"

From 2014.igem.org

/*!

* skrollr
*
* https://github.com/Prinzhorn/skrollr
*
* free to use under terms of MIT license
*/

(function(window, document, undefined) { 'use strict';

/* * Global api. */ var skrollr = window.skrollr = { get: function() { return _instance; }, //Main entry point. init: function(options) { return _instance || new Skrollr(options); }, VERSION: '0.5.10' };

//Minify optimization. var hasProp = Object.prototype.hasOwnProperty;

//They will be filled when skrollr gets initialized. var documentElement; var body;

var RENDERED_CLASS = 'rendered'; var UNRENDERED_CLASS = 'un' + RENDERED_CLASS; var SKROLLABLE_CLASS = 'skrollable'; var SKROLLR_CLASS = 'skrollr'; var NO_SKROLLR_CLASS = 'no-' + SKROLLR_CLASS;

var DEFAULT_EASING = 'linear'; var DEFAULT_DURATION = 1000;

var SMOOTH_SCROLLING_DURATION = 200;

var ANCHOR_START = 'start'; var ANCHOR_END = 'end'; var ANCHOR_TOP = 'top'; var ANCHOR_CENTER = 'center'; var ANCHOR_BOTTOM = 'bottom';

var SKROLLABLE_HAS_RENDERED_CLASS_PROPERTY = '___has_rendered_class';

//The property which will be added to the DOM element to hold the ID of the skrollable. var SKROLLABLE_ID_DOM_PROPERTY = '___skrollable_id';

var requestAnimFrame = window.requestAnimationFrame;

//Request animation frame polyfill. //Credits go to Erik Möller (http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating) (function() { var vendors = ['ms', 'moz', 'webkit', 'o']; var i;

for(i = 0; i < vendors.length && !requestAnimFrame; i++) { requestAnimFrame = window[vendors[i] + 'RequestAnimationFrame']; }

var lastTime = 0;

if (!requestAnimFrame) { requestAnimFrame = function(callback) { var currTime = _now(); var timeToCall = Math.max(0, 30 - (currTime - lastTime));

window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall);

lastTime = currTime + timeToCall; }; } }());

var rxTrim = /^\s*(.+)\s*$/m;

//Find all data-attributes. data-[_constant]-[offset]-[anchor]-[anchor]. var rxKeyframeAttribute = /^data(?:-(_\w+))?(?:-?(-?\d+))?(?:-?(start|end|top|center|bottom))?(?:-?(top|center|bottom))?$/;

var rxPropValue = /\s*([a-z\-\[\]]+)\s*:\s*(.+?)\s*(?:;|$)/gi;

//Easing function names follow the property in square brackets. var rxPropEasing = /^([a-z\-]+)\[(\w+)\]$/;

var rxCamelCase = /-([a-z])/g; var rxCamelCaseFn = function(str, letter) { return letter.toUpperCase(); };

//Numeric values with optional sign. var rxNumericValue = /[\-+]?[\d]*\.?[\d]+/g;

//Used to replace occurences of {?} with a number. var rxInterpolateString = /\{\?\}/g;

//Finds rgb(a) colors, which don't use the percentage notation. var rxRGBAIntegerColor = /rgba?\(\s*-?\d+\s*,\s*-?\d+\s*,\s*-?\d+/g;

//Finds all gradients. var rxGradient = /[a-z\-]+-gradient/g;

//Vendor prefix. Will be set once skrollr gets initialized. var theCSSPrefix; var theDashedCSSPrefix;

//Will be called once (when skrollr gets initialized). var detectCSSPrefix = function() { //Only relevant prefixes. May be extended. //Could be dangerous if there will ever be a CSS property which actually starts with "ms". Don't hope so. var rxPrefixes = /^(?:O|Moz|webkit|ms)/;

//Detect prefix for current browser by finding the first property using a prefix. if(window.getComputedStyle) { var style = window.getComputedStyle(body, null);

for(var k in style) { //We check the key and if the key is a number, we check the value as well, because safari's getComputedStyle returns some weird array-like thingy. theCSSPrefix = (k.match(rxPrefixes) || (+k == k && style[k].match(rxPrefixes)));

if(theCSSPrefix) { break; } } }

//Empty string if no prefix detected theCSSPrefix = (theCSSPrefix || [])[0];

