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+/**
+ * impress.js
+ *
+ * impress.js is a presentation tool based on the power of CSS3 transforms and transitions
+ * in modern browsers and inspired by the idea behind prezi.com.
+ *
+ *
+ * Copyright 2011-2012 Bartek Szopka (@bartaz)
+ *
+ * Released under the MIT and GPL Licenses.
+ *
+ * ------------------------------------------------
+ * author: Bartek Szopka
+ * version: 0.5.3
+ * url: http://bartaz.github.com/impress.js/
+ * source: http://github.com/bartaz/impress.js/
+ */
+
+/*jshint bitwise:true, curly:true, eqeqeq:true, forin:true, latedef:true, newcap:true,
+ noarg:true, noempty:true, undef:true, strict:true, browser:true */
+
+// You are one of those who like to know how things work inside?
+// Let me show you the cogs that make impress.js run...
+(function ( document, window ) {
+ 'use strict';
+
+ // HELPER FUNCTIONS
+
+ // `pfx` is a function that takes a standard CSS property name as a parameter
+ // and returns it's prefixed version valid for current browser it runs in.
+ // The code is heavily inspired by Modernizr http://www.modernizr.com/
+ var pfx = (function () {
+
+ var style = document.createElement('dummy').style,
+ prefixes = 'Webkit Moz O ms Khtml'.split(' '),
+ memory = {};
+
+ return function ( prop ) {
+ if ( typeof memory[ prop ] === "undefined" ) {
+
+ var ucProp = prop.charAt(0).toUpperCase() + prop.substr(1),
+ props = (prop + ' ' + prefixes.join(ucProp + ' ') + ucProp).split(' ');
+
+ memory[ prop ] = null;
+ for ( var i in props ) {
+ if ( style[ props[i] ] !== undefined ) {
+ memory[ prop ] = props[i];
+ break;
+ }
+ }
+
+ }
+
+ return memory[ prop ];
+ };
+
+ })();
+
+ // `arraify` takes an array-like object and turns it into real Array
+ // to make all the Array.prototype goodness available.
+ var arrayify = function ( a ) {
+ return [].slice.call( a );
+ };
+
+ // `css` function applies the styles given in `props` object to the element
+ // given as `el`. It runs all property names through `pfx` function to make
+ // sure proper prefixed version of the property is used.
+ var css = function ( el, props ) {
+ var key, pkey;
+ for ( key in props ) {
+ if ( props.hasOwnProperty(key) ) {
+ pkey = pfx(key);
+ if ( pkey !== null ) {
+ el.style[pkey] = props[key];
+ }
+ }
+ }
+ return el;
+ };
+
+ // `toNumber` takes a value given as `numeric` parameter and tries to turn
+ // it into a number. If it is not possible it returns 0 (or other value
+ // given as `fallback`).
+ var toNumber = function (numeric, fallback) {
+ return isNaN(numeric) ? (fallback || 0) : Number(numeric);
+ };
+
+ // `byId` returns element with given `id` - you probably have guessed that ;)
+ var byId = function ( id ) {
+ return document.getElementById(id);
+ };
+
+ // `$` returns first element for given CSS `selector` in the `context` of
+ // the given element or whole document.
+ var $ = function ( selector, context ) {
+ context = context || document;
+ return context.querySelector(selector);
+ };
+
+ // `$$` return an array of elements for given CSS `selector` in the `context` of
+ // the given element or whole document.
+ var $$ = function ( selector, context ) {
+ context = context || document;
+ return arrayify( context.querySelectorAll(selector) );
+ };
+
+ // `triggerEvent` builds a custom DOM event with given `eventName` and `detail` data
+ // and triggers it on element given as `el`.
+ var triggerEvent = function (el, eventName, detail) {
+ var event = document.createEvent("CustomEvent");
+ event.initCustomEvent(eventName, true, true, detail);
+ el.dispatchEvent(event);
+ };
+
+ // `translate` builds a translate transform string for given data.
