528 lines
17 KiB
JavaScript
528 lines
17 KiB
JavaScript
/** @license
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* DHTML Snowstorm! JavaScript-based Snow for web pages
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* --------------------------------------------------------
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* Version 1.41.20101113 (Previous rev: 1.4.20091115)
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* Copyright (c) 2007, Scott Schiller. All rights reserved.
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* Code provided under the BSD License:
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* http://schillmania.com/projects/snowstorm/license.txt
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*/
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/*global window, document, navigator, clearInterval, setInterval */
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/*jslint white: false, onevar: true, plusplus: false, undef: true, nomen: true, eqeqeq: true, bitwise: true, regexp: true, newcap: true, immed: true */
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var snowStorm = (function(window, document) {
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// --- common properties ---
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this.flakesMax = 128; // Limit total amount of snow made (falling + sticking)
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this.flakesMaxActive = 64; // Limit amount of snow falling at once (less = lower CPU use)
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this.animationInterval = 33; // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower
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this.excludeMobile = true; // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) By default, be nice.
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this.flakeBottom = null; // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect
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this.followMouse = true; // Snow movement can respond to the user's mouse
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this.snowColor = '#fff'; // Don't eat (or use?) yellow snow.
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this.snowCharacter = '•'; // • = bullet, · is square on some systems etc.
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this.snowStick = true; // Whether or not snow should "stick" at the bottom. When off, will never collect.
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this.targetElement = null; // element which snow will be appended to (null = document.body) - can be an element ID eg. 'myDiv', or a DOM node reference
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this.useMeltEffect = true; // When recycling fallen snow (or rarely, when falling), have it "melt" and fade out if browser supports it
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this.useTwinkleEffect = false; // Allow snow to randomly "flicker" in and out of view while falling
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this.usePositionFixed = false; // true = snow does not shift vertically when scrolling. May increase CPU load, disabled by default - if enabled, used only where supported
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// --- less-used bits ---
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this.freezeOnBlur = true; // Only snow when the window is in focus (foreground.) Saves CPU.
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this.flakeLeftOffset = 0; // Left margin/gutter space on edge of container (eg. browser window.) Bump up these values if seeing horizontal scrollbars.
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this.flakeRightOffset = 0; // Right margin/gutter space on edge of container
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this.flakeWidth = 8; // Max pixel width reserved for snow element
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this.flakeHeight = 8; // Max pixel height reserved for snow element
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this.vMaxX = 5; // Maximum X velocity range for snow
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this.vMaxY = 4; // Maximum Y velocity range for snow
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this.zIndex = 0; // CSS stacking order applied to each snowflake
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// --- End of user section ---
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var s = this, storm = this, i,
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// UA sniffing and backCompat rendering mode checks for fixed position, etc.
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isIE = navigator.userAgent.match(/msie/i),
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isIE6 = navigator.userAgent.match(/msie 6/i),
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isWin98 = navigator.appVersion.match(/windows 98/i),
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isMobile = navigator.userAgent.match(/mobile/i),
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isBackCompatIE = (isIE && document.compatMode === 'BackCompat'),
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noFixed = (isMobile || isBackCompatIE || isIE6),
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screenX = null, screenX2 = null, screenY = null, scrollY = null, vRndX = null, vRndY = null,
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windOffset = 1,
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windMultiplier = 2,
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flakeTypes = 6,
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fixedForEverything = false,
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opacitySupported = (function(){
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try {
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document.createElement('div').style.opacity = '0.5';
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} catch(e) {
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return false;
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}
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return true;
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}()),
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didInit = false,
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docFrag = document.createDocumentFragment();
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this.timers = [];
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this.flakes = [];
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this.disabled = false;
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this.active = false;
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this.meltFrameCount = 20;
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this.meltFrames = [];
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this.events = (function() {
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var old = (!window.addEventListener && window.attachEvent), slice = Array.prototype.slice,
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evt = {
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add: (old?'attachEvent':'addEventListener'),
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remove: (old?'detachEvent':'removeEventListener')
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};
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function getArgs(oArgs) {
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var args = slice.call(oArgs), len = args.length;
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if (old) {
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args[1] = 'on' + args[1]; // prefix
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if (len > 3) {
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args.pop(); // no capture
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}
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} else if (len === 3) {
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args.push(false);
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}
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return args;
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}
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function apply(args, sType) {
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var element = args.shift(),
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method = [evt[sType]];
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if (old) {
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element[method](args[0], args[1]);
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} else {
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element[method].apply(element, args);
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}
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}
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function addEvent() {
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apply(getArgs(arguments), 'add');
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}
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function removeEvent() {
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apply(getArgs(arguments), 'remove');
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}
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return {
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add: addEvent,
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remove: removeEvent
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};
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}());
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function rnd(n,min) {
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if (isNaN(min)) {
