Winter.js

var snowStorm=null;function SnowStorm(){this.flakesMax=128,this.flakesMaxActive=64,this.animationInterval=33,this.flakeBottom=null,this.targetElement=null,this.followMouse=true,this.snowColor="#fff",this.snowCharacter="&bull;",this.snowStick=!0,this.useMeltEffect=!0,this.useTwinkleEffect=!1,this.usePositionFixed=!1,this.flakeLeftOffset=0,this.flakeRightOffset=0,this.flakeWidth=8,this.flakeHeight=8,this.vMaxX=5,this.vMaxY=4,this.zIndex=0;var e=void 0===window.attachEvent?function(e,t,i){return e.addEventListener(t,i,!1)}:function(e,t,i){return e.attachEvent("on"+t,i)},t=void 0===window.attachEvent?function(e,t,i){return e.removeEventListener(t,i,!1)}:function(e,t,i){return e.detachEvent("on"+t,i)};function i(e,t){return isNaN(t)&&(t=0),Math.random()*e+t}var n=this,o=this;this.timers=[],this.flakes=[],this.disabled=!1,this.active=!1;var s=navigator.userAgent.match(/msie/i),l=navigator.userAgent.match(/msie 6/i),a=s&&(l||navigator.userAgent.match(/msie 5/i)),r=navigator.appVersion.match(/windows 98/i),f=navigator.userAgent.match(/iphone/i),m=!!(s&&"BackCompat"==document.compatMode||l||f),h=null,c=null,d=null,u=null,v=null,k=null,g=1,w=!1,y=function(){try{document.createElement("div").style.opacity="0.5"}catch(e){return!1}return!0}(),p=document.createDocumentFragment();null===n.flakeLeftOffset&&(n.flakeLeftOffset=0),null===n.flakeRightOffset&&(n.flakeRightOffset=0),this.meltFrameCount=20,this.meltFrames=[];for(var x=0;x<this.meltFrameCount;x++)this.meltFrames.push(1-x/this.meltFrameCount);this.randomizeWind=function(){var e;if(e=i(n.vMaxX,.2),v=1==parseInt(i(2),10)?-1*e:e,k=i(n.vMaxY,.2),this.flakes)for(var t=0;t<this.flakes.length;t++)this.flakes[t].active&&this.flakes[t].setVelocities()},this.scrollHandler=function(){if(u=n.flakeBottom?0:parseInt(window.scrollY||document.documentElement.scrollTop||document.body.scrollTop,10),isNaN(u)&&(u=0),!w&&!n.flakeBottom&&n.flakes)for(var e=n.flakes.length;e--;)0===n.flakes[e].active&&n.flakes[e].stick()},this.resizeHandler=function(){window.innerWidth||window.innerHeight?(h=window.innerWidth-(s?2:16)-n.flakeRightOffset,d=n.flakeBottom?n.flakeBottom:window.innerHeight):(h=(document.documentElement.clientWidth||document.body.clientWidth||document.body.scrollWidth)-(s?0:8)-n.flakeRightOffset,d=n.flakeBottom?n.flakeBottom:document.documentElement.clientHeight||document.body.clientHeight||document.body.scrollHeight),c=parseInt(h/2,10)},this.resizeHandlerAlt=function(){h=n.targetElement.offsetLeft+n.targetElement.offsetWidth-n.flakeRightOffset,d=n.flakeBottom?n.flakeBottom:n.targetElement.offsetTop+n.targetElement.offsetHeight,c=parseInt(h/2,10)},this.freeze=function(){if(n.disabled)return!1;n.disabled=1;for(var e=n.timers.length;e--;)clearInterval(n.timers[e])},this.resume=function(){if(!n.disabled)return!1;n.disabled=0,n.timerInit()},this.toggleSnow=function(){n.flakes.length?(n.active=!n.active,n.active?(n.show(),n.resume()):(n.stop(),n.freeze())):n.start()},this.stop=function(){this.freeze();for(var e=this.flakes.length;e--;)this.flakes[e].o.style.display="none";t(window,"scroll",n.scrollHandler),t(window,"resize",n.resizeHandler),a||(t(window,"blur",n.freeze),t(window,"focus",n.resume))},this.show=function(){for(var e=this.flakes.length;e--;)this.flakes[e].o.style.display="block"},this.SnowFlake=function(e,t,n,o){var s=this,l=e;this.type=t,this.x=n||parseInt(i(h-20),10),this.y=isNaN(o)?-i(d)-12:o,this.vX=null,this.vY=null,this.vAmpTypes=[1,1.2,1.4,1.6,1.8],this.vAmp=this.vAmpTypes[this.type],this.melting=!1,this.meltFrameCount=l.meltFrameCount,this.meltFrames=l.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=l.snowCharacter,this.o.style.color=l.snowColor,this.o.style.position=w?"fixed":"absolute",this.o.style.width=l.flakeWidth+"px",this.o.style.height=l.flakeHeight+"px",this.o.style.fontFamily="arial,verdana",this.o.style.overflow="hidden",this.o.style.fontWeight="normal",this.o.style.zIndex=l.zIndex,p.appendChild(this.o),this.refresh=function(){if(isNaN(s.x)||isNaN(s.y))return!1;s.o.style.left=s.x+"px",s.o.style.top=s.y+"px"},this.stick=function(){m||l.targetElement!