+ var translate = function ( t ) {
+ return " translate3d(" + t.x + "px," + t.y + "px," + t.z + "px) ";
+ };
+
+ // `rotate` builds a rotate transform string for given data.
+ // By default the rotations are in X Y Z order that can be reverted by passing `true`
+ // as second parameter.
+ var rotate = function ( r, revert ) {
+ var rX = " rotateX(" + r.x + "deg) ",
+ rY = " rotateY(" + r.y + "deg) ",
+ rZ = " rotateZ(" + r.z + "deg) ";
+
+ return revert ? rZ+rY+rX : rX+rY+rZ;
+ };
+
+ // `scale` builds a scale transform string for given data.
+ var scale = function ( s ) {
+ return " scale(" + s + ") ";
+ };
+
+ // `perspective` builds a perspective transform string for given data.
+ var perspective = function ( p ) {
+ return " perspective(" + p + "px) ";
+ };
+
+ // `getElementFromHash` returns an element located by id from hash part of
+ // window location.
+ var getElementFromHash = function () {
+ // get id from url # by removing `#` or `#/` from the beginning,
+ // so both "fallback" `#slide-id` and "enhanced" `#/slide-id` will work
+ return byId( window.location.hash.replace(/^#\/?/,"") );
+ };
+
+ // `computeWindowScale` counts the scale factor between window size and size
+ // defined for the presentation in the config.
+ var computeWindowScale = function ( config ) {
+ var hScale = window.innerHeight / config.height,
+ wScale = window.innerWidth / config.width,
+ scale = hScale > wScale ? wScale : hScale;
+
+ if (config.maxScale && scale > config.maxScale) {
+ scale = config.maxScale;
+ }
+
+ if (config.minScale && scale < config.minScale) {
+ scale = config.minScale;
+ }
+
+ return scale;
+ };
+
+ // CHECK SUPPORT
+ var body = document.body;
+
+ var ua = navigator.userAgent.toLowerCase();
+ var impressSupported =
+ // browser should support CSS 3D transtorms
+ ( pfx("perspective") !== null ) &&
+
+ // and `classList` and `dataset` APIs
+ ( body.classList ) &&
+ ( body.dataset ) &&
+
+ // but some mobile devices need to be blacklisted,
+ // because their CSS 3D support or hardware is not
+ // good enough to run impress.js properly, sorry...
+ ( ua.search(/(iphone)|(ipod)|(android)/) === -1 );
+
+ if (!impressSupported) {
+ // we can't be sure that `classList` is supported
+ body.className += " impress-not-supported ";
+ } else {
+ body.classList.remove("impress-not-supported");
+ body.classList.add("impress-supported");
+ }
+
+ // GLOBALS AND DEFAULTS
+
+ // This is where the root elements of all impress.js instances will be kept.
+ // Yes, this means you can have more than one instance on a page, but I'm not
+ // sure if it makes any sense in practice ;)
+ var roots = {};
+
+ // some default config values.
+ var defaults = {
+ width: 1024,
+ height: 768,
+ maxScale: 1,
+ minScale: 0,
+
+ perspective: 1000,
+
+ transitionDuration: 1000
+ };
+
+ // it's just an empty function ... and a useless comment.
+ var empty = function () { return false; };
+
+ // IMPRESS.JS API
+
+ // And that's where interesting things will start to happen.
+ // It's the core `impress` function that returns the impress.js API
+ // for a presentation based on the element with given id ('impress'
+ // by default).
+ var impress = window.impress = function ( rootId ) {
+
+ // If impress.js is not supported by the browser return a dummy API
+ // it may not be a perfect solution but we return early and avoid
+ // running code that may use features not implemented in the browser.
