snow.js

var snowStorm=(function(window,document){this.autoStart=true;this.excludeMobile=true;this.flakesMax=128;this.flakesMaxActive=64;this.animationInterval=50;this.useGPU=true;this.className=null;this.excludeMobile=true;this.flakeBottom=null;this.followMouse=false;this.snowColor='#fff';this.snowCharacter='&bull;';this.snowStick=true;this.targetElement=null;this.useMeltEffect=true;this.useTwinkleEffect=false;this.usePositionFixed=false;this.usePixelPosition=false;this.freezeOnBlur=true;this.flakeLeftOffset=0;this.flakeRightOffset=0;this.flakeWidth=8;this.flakeHeight=8;this.vMaxX=5;this.vMaxY=4;this.zIndex=0;var storm=this,features,isIE=navigator.userAgent.match(/msie/i),isIE6=navigator.userAgent.match(/msie 6/i),isMobile=navigator.userAgent.match(/mobile|opera m(ob|in)/i),isBackCompatIE=(isIE&&document.compatMode==='BackCompat'),noFixed=(isBackCompatIE||isIE6),screenX=null,screenX2=null,screenY=null,scrollY=null,docHeight=null,vRndX=null,vRndY=null,windOffset=1,windMultiplier=2,flakeTypes=6,fixedForEverything=false,targetElementIsRelative=false,opacitySupported=(function(){try{document.createElement('div').style.opacity='0.5'}catch(e){return false}return true}()),didInit=false,docFrag=document.createDocumentFragment();features=(function(){var getAnimationFrame;function timeoutShim(callback){window.setTimeout(callback,1000/(storm.animationInterval||20))}var _animationFrame=(window.requestAnimationFrame||window.webkitRequestAnimationFrame||window.mozRequestAnimationFrame||window.oRequestAnimationFrame||window.msRequestAnimationFrame||timeoutShim);getAnimationFrame=_animationFrame?function(){return _animationFrame.apply(window,arguments)}:null;var testDiv;testDiv=document.createElement('div');function has(prop){var result=testDiv.style[prop];return(result!==undefined?prop:null)}var localFeatures={transform:{ie:has('-ms-transform'),moz:has('MozTransform'),opera:has('OTransform'),webkit:has('webkitTransform'),w3:has('transform'),prop:null },getAnimationFrame:getAnimationFrame};localFeatures.transform.prop=(localFeatures.transform.w3||localFeatures.transform.moz||localFeatures.transform.webkit||localFeatures.transform.ie||localFeatures.transform.opera);testDiv=null;return localFeatures}());this.timer=null;this.flakes=[];this.disabled=false;this.active=false;this.meltFrameCount=20;this.meltFrames=[];this.setXY=function(o,x,y){if(!o){return false}if(storm.usePixelPosition||targetElementIsRelative){o.style.left=(x-storm.flakeWidth)+'px';o.style.top=(y-storm.flakeHeight)+'px'}else if(noFixed){o.style.right=(100-(x/screenX*100))+'%';o.style.top=(Math.min(y,docHeight-storm.flakeHeight))+'px'}else{if(!storm.flakeBottom){o.style.right=(100-(x/screenX*100))+'%';o.style.bottom=(100-(y/screenY*100))+'%'}else{o.style.right=(100-(x/screenX*100))+'%';o.style.top=(Math.min(y,docHeight-storm.flakeHeight))+'px'}}};this.events=(function(){var old=(!window.addEventListener&&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];if(len>3){args.pop();}}else if(len===3){args.push(false)}return args}function apply(args,sType){var element=args.shift(),method=[evt[sType]];if(old){element[method](args[0],args[1])}else{element[method].apply(element,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(){var i;vRndX=plusMinus(rnd(storm.vMaxX,0.2));vRndY=rnd(storm.vMaxY,0.2);if(this.flakes){for(i=0;i<this.flakes.length;i+=1){if(this.flakes[i].active){this.flakes[i].setVelocities()}}}};this.scrollHandler=function(){var i;scrollY=(storm.flakeBottom?0:parseInt(window.scrollY||document.documentElement.scrollTop||(noFixed?document.body.scrollTop:0),10));if(isNaN(scrollY)){scrollY=0;}if(!fixedForEverything&&!storm.flakeBottom&&storm.flakes){for(i=0;i<storm.flakes.length;i+=1){if(storm.flakes[i].active===0){storm.flakes[i].stick()}}}};this.resizeHandler=function(){if(window.innerWidth||window.innerHeight){screenX=window.innerWidth-16-storm.flakeRightOffset;screenY=(storm.flakeBottom||window.innerHeight)}else{screenX=(document.documentElement.clientWidth||document.body.clientWidth||document.body.scrollWidth)-(!isIE?8:0)-storm.flakeRightOffset;screenY=storm.flakeBottom||document.documentElement.clientHeight||document.body.clientHeight||document.body.scrollHeight}docHeight=document.body.offsetHeight;screenX2=parseInt(screenX/2,10)};this.resizeHandlerAlt=function(){screenX=storm.targetElement.offsetWidth-storm.flakeRightOffset;screenY=storm.flakeBottom||storm.targetElement.offsetHeight;screenX2=parseInt(screenX/2,10);docHeight=document.body.offsetHeight};this.freeze=function(){if(!storm.disabled){storm.disabled=1}else{return