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/** @license
* DHTML Snowstorm! JavaScript-based Snow for web pages
* --------------------------------------------------------
* Version 1.43.20111201 (Previous rev: 1.42.20111120)
* Copyright (c) 2007, Scott Schiller. All rights reserved.
* Code provided under the BSD License:
* http://schillmania.com/projects/snowstorm/license.txt
*/
/*global window, document, navigator, clearInterval, setInterval */
/*jslint white: false, onevar: true, plusplus: false, undef: true, nomen: true, eqeqeq: true, bitwise: true, regexp: true, newcap: true, immed: true */
window.snowStorm = {
// --- common properties ---
autoStart: true, // Whether the snow should start automatically or not.
flakesMax: 50, // Limit total amount of snow made (falling + sticking)
flakesMaxActive: 50, // Limit amount of snow falling at once (less = lower CPU use)
animationInterval: 35, // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower
excludeMobile: true, // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) By default, be nice.
flakeBottom: null, // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect
followMouse: false, // Snow movement can respond to the user's mouse
snowColor: '#fff', // Don't eat (or use?) yellow snow.
snowCharacter: '•', // • = bullet, · is square on some systems etc.
snowStick: false, // Whether or not snow should "stick" at the bottom. When off, will never collect.
targetElement: document.body, // element which snow will be appended to (null = document.body) - can be an element ID eg. 'myDiv', or a DOM node reference
useMeltEffect: true, // When recycling fallen snow (or rarely, when falling), have it "melt" and fade out if browser supports it
useTwinkleEffect: false, // Allow snow to randomly "flicker" in and out of view while falling
usePositionFixed: true, // true = snow does not shift vertically when scrolling. May increase CPU load, disabled by default - if enabled, used only where supported
// --- less-used bits ---
freezeOnBlur: true, // Only snow when the window is in focus (foreground.) Saves CPU.
flakeLeftOffset: 0, // Left margin/gutter space on edge of container (eg. browser window.) Bump up these values if seeing horizontal scrollbars.
flakeRightOffset: 0, // Right margin/gutter space on edge of container
flakeWidth: 8, // Max pixel width reserved for snow element
flakeHeight: 8, // Max pixel height reserved for snow element
vMaxX: 5, // Maximum X velocity range for snow
vMaxY: 4, // Maximum Y velocity range for snow
zIndex: 0 // CSS stacking order applied to each snowflake
};
// --- End of user section ---
snowStorm.internal = {
// UA sniffing and backCompat rendering mode checks for fixed position, etc.
isIE: navigator.userAgent.match(/msie/i),
isIE6: navigator.userAgent.match(/msie 6/i),
isWin98: navigator.appVersion.match(/windows 98/i),
isMobile: navigator.userAgent.match(/mobile|opera m(ob|in)/i),
screenX: null,
screenX2: null,
screenY: null,
scrollY: null,
vRndX: null,
vRndY: null,
windOffset: 1,
windMultiplier: 2,
flakeTypes: 6,
fixedForEverything: false,
opacitySupported: true,
didInit: false,
docFrag: document.createDocumentFragment()
};
snowStorm.internal.isBackCompatIE = (snowStorm.internal.isIE && document.compatMode == 'BackCompat');
snowStorm.internal.noFixed = (snowStorm.internal.isMobile || snowStorm.internal.isBackCompatIE || snowStorm.internal.isIE6);
try {
document.createElement('div').style.opacity = '0.5';
} catch(e) {
snowStorm.internal.opacitySupported = false;
}
snowStorm.timers = [];
snowStorm.flakes = [];
snowStorm.disabled = false;
snowStorm.active = false;
snowStorm.meltFrameCount = 20;
snowStorm.meltFrames = [];
snowStorm.events = {};
