707 lines
20 KiB
JavaScript
707 lines
20 KiB
JavaScript
/** @license
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* DHTML Snowstorm! JavaScript-based snow for web pages
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* Making it snow on the internets since 2003. You're welcome.
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* -----------------------------------------------------------
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* Version 1.44.20131208 (Previous rev: 1.44.20131125)
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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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/*jslint nomen: true, plusplus: true, sloppy: true, vars: true, white: true */
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/*global window, document, navigator, clearInterval, setInterval */
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function snow(flakesMax) {
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// --- common properties ---
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this.autoStart = true; // Whether the snow should start automatically or not.
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this.excludeMobile = false; // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) Enable at your own risk.
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this.flakesMax = flakesMax; // Limit total amount of snow made (falling + sticking)
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this.flakesMaxActive = 30; // Limit amount of snow falling at once (less = lower CPU use)
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this.animationInterval = 70; // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower
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this.useGPU = true; // Enable transform-based hardware acceleration, reduce CPU load.
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this.className = null; // CSS class name for further customization on snow elements
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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 = false; // 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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this.usePixelPosition = false; // Whether to use pixel values for snow top/left vs. percentages. Auto-enabled if body is position:relative or targetElement is specified.
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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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// --- "No user-serviceable parts inside" past this point, yadda yadda ---
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var storm = this,
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features,
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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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isMobile = navigator.userAgent.match(/mobile|opera m(ob|in)/i),
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isBackCompatIE = isIE && document.compatMode === "BackCompat",
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noFixed = isBackCompatIE || isIE6,
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screenX = null,
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screenX2 = null,
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screenY = null,
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scrollY = null,
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docHeight = null,
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vRndX = null,
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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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targetElementIsRelative = 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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features = (function () {
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var getAnimationFrame;
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/**
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* hat tip: paul irish
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* http://paulirish.com/2011/requestanimationframe-for-smart-animating/
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* https://gist.github.com/838785
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*/
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function timeoutShim(callback) {
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window.setTimeout(callback, 1000 / (storm.animationInterval || 20));
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}
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var _animationFrame =
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window.requestAnimationFrame ||
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window.webkitRequestAnimationFrame ||
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window.mozRequestAnimationFrame ||
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window.oRequestAnimationFrame ||
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window.msRequestAnimationFrame ||
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timeoutShim;
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// apply to window, avoid "illegal invocation" errors in Chrome
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getAnimationFrame = _animationFrame
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? function () {
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return _animationFrame.apply(window, arguments);
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}
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: null;
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var testDiv;
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testDiv = document.createElement("div");
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function has(prop) {
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// test for feature support
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var result = testDiv.style[prop];
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return result !== undefined ? prop : null;
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}
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// note local scope.
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var localFeatures = {
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transform: {
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ie: has("-ms-transform"),
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moz: has("MozTransform"),
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opera: has("OTransform"),
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webkit: has("webkitTransform"),
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w3: has("transform"),
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prop: null // the normalized property value
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},
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getAnimationFrame: getAnimationFrame
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};
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localFeatures.transform.prop =
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localFeatures.transform.w3 ||
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localFeatures.transform.moz ||
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localFeatures.transform.webkit ||
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localFeatures.transform.ie ||
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localFeatures.transform.opera;
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testDiv = null;
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return localFeatures;
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})();
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this.timer = null;
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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.setXY = function (o, x, y) {
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if (!o) {
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return false;
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}
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if (storm.usePixelPosition || targetElementIsRelative) {
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o.style.left = x - storm.flakeWidth + "px";
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o.style.top = y - storm.flakeHeight + "px";
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} else if (noFixed) {
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o.style.right = 100 - (x / screenX) * 100 + "%";
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// avoid creating vertical scrollbars
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o.style.top = Math.min(y, docHeight - storm.flakeHeight) + "px";
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} else {
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if (!storm.flakeBottom) {
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// if not using a fixed bottom coordinate...
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o.style.right = 100 - (x / screenX) * 100 + "%";
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o.style.bottom = 100 - (y / screenY) * 100 + "%";
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} else {
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// absolute top.
