
1589                         slide( indexh, indexv + 1 );
1590                 }
1591
1592         }
1593
1594         /**
1595          * Navigates backwards, prioritized in the following order:
1596          * 1) Previous fragment
1597          * 2) Previous vertical slide
1598          * 3) Previous horizontal slide
1599          */
1600         function navigatePrev() {
1601
1602                 // Prioritize revealing fragments
1603                 if( previousFragment() === false ) {
1604                         if( availableRoutes().up ) {
1605                                 navigateUp();
1606                         }
1607                         else {
1608                                 // Fetch the previous horizontal slide, if there is one
1609                                 var previousSlide = document.querySelector( HORIZONTAL_SLIDES_SELECTOR + '.past:nth-child(' + indexh + ')' );
1610
1611                                 if( previousSlide ) {
1612                                         indexv = ( previousSlide.querySelectorAll( 'section' ).length + 1 ) || undefined;
1613                                         indexh --;
1614                                         slide();
1615                                 }
1616                         }
1617                 }
1618
1619         }
1620
1621         /**
1622          * Same as #navigatePrev() but navigates forwards.
1623          */
1624         function navigateNext() {
1625
1626                 // Prioritize revealing fragments
1627                 if( nextFragment() === false ) {
1628                         availableRoutes().down ? navigateDown() : navigateRight();
1629                 }
1630
1631                 // If auto-sliding is enabled we need to cue up
1632                 // another timeout
1633                 cueAutoSlide();
1634
1635         }
1636
1637
1638         // --------------------------------------------------------------------//
1639         // ----------------------------- EVENTS -------------------------------//
1640         // --------------------------------------------------------------------//
1641
1642
1643         /**
1644          * Handler for the document level 'keydown' event.
1645          *
1646          * @param {Object} event
1647          */
1648         function onDocumentKeyDown( event ) {
1649
1650                 // Check if there's a focused element that could be using
1651                 // the keyboard
1652                 var activeElement = document.activeElement;
1653                 var hasFocus = !!( document.activeElement && ( document.activeElement.type || document.activeElement.href || document.activeElement.contentEditable !== 'inherit' ) );
1654
1655                 // Disregard the event if there's a focused element or a
1656                 // keyboard modifier key is present
1657                 if( hasFocus || event.shiftKey || event.altKey || event.ctrlKey || event.metaKey ) return;
1658
1659                 var triggered = true;
1660
1661                 // while paused only allow "unpausing" keyboard events (b and .)
1662                 if( isPaused() && [66,190,191].indexOf( event.keyCode ) === -1 ) {
1663                         return false;
1664                 }
1665
1666                 switch( event.keyCode ) {
1667                         // p, page up
1668                         case 80: case 33: navigatePrev(); break;
1669                         // n, page down
1670                         case 78: case 34: navigateNext(); break;
1671                         // h, left
1672                         case 72: case 37: navigateLeft(); break;
1673                         // l, right
1674                         case 76: case 39: navigateRight(); break;
1675                         // k, up
1676                         case 75: case 38: navigateUp(); break;
1677                         // j, down
1678                         case 74: case 40: navigateDown(); break;
1679                         // home
1680                         case 36: slide( 0 ); break;
1681                         // end
1682                         case 35: slide( Number.MAX_VALUE ); break;
1683                         // space
1684                         case 32: isOverview() ? deactivateOverview() : navigateNext(); break;
1685                         // return
1686                         case 13: isOverview() ? deactivateOverview() : triggered = false; break;
1687                         // b, period, Logitech presenter tools "black screen" button
1688                         case 66: case 190: case 191: togglePause(); break;
1689                         // f
1690                         case 70: enterFullscreen(); break;
1691                         default:
1692                                 triggered = false;
1693                 }
1694
1695                 // If the input resulted in a triggered action we should prevent
1696                 // the browsers default behavior
1697                 if( triggered ) {
1698                         event.preventDefault();
1699                 }
1700                 else if ( event.keyCode === 27 && supports3DTransforms ) {
1701                         toggleOverview();
1702
1703                         event.preventDefault();
1704                 }
1705
1706                 // If auto-sliding is enabled we need to cue up
1707                 // another timeout
1708                 cueAutoSlide();
1709
1710         }
1711
1712         /**
1713          * Handler for the 'touchstart' event, enables support for
1714          * swipe and pinch gestures.