//Will be "--" if no prefix detected. No problem, browser will ignore "--transform" and stuff. theDashedCSSPrefix = '-' + theCSSPrefix.toLowerCase() + '-'; };

//Built-in easing functions. var easings = { begin: function() { return 0; }, end: function() { return 1; }, linear: function(p) { return p; }, quadratic: function(p) { return p * p; }, cubic: function(p) { return p * p * p; }, swing: function(p) { return (-Math.cos(p * Math.PI) / 2) + 0.5; }, sqrt: function(p) { return Math.sqrt(p); }, //see https://www.desmos.com/calculator/tbr20s8vd2 for how I did this bounce: function(p) { var a;

if(p <= 0.5083) { a = 3; } else if(p <= 0.8489) { a = 9; } else if(p <= 0.96208) { a = 27; } else if(p <= 0.99981) { a = 91; } else { return 1; }

return 1 - Math.abs(3 * Math.cos(p * a * 1.028) / a); } };

/** * Constructor. */ function Skrollr(options) { documentElement = document.documentElement; body = document.body;

detectCSSPrefix();

_instance = this;

options = options || {};

_constants = options.constants || {};

//We allow defining custom easings or overwrite existing if(options.easing) { for(var e in options.easing) { easings[e] = options.easing[e]; } }

_listeners = { //Function to be called right before rendering. beforerender: options.beforerender,

//Function to be called right after finishing rendering. render: options.render };

//forceHeight is true by default _forceHeight = options.forceHeight !== false;

_smoothScrollingEnabled = options.smoothScrolling !== false;

//Dummy object. Will be overwritten in the _render method when smooth scrolling is calculated. _smoothScrolling = { targetTop: _instance.getScrollTop() };

if(_forceHeight) { _scale = options.scale || 1; }

//Remove "no-skrollr" and add "skrollr" to the HTML element. _updateClass(documentElement, [SKROLLR_CLASS], [NO_SKROLLR_CLASS]);

if(_forceHeight) { //Add a dummy element in order to get a large enough scrollbar. //On mobile and later desktop versions a #skrollr-body element takes this role.

var dummy = document.getElementById('skrollr-body') || document.createElement('div'); var dummyStyle = dummy.style;

dummyStyle.minWidth = '1px'; dummyStyle.position = 'absolute'; dummyStyle.top = dummyStyle.zIndex = '0';

//It's the dummy we just created. if(!dummy.id) { //Give the dummy element a small width and move it to the right to not overlap or interfere with the content. //Fixes #76. dummyStyle.width = '1px'; dummyStyle.right = '0';

body.appendChild(dummy); }

//Update height of dummy div when window size is changed. _reflow = function() { //Will be recalculated by _updateDependentKeyFrames. _maxKeyFrame = 0;

_updateDependentKeyFrames();

dummyStyle.height = (_maxKeyFrame + documentElement.clientHeight) + 'px';

if(skrollr.iscroll) { window.setTimeout(function () { skrollr.iscroll.refresh(); }, 0); } }; } else { _reflow = function() { _maxKeyFrame = body.scrollHeight - documentElement.clientHeight; _updateDependentKeyFrames(); _forceRender = true;

if(skrollr.iscroll) { window.setTimeout(function () { skrollr.iscroll.refresh(); }, 0); } }; }

_instance.refresh();

_addEvent('resize', _reflow);

//Let's go. (function animloop(){ //This is how the cool kids use requestAnimationFrame //http://paulirish.com/2011/requestanimationframe-for-smart-animating/ requestAnimFrame(animloop); _render(); }());

return _instance; }

/** * (Re)parses some or all elements. */ Skrollr.prototype.refresh = function(elements) { var elementIndex; var ignoreID = false;

//Completely reparse anything without argument. if(elements === undefined) { //Ignore that some elements may already have a skrollable ID. ignoreID = true;

_skrollables = []; _skrollableIdCounter = 0;

elements = document.getElementsByTagName('*'); } else { //We accept a single element or an array of elements. elements = [].concat(elements); }

for(elementIndex = 0; elementIndex < elements.length; elementIndex++) { var el = elements[elementIndex]; var anchorTarget = el; var keyFrames = [];

