/** @license
* DHTML Snowstorm! JavaScript-based Snow for web pages
* --------------------------------------------------------
* Version 1.41.20101113 (Previous rev: 1.4.20091115)
* 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 */
var snowStorm = (function(window, document) {
// --- common properties ---
this.flakesMax = 128; // Limit total amount of snow made (falling + sticking)
this.flakesMaxActive = 64; // Limit amount of snow falling at once (less = lower CPU use)
this.animationInterval = 33; // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower
this.excludeMobile = true; // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) By default, be nice.
this.flakeBottom = null; // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect
this.followMouse = true; // Snow movement can respond to the user's mouse
this.snowColor = '#fff'; // Don't eat (or use?) yellow snow.
this.snowCharacter = '•'; // • = bullet, · is square on some systems etc.
this.snowStick = true; // Whether or not snow should "stick" at the bottom. When off, will never collect.
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
this.useMeltEffect = true; // When recycling fallen snow (or rarely, when falling), have it "melt" and fade out if browser supports it
this.useTwinkleEffect = false; // Allow snow to randomly "flicker" in and out of view while falling
this.usePositionFixed = false; // true = snow does not shift vertically when scrolling. May increase CPU load, disabled by default - if enabled, used only where supported
// --- less-used bits ---
this.freezeOnBlur = true; // Only snow when the window is in focus (foreground.) Saves CPU.
this.flakeLeftOffset = 0; // Left margin/gutter space on edge of container (eg. browser window.) Bump up these values if seeing horizontal scrollbars.
this.flakeRightOffset = 0; // Right margin/gutter space on edge of container
this.flakeWidth = 8; // Max pixel width reserved for snow element
this.flakeHeight = 8; // Max pixel height reserved for snow element
this.vMaxX = 5; // Maximum X velocity range for snow
this.vMaxY = 4; // Maximum Y velocity range for snow
this.zIndex = 0; // CSS stacking order applied to each snowflake
// --- End of user section ---
var s = this, storm = this, i,
// 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/i),
isBackCompatIE = (isIE && document.compatMode === 'BackCompat'),
noFixed = (isMobile || isBackCompatIE || isIE6),
screenX = null, screenX2 = null, screenY = null, scrollY = null, vRndX = null, vRndY = null,
windOffset = 1,
windMultiplier = 2,
flakeTypes = 6,
fixedForEverything = false,
opacitySupported = (function(){
try {
document.createElement('div').style.opacity = '0.5';
} catch(e) {
return false;
}
return true;
}()),
didInit = false,
docFrag = document.createDocumentFragment();
this.timers = [];
this.flakes = [];
this.disabled = false;
this.active = false;
this.meltFrameCount = 20;
this.meltFrames = [];
this.events = (function() {
var old = (window.attachEvent), slice = Array.prototype.slice,
evt = {
add: (old?'attachEvent':'addEventListener'),
remove: (old?'detachEvent':'removeEventListener')
};
function getArgs(oArgs) {
var args = slice.call(oArgs), len = args.length;
if (old) {
args[1] = 'on' + args[1]; // prefix
if (len > 3) {
args.pop(); // no capture
}
} else if (len === 3) {
args.push(false);
}
return args;
}
function apply(args, sType) {
var oFunc = args.shift()[evt[sType]];
if (old) {
oFunc(args[0], args[1]);
} else {
oFunc.apply(this, args);
}
}
function addEvent() {
apply(getArgs(arguments), 'add');
}
function removeEvent() {
apply(getArgs(arguments), 'remove');
}
return {
add: addEvent,
remove: removeEvent
};
}());
function rnd(n,min) {
if (isNaN(min)) {
min = 0;
}
return (Math.random()*n)+min;
}
function plusMinus(n) {
return (parseInt(rnd(2),10)===1?n*-1:n);
}
this.randomizeWind = function() {
vRndX = plusMinus(rnd(s.vMaxX,0.2));
vRndY = rnd(s.vMaxY,0.2);
if (this.flakes) {
for (var i=0; i=0 && s.vX<0.2) {
s.vX = 0.2;
} else if (s.vX<0 && s.vX>-0.2) {
s.vX = -0.2;
}
if (s.vY>=0 && s.vY<0.2) {
s.vY = 0.2;
}
};
this.move = function() {
var vX = s.vX*windOffset, yDiff;
s.x += vX;
s.y += (s.vY*s.vAmp);
if (s.x >= screenX || screenX-s.x < storm.flakeWidth) { // X-axis scroll check
s.x = 0;
} else if (vX < 0 && s.x-storm.flakeLeftOffset < 0-storm.flakeWidth) {
s.x = screenX-storm.flakeWidth-1; // flakeWidth;
}
s.refresh();
yDiff = screenY+scrollY-s.y;
if (yDiff0.998) {
// ~1/1000 chance of melting mid-air, with each frame
s.melting = true;
s.melt();
// only incrementally melt one frame
// s.melting = false;
}
if (storm.useTwinkleEffect) {
if (!s.twinkleFrame) {
if (Math.random()>0.9) {
s.twinkleFrame = parseInt(Math.random()*20,10);
}
} else {
s.twinkleFrame--;
s.o.style.visibility = (s.twinkleFrame && s.twinkleFrame%2===0?'hidden':'visible');
}
}
}
};
this.animate = function() {
// main animation loop
// move, check status, die etc.
s.move();
};
this.setVelocities = function() {
s.vX = vRndX+rnd(storm.vMaxX*0.12,0.1);
s.vY = vRndY+rnd(storm.vMaxY*0.12,0.1);
};
this.setOpacity = function(o,opacity) {
if (!opacitySupported) {
return false;
}
o.style.opacity = opacity;
};
this.melt = function() {
if (!storm.useMeltEffect || !s.melting) {
s.recycle();
} else {
if (s.meltFrame < s.meltFrameCount) {
s.meltFrame++;
s.setOpacity(s.o,s.meltFrames[s.meltFrame]);
s.o.style.fontSize = 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';
} 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, used = 0, waiting = 0, flake = null, i;
for (i=s.flakes.length; i--;) {
if (s.flakes[i].active === 1) {
s.flakes[i].move();
active++;
} else if (s.flakes[i].active === 0) {
used++;
} else {
waiting++;
}
if (s.flakes[i].melting) {
s.flakes[i].melt();
}
}
if (actives.flakesMaxActive) {
s.flakes[s.flakes.length-1].active = -1;
}
}
storm.targetElement.appendChild(docFrag);
};
this.timerInit = function() {
s.timers = (!isWin98?[setInterval(s.snow,s.animationInterval)]:[setInterval(s.snow,s.animationInterval*3),setInterval(s.snow,s.animationInterval)]);
};
this.init = function() {
for (var i=0; i
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