+ if (!impressSupported) {
+ return {
+ init: empty,
+ goto: empty,
+ prev: empty,
+ next: empty
+ };
+ }
+
+ rootId = rootId || "impress";
+
+ // if given root is already initialized just return the API
+ if (roots["impress-root-" + rootId]) {
+ return roots["impress-root-" + rootId];
+ }
+
+ // data of all presentation steps
+ var stepsData = {};
+
+ // element of currently active step
+ var activeStep = null;
+
+ // current state (position, rotation and scale) of the presentation
+ var currentState = null;
+
+ // array of step elements
+ var steps = null;
+
+ // configuration options
+ var config = null;
+
+ // scale factor of the browser window
+ var windowScale = null;
+
+ // root presentation elements
+ var root = byId( rootId );
+ var canvas = document.createElement("div");
+
+ var initialized = false;
+
+ // STEP EVENTS
+ //
+ // There are currently two step events triggered by impress.js
+ // `impress:stepenter` is triggered when the step is shown on the
+ // screen (the transition from the previous one is finished) and
+ // `impress:stepleave` is triggered when the step is left (the
+ // transition to next step just starts).
+
+ // reference to last entered step
+ var lastEntered = null;
+
+ // `onStepEnter` is called whenever the step element is entered
+ // but the event is triggered only if the step is different than
+ // last entered step.
+ var onStepEnter = function (step) {
+ if (lastEntered !== step) {
+ triggerEvent(step, "impress:stepenter");
+ lastEntered = step;
+ }
+ };
+
+ // `onStepLeave` is called whenever the step element is left
+ // but the event is triggered only if the step is the same as
+ // last entered step.
+ var onStepLeave = function (step) {
+ if (lastEntered === step) {
+ triggerEvent(step, "impress:stepleave");
+ lastEntered = null;
+ }
+ };
+
+ // `initStep` initializes given step element by reading data from its
+ // data attributes and setting correct styles.
+ var initStep = function ( el, idx ) {
+ var data = el.dataset,
+ step = {
+ translate: {
+ x: toNumber(data.x),
+ y: toNumber(data.y),
+ z: toNumber(data.z)
+ },
+ rotate: {
+ x: toNumber(data.rotateX),
+ y: toNumber(data.rotateY),
+ z: toNumber(data.rotateZ || data.rotate)
+ },
+ scale: toNumber(data.scale, 1),
+ el: el
+ };
+
+ if ( !el.id ) {
+ el.id = "step-" + (idx + 1);
+ }
+
+ stepsData["impress-" + el.id] = step;
+
+ css(el, {
+ position: "absolute",
+ transform: "translate(-50%,-50%)" +
+ translate(step.translate) +
+ rotate(step.rotate) +
+ scale(step.scale),
+ transformStyle: "preserve-3d"
+ });
+ };
+
+ // `init` API function that initializes (and runs) the presentation.
+ var init = function () {
+ if (initialized) { return; }
+
+ // First we set up the viewport for mobile devices.
+ // For some reason iPad goes nuts when it is not done properly.