//If this particular element should be smooth scrolled. var smoothScrollThis = _smoothScrollingEnabled;

if(!el.attributes) { continue; }

//Iterate over all attributes and search for key frame attributes. for (var attributeIndex = 0; attributeIndex < el.attributes.length; attributeIndex++) { var attr = el.attributes[attributeIndex];

if(attr.name === 'data-anchor-target') { anchorTarget = document.querySelector(attr.value);

if(anchorTarget === null) { throw 'Unable to find anchor target "' + attr.value + '"'; }

continue; }

//Global smooth scrolling can be overridden by the element attribute. if(attr.name === 'data-smooth-scrolling') { smoothScrollThis = attr.value !== 'off';

continue; }

var match = attr.name.match(rxKeyframeAttribute);

if(match !== null) { var constant = match[1];

//If there is a constant, get it's value or fall back to 0. constant = constant && _constants[constant.substr(1)] || 0;

//Parse key frame offset. If undefined will be casted to 0. var offset = (match[2] | 0) + constant; var anchor1 = match[3]; //If second anchor is not set, the first will be taken for both. var anchor2 = match[4] || anchor1;

var kf = { offset: offset, props: attr.value, //Point back to the element as well. element: el };

keyFrames.push(kf);

//"absolute" (or "classic") mode, where numbers mean absolute scroll offset. if(!anchor1 || anchor1 === ANCHOR_START || anchor1 === ANCHOR_END) { kf.mode = 'absolute';

//data-end needs to be calculated after all key frames are know. if(anchor1 === ANCHOR_END) { kf.isEnd = true; } else { //For data-start we can already set the key frame w/o calculations. //#59: "scale" options should only affect absolute mode. kf.frame = offset * _scale;

delete kf.offset; } } //"relative" mode, where numbers are relative to anchors. else { kf.mode = 'relative'; kf.anchors = [anchor1, anchor2]; } } }

//Does this element have key frames? if(keyFrames.length) { //Will hold the original style and class attributes before we controlled the element (see #80). var styleAttr, classAttr;

var id;

if(!ignoreID && SKROLLABLE_ID_DOM_PROPERTY in el) { //We already have this element under control. Grab the corresponding skrollable id. id = el[SKROLLABLE_ID_DOM_PROPERTY]; styleAttr = _skrollables[id].styleAttr; classAttr = _skrollables[id].classAttr; } else { //It's an unknown element. Asign it a new skrollable id. id = (el[SKROLLABLE_ID_DOM_PROPERTY] = _skrollableIdCounter++); styleAttr = el.style.cssText; classAttr = _getClass(el); }

var skrollable = _skrollables[id] = { element: el, styleAttr: styleAttr, classAttr: classAttr, anchorTarget: anchorTarget, keyFrames: keyFrames, smoothScrolling: smoothScrollThis };

_updateClass(el, [SKROLLABLE_CLASS, RENDERED_CLASS], [UNRENDERED_CLASS]); skrollable[SKROLLABLE_HAS_RENDERED_CLASS_PROPERTY] = true; } }

//Reflow for the first time. _reflow();

//Now that we got all key frame numbers right, actually parse the properties. for(elementIndex = 0; elementIndex < elements.length; elementIndex++) { var sk = _skrollables[elements[elementIndex][SKROLLABLE_ID_DOM_PROPERTY]];

if(sk === undefined) { continue; }

//Make sure they are in order sk.keyFrames.sort(_keyFrameComparator);

//Parse the property string to objects _parseProps(sk);

//Fill key frames with missing properties from left and right _fillProps(sk); }

return _instance; };

/** * Transform "relative" mode to "absolute" mode. * That is, calculate anchor position and offset of element. */ Skrollr.prototype.relativeToAbsolute = function(element, viewportAnchor, elementAnchor) { var viewportHeight = documentElement.clientHeight; var box = element.getBoundingClientRect(); var absolute = box.top;

//#100: IE doesn't supply "height" with getBoundingClientRect. var boxHeight = box.bottom - box.top;

if(viewportAnchor === ANCHOR_BOTTOM) { absolute -= viewportHeight; } else if(viewportAnchor === ANCHOR_CENTER) { absolute -= viewportHeight / 2; }

if(elementAnchor === ANCHOR_BOTTOM) { absolute += boxHeight; } else if(elementAnchor === ANCHOR_CENTER) { absolute += boxHeight / 2; }

//Compensate scrolling since getBoundingClientRect is relative to viewport. absolute += _instance.getScrollTop();

return (absolute + 0.5) | 0; };

/** * Animates scroll top to new position. */ Skrollr.prototype.animateTo = function(top, options) { options = options || {};

var now = _now(); var scrollTop = _instance.getScrollTop();