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min = 0;
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}
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return (Math.random()*n)+min;
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}
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function plusMinus(n) {
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return (parseInt(rnd(2),10)===1?n*-1:n);
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}
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this.randomizeWind = function() {
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vRndX = plusMinus(rnd(s.vMaxX,0.2));
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vRndY = rnd(s.vMaxY,0.2);
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if (this.flakes) {
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for (var i=0; i<this.flakes.length; i++) {
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if (this.flakes[i].active) {
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this.flakes[i].setVelocities();
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}
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}
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}
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};
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this.scrollHandler = function() {
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// "attach" snowflakes to bottom of window if no absolute bottom value was given
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scrollY = (s.flakeBottom?0:parseInt(window.scrollY||document.documentElement.scrollTop||document.body.scrollTop,10));
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if (isNaN(scrollY)) {
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scrollY = 0; // Netscape 6 scroll fix
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}
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if (!fixedForEverything && !s.flakeBottom && s.flakes) {
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for (var i=s.flakes.length; i--;) {
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if (s.flakes[i].active === 0) {
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s.flakes[i].stick();
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}
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}
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}
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};
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this.resizeHandler = function() {
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if (window.innerWidth || window.innerHeight) {
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screenX = window.innerWidth-(!isIE?16:2)-s.flakeRightOffset;
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screenY = (s.flakeBottom?s.flakeBottom:window.innerHeight);
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} else {
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screenX = (document.documentElement.clientWidth||document.body.clientWidth||document.body.scrollWidth)-(!isIE?8:0)-s.flakeRightOffset;
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screenY = s.flakeBottom?s.flakeBottom:(document.documentElement.clientHeight||document.body.clientHeight||document.body.scrollHeight);
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}
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screenX2 = parseInt(screenX/2,10);
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};
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this.resizeHandlerAlt = function() {
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screenX = s.targetElement.offsetLeft+s.targetElement.offsetWidth-s.flakeRightOffset;
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screenY = s.flakeBottom?s.flakeBottom:s.targetElement.offsetTop+s.targetElement.offsetHeight;
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screenX2 = parseInt(screenX/2,10);
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};
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this.freeze = function() {
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// pause animation
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if (!s.disabled) {
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s.disabled = 1;
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} else {
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return false;
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}
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for (var i=s.timers.length; i--;) {
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clearInterval(s.timers[i]);
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}
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};
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this.resume = function() {
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if (s.disabled) {
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s.disabled = 0;
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} else {
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return false;
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}
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s.timerInit();
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};
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this.toggleSnow = function() {
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if (!s.flakes.length) {
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// first run
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s.start();
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} else {
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s.active = !s.active;
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if (s.active) {
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s.show();
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s.resume();
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} else {
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s.stop();
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s.freeze();
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}
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}
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};
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this.stop = function() {
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this.freeze();
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for (var i=this.flakes.length; i--;) {
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this.flakes[i].o.style.display = 'none';
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}
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s.events.remove(window,'scroll',s.scrollHandler);
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s.events.remove(window,'resize',s.resizeHandler);
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if (s.freezeOnBlur) {
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if (isIE) {
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s.events.remove(document,'focusout',s.freeze);
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s.events.remove(document,'focusin',s.resume);
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} else {
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s.events.remove(window,'blur',s.freeze);
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s.events.remove(window,'focus',s.resume);
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}
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}
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};
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this.show = function() {
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for (var i=this.flakes.length; i--;) {
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this.flakes[i].o.style.display = 'block';
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}
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};
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this.SnowFlake = function(parent,type,x,y) {
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var s = this, storm = parent;
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this.type = type;
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this.x = x||parseInt(rnd(screenX-20),10);
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this.y = (!isNaN(y)?y:-rnd(screenY)-12);
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this.vX = null;
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this.vY = null;
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this.vAmpTypes = [1,1.2,1.4,1.6,1.8]; // "amplification" for vX/vY (based on flake size/type)
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this.vAmp = this.vAmpTypes[this.type];
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this.melting = false;
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this.meltFrameCount = storm.meltFrameCount;
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this.meltFrames = storm.meltFrames;
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this.meltFrame = 0;
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this.twinkleFrame = 0;
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this.active = 1;
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this.fontSize = (10+(this.type/5)*10);
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this.o = document.createElement('div');
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this.o.innerHTML = storm.snowCharacter;
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this.o.style.color = storm.snowColor;
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this.o.style.position = (fixedForEverything?'fixed':'absolute');
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this.o.style.width = storm.flakeWidth+'px';