1715          */
1716         function onTouchStart( event ) {
1717
1718                 touch.startX = event.touches[0].clientX;
1719                 touch.startY = event.touches[0].clientY;
1720                 touch.startCount = event.touches.length;
1721
1722                 // If there's two touches we need to memorize the distance
1723                 // between those two points to detect pinching
1724                 if( event.touches.length === 2 && config.overview ) {
1725                         touch.startSpan = distanceBetween( {
1726                                 x: event.touches[1].clientX,
1727                                 y: event.touches[1].clientY
1728                         }, {
1729                                 x: touch.startX,
1730                                 y: touch.startY
1731                         } );
1732                 }
1733
1734         }
1735
1736         /**
1737          * Handler for the 'touchmove' event.
1738          */
1739         function onTouchMove( event ) {
1740
1741                 // Each touch should only trigger one action
1742                 if( !touch.handled ) {
1743                         var currentX = event.touches[0].clientX;
1744                         var currentY = event.touches[0].clientY;
1745
1746                         // If the touch started off with two points and still has
1747                         // two active touches; test for the pinch gesture
1748                         if( event.touches.length === 2 && touch.startCount === 2 && config.overview ) {
1749
1750                                 // The current distance in pixels between the two touch points
1751                                 var currentSpan = distanceBetween( {
1752                                         x: event.touches[1].clientX,
1753                                         y: event.touches[1].clientY
1754                                 }, {
1755                                         x: touch.startX,
1756                                         y: touch.startY
1757                                 } );
1758
1759                                 // If the span is larger than the desire amount we've got
1760                                 // ourselves a pinch
1761                                 if( Math.abs( touch.startSpan - currentSpan ) > touch.threshold ) {
1762                                         touch.handled = true;
1763
1764                                         if( currentSpan < touch.startSpan ) {
1765                                                 activateOverview();
1766                                         }
1767                                         else {
1768                                                 deactivateOverview();
1769                                         }
1770                                 }
1771
1772                                 event.preventDefault();
1773
1774                         }
1775                         // There was only one touch point, look for a swipe
1776                         else if( event.touches.length === 1 && touch.startCount !== 2 ) {
1777
1778                                 var deltaX = currentX - touch.startX,
1779                                         deltaY = currentY - touch.startY;
1780
1781                                 if( deltaX > touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
1782                                         touch.handled = true;
1783                                         navigateLeft();
1784                                 }
1785                                 else if( deltaX < -touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
1786                                         touch.handled = true;
1787                                         navigateRight();
1788                                 }
1789                                 else if( deltaY > touch.threshold ) {
1790                                         touch.handled = true;
1791                                         navigateUp();
1792                                 }
1793                                 else if( deltaY < -touch.threshold ) {
1794                                         touch.handled = true;
1795                                         navigateDown();
1796                                 }
1797
1798                                 event.preventDefault();
1799
1800                         }
1801                 }
1802                 // There's a bug with swiping on some Android devices unless
1803                 // the default action is always prevented
1804                 else if( navigator.userAgent.match( /android/gi ) ) {
1805                         event.preventDefault();
1806                 }
1807
1808         }
1809
1810         /**
1811          * Handler for the 'touchend' event.
1812          */
1813         function onTouchEnd( event ) {
1814
1815                 touch.handled = false;
1816
1817         }
1818
1819         /**
1820          * Convert pointer down to touch start.
1821          */
1822         function onPointerDown( event ) {
1823
1824                 if( event.pointerType === event.MSPOINTER_TYPE_TOUCH ) {
1825                         event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
1826                         this.onTouchStart( event );
1827                 }
1828
1829         }
1830
1831         /**
1832          * Convert pointer move to touch move.
