MediaWiki:Snow.js

/*  DHTML Snowstorm! OO-style Jascript-based Snow effect Version 1.4.20091115 (Previous rev: v1.3.20081215) Code by Scott Schiller - http://schillmania.com Initializes after body onload by default (via addEventHandler call at bottom.) To customize properties, edit below or override configuration after this script has run (but before body.onload), eg. snowStorm.snowStick = false;



var snowStorm = null;

function SnowStorm {

// --- PROPERTIES ---

this.flakesMax = 96;          // Limit total amount of snow made (falling + sticking) this.flakesMaxActive = 96;     // 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.flakeBottom = null;       // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect this.targetElement = null;     // element which snow will be appended to (document body if null/undefined) - can be an element ID string, or a DOM node reference this.followMouse = true;       // Snow will change movement with the user's mouse this.snowColor = '#fff';       // Don't eat (or use?) yellow snow. this.snowCharacter = '&bull;'; // &bull; = bullet, &middot; is square on some systems etc. this.snowStick = false;         // Whether or not snow should "stick" at the bottom. When off, will never collect. 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 = true; // true = snow not affected by window scroll. may increase CPU load, disabled by default - if enabled, used only where supported

// --- less-used bits ---

this.flakeLeftOffset = 0;      // amount to subtract from edges of container this.flakeRightOffset = 0;     // amount to subtract from edges of container this.flakeWidth = 8;           // max pixel width for snow element this.flakeHeight = 8;          // max pixel height for snow element this.vMaxX = 5;                // Maximum X velocity range for snow this.vMaxY = 10;                // Maximum Y velocity range this.zIndex = 0;               // CSS stacking order applied to each snowflake

// --- End of user section ---

// jslint global declarations /*global window, document, navigator, clearInterval, setInterval */

var addEvent = (typeof(window.attachEvent)=='undefined'?function(o,evtName,evtHandler) {	return o.addEventListener(evtName,evtHandler,false); }:function(o,evtName,evtHandler) {	return o.attachEvent('on'+evtName,evtHandler);  });

var removeEvent = (typeof(window.attachEvent)=='undefined'?function(o,evtName,evtHandler) {   return o.removeEventListener(evtName,evtHandler,false);  }:function(o,evtName,evtHandler) {	return o.detachEvent('on'+evtName,evtHandler);  });

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); }

var s = this; var storm = this; this.timers = []; this.flakes = []; this.disabled = false; this.active = false;

var isIE = navigator.userAgent.match(/msie/i); var isIE6 = navigator.userAgent.match(/msie 6/i); var isOldIE = (isIE && (isIE6 || navigator.userAgent.match(/msie 5/i))); var isWin9X = navigator.appVersion.match(/windows 98/i); var isiPhone = navigator.userAgent.match(/iphone/i); var isBackCompatIE = (isIE && document.compatMode == 'BackCompat'); var noFixed = ((isBackCompatIE || isIE6 || isiPhone)?true:false); var screenX = null; var screenX2 = null; var screenY = null; var scrollY = null; var vRndX = null; var vRndY = null; var windOffset = 1; var windMultiplier = 2; var flakeTypes = 6; var fixedForEverything = false; var opacitySupported = (function{   try {	  document.createElement('div').style.opacity = '0.5';    } catch (e) {	  return false;    }    return true;  }); var docFrag = document.createDocumentFragment; if (s.flakeLeftOffset === null) { s.flakeLeftOffset = 0; } if (s.flakeRightOffset === null) { s.flakeRightOffset = 0; }

this.meltFrameCount = 20; this.meltFrames = []; for (var i=0; i<this.meltFrameCount; i++) { this.meltFrames.push(1-(i/this.meltFrameCount)); }

this.randomizeWind = function { vRndX = plusMinus(rnd(s.vMaxX,0.2)); vRndY = rnd(s.vMaxY,0.2); if (this.flakes) { for (var i=0; i<this.flakes.length; i++) { if (this.flakes[i].active) { this.flakes[i].setVelocities; }     }    }  };

this.scrollHandler = function { // "attach" snowflakes to bottom of window if no absolute bottom value was given scrollY = (s.flakeBottom?0:parseInt(window.scrollY||document.documentElement.scrollTop||document.body.scrollTop,10)); if (isNaN(scrollY)) { scrollY = 0; // Netscape 6 scroll fix }   if (!fixedForEverything && !s.flakeBottom && s.flakes) { for (var i=s.flakes.length; i--;) { if (s.flakes[i].active === 0) { s.flakes[i].stick; }     }    }  };