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o.style.right = 100 - (x / screenX) * 100 + "%";
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o.style.top = Math.min(y, docHeight - storm.flakeHeight) + "px";
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}
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}
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};
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this.events = (function () {
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var old = !window.addEventListener && window.attachEvent,
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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),
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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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var i;
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vRndX = plusMinus(rnd(storm.vMaxX, 0.2));
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vRndY = rnd(storm.vMaxY, 0.2);
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if (this.flakes) {
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for (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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var i;
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// "attach" snowflakes to bottom of window if no absolute bottom value was given
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scrollY = storm.flakeBottom
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? 0
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: parseInt(
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window.scrollY ||
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document.documentElement.scrollTop ||
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(noFixed ? document.body.scrollTop : 0),
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10
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);
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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 && !storm.flakeBottom && storm.flakes) {
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for (i = 0; i < storm.flakes.length; i++) {
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if (storm.flakes[i].active === 0) {
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storm.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 - 16 - storm.flakeRightOffset;
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screenY = storm.flakeBottom || window.innerHeight;
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} else {
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screenX =
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(document.documentElement.clientWidth ||
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document.body.clientWidth ||
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document.body.scrollWidth) -
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(!isIE ? 8 : 0) -
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storm.flakeRightOffset;
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screenY =
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storm.flakeBottom ||
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document.documentElement.clientHeight ||
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document.body.clientHeight ||
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document.body.scrollHeight;
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}
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docHeight = document.body.offsetHeight;
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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 = storm.targetElement.offsetWidth - storm.flakeRightOffset;
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screenY = storm.flakeBottom || storm.targetElement.offsetHeight;
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screenX2 = parseInt(screenX / 2, 10);
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docHeight = document.body.offsetHeight;
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};
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this.freeze = function () {
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// pause animation
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if (!storm.disabled) {
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storm.disabled = 1;
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} else {
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return false;
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}
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storm.timer = null;
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};
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this.resume = function () {
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if (storm.disabled) {
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storm.disabled = 0;
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} else {
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return false;
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}
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storm.timerInit();
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};
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this.toggleSnow = function () {
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if (!storm.flakes.length) {
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// first run
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storm.start();
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} else {
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storm.active = !storm.active;
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if (storm.active) {
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storm.show();
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storm.resume();
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} else {
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storm.stop();
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storm.freeze();
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}
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}
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};
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this.stop = function () {
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var i;
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this.freeze();
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for (i = 0; i < this.flakes.length; i++) {
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this.flakes[i].o.style.display = "none";
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}
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storm.events.remove(window, "scroll", storm.scrollHandler);
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storm.events.remove(window, "resize", storm.resizeHandler);
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if (storm.freezeOnBlur) {
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if (isIE) {
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storm.events.remove(document, "focusout", storm.freeze);
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storm.events.remove(document, "focusin", storm.resume);
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} else {
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storm.events.remove(window, "blur", storm.freeze);
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storm.events.remove(window, "focus", storm.resume);
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}
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}
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};
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this.show = function () {
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var i;
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for (i = 0; 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 (type, x, y) {
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var s = this;
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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] || 1;
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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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if (storm.className) {
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this.o.setAttribute("class", storm.className);
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}
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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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if (storm.useGPU && features.transform.prop) {
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// GPU-accelerated snow.