1833          */
1834         function onPointerMove( event ) {
1835
1836                 if( event.pointerType === event.MSPOINTER_TYPE_TOUCH ) {
1837                         event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
1838                         this.onTouchMove( event );
1839                 }
1840
1841         }
1842
1843         /**
1844          * Convert pointer up to touch end.
1845          */
1846         function onPointerUp( event ) {
1847
1848                 if( event.pointerType === event.MSPOINTER_TYPE_TOUCH ) {
1849                         event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
1850                         this.onTouchEnd( event );
1851                 }
1852
1853         }
1854
1855         /**
1856          * Handles mouse wheel scrolling, throttled to avoid skipping
1857          * multiple slides.
1858          */
1859         function onDocumentMouseScroll( event ) {
1860
1861                 clearTimeout( mouseWheelTimeout );
1862
1863                 mouseWheelTimeout = setTimeout( function() {
1864                         var delta = event.detail || -event.wheelDelta;
1865                         if( delta > 0 ) {
1866                                 navigateNext();
1867                         }
1868                         else {
1869                                 navigatePrev();
1870                         }
1871                 }, 100 );
1872
1873         }
1874
1875         /**
1876          * Clicking on the progress bar results in a navigation to the
1877          * closest approximate horizontal slide using this equation:
1878          *
1879          * ( clickX / presentationWidth ) * numberOfSlides
1880          */
1881         function onProgressClicked( event ) {
1882
1883                 event.preventDefault();
1884
1885                 var slidesTotal = toArray( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).length;
1886                 var slideIndex = Math.floor( ( event.clientX / dom.wrapper.offsetWidth ) * slidesTotal );
1887
1888                 slide( slideIndex );
1889
1890         }
1891
1892         /**
1893          * Event handler for navigation control buttons.
1894          */
1895         function onNavigateLeftClicked( event ) { event.preventDefault(); navigateLeft(); }
1896         function onNavigateRightClicked( event ) { event.preventDefault(); navigateRight(); }
1897         function onNavigateUpClicked( event ) { event.preventDefault(); navigateUp(); }
1898         function onNavigateDownClicked( event ) { event.preventDefault(); navigateDown(); }
1899         function onNavigatePrevClicked( event ) { event.preventDefault(); navigatePrev(); }
1900         function onNavigateNextClicked( event ) { event.preventDefault(); navigateNext(); }
1901
1902         /**
1903          * Handler for the window level 'hashchange' event.
1904          */
1905         function onWindowHashChange( event ) {
1906
1907                 readURL();
1908
1909         }
1910
1911         /**
1912          * Handler for the window level 'resize' event.
1913          */
1914         function onWindowResize( event ) {
1915
1916                 layout();
1917
1918         }
1919
1920         /**
1921          * Invoked when a slide is and we're in the overview.
1922          */
1923         function onOverviewSlideClicked( event ) {
1924
1925                 // TODO There's a bug here where the event listeners are not
1926                 // removed after deactivating the overview.