//Setting this to a new value will automatically cause the current animation to stop, if any. _scrollAnimation = { startTop: scrollTop, topDiff: top - scrollTop, targetTop: top, duration: options.duration || DEFAULT_DURATION, startTime: now, endTime: now + (options.duration || DEFAULT_DURATION), easing: easings[options.easing || DEFAULT_EASING], done: options.done };

//Don't queue the animation if there's nothing to animate. if(!_scrollAnimation.topDiff) { if(_scrollAnimation.done) { _scrollAnimation.done.call(_instance, false); }

_scrollAnimation = undefined; }

return _instance; };

/** * Stops animateTo animation. */ Skrollr.prototype.stopAnimateTo = function() { if(_scrollAnimation && _scrollAnimation.done) { _scrollAnimation.done.call(_instance, true); }

_scrollAnimation = undefined; };

/** * Returns if an animation caused by animateTo is currently running. */ Skrollr.prototype.isAnimatingTo = function() { return !!_scrollAnimation; };

Skrollr.prototype.setScrollTop = function(top) { //skrollr.iscroll is an instance of iscroll available in mobile mode if(skrollr.iscroll) { //Notice the minus. skrollr.iscroll.scrollTo(0, -top); } else { window.scrollTo(0, top); }

return _instance; };

Skrollr.prototype.getScrollTop = function() { //skrollr.iscroll is an instance of iscroll available in mobile mode if(skrollr.iscroll) { return -skrollr.iscroll.y; } else { return window.pageYOffset || documentElement.scrollTop || body.scrollTop || 0; } };

Skrollr.prototype.on = function(name, fn) { _listeners[name] = fn;

return _instance; };

Skrollr.prototype.off = function(name) { delete _listeners[name];

return _instance; };

/* Private methods. */

/** * Updates key frames which depend on others. * That is "end" in "absolute" mode and all key frames in "relative" mode. */ var _updateDependentKeyFrames = function() { var skrollable; var element; var anchorTarget; var keyFrames; var kf; var skrollableIndex; var keyFrameIndex;

//For relative mode, we need to reset style and class. See #80 var styleAttr; var classAttr;

//First process all relative-mode elements and find the max key frame. for(skrollableIndex = 0; skrollableIndex < _skrollables.length; skrollableIndex++) { skrollable = _skrollables[skrollableIndex]; element = skrollable.element; anchorTarget = skrollable.anchorTarget; keyFrames = skrollable.keyFrames;

for(keyFrameIndex = 0; keyFrameIndex < keyFrames.length; keyFrameIndex++) { kf = keyFrames[keyFrameIndex];

if(kf.mode === 'relative') { //Save the current style and class (#80) styleAttr = element.style.cssText; classAttr = _getClass(element);

//Reset style and class to original (#80) element.style.cssText = skrollable.styleAttr; _updateClass(element, skrollable.classAttr);

kf.frame = _instance.relativeToAbsolute(anchorTarget, kf.anchors[0], kf.anchors[1]) - kf.offset;

//Now set style and class back to what skrollr did to it. element.style.cssText = styleAttr; _updateClass(element, classAttr); }

//Only search for max key frame when forceHeight is enabled. if(_forceHeight) { //Find the max key frame, but don't use one of the data-end ones for comparison. if(!kf.isEnd && kf.frame > _maxKeyFrame) { _maxKeyFrame = kf.frame; } } } }

//Now process all data-end keyframes. for(skrollableIndex = 0; skrollableIndex < _skrollables.length; skrollableIndex++) { skrollable = _skrollables[skrollableIndex]; keyFrames = skrollable.keyFrames;

for(keyFrameIndex = 0; keyFrameIndex < keyFrames.length; keyFrameIndex++) { kf = keyFrames[keyFrameIndex];

if(kf.isEnd) { kf.frame = _maxKeyFrame - kf.offset; } } } };

/** * Calculates and sets the style properties for the element at the given frame. * @param fakeFrame The frame to render at when smooth scrolling is enabled. * @param actualFrame The actual frame we are at. */ var _calcSteps = function(fakeFrame, actualFrame) { //Iterate over all skrollables. for(var skrollableIndex = 0; skrollableIndex < _skrollables.length; skrollableIndex++) { var skrollable = _skrollables[skrollableIndex]; var frame = skrollable.smoothScrolling ? fakeFrame : actualFrame; var frames = skrollable.keyFrames; var firstFrame = frames[0].frame; var lastFrame = frames[frames.length - 1].frame; var atFirst = frame <= firstFrame; var atLast = frame >= lastFrame; var key; var value;

