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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 thing 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 were 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.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(".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.