js/reveal.js

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