+ var meta = $("meta[name='viewport']") || document.createElement("meta");
+ meta.content = "width=device-width, minimum-scale=1, maximum-scale=1, user-scalable=no";
+ if (meta.parentNode !== document.head) {
+ meta.name = 'viewport';
+ document.head.appendChild(meta);
+ }
+
+ // initialize configuration object
+ var rootData = root.dataset;
+ config = {
+ width: toNumber( rootData.width, defaults.width ),
+ height: toNumber( rootData.height, defaults.height ),
+ maxScale: toNumber( rootData.maxScale, defaults.maxScale ),
+ minScale: toNumber( rootData.minScale, defaults.minScale ),
+ perspective: toNumber( rootData.perspective, defaults.perspective ),
+ transitionDuration: toNumber( rootData.transitionDuration, defaults.transitionDuration )
+ };
+
+ windowScale = computeWindowScale( config );
+
+ // wrap steps with "canvas" element
+ arrayify( root.childNodes ).forEach(function ( el ) {
+ canvas.appendChild( el );
+ });
+ root.appendChild(canvas);
+
+ // set initial styles
+ document.documentElement.style.height = "100%";
+
+ css(body, {
+ height: "100%",
+ overflow: "hidden"
+ });
+
+ var rootStyles = {
+ position: "absolute",
+ transformOrigin: "top left",
+ transition: "all 0s ease-in-out",
+ transformStyle: "preserve-3d"
+ };
+
+ css(root, rootStyles);
+ css(root, {
+ top: "50%",
+ left: "50%",
+ transform: perspective( config.perspective/windowScale ) + scale( windowScale )
+ });
+ css(canvas, rootStyles);
+
+ body.classList.remove("impress-disabled");
+ body.classList.add("impress-enabled");
+
+ // get and init steps
+ steps = $$(".step", root);
+ steps.forEach( initStep );
+
+ // set a default initial state of the canvas
+ currentState = {
+ translate: { x: 0, y: 0, z: 0 },
+ rotate: { x: 0, y: 0, z: 0 },
+ scale: 1
+ };
+
+ initialized = true;
+
+ triggerEvent(root, "impress:init", { api: roots[ "impress-root-" + rootId ] });
+ };
+
+ // `getStep` is a helper function that returns a step element defined by parameter.
+ // If a number is given, step with index given by the number is returned, if a string
+ // is given step element with such id is returned, if DOM element is given it is returned
+ // if it is a correct step element.
+ var getStep = function ( step ) {
+ if (typeof step === "number") {
+ step = step < 0 ? steps[ steps.length + step] : steps[ step ];
+ } else if (typeof step === "string") {
+ step = byId(step);
+ }
+ return (step && step.id && stepsData["impress-" + step.id]) ? step : null;
+ };
+
+ // used to reset timeout for `impress:stepenter` event
+ var stepEnterTimeout = null;
+
+ // `goto` API function that moves to step given with `el` parameter (by index, id or element),
+ // with a transition `duration` optionally given as second parameter.
+ var goto = function ( el, duration ) {
+
+ if ( !initialized || !(el = getStep(el)) ) {
+ // presentation not initialized or given element is not a step
+ return false;
+ }
+
+ // Sometimes it's possible to trigger focus on first link with some keyboard action.
+ // Browser in such a case tries to scroll the page to make this element visible
+ // (even that body overflow is set to hidden) and it breaks our careful positioning.
+ //
+ // So, as a lousy (and lazy) workaround we will make the page scroll back to the top
+ // whenever slide is selected
+ //
+ // If you are reading this and know any better way to handle it, I'll be glad to hear about it!
+ window.scrollTo(0, 0);
+
+ var step = stepsData["impress-" + el.id];
+
+ if ( activeStep ) {
+ activeStep.classList.remove("active");
+ body.classList.remove("impress-on-" + activeStep.id);
+ }
+ el.classList.add("active");
+
+ body.classList.add("impress-on-" + el.id);
+
+ // compute target state of the canvas based on given step
+ var target = {
+ rotate: {
+ x: -step.rotate.x,
+ y: -step.rotate.y,
+ z: -step.rotate.z
+ },
+ translate: {
+ x: -step.translate.x,
+ y: -step.translate.y,
+ z: -step.translate.z
+ },
+ scale: 1 / step.scale
+ };
+
+ // Check if the transition is zooming in or not.
+ //
+ // This information is used to alter the transition style:
+ // when we are zooming in - we start with move and rotate transition
+ // and the scaling is delayed, but when we are zooming out we start
+ // with scaling down and move and rotation are delayed.