=document.documentElement&&l.targetElement!=document.body?s.o.style.top=d+u-l.flakeHeight+"px":l.flakeBottom?s.o.style.top=l.flakeBottom+"px":(s.o.style.display="none",s.o.style.top="auto",s.o.style.bottom="0px",s.o.style.position="fixed",s.o.style.display="block")},this.vCheck=function(){s.vX>=0&&s.vX<.2?s.vX=.2:s.vX<0&&s.vX>-.2&&(s.vX=-.2),s.vY>=0&&s.vY<.2&&(s.vY=.2)},this.move=function(){var e=s.vX*g;s.x+=e,s.y+=s.vY*s.vAmp,s.x>=h||h-s.x<l.flakeWidth?s.x=0:e<0&&s.x-l.flakeLeftOffset<0-l.flakeWidth&&(s.x=h-l.flakeWidth-1),s.refresh(),d+u-s.y<l.flakeHeight?(s.active=0,l.snowStick?s.stick():s.recycle()):(l.useMeltEffect&&s.active&&s.type<3&&!s.melting&&Math.random()>.998&&(s.melting=!0,s.melt()),l.useTwinkleEffect&&(s.twinkleFrame?(s.twinkleFrame--,s.o.style.visibility=s.twinkleFrame&&s.twinkleFrame%2==0?"hidden":"visible"):Math.random()>.9&&(s.twinkleFrame=parseInt(20*Math.random(),10))))},this.animate=function(){s.move()},this.setVelocities=function(){s.vX=v+i(.12*l.vMaxX,.1),s.vY=k+i(.12*l.vMaxY,.1)},this.setOpacity=function(e,t){if(!y)return!1;e.style.opacity=t},this.melt=function(){l.useMeltEffect&&s.melting&&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=l.flakeHeight+2+.75*l.flakeHeight*(s.meltFrame/s.meltFrameCount)+"px"):s.recycle()},this.recycle=function(){s.o.style.display="none",s.o.style.position=w?"fixed":"absolute",s.o.style.bottom="auto",s.setVelocities(),s.vCheck(),s.meltFrame=0,s.melting=!1,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=l.flakeHeight+2+"px",s.o.style.textAlign="center",s.o.style.verticalAlign="baseline",s.x=parseInt(i(h-l.flakeWidth-20),10),s.y=parseInt(-1*i(d),10)-l.flakeHeight,s.refresh(),s.o.style.display="block",s.active=1},this.recycle(),this.refresh()},this.snow=function(){for(var e=0,t=null,o=n.flakes.length;o--;)1==n.flakes[o].active?(n.flakes[o].move(),e++):0===n.flakes[o].active?0:0,n.flakes[o].melting&&n.flakes[o].melt();e<n.flakesMaxActive&&0===(t=n.flakes[parseInt(i(n.flakes.length),10)]).active&&(t.melting=!0)},this.mouseMove=function(e){if(!n.followMouse)return!0;var t=parseInt(e.clientX,10);g=t<c?t/c*2-2:(t-=c)/c*2},this.createSnow=function(e,t){for(var s=0;s<e;s++)n.flakes[n.flakes.length]=new n.SnowFlake(n,parseInt(i(6),10)),(t||s>n.flakesMaxActive)&&(n.flakes[n.flakes.length-1].active=-1);o.targetElement.appendChild(p)},this.timerInit=function(){n.timers=r?[setInterval(n.snow,3*n.animationInterval),setInterval(n.snow,n.animationInterval)]:[setInterval(n.snow,n.animationInterval)]},this.init=function(){n.randomizeWind(),n.createSnow(n.flakesMax),e(window,"resize",n.resizeHandler),e(window,"scroll",n.scrollHandler),a||(e(window,"blur",n.freeze),e(window,"focus",n.resume)),n.resizeHandler(),n.scrollHandler(),n.followMouse&&e(document,"mousemove",n.mouseMove),n.animationInterval=Math.max(20,n.animationInterval),n.timerInit()};var E=!1;function F(){n.start(!0)}this.start=function(e){if(E){if(e)return!0}else E=!0;if("string"==typeof n.targetElement){var t=n.targetElement;if(n.targetElement=document.getElementById(t),!n.targetElement)throw new Error('Snowstorm: Unable to get targetElement "'+t+'"')}n.targetElement||(n.targetElement=s?document.body:document.documentElement?document.documentElement:document.body),n.targetElement!=document.documentElement&&n.targetElement!=document.body&&(n.resizeHandler=n.resizeHandlerAlt),n.resizeHandler(),n.usePositionFixed=n.usePositionFixed&&!m,w=n.usePositionFixed,h&&d&&!n.disabled&&(n.init(),n.active=!0)},document.addEventListener?(document.addEventListener("DOMContentLoaded",F,!1),window.addEventListener("load",F,!1)):e(window,"load",F)}snowStorm=new SnowStorm;