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this.o.style[features.transform.prop] = "translate3d(0px, 0px, 0px)";
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}
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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.cursor = "default";
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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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storm.setXY(s.o, s.x, s.y);
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};
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this.stick = function () {
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if (
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noFixed ||
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(storm.targetElement !== document.documentElement &&
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storm.targetElement !== document.body)
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) {
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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.bottom = "0%";
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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,
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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) {
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// X-axis scroll check
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s.x = 0;
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} else if (vX < 0 && s.x - storm.flakeLeftOffset < -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 + storm.flakeHeight;
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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 (
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storm.useMeltEffect &&
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s.active &&
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s.type < 3 &&
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!s.melting &&
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Math.random() > 0.998
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) {
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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 < 0) {
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if (Math.random() > 0.97) {
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s.twinkleFrame = parseInt(Math.random() * 8, 10);
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}
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} else {
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s.twinkleFrame--;
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if (!opacitySupported) {
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s.o.style.visibility =
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s.twinkleFrame && s.twinkleFrame % 2 === 0
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? "hidden"
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: "visible";
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} else {
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s.o.style.opacity =
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s.twinkleFrame && s.twinkleFrame % 2 === 0 ? 0 : 1;
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}
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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.setOpacity(s.o, s.meltFrames[s.meltFrame]);
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s.o.style.fontSize =
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s.fontSize - s.fontSize * (s.meltFrame / s.meltFrameCount) + "px";
|
|
s.o.style.lineHeight =
|
|
storm.flakeHeight +
|
|
2 +
|
|
storm.flakeHeight * 0.75 * (s.meltFrame / s.meltFrameCount) +
|
|
"px";
|
|
s.meltFrame++;
|
|
} else {
|
|
s.recycle();
|
|
}
|
|
}
|
|
};
|
|
|
|
this.recycle = function () {
|
|
s.o.style.display = "none";
|
|
s.o.style.position = fixedForEverything ? "fixed" : "absolute";
|
|
s.o.style.bottom = "auto";
|
|
s.setVelocities();
|
|
s.vCheck();
|
|
s.meltFrame = 0;
|
|
s.melting = false;
|
|
s.setOpacity(s.o, 1);
|
|
s.o.style.padding = "0px";
|
|
s.o.style.margin = "0px";
|
|
s.o.style.fontSize = s.fontSize + "px";
|
|
s.o.style.lineHeight = storm.flakeHeight + 2 + "px";
|
|
s.o.style.textAlign = "center";
|
|
s.o.style.verticalAlign = "baseline";
|
|
s.x = parseInt(rnd(screenX - storm.flakeWidth - 20), 10);
|
|
s.y = parseInt(rnd(screenY) * -1, 10) - storm.flakeHeight;
|
|
s.refresh();
|
|