+ var zoomin = target.scale >= currentState.scale;
+
+ duration = toNumber(duration, config.transitionDuration);
+ var delay = (duration / 2);
+
+ // if the same step is re-selected, force computing window scaling,
+ // because it is likely to be caused by window resize
+ if (el === activeStep) {
+ windowScale = computeWindowScale(config);
+ }
+
+ var targetScale = target.scale * windowScale;
+
+ // trigger leave of currently active element (if it's not the same step again)
+ if (activeStep && activeStep !== el) {
+ onStepLeave(activeStep);
+ }
+
+ // Now we alter transforms of `root` and `canvas` to trigger transitions.
+ //
+ // And here is why there are two elements: `root` and `canvas` - they are
+ // being animated separately:
+ // `root` is used for scaling and `canvas` for translate and rotations.
+ // Transitions on them are triggered with different delays (to make
+ // visually nice and 'natural' looking transitions), so we need to know
+ // that both of them are finished.
+ css(root, {
+ // to keep the perspective look similar for different scales
+ // we need to 'scale' the perspective, too
+ transform: perspective( config.perspective / targetScale ) + scale( targetScale ),
+ transitionDuration: duration + "ms",
+ transitionDelay: (zoomin ? delay : 0) + "ms"
+ });
+
+ css(canvas, {
+ transform: rotate(target.rotate, true) + translate(target.translate),
+ transitionDuration: duration + "ms",
+ transitionDelay: (zoomin ? 0 : delay) + "ms"
+ });
+
+ // Here is a tricky part...
+ //
+ // If there is no change in scale or no change in rotation and translation, it means there was actually
+ // no delay - because there was no transition on `root` or `canvas` elements.
+ // We want to trigger `impress:stepenter` event in the correct moment, so here we compare the current
+ // and target values to check if delay should be taken into account.
+ //
+ // I know that this `if` statement looks scary, but it's pretty simple when you know what is going on
+ // - it's simply comparing all the values.
+ if ( currentState.scale === target.scale ||
+ (currentState.rotate.x === target.rotate.x && currentState.rotate.y === target.rotate.y &&
+ currentState.rotate.z === target.rotate.z && currentState.translate.x === target.translate.x &&
+ currentState.translate.y === target.translate.y && currentState.translate.z === target.translate.z) ) {
+ delay = 0;
+ }
+
+ // store current state
+ currentState = target;
+ activeStep = el;
+
+ // And here is where we trigger `impress:stepenter` event.
+ // We simply set up a timeout to fire it taking transition duration (and possible delay) into account.
+ //
+ // I really wanted to make it in more elegant way. The `transitionend` event seemed to be the best way
+ // to do it, but the fact that I'm using transitions on two separate elements and that the `transitionend`
+ // event is only triggered when there was a transition (change in the values) caused some bugs and
+ // made the code really complicated, cause I had to handle all the conditions separately. And it still
+ // needed a `setTimeout` fallback for the situations when there is no transition at all.
+ // So I decided that I'd rather make the code simpler than use shiny new `transitionend`.
+ //
+ // If you want learn something interesting and see how it was done with `transitionend` go back to
+ // version 0.5.2 of impress.js: http://github.com/bartaz/impress.js/blob/0.5.2/js/impress.js
+ window.clearTimeout(stepEnterTimeout);
+ stepEnterTimeout = window.setTimeout(function() {
+ onStepEnter(activeStep);
+ }, duration + delay);
+
+ return el;
+ };
+
+ // `prev` API function goes to previous step (in document order)
+ var prev = function () {
+ var prev = steps.indexOf( activeStep ) - 1;
+ prev = prev >= 0 ? steps[ prev ] : steps[ steps.length-1 ];
+
+ return goto(prev);
+ };
+
+ // `next` API function goes to next step (in document order)
+ var next = function () {
+ var next = steps.indexOf( activeStep ) + 1;
+ next = next < steps.length ? steps[ next ] : steps[ 0 ];
+
+ return goto(next);
+ };
+
+ // Adding some useful classes to step elements.
+ //
+ // All the steps that have not been shown yet are given `future` class.
+ // When the step is entered the `future` class is removed and the `present`
+ // class is given. When the step is left `present` class is replaced with
+ // `past` class.