false}storm.timer=null};this.resume=function(){if(storm.disabled){storm.disabled=0}else{return false}storm.timerInit()};this.toggleSnow=function(){if(!storm.flakes.length){storm.start()}else{storm.active=!storm.active;if(storm.active){storm.show();storm.resume()}else{storm.stop();storm.freeze()}}};this.stop=function(){var i;this.freeze();for(i=0;i<this.flakes.length;i+=1){this.flakes[i].o.style.display='none'}storm.events.remove(window,'scroll',storm.scrollHandler);storm.events.remove(window,'resize',storm.resizeHandler);if(storm.freezeOnBlur){if(isIE){storm.events.remove(document,'focusout',storm.freeze);storm.events.remove(document,'focusin',storm.resume)}else{storm.events.remove(window,'blur',storm.freeze);storm.events.remove(window,'focus',storm.resume)}}};this.show=function(){var i;for(i=0;i<this.flakes.length;i+=1){this.flakes[i].o.style.display='block'}};this.SnowFlake=function(type,x,y){var s=this;this.type=type;this.x=x||parseInt(rnd(screenX-20),10);this.y=(!isNaN(y)?y: -rnd(screenY)-12);this.vX=null;this.vY=null;this.vAmpTypes=[1,1.2,1.4,1.6,1.8];this.vAmp=this.vAmpTypes[this.type]||1;this.melting=false;this.meltFrameCount=storm.meltFrameCount;this.meltFrames=storm.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=storm.snowCharacter;if(storm.className){this.o.setAttribute('class',storm.className)}this.o.style.color=storm.snowColor;this.o.style.position=(fixedForEverything?'fixed':'absolute');if(storm.useGPU&&features.transform.prop){this.o.style[features.transform.prop]='translate3d(0px, 0px, 0px)'}this.o.style.width=storm.flakeWidth+'px';this.o.style.height=storm.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=storm.zIndex;docFrag.appendChild(this.o);this.refresh=function(){if(isNaN(s.x)||isNaN(s.y)){return false}storm.setXY(s.o,s.x,s.y)};this.stick=function(){if(noFixed||(storm.targetElement!==document.documentElement&&storm.targetElement!==document.body)){s.o.style.top=(screenY+scrollY-storm.flakeHeight)+'px'}else if(storm.flakeBottom){s.o.style.top=storm.flakeBottom+'px'}else{s.o.style.display='none';s.o.style.bottom='0%';s.o.style.position='fixed';s.o.style.display='block'}};this.vCheck=function(){if(s.vX>=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){s.x=0}else if(vX<0&&s.x-storm.flakeLeftOffset< -storm.flakeWidth){s.x=screenX-storm.flakeWidth-1;}s.refresh();yDiff=screenY+scrollY-s.y+storm.flakeHeight;if(yDiff<storm.flakeHeight){s.active=0;if(storm.snowStick){s.stick()}else{s.recycle()}}else{if(storm.useMeltEffect&&s.active&&s.type<3&&!s.melting&&Math.random()>0.998){s.melting=true;s.melt();}if(storm.useTwinkleEffect){if(s.twinkleFrame<0){if(Math.random()>0.97){s.twinkleFrame=parseInt(Math.random()*8,10)}}else{s.twinkleFrame-=1;if(!opacitySupported){s.o.style.visibility=(s.twinkleFrame&&s.twinkleFrame%2===0?'hidden':'visible')}else{s.o.style.opacity=(s.twinkleFrame&&s.twinkleFrame%2===0?0:1)}}}}};this.animate=function(){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.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';s.meltFrame+=1}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();this.refresh()};this.snow=function(){var active=0,flake=null,i,j;for(i=0,j=storm.flakes.length;i<j;i+=1){if(storm.flakes[i].active===1){storm.flakes[i].move();active+=1}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+=1){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+=1){storm.meltFrames.push(1-(i/storm.meltFrameCount))}storm.randomizeWind();storm.createSnow(storm.flakesMax);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){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){storm.resizeHandler=storm.resizeHandlerAlt;storm.usePixelPosition=true}storm.resizeHandler();storm.usePositionFixed=(storm.usePositionFixed&&!noFixed&&!storm.flakeBottom);if(window.getComputedStyle){try{targetElementIsRelative=(window.getComputedStyle(storm.targetElement,null).getPropertyValue('position')==='relative')}catch(e){targetElementIsRelative=false}}fixedForEverything=storm.usePositionFixed;if(screenX&&screenY&&!storm.disabled){storm.init();storm.active=true}};function doDelayedStart(){window.setTimeout(function(){storm.start(true)},20);storm.events.remove(isIE?document:window,'mousemove',doDelayedStart)}function doStart(){if(!storm.excludeMobile||!isMobile){doDelayedStart()}storm.events.remove(window,'load',doStart)}if(storm.autoStart){storm.events.add(window,'load',doStart,false)}return this}(window,document));