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this.o.style.height = storm.flakeHeight+'px';
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this.o.style.fontFamily = 'arial,verdana';
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this.o.style.overflow = 'hidden';
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this.o.style.fontWeight = 'normal';
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this.o.style.zIndex = storm.zIndex;
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docFrag.appendChild(this.o);
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this.refresh = function() {
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if (isNaN(s.x) || isNaN(s.y)) {
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// safety check
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return false;
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}
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s.o.style.left = s.x+'px';
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s.o.style.top = s.y+'px';
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};
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this.stick = function() {
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if (noFixed || (storm.targetElement !== document.documentElement && storm.targetElement !== document.body)) {
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s.o.style.top = (screenY+scrollY-storm.flakeHeight)+'px';
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} else if (storm.flakeBottom) {
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s.o.style.top = storm.flakeBottom+'px';
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} else {
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s.o.style.display = 'none';
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s.o.style.top = 'auto';
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s.o.style.bottom = '0px';
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s.o.style.position = 'fixed';
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s.o.style.display = 'block';
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}
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};
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this.vCheck = function() {
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if (s.vX>=0 && s.vX<0.2) {
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s.vX = 0.2;
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} else if (s.vX<0 && s.vX>-0.2) {
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s.vX = -0.2;
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}
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if (s.vY>=0 && s.vY<0.2) {
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s.vY = 0.2;
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}
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};
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this.move = function() {
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var vX = s.vX*windOffset, yDiff;
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s.x += vX;
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s.y += (s.vY*s.vAmp);
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if (s.x >= screenX || screenX-s.x < storm.flakeWidth) { // X-axis scroll check
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s.x = 0;
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} else if (vX < 0 && s.x-storm.flakeLeftOffset < 0-storm.flakeWidth) {
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s.x = screenX-storm.flakeWidth-1; // flakeWidth;
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}
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s.refresh();
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yDiff = screenY+scrollY-s.y;
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if (yDiff<storm.flakeHeight) {
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s.active = 0;
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if (storm.snowStick) {
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s.stick();
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} else {
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s.recycle();
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}
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} else {
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if (storm.useMeltEffect && s.active && s.type < 3 && !s.melting && Math.random()>0.998) {
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// ~1/1000 chance of melting mid-air, with each frame
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s.melting = true;
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s.melt();
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// only incrementally melt one frame
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// s.melting = false;
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}
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if (storm.useTwinkleEffect) {
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if (!s.twinkleFrame) {
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if (Math.random()>0.9) {
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s.twinkleFrame = parseInt(Math.random()*20,10);
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}
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} else {
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s.twinkleFrame--;
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s.o.style.visibility = (s.twinkleFrame && s.twinkleFrame%2===0?'hidden':'visible');
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}
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}
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}
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};
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this.animate = function() {
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// main animation loop
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// move, check status, die etc.
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s.move();
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};
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this.setVelocities = function() {
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s.vX = vRndX+rnd(storm.vMaxX*0.12,0.1);
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s.vY = vRndY+rnd(storm.vMaxY*0.12,0.1);
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};
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this.setOpacity = function(o,opacity) {
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if (!opacitySupported) {
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return false;
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}
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o.style.opacity = opacity;
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};
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this.melt = function() {
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if (!storm.useMeltEffect || !s.melting) {
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s.recycle();
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} else {
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if (s.meltFrame < s.meltFrameCount) {
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s.meltFrame++;
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s.setOpacity(s.o,s.meltFrames[s.meltFrame]);
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s.o.style.fontSize = s.fontSize-(s.fontSize*(s.meltFrame/s.meltFrameCount))+'px';
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s.o.style.lineHeight = storm.flakeHeight+2+(storm.flakeHeight*0.75*(s.meltFrame/s.meltFrameCount))+'px';
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} else {
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s.recycle();
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}
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}
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};
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this.recycle = function() {
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s.o.style.display = 'none';
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s.o.style.position = (fixedForEverything?'fixed':'absolute');
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s.o.style.bottom = 'auto';
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s.setVelocities();
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s.vCheck();
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s.meltFrame = 0;
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s.melting = false;
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s.setOpacity(s.o,1);
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s.o.style.padding = '0px';
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s.o.style.margin = '0px';
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s.o.style.fontSize = s.fontSize+'px';
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s.o.style.lineHeight = (storm.flakeHeight+2)+'px';
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s.o.style.textAlign = 'center';
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s.o.style.verticalAlign = 'baseline';
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s.x = parseInt(rnd(screenX-storm.flakeWidth-20),10);
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s.y = parseInt(rnd(screenY)*-1,10)-storm.flakeHeight;
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s.refresh();
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s.o.style.display = 'block';
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s.active = 1;
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};
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this.recycle(); // set up x/y coords etc.