1927                 if( eventsAreBound && isOverview() ) {
1928                         event.preventDefault();
1929
1930                         var element = event.target;
1931
1932                         while( element && !element.nodeName.match( /section/gi ) ) {
1933                                 element = element.parentNode;
1934                         }
1935
1936                         if( element && !element.classList.contains( 'disabled' ) ) {
1937
1938                                 deactivateOverview();
1939
1940                                 if( element.nodeName.match( /section/gi ) ) {
1941                                         var h = parseInt( element.getAttribute( 'data-index-h' ), 10 ),
1942                                                 v = parseInt( element.getAttribute( 'data-index-v' ), 10 );
1943
1944                                         slide( h, v );
1945                                 }
1946
1947                         }
1948                 }
1949
1950         }
1951
1952
1953         // --------------------------------------------------------------------//
1954         // ------------------------------- API --------------------------------//
1955         // --------------------------------------------------------------------//
1956
1957
1958         return {
1959                 initialize: initialize,
1960                 configure: configure,
1961
1962                 // Navigation methods
1963                 slide: slide,
1964                 left: navigateLeft,
1965                 right: navigateRight,
1966                 up: navigateUp,
1967                 down: navigateDown,
1968                 prev: navigatePrev,
1969                 next: navigateNext,
1970                 prevFragment: previousFragment,
1971                 nextFragment: nextFragment,
1972
1973                 // Deprecated aliases
1974                 navigateTo: slide,
1975                 navigateLeft: navigateLeft,
1976                 navigateRight: navigateRight,
1977                 navigateUp: navigateUp,
1978                 navigateDown: navigateDown,
1979                 navigatePrev: navigatePrev,
1980                 navigateNext: navigateNext,
1981
1982                 // Forces an update in slide layout
1983                 layout: layout,
1984
1985                 // Toggles the overview mode on/off
1986                 toggleOverview: toggleOverview,
1987
1988                 // Toggles the "black screen" mode on/off
1989                 togglePause: togglePause,
1990
1991                 // State checks
1992                 isOverview: isOverview,
1993                 isPaused: isPaused,
1994
1995                 // Adds or removes all internal event listeners (such as keyboard)
1996                 addEventListeners: addEventListeners,
1997                 removeEventListeners: removeEventListeners,
1998
1999                 // Returns the indices of the current, or specified, slide
2000                 getIndices: getIndices,
2001
2002                 // Returns the slide at the specified index, y is optional
2003                 getSlide: function( x, y ) {
2004                         var horizontalSlide = document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR )[ x ];
2005                         var verticalSlides = horizontalSlide && horizontalSlide.querySelectorAll( 'section' );
2006
2007                         if( typeof y !== 'undefined' ) {
2008                                 return verticalSlides ? verticalSlides[ y ] : undefined;
2009                         }
2010
2011                         return horizontalSlide;
2012                 },
2013
2014                 // Returns the previous slide element, may be null
2015                 getPreviousSlide: function() {
2016                         return previousSlide;
2017                 },
2018
2019                 // Returns the current slide element
2020                 getCurrentSlide: function() {
2021                         return currentSlide;
2022                 },
2023
2024                 // Returns the current scale of the presentation content
2025                 getScale: function() {
2026                         return scale;
2027                 },
2028
2029                 // Helper method, retrieves query string as a key/value hash
2030                 getQueryHash: function() {
2031                         var query = {};
2032
2033                         location.search.replace( /[A-Z0-9]+?=(\w*)/gi, function(a) {
2034                                 query[ a.split( '=' ).shift() ] = a.split( '=' ).pop();
2035                         } );
2036
2037                         return query;
2038                 },
2039
2040                 // Returns true if we're currently on the first slide
2041                 isFirstSlide: function() {
2042                         return document.querySelector( SLIDES_SELECTOR + '.past' ) == null ? true : false;
2043                 },
2044
2045                 // Returns true if we're currently on the last slide
2046                 isLastSlide: function() {
2047                         if( currentSlide && currentSlide.classList.contains( '.stack' ) ) {
2048                                 return currentSlide.querySelector( SLIDES_SELECTOR + '.future' ) == null ? true : false;
2049                         }
2050                         else {
2051                                 return document.querySelector( SLIDES_SELECTOR + '.future' ) == null ? true : false;
2052                         }
2053                 },
2054
2055                 // Forward event binding to the reveal DOM element
2056                 addEventListener: function( type, listener, useCapture ) {
2057                         if( 'addEventListener' in window ) {
2058                                 ( dom.wrapper || document.querySelector( '.reveal' ) ).addEventListener( type, listener, useCapture );
2059                         }
2060                 },
2061                 removeEventListener: function( type, listener, useCapture ) {
2062                         if( 'addEventListener' in window ) {
2063                                 ( dom.wrapper || document.querySelector( '.reveal' ) ).removeEventListener( type, listener, useCapture );
2064                         }
2065                 }
2066         };
2067
2068 })();