//If we are before/after or exactly at the first/last frame, the element gets all props from this key frame. if(atFirst || atLast) { var props = frames[atFirst ? 0 : frames.length - 1].props;

for(key in props) { if(hasProp.call(props, key)) { value = _interpolateString(props[key].value);

skrollr.setStyle(skrollable.element, key, value); } }

//Add the unrendered class when before or after first/last frame. if(skrollable[SKROLLABLE_HAS_RENDERED_CLASS_PROPERTY] && (frame < firstFrame || frame > lastFrame)) { _updateClass(skrollable.element, [UNRENDERED_CLASS], [RENDERED_CLASS]);

//Does a faster job than sth. like hasClass('string') skrollable[SKROLLABLE_HAS_RENDERED_CLASS_PROPERTY] = false; }

continue; }

//We are between two frames. if(!skrollable[SKROLLABLE_HAS_RENDERED_CLASS_PROPERTY]) { _updateClass(skrollable.element, [RENDERED_CLASS], [UNRENDERED_CLASS]);

skrollable[SKROLLABLE_HAS_RENDERED_CLASS_PROPERTY] = true; }

//Find out between which two key frames we are right now. for(var keyFrameIndex = 0; keyFrameIndex < frames.length - 1; keyFrameIndex++) { if(frame >= frames[keyFrameIndex].frame && frame <= frames[keyFrameIndex + 1].frame) { var left = frames[keyFrameIndex]; var right = frames[keyFrameIndex + 1];

for(key in left.props) { if(hasProp.call(left.props, key)) { var progress = (frame - left.frame) / (right.frame - left.frame);

//Transform the current progress using the given easing function. progress = left.props[key].easing(progress);

//Interpolate between the two values value = _calcInterpolation(left.props[key].value, right.props[key].value, progress);

value = _interpolateString(value);

skrollr.setStyle(skrollable.element, key, value); } }

break; } } } };

/** * Renders all elements */ var _render = function() { //We may render something else than the actual scrollbar position. var renderTop = _instance.getScrollTop();

//If there's an animation, which ends in current render call, call the callback after rendering. var afterAnimationCallback; var now = _now(); var progress;

//Before actually rendering handle the scroll animation, if any. if(_scrollAnimation) { //It's over if(now >= _scrollAnimation.endTime) { renderTop = _scrollAnimation.targetTop; afterAnimationCallback = _scrollAnimation.done; _scrollAnimation = undefined; } else { //Map the current progress to the new progress using given easing function. progress = _scrollAnimation.easing((now - _scrollAnimation.startTime) / _scrollAnimation.duration);

renderTop = (_scrollAnimation.startTop + progress * _scrollAnimation.topDiff) | 0; }

_instance.setScrollTop(renderTop); } //Smooth scrolling only if there's no animation running. else { var smoothScrollingDiff = _smoothScrolling.targetTop - renderTop;

//The user scrolled, start new smooth scrolling. if(smoothScrollingDiff) { _smoothScrolling = { startTop: _lastTop, topDiff: renderTop - _lastTop, targetTop: renderTop, startTime: _lastRenderCall, endTime: _lastRenderCall + SMOOTH_SCROLLING_DURATION }; }

//Interpolate the internal scroll position (not the actual scrollbar). if(now <= _smoothScrolling.endTime) { //Map the current progress to the new progress using easing function. progress = easings.sqrt((now - _smoothScrolling.startTime) / SMOOTH_SCROLLING_DURATION);

renderTop = (_smoothScrolling.startTop + progress * _smoothScrolling.topDiff) | 0; } }

//In OSX it's possible to have a negative scrolltop, so, we set it to zero. if(renderTop < 0) { renderTop = 0; }

//Did the scroll position even change? if(_forceRender || _lastTop !== renderTop) { //Remember in which direction are we scrolling? _direction = (renderTop >= _lastTop) ? 'down' : 'up';

_forceRender = false;

var listenerParams = { curTop: renderTop, lastTop: _lastTop, maxTop: _maxKeyFrame, direction: _direction };

//Tell the listener we are about to render. var continueRendering = _listeners.beforerender && _listeners.beforerender.call(_instance, listenerParams);