snowStorm.events.add = function(element, listener, func) {
if (!window.addEventListener && window.attachEvent) {
element.attachEvent('on' + listener, func);
}
else {
element.addEventListener.apply(element, Array.prototype.slice.call(arguments, 1))
}
}
snowStorm.events.remove = function(element, listener, func) {
if (!window.addEventListener && window.attachEvent) {
element.detachEvent('on' + listener, func);
}
else {
element.removeEventListener.apply(element, Array.prototype.slice.call(arguments, 1))
}
}
function rnd(n, min) {
if (isNaN(min)) {
min = 0;
}
return (Math.random() * n) + min;
}
function plusMinus(n) {
if (parseInt(rnd(2), 10) == 1) {
return n * -1;
}
else {
return n;
}
}
snowStorm.randomizeWind = function() {
snowStorm.internal.vRndX = plusMinus(rnd(snowStorm.vMaxX, 0.2));
snowStorm.internal.vRndY = rnd(snowStorm.vMaxY, 0.2);
if (snowStorm.flakes) {
for (var i = 0; i < snowStorm.flakes.length; i++) {
if (snowStorm.flakes[i].active) {
snowStorm.flakes[i].setVelocities();
}
}
}
};
snowStorm.scrollHandler = function() {
// "attach" snowflakes to bottom of window if no absolute bottom value was given
snowStorm.internal.scrollY = (snowStorm.flakeBottom ? 0 : parseInt(window.scrollY || document.documentElement.scrollTop || document.body.scrollTop, 10));
if (isNaN(snowStorm.internal.scrollY)) {
snowStorm.internal.scrollY = 0; // Netscape 6 scroll fix
}
if (!snowStorm.internal.fixedForEverything && !snowStorm.flakeBottom && snowStorm.flakes) {
for (var i = snowStorm.flakes.length - 1; i >= 0; i--) {
if (snowStorm.flakes[i].active == 0) {
snowStorm.flakes[i].stick();
}
}
}
};
snowStorm.resizeHandler = function() {
if (window.innerWidth || window.innerHeight) {
snowStorm.internal.screenX = window.innerWidth - 16 - snowStorm.flakeRightOffset;
snowStorm.internal.screenY = (snowStorm.flakeBottom ? snowStorm.flakeBottom : window.innerHeight);
} else {
snowStorm.internal.screenX = (document.documentElement.clientWidth || document.body.clientWidth || document.body.scrollWidth) - (!snowStorm.internal.isIE ? 8 : 0) - snowStorm.flakeRightOffset;
snowStorm.internal.screenY = snowStorm.flakeBottom ? snowStorm.flakeBottom : (document.documentElement.clientHeight || document.body.clientHeight || document.body.scrollHeight);
}
snowStorm.internal.screenX2 = parseInt(snowStorm.internal.screenX / 2, 10);
};
snowStorm.resizeHandlerAlt = function() {
snowStorm.internal.screenX = snowStorm.targetElement.offsetLeft + snowStorm.targetElement.offsetWidth - snowStorm.flakeRightOffset;
snowStorm.internal.screenY = snowStorm.flakeBottom ? snowStorm.flakeBottom : snowStorm.targetElement.offsetTop + snowStorm.targetElement.offsetHeight;
snowStorm.internal.screenX2 = parseInt(snowStorm.internal.screenX/2,10);
};
snowStorm.freeze = function() {
// pause animation
if (!snowStorm.disabled) {
snowStorm.disabled = 1;
} else {
return false;
}
for (var i = snowStorm.timers.length - 1; i >= 0; i--) {
clearInterval(snowStorm.timers[i]);
}
};
snowStorm.resume = function() {
if (snowStorm.disabled) {
snowStorm.disabled = 0;
} else {
return false;
}
snowStorm.timerInit();
};
snowStorm.toggleSnow = function() {
if (!snowStorm.flakes.length) {
// first run
snowStorm.start();
} else {
snowStorm.active = !snowStorm.active;
if (snowStorm.active) {
snowStorm.show();
snowStorm.resume();
} else {
snowStorm.stop();
snowStorm.freeze();
}
}
};
snowStorm.stop = function() {
snowStorm.freeze();
for (var i = snowStorm.flakes.length - 1; i >= 0; i--) {
snowStorm.flakes[i].o.style.display = 'none';
}
snowStorm.events.remove(window, 'scroll', snowStorm.scrollHandler);
snowStorm.events.remove(window, 'resize', snowStorm.resizeHandler);
if (snowStorm.freezeOnBlur) {
if (snowStorm.internal.isIE) {