+ //
+ // So every step element is always in one of three possible states:
+ // `future`, `present` and `past`.
+ //
+ // There classes can be used in CSS to style different types of steps.
+ // For example the `present` class can be used to trigger some custom
+ // animations when step is shown.
+ root.addEventListener("impress:init", function(){
+ // STEP CLASSES
+ steps.forEach(function (step) {
+ step.classList.add("future");
+ });
+
+ root.addEventListener("impress:stepenter", function (event) {
+ event.target.classList.remove("past");
+ event.target.classList.remove("future");
+ event.target.classList.add("present");
+ }, false);
+
+ root.addEventListener("impress:stepleave", function (event) {
+ event.target.classList.remove("present");
+ event.target.classList.add("past");
+ }, false);
+
+ }, false);
+
+ // Adding hash change support.
+ root.addEventListener("impress:init", function(){
+
+ // last hash detected
+ var lastHash = "";
+
+ // `#/step-id` is used instead of `#step-id` to prevent default browser
+ // scrolling to element in hash.
+ //
+ // And it has to be set after animation finishes, because in Chrome it
+ // makes transtion laggy.
+ // BUG: http://code.google.com/p/chromium/issues/detail?id=62820
+ root.addEventListener("impress:stepenter", function (event) {
+ window.location.hash = lastHash = "#/" + event.target.id;
+ }, false);
+
+ window.addEventListener("hashchange", function () {
+ // When the step is entered hash in the location is updated
+ // (just few lines above from here), so the hash change is
+ // triggered and we would call `goto` again on the same element.
+ //
+ // To avoid this we store last entered hash and compare.
+ if (window.location.hash !== lastHash) {
+ goto( getElementFromHash() );
+ }
+ }, false);
+
+ // START
+ // by selecting step defined in url or first step of the presentation
+ goto(getElementFromHash() || steps[0], 0);
+ }, false);
+
+ body.classList.add("impress-disabled");
+
+ // store and return API for given impress.js root element
+ return (roots[ "impress-root-" + rootId ] = {
+ init: init,
+ goto: goto,
+ next: next,
+ prev: prev
+ });
+
+ };
+
+ // flag that can be used in JS to check if browser have passed the support test
+ impress.supported = impressSupported;
+
+})(document, window);
+
+// NAVIGATION EVENTS
+
+// As you can see this part is separate from the impress.js core code.
+// It's because these navigation actions only need what impress.js provides with
+// its simple API.
+//
+// In future I think about moving it to make them optional, move to separate files
+// and treat more like a 'plugins'.
+(function ( document, window ) {
+ 'use strict';
+
+ // throttling function calls, by Remy Sharp
+ // http://remysharp.com/2010/07/21/throttling-function-calls/
+ var throttle = function (fn, delay) {
+ var timer = null;
+ return function () {
+ var context = this, args = arguments;
+ clearTimeout(timer);
+ timer = setTimeout(function () {
+ fn.apply(context, args);
+ }, delay);
+ };
+ };
+
+ // wait for impress.js to be initialized
+ document.addEventListener("impress:init", function (event) {
+ // Getting API from event data.
+ // So you don't event need to know what is the id of the root element
+ // or anything. `impress:init` event data gives you everything you
+ // need to control the presentation that was just initialized.
+ var api = event.detail.api;
+
+ // KEYBOARD NAVIGATION HANDLERS
+
+ // Prevent default keydown action when one of supported key is pressed.
+ document.addEventListener("keydown", function ( event ) {
+ if ( event.keyCode === 9 || ( event.keyCode >= 32 && event.keyCode <= 34 ) || (event.keyCode >= 37 && event.keyCode <= 40) ) {
+ event.preventDefault();
+ }
+ }, false);
+
+ // Trigger impress action (next or prev) on keyup.