//The beforerender listener function is able the cancel rendering. if(continueRendering !== false) { //Now actually interpolate all the styles. _calcSteps(renderTop, _instance.getScrollTop());

//Remember when we last rendered. _lastTop = renderTop;

if(_listeners.render) { _listeners.render.call(_instance, listenerParams); } }

if(afterAnimationCallback) { afterAnimationCallback.call(_instance, false); } }

_lastRenderCall = now; };

/** * Parses the properties for each key frame of the given skrollable. */ var _parseProps = function(skrollable) { //Iterate over all key frames for(var keyFrameIndex = 0; keyFrameIndex < skrollable.keyFrames.length; keyFrameIndex++) { var frame = skrollable.keyFrames[keyFrameIndex]; var easing; var value; var prop; var props = {};

var match;

while((match = rxPropValue.exec(frame.props)) !== null) { prop = match[1]; value = match[2];

easing = prop.match(rxPropEasing);

//Is there an easing specified for this prop? if(easing !== null) { prop = easing[1]; easing = easing[2]; } else { easing = DEFAULT_EASING; }

//Exclamation point at first position forces the value to be taken literal. value = value.indexOf('!') ? _parseProp(value) : [value.slice(1)];

//Save the prop for this key frame with his value and easing function props[prop] = { value: value, easing: easings[easing] }; }

frame.props = props; } };

/** * Parses a value extracting numeric values and generating a format string * for later interpolation of the new values in old string. * * @param val The CSS value to be parsed. * @return Something like ["rgba(?%,?%, ?%,?)", 100, 50, 0, .7] * where the first element is the format string later used * and all following elements are the numeric value. */ var _parseProp = function(val) { var numbers = [];

//One special case, where floats don't work. //We replace all occurences of rgba colors //which don't use percentage notation with the percentage notation. rxRGBAIntegerColor.lastIndex = 0; val = val.replace(rxRGBAIntegerColor, function(rgba) { return rgba.replace(rxNumericValue, function(n) { return n / 255 * 100 + '%'; }); });

//Handle prefixing of "gradient" values. //For now only the prefixed value will be set. Unprefixed isn't supported anyway. rxGradient.lastIndex = 0; val = val.replace(rxGradient, function(s) { return theDashedCSSPrefix + s; });

//Now parse ANY number inside this string and create a format string. val = val.replace(rxNumericValue, function(n) { numbers.push(+n); return '{?}'; });

//Add the formatstring as first value. numbers.unshift(val);

return numbers; };

/** * Fills the key frames with missing left and right hand properties. * If key frame 1 has property X and key frame 2 is missing X, * but key frame 3 has X again, then we need to assign X to key frame 2 too. * * @param sk A skrollable. */ var _fillProps = function(sk) { //Will collect the properties key frame by key frame var propList = {}; var keyFrameIndex;

//Iterate over all key frames from left to right for(keyFrameIndex = 0; keyFrameIndex < sk.keyFrames.length; keyFrameIndex++) { _fillPropForFrame(sk.keyFrames[keyFrameIndex], propList); }

//Now do the same from right to fill the last gaps

propList = {};

//Iterate over all key frames from right to left for(keyFrameIndex = sk.keyFrames.length - 1; keyFrameIndex >= 0; keyFrameIndex--) { _fillPropForFrame(sk.keyFrames[keyFrameIndex], propList); } };

var _fillPropForFrame = function(frame, propList) { var key;

//For each key frame iterate over all right hand properties and assign them, //but only if the current key frame doesn't have the property by itself for(key in propList) { //The current frame misses this property, so assign it. if(!hasProp.call(frame.props, key)) { frame.props[key] = propList[key]; } }

//Iterate over all props of the current frame and collect them for(key in frame.props) { propList[key] = frame.props[key]; } };

/** * Calculates the new values for two given values array. */ var _calcInterpolation = function(val1, val2, progress) { //They both need to have the same length if(val1.length !== val2.length) { throw 'Can\'t interpolate between "' + val1[0] + '" and "' + val2[0] + '"'; }

//Add the format string as first element. var interpolated = [val1[0]];

for(var valueIndex = 1; valueIndex < val1.length; valueIndex++) { //That's the line where the two numbers are actually interpolated. interpolated[valueIndex] = val1[valueIndex] + ((val2[valueIndex] - val1[valueIndex]) * progress); }

return interpolated; };