snowStorm.events.remove(document, 'focusout', snowStorm.freeze);
snowStorm.events.remove(document, 'focusin', snowStorm.resume);
} else {
snowStorm.events.remove(window, 'blur', snowStorm.freeze);
snowStorm.events.remove(window, 'focus', snowStorm.resume);
}
}
};
snowStorm.show = function() {
for (var i = snowStorm.flakes.length - 1; i >= 0; i--) {
snowStorm.flakes[i].o.style.display = 'block';
}
};
snowStorm.SnowFlake = function(type, x, y) {
this.type = type;
this.x = x || parseInt(rnd(snowStorm.internal.screenX - 20), 10);
this.y = (!isNaN(y) ? y : -rnd(snowStorm.internal.screenY) - 12);
this.vX = null;
this.vY = null;
this.vAmpTypes = [1, 1.2, 1.4, 1.6, 1.8]; // "amplification" for vX/vY (based on flake size/type)
this.vAmp = this.vAmpTypes[this.type];
this.melting = false;
this.meltFrameCount = snowStorm.meltFrameCount;
this.meltFrames = snowStorm.meltFrames;
this.meltFrame = 0;
this.twinkleFrame = 0;
this.active = 1;
this.fontSize = (10 + (this.type / 5) * 10);
this.o = document.createElement('div');
this.o.innerHTML = snowStorm.snowCharacter;
this.o.style.color = snowStorm.snowColor;
this.o.style.position = (snowStorm.internal.fixedForEverything ? 'fixed' : 'absolute');
this.o.style.width = snowStorm.flakeWidth + 'px';
this.o.style.height = snowStorm.flakeHeight + 'px';
this.o.style.fontFamily = 'arial,verdana';
this.o.style.cursor = 'default';
this.o.style.overflow = 'hidden';
this.o.style.fontWeight = 'normal';
this.o.style.zIndex = snowStorm.zIndex;
snowStorm.internal.docFrag.appendChild(this.o);
this.refresh = function() {
if (isNaN(this.x) || isNaN(this.y)) {
// safety check
return false;
}
this.o.style.left = this.x + 'px';
this.o.style.top = this.y + 'px';
};
this.stick = function() {
if (snowStorm.internal.noFixed || (snowStorm.targetElement !== document.documentElement && snowStorm.targetElement !== document.body)) {
this.o.style.top = (snowStorm.internal.screenY + snowStorm.internal.scrollY - snowStorm.flakeHeight) + 'px';
} else if (snowStorm.flakeBottom) {
this.o.style.top = snowStorm.flakeBottom + 'px';
} else {
this.o.style.display = 'none';
this.o.style.top = 'auto';
this.o.style.bottom = '0px';
this.o.style.position = 'fixed';
this.o.style.display = 'block';
}
};
this.vCheck = function() {
if (this.vX >= 0 && this.vX < 0.2) {
this.vX = 0.2;
} else if (this.vX < 0 && this.vX > -0.2) {
this.vX = -0.2;
}
if (this.vY >= 0 && this.vY < 0.2) {
this.vY = 0.2;
}
};
this.move = function() {
var vX = this.vX * snowStorm.internal.windOffset;
this.x += vX;
this.y += (this.vY * this.vAmp);
if (this.x >= snowStorm.internal.screenX || snowStorm.internal.screenX - this.x < snowStorm.flakeWidth) { // X-axis scroll check
this.x = 0;
} else if (vX < 0 && this.x - snowStorm.flakeLeftOffset < -snowStorm.flakeWidth) {
this.x = snowStorm.internal.screenX - snowStorm.flakeWidth-1; // flakeWidth;
}
this.refresh();
var yDiff = snowStorm.internal.screenY + snowStorm.internal.scrollY - this.y;
if (yDiff < snowStorm.flakeHeight) {
this.active = 0;
if (snowStorm.snowStick) {
this.stick();
} else {
this.recycle();
}
} else {
if (snowStorm.useMeltEffect && this.active && this.type < 3 && !this.melting && Math.random() > 0.998) {
// ~1/1000 chance of melting mid-air, with each frame
this.melting = true;
this.melt();
// only incrementally melt one frame
// this.melting = false;
}
if (snowStorm.useTwinkleEffect) {
if (!this.twinkleFrame) {
if (Math.random() > 0.9) {
this.twinkleFrame = parseInt(Math.random() * 20, 10);
}
} else {
this.twinkleFrame--;
this.o.style.visibility = (this.twinkleFrame && this.twinkleFrame % 2 == 0 ? 'hidden' : 'visible');
}
}
}
};
this.animate = function() {
// main animation loop
// move, check status, die etc.