+
+ // Supported keys are:
+ // [space] - quite common in presentation software to move forward
+ // [up] [right] / [down] [left] - again common and natural addition,
+ // [pgdown] / [pgup] - often triggered by remote controllers,
+ // [tab] - this one is quite controversial, but the reason it ended up on
+ // this list is quite an interesting story... Remember that strange part
+ // in the impress.js code where window is scrolled to 0,0 on every presentation
+ // step, because sometimes browser scrolls viewport because of the focused element?
+ // Well, the [tab] key by default navigates around focusable elements, so clicking
+ // it very often caused scrolling to focused element and breaking impress.js
+ // positioning. I didn't want to just prevent this default action, so I used [tab]
+ // as another way to moving to next step... And yes, I know that for the sake of
+ // consistency I should add [shift+tab] as opposite action...
+ document.addEventListener("keyup", function ( event ) {
+
+ if ( event.shiftKey || event.altKey || event.ctrlKey || event.metaKey ){
+ return;
+ }
+
+ if ( event.keyCode === 9 || ( event.keyCode >= 32 && event.keyCode <= 34 ) || (event.keyCode >= 37 && event.keyCode <= 40) ) {
+ switch( event.keyCode ) {
+ case 33: // pg up
+ case 37: // left
+ case 38: // up
+ api.prev();
+ break;
+ case 9: // tab
+ case 32: // space
+ case 34: // pg down
+ case 39: // right
+ case 40: // down
+ api.next();
+ break;
+ }
+
+ event.preventDefault();
+ }
+ }, false);
+
+ // delegated handler for clicking on the links to presentation steps
+ document.addEventListener("click", function ( event ) {
+ // event delegation with "bubbling"
+ // check if event target (or any of its parents is a link)
+ var target = event.target;
+ while ( (target.tagName !== "A") &&
+ (target !== document.documentElement) ) {
+ target = target.parentNode;
+ }
+
+ if ( target.tagName === "A" ) {
+ var href = target.getAttribute("href");
+
+ // if it's a link to presentation step, target this step
+ if ( href && href[0] === '#' ) {
+ target = document.getElementById( href.slice(1) );
+ }
+ }
+
+ if ( api.goto(target) ) {
+ event.stopImmediatePropagation();
+ event.preventDefault();
+ }
+ }, false);
+
+ // delegated handler for clicking on step elements
+ document.addEventListener("click", function ( event ) {
+ var target = event.target;
+ // find closest step element that is not active
+ while ( !(target.classList.contains("step") && !target.classList.contains("active")) &&
+ (target !== document.documentElement) ) {
+ target = target.parentNode;
+ }
+
+ if ( api.goto(target) ) {
+ event.preventDefault();
+ }
+ }, false);
+
+ // touch handler to detect taps on the left and right side of the screen
+ // based on awesome work of @hakimel: https://github.com/hakimel/reveal.js
+ document.addEventListener("touchstart", function ( event ) {
+ if (event.touches.length === 1) {
+ var x = event.touches[0].clientX,
+ width = window.innerWidth * 0.3,
+ result = null;
+
+ if ( x < width ) {
+ result = api.prev();
+ } else if ( x > window.innerWidth - width ) {
+ result = api.next();
+ }
+
+ if (result) {
+ event.preventDefault();
+ }
+ }
+ }, false);
+
+ // rescale presentation when window is resized
+ window.addEventListener("resize", throttle(function () {
+ // force going to active step again, to trigger rescaling
+ api.goto( document.querySelector(".step.active"), 500 );
+ }, 250), false);
+
+ }, false);
+
+})(document, window);
+
+// THAT'S ALL FOLKS!
+//
+// Thanks for reading it all.
+// Or thanks for scrolling down and reading the last part.
+//
+// I've learnt a lot when building impress.js and I hope this code and comments
+// will help somebody learn at least some part of it.
generated by cgit v1.3.1 (git 2.54.0) at 2026-08-02 03:27:07 +0000