/** * Interpolates the numeric values into the format string. */ var _interpolateString = function(val) { var valueIndex = 1;

rxInterpolateString.lastIndex = 0;

return val[0].replace(rxInterpolateString, function() { return val[valueIndex++]; }); };

/** * Set the CSS property on the given element. Sets prefixed properties as well. */ skrollr.setStyle = function(el, prop, val) { var style = el.style;

//Camel case. prop = prop.replace(rxCamelCase, rxCamelCaseFn).replace('-', );

//Make sure z-index gets a <integer>. //This is the only <integer> case we need to handle. if(prop === 'zIndex') { //Floor style[prop] = + (val | 0); } //#64: "float" can't be set across browsers. Needs to use "cssFloat" for all except IE. else if(prop === 'float') { style.styleFloat = style.cssFloat = val; } else { //Need try-catch for old IE. try { //Set prefixed property. style[theCSSPrefix + prop.slice(0,1).toUpperCase() + prop.slice(1)] = val;

//Set unprefixed. style[prop] = val; } catch(ignore) {} } };

/** * Cross browser event handling. */ var _addEvent = function(name, fn) { if(window.addEventListener) { window.addEventListener(name, fn, false); } else { window.attachEvent('on' + name, fn); } };

/** * Returns a string of space separated classnames for the current element. * Works with SVG as well. */ var _getClass = function(element) { var prop = 'className';

//SVG support by using className.baseVal instead of just className if(window.SVGElement && element instanceof window.SVGElement) { element = element[prop]; prop = 'baseVal'; }

return element[prop]; };

/** * Adds and removes a CSS classes. * Works with SVG as well. * add and remove are either arrays of strings, * or if remove is ommited add is a string and overwrites all classes. */ var _updateClass = function(element, add, remove) { var prop = 'className';

//SVG support by using className.baseVal instead of just className if(window.SVGElement && element instanceof window.SVGElement) { element = element[prop]; prop = 'baseVal'; }

//When remove is ommited, we want to overwrite/set the classes. if(remove === undefined) { element[prop] = add; return; }

//Cache current classes. We will work on a string before passing back to DOM. var val = element[prop];

//All classes to be added. for(var classAddIndex = 0; classAddIndex < add.length; classAddIndex++) { //Only add if el not already has class. if(_untrim(val).indexOf(_untrim(add[classAddIndex])) === -1) { val += ' ' + add[classAddIndex]; } }

//All classes to be removed. for(var classRemoveIndex = 0; classRemoveIndex < remove.length; classRemoveIndex++) { val = _untrim(val).replace(_untrim(remove[classRemoveIndex]), ' '); }

element[prop] = _trim(val); };

var _trim = function(a) { return a.replace(rxTrim, '$1'); };

/** * Adds a space before and after the string. */ var _untrim = function(a) { return ' ' + a + ' '; };

var _now = Date.now || function() { return +new Date(); };

var _keyFrameComparator = function(a, b) { return a.frame - b.frame; };

/* * Private variables. */

//Singleton var _instance;

/* A list of all elements which should be animated associated with their the metadata. Exmaple skrollable with two key frames animating from 100px width to 20px:

skrollable = { element: <the DOM element>, styleAttr: <style attribute of the element before skrollr>, classAttr: <class attribute of the element before skrollr>, keyFrames: [ { frame: 100, props: { width: { value: ['{?}px', 100], easing: <reference to easing function> } }, mode: "absolute" }, { frame: 200, props: { width: { value: ['{?}px', 20], easing: <reference to easing function> } }, mode: "absolute" } ] }; */ var _skrollables;

var _listeners; var _forceHeight; var _maxKeyFrame = 0; var _reflow;

var _scale = 1; var _constants;

//Current direction (up/down). var _direction = 'down';

//The last top offset value. Needed to determine direction. var _lastTop = -1;

//The last time we called the render method (doesn't mean we rendered!). var _lastRenderCall = _now();

//Will contain data about a running scrollbar animation, if any. var _scrollAnimation;

var _smoothScrollingEnabled;

//Will contain settins for smooth scrolling if enabled. var _smoothScrolling;

//Can be set by any operation/event to force rendering even if the scrollbar didn't move. var _forceRender;

//Each skrollable gets an unique ID incremented for each skrollable. //The ID is the index in the _skrollables array. var _skrollableIdCounter = 0; }(window, document));