this.move();
};
this.setVelocities = function() {
this.vX = snowStorm.internal.vRndX + rnd(snowStorm.vMaxX * 0.12, 0.1);
this.vY = snowStorm.internal.vRndY + rnd(snowStorm.vMaxY * 0.12, 0.1);
};
this.setOpacity = function(o, opacity) {
if (!snowStorm.internal.opacitySupported) {
return false;
}
o.style.opacity = opacity;
};
this.melt = function() {
if (!snowStorm.useMeltEffect || !this.melting) {
this.recycle();
} else {
if (this.meltFrame < this.meltFrameCount) {
this.setOpacity(this.o, this.meltFrames[this.meltFrame]);
this.o.style.fontSize = this.fontSize - (this.fontSize * (this.meltFrame / this.meltFrameCount)) + 'px';
this.o.style.lineHeight = snowStorm.flakeHeight + 2 + (snowStorm.flakeHeight * 0.75 * (this.meltFrame / this.meltFrameCount)) + 'px';
this.meltFrame++;
} else {
this.recycle();
}
}
};
this.recycle = function() {
this.o.style.display = 'none';
this.o.style.position = (snowStorm.internal.fixedForEverything ? 'fixed' : 'absolute');
this.o.style.bottom = 'auto';
this.setVelocities();
this.vCheck();
this.meltFrame = 0;
this.melting = false;
this.setOpacity(this.o, 1);
this.o.style.padding = '0px';
this.o.style.margin = '0px';
this.o.style.fontSize = this.fontSize + 'px';
this.o.style.lineHeight = (snowStorm.flakeHeight + 2) + 'px';
this.o.style.textAlign = 'center';
this.o.style.verticalAlign = 'baseline';
this.x = parseInt(rnd(snowStorm.internal.screenX - snowStorm.flakeWidth - 20), 10);
this.y = parseInt(rnd(snowStorm.internal.screenY) * -1, 10) - snowStorm.flakeHeight;
this.refresh();
this.o.style.display = 'block';
this.active = 1;
};
this.recycle(); // set up x/y coords etc.
this.refresh();
};
snowStorm.snow = function() {
var active = 0;
var used = 0;
var waiting = 0;
var flake = null;
for (var i = snowStorm.flakes.length - 1; i >= 0; i--) {
if (snowStorm.flakes[i].active == 1) {
snowStorm.flakes[i].move();
active++;
} else if (snowStorm.flakes[i].active == 0) {
used++;
} else {
waiting++;
}
if (snowStorm.flakes[i].melting) {
snowStorm.flakes[i].melt();
}
}
if (active < snowStorm.flakesMaxActive) {
flake = snowStorm.flakes[parseInt(rnd(snowStorm.flakes.length), 10)];
if (flake.active == 0) {
flake.melting = true;
}
}
};
snowStorm.mouseMove = function(e) {
if (!snowStorm.followMouse) {
return true;
}
var x = parseInt(e.clientX, 10);
if (x < snowStorm.internal.screenX2) {
snowStorm.internal.windOffset = -snowStorm.internal.windMultiplier + (x / snowStorm.internal.screenX2 * snowStorm.internal.windMultiplier);
} else {
x -= snowStorm.internal.screenX2;
snowStorm.internal.windOffset = (x / snowStorm.internal.screenX2) * snowStorm.internal.windMultiplier;
}
};
snowStorm.createSnow = function(limit, allowInactive) {
for (var i = 0; i < limit; i++) {
snowStorm.flakes.push(new snowStorm.SnowFlake(parseInt(rnd(snowStorm.internal.flakeTypes), 10)));
if (allowInactive || i > snowStorm.flakesMaxActive) {
snowStorm.flakes[snowStorm.flakes.length - 1].active = -1;
}
}
snowStorm.targetElement.appendChild(snowStorm.internal.docFrag);
};
snowStorm.timerInit = function() {