s.o.style.display = "block";
|
|
s.active = 1;
|
|
};
|
|
|
|
this.recycle(); // set up x/y coords etc.
|
|
this.refresh();
|
|
};
|
|
|
|
this.snow = function () {
|
|
var active = 0,
|
|
flake = null,
|
|
i,
|
|
j;
|
|
for (i = 0, j = storm.flakes.length; i < j; i++) {
|
|
if (storm.flakes[i].active === 1) {
|
|
storm.flakes[i].move();
|
|
active++;
|
|
}
|
|
if (storm.flakes[i].melting) {
|
|
storm.flakes[i].melt();
|
|
}
|
|
}
|
|
if (active < storm.flakesMaxActive) {
|
|
flake = storm.flakes[parseInt(rnd(storm.flakes.length), 10)];
|
|
if (flake.active === 0) {
|
|
flake.melting = true;
|
|
}
|
|
}
|
|
if (storm.timer) {
|
|
features.getAnimationFrame(storm.snow);
|
|
}
|
|
};
|
|
|
|
this.mouseMove = function (e) {
|
|
if (!storm.followMouse) {
|
|
return true;
|
|
}
|
|
var x = parseInt(e.clientX, 10);
|
|
if (x < screenX2) {
|
|
windOffset = -windMultiplier + (x / screenX2) * windMultiplier;
|
|
} else {
|
|
x -= screenX2;
|
|
windOffset = (x / screenX2) * windMultiplier;
|
|
}
|
|
};
|
|
|
|
this.createSnow = function (limit, allowInactive) {
|
|
var i;
|
|
for (i = 0; i < limit; i++) {
|
|
storm.flakes[storm.flakes.length] = new storm.SnowFlake(
|
|
parseInt(rnd(flakeTypes), 10)
|
|
);
|
|
if (allowInactive || i > storm.flakesMaxActive) {
|
|
storm.flakes[storm.flakes.length - 1].active = -1;
|
|
}
|
|
}
|
|
storm.targetElement.appendChild(docFrag);
|
|
};
|
|
|
|
this.timerInit = function () {
|
|
storm.timer = true;
|
|
storm.snow();
|
|
};
|
|
|
|
this.init = function () {
|
|
var i;
|
|
for (i = 0; i < storm.meltFrameCount; i++) {
|
|
storm.meltFrames.push(1 - i / storm.meltFrameCount);
|
|
}
|
|
storm.randomizeWind();
|
|
storm.createSnow(storm.flakesMax); // create initial batch
|
|
storm.events.add(window, "resize", storm.resizeHandler);
|
|
storm.events.add(window, "scroll", storm.scrollHandler);
|
|
if (storm.freezeOnBlur) {
|
|
if (isIE) {
|
|
storm.events.add(document, "focusout", storm.freeze);
|
|
storm.events.add(document, "focusin", storm.resume);
|
|
} else {
|
|
storm.events.add(window, "blur", storm.freeze);
|
|
storm.events.add(window, "focus", storm.resume);
|
|
}
|
|
}
|
|
storm.resizeHandler();
|
|
storm.scrollHandler();
|
|
if (storm.followMouse) {
|
|
storm.events.add(isIE ? document : window, "mousemove", storm.mouseMove);
|
|
}
|
|
storm.animationInterval = Math.max(20, storm.animationInterval);
|
|
storm.timerInit();
|
|
};
|
|
|
|
this.start = function (bFromOnLoad) {
|
|
if (!didInit) {
|
|
didInit = true;
|
|
} else if (bFromOnLoad) {
|
|
// already loaded and running
|
|
return true;
|
|
}
|
|
if (typeof storm.targetElement === "string") {
|
|
var targetID = storm.targetElement;
|
|
storm.targetElement = document.getElementById(targetID);
|
|
if (!storm.targetElement) {
|
|
throw new Error(
|
|
'Snowstorm: Unable to get targetElement "' + targetID + '"'
|
|
);
|
|
}
|
|
}
|
|
if (!storm.targetElement) {
|
|
storm.targetElement = document.body || document.documentElement;
|
|
}
|
|
if (
|
|
storm.targetElement !== document.documentElement &&
|
|
storm.targetElement !== document.body
|
|
) {
|
|
// re-map handler to get element instead of screen dimensions
|
|
storm.resizeHandler = storm.resizeHandlerAlt;
|
|
//and force-enable pixel positioning
|
|
storm.usePixelPosition = true;
|
|
}
|
|
storm.resizeHandler(); // get bounding box elements
|
|
storm.usePositionFixed =
|
|
storm.usePositionFixed && !noFixed && !storm.flakeBottom; // whether or not position:fixed is to be used
|
|
if (window.getComputedStyle) {
|
|
// attempt to determine if body or user-specified snow parent element is relatlively-positioned.
|
|
try {
|
|
targetElementIsRelative =
|
|
window
|
|
.getComputedStyle(storm.targetElement, null)
|
|
.getPropertyValue("position") === "relative";
|
|
} catch (e) {
|
|
// oh well
|
|
targetElementIsRelative = false;
|
|
}
|
|
}
|
|
fixedForEverything = storm.usePositionFixed;
|
|
if (screenX && screenY && !storm.disabled) {
|
|
storm.init();
|
|
storm.active = true;
|
|
}
|
|
};
|
|
|
|
function doDelayedStart() {
|
|
window.setTimeout(function () {
|
|
storm.start(true);
|
|
}, 20);
|
|
// event cleanup
|
|
storm.events.remove(isIE ? document : window, "mousemove", doDelayedStart);
|
|
}
|
|
|
|
function doStart() {
|
|
if (!storm.excludeMobile || !isMobile) {
|
|
doDelayedStart();
|
|
}
|
|
// event cleanup
|
|
storm.events.remove(window, "load", doStart);
|
|
}
|
|
|
|
// hooks for starting the snow
|
|
if (storm.autoStart) {
|
|
storm.events.add(window, "load", doStart, false);
|
|
}
|
|
|
|
return this;
|
|
}
|
|
|
|
snow(80)
|