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