snowStorm.timers = (!snowStorm.internal.isWin98 ? [setInterval(snowStorm.snow, snowStorm.animationInterval)] : [setInterval(snowStorm.snow, snowStorm.animationInterval * 3), setInterval(snowStorm.snow, snowStorm.animationInterval)]);
};
snowStorm.init = function() {
for (var i = 0; i < snowStorm.meltFrameCount; i++) {
snowStorm.meltFrames.push(1 - (i / snowStorm.meltFrameCount));
}
snowStorm.randomizeWind();
snowStorm.createSnow(snowStorm.flakesMax); // create initial batch
snowStorm.events.add(window, 'resize', snowStorm.resizeHandler);
snowStorm.events.add(window, 'scroll', snowStorm.scrollHandler);
if (snowStorm.freezeOnBlur) {
if (snowStorm.internal.isIE) {
snowStorm.events.add(document, 'focusout', snowStorm.freeze);
snowStorm.events.add(document, 'focusin', snowStorm.resume);
} else {
snowStorm.events.add(window, 'blur', snowStorm.freeze);
snowStorm.events.add(window, 'focus', snowStorm.resume);
}
}
snowStorm.resizeHandler();
snowStorm.scrollHandler();
if (snowStorm.followMouse) {
snowStorm.events.add(snowStorm.internal.isIE ? document : window, 'mousemove', snowStorm.mouseMove);
}
snowStorm.animationInterval = Math.max(20, snowStorm.animationInterval);
snowStorm.timerInit();
};
snowStorm.start = function(bFromOnLoad) {
if (!snowStorm.internal.didInit) {
snowStorm.internal.didInit = true;
} else if (bFromOnLoad) {
// already loaded and running
return true;
}
if (typeof snowStorm.targetElement == 'string') {
var targetID = snowStorm.targetElement;
snowStorm.targetElement = document.getElementById(targetID);
if (!snowStorm.targetElement) {
throw new Error('Snowstorm: Unable to get targetElement "' + targetID + '"');
}
}
if (!snowStorm.targetElement) {
snowStorm.targetElement = (!snowStorm.internal.isIE ? (document.documentElement ? document.documentElement : document.body) : document.body);
}
if (snowStorm.targetElement !== document.documentElement && snowStorm.targetElement !== document.body) {
snowStorm.resizeHandler = snowStorm.resizeHandlerAlt; // re-map handler to get element instead of screen dimensions
}
snowStorm.resizeHandler(); // get bounding box elements
snowStorm.usePositionFixed = (snowStorm.usePositionFixed && !snowStorm.internal.noFixed); // whether or not position:fixed is supported
snowStorm.internal.fixedForEverything = snowStorm.usePositionFixed;
if (snowStorm.internal.screenX && snowStorm.internal.screenY && !snowStorm.disabled) {
snowStorm.init();
snowStorm.active = true;
}
};
function doDelayedStart() {
setTimeout(function() {
snowStorm.start(true);
}, 20);
// event cleanup
snowStorm.events.remove(snowStorm.internal.isIE ? document : window, 'mousemove', doDelayedStart);
}
function doStart() {
if (!snowStorm.excludeMobile || !snowStorm.internal.isMobile) {
if (snowStorm.freezeOnBlur) {
snowStorm.events.add(snowStorm.internal.isIE ? document : window, 'mousemove', doDelayedStart);
} else {
doDelayedStart();
}
}
// event cleanup
snowStorm.events.remove(window, 'load', doStart);
}
// hooks for starting the snow
if (snowStorm.autoStart) {
snowStorm.events.add(window, 'load', doStart, false);
}