this.resizeHandler = function { if (window.innerWidth || window.innerHeight) { screenX = window.innerWidth-(!isIE?16:2)-s.flakeRightOffset; screenY = (s.flakeBottom?s.flakeBottom:window.innerHeight); } else { screenX = (document.documentElement.clientWidth||document.body.clientWidth||document.body.scrollWidth)-(!isIE?8:0)-s.flakeRightOffset; screenY = s.flakeBottom?s.flakeBottom:(document.documentElement.clientHeight||document.body.clientHeight||document.body.scrollHeight); }   screenX2 = parseInt(screenX/2,10); };

this.resizeHandlerAlt = function { screenX = s.targetElement.offsetLeft+s.targetElement.offsetWidth-s.flakeRightOffset; screenY = s.flakeBottom?s.flakeBottom:s.targetElement.offsetTop+s.targetElement.offsetHeight; screenX2 = parseInt(screenX/2,10); };

this.freeze = function { // pause animation if (!s.disabled) { s.disabled = 1; } else { return false; }   for (var i=s.timers.length; i--;) { clearInterval(s.timers[i]); } };

this.resume = function { if (s.disabled) { s.disabled = 0; } else { return false; }   s.timerInit; };

this.toggleSnow = function { if (!s.flakes.length) { // first run s.start; } else { s.active = !s.active; if (s.active) { s.show; s.resume; } else { s.stop; s.freeze; }   }  };

this.stop = function { this.freeze; for (var i=this.flakes.length; i--;) { this.flakes[i].o.style.display = 'none'; }   removeEvent(window,'scroll',s.scrollHandler); removeEvent(window,'resize',s.resizeHandler); if (!isOldIE) { removeEvent(window,'blur',s.freeze); removeEvent(window,'focus',s.resume); } };

this.show = function { for (var i=this.flakes.length; i--;) { this.flakes[i].o.style.display = 'block'; } };

this.SnowFlake = function(parent,type,x,y) { var s = this; var storm = parent; 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]; // "amplification" for vX/vY (based on flake size/type) this.vAmp = this.vAmpTypes[this.type]; 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; this.o.style.color = storm.snowColor; this.o.style.position = (fixedForEverything?'fixed':'absolute'); this.o.style.width = storm.flakeWidth+'px'; this.o.style.height = storm.flakeHeight+'px'; this.o.style.fontFamily = 'arial,verdana'; 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)) { // safety check return false; }     s.o.style.left = s.x+'px'; s.o.style.top = s.y+'px'; };

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.top = 'auto'; s.o.style.bottom = '0px'; 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; 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; var 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; var used = 0; var waiting = 0; var flake = null; for (var 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 (active<s.flakesMaxActive) { flake = s.flakes[parseInt(rnd(s.flakes.length),10)]; if (flake.active === 0) { flake.melting = true; }   }  };

this.mouseMove = function(e) { if (!s.followMouse) { return true; }   var x = parseInt(e.clientX,10); if (xs.flakesMaxActive) { s.flakes[s.flakes.length-1].active = -1; }   }    storm.targetElement.appendChild(docFrag); };

this.timerInit = function { s.timers = (!isWin9X?[setInterval(s.snow,s.animationInterval)]:[setInterval(s.snow,s.animationInterval*3),setInterval(s.snow,s.animationInterval)]); };

this.init = function { s.randomizeWind; s.createSnow(s.flakesMax); // create initial batch addEvent(window,'resize',s.resizeHandler); addEvent(window,'scroll',s.scrollHandler); if (!isOldIE) { addEvent(window,'blur',s.freeze); addEvent(window,'focus',s.resume); }   s.resizeHandler; s.scrollHandler; if (s.followMouse) { addEvent(document,'mousemove',s.mouseMove); }   s.animationInterval = Math.max(20,s.animationInterval); s.timerInit; };

var didInit = false;

this.start = function(bFromOnLoad) { if (!didInit) { didInit = true; } else if (bFromOnLoad) { // already loaded and running return true; }   if (typeof s.targetElement == 'string') { var targetID = s.targetElement; s.targetElement = document.getElementById(targetID); if (!s.targetElement) { throw new Error('Snowstorm: Unable to get targetElement "'+targetID+'"'); }   }	if (!s.targetElement) { s.targetElement = (!isIE?(document.documentElement?document.documentElement:document.body):document.body); }   if (s.targetElement != document.documentElement && s.targetElement != document.body) { s.resizeHandler = s.resizeHandlerAlt; // re-map handler to get element instead of screen dimensions }   s.resizeHandler; // get bounding box elements s.usePositionFixed = (s.usePositionFixed && !noFixed); // whether or not position:fixed is supported fixedForEverything = s.usePositionFixed; if (screenX && screenY && !s.disabled) { s.init; s.active = true; } };

function doStart { s.start(true); }

if (document.addEventListener) { // safari 3.0.4 doesn't do DOMContentLoaded, maybe others - use a fallback to be