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this.refresh();
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};
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this.snow = function() {
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var active = 0, used = 0, waiting = 0, flake = null, i;
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for (i=s.flakes.length; i--;) {
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if (s.flakes[i].active === 1) {
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s.flakes[i].move();
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active++;
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} else if (s.flakes[i].active === 0) {
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used++;
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} else {
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waiting++;
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}
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if (s.flakes[i].melting) {
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s.flakes[i].melt();
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}
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}
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if (active<s.flakesMaxActive) {
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flake = s.flakes[parseInt(rnd(s.flakes.length),10)];
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if (flake.active === 0) {
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flake.melting = true;
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}
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}
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};
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this.mouseMove = function(e) {
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if (!s.followMouse) {
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return true;
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}
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var x = parseInt(e.clientX,10);
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if (x<screenX2) {
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windOffset = -windMultiplier+(x/screenX2*windMultiplier);
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} else {
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x -= screenX2;
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windOffset = (x/screenX2)*windMultiplier;
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}
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};
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this.createSnow = function(limit,allowInactive) {
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for (var i=0; i<limit; i++) {
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s.flakes[s.flakes.length] = new s.SnowFlake(s,parseInt(rnd(flakeTypes),10));
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if (allowInactive || i>s.flakesMaxActive) {
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s.flakes[s.flakes.length-1].active = -1;
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}
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}
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storm.targetElement.appendChild(docFrag);
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};
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this.timerInit = function() {
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s.timers = (!isWin98?[setInterval(s.snow,s.animationInterval)]:[setInterval(s.snow,s.animationInterval*3),setInterval(s.snow,s.animationInterval)]);
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};
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this.init = function() {
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for (var i=0; i<s.meltFrameCount; i++) {
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s.meltFrames.push(1-(i/s.meltFrameCount));
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}
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s.randomizeWind();
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s.createSnow(s.flakesMax); // create initial batch
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s.events.add(window,'resize',s.resizeHandler);
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s.events.add(window,'scroll',s.scrollHandler);
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if (s.freezeOnBlur) {
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if (isIE) {
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s.events.add(document,'focusout',s.freeze);
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s.events.add(document,'focusin',s.resume);
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} else {
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s.events.add(window,'blur',s.freeze);
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s.events.add(window,'focus',s.resume);
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}
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}
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s.resizeHandler();
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s.scrollHandler();
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if (s.followMouse) {
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s.events.add(isIE?document:window,'mousemove',s.mouseMove);
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}
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s.animationInterval = Math.max(20,s.animationInterval);
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s.timerInit();
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};
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this.start = function(bFromOnLoad) {
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if (!didInit) {
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didInit = true;
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} else if (bFromOnLoad) {
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|
// already loaded and running
|
|
return true;
|
|
}
|
|
if (typeof s.targetElement === 'string') {
|
|
var targetID = s.targetElement;
|
|
s.targetElement = document.getElementById(targetID);
|
|
if (!s.targetElement) {
|
|
throw new Error('Snowstorm: Unable to get targetElement "'+targetID+'"');
|
|
}
|
|
}
|
|
if (!s.targetElement) {
|
|
s.targetElement = (!isIE?(document.documentElement?document.documentElement:document.body):document.body);
|
|
}
|
|
if (s.targetElement !== document.documentElement && s.targetElement !== document.body) {
|
|
s.resizeHandler = s.resizeHandlerAlt; // re-map handler to get element instead of screen dimensions
|
|
}
|
|
s.resizeHandler(); // get bounding box elements
|
|
s.usePositionFixed = (s.usePositionFixed && !noFixed); // whether or not position:fixed is supported
|
|
fixedForEverything = s.usePositionFixed;
|
|
if (screenX && screenY && !s.disabled) {
|
|
s.init();
|
|
s.active = true;
|
|
}
|
|
};
|
|
|
|
function doDelayedStart() {
|
|
window.setTimeout(function() {
|
|
s.start(true);
|
|
}, 20);
|
|
// event cleanup
|
|
s.events.remove(isIE?document:window,'mousemove',doDelayedStart);
|
|
}
|
|
|
|
function doStart() {
|
|
if (!s.excludeMobile || !isMobile) {
|
|
if (s.freezeOnBlur) {
|
|
s.events.add(isIE?document:window,'mousemove',doDelayedStart);
|
|
} else {
|
|
doDelayedStart();
|
|
}
|
|
}
|
|
// event cleanup
|
|
s.events.remove(window, 'load', doStart);
|
|
}
|
|
|
|
// hooks for starting the snow
|
|
s.events.add(window, 'load', doStart, false);
|
|
|
|
return this;
|
|
|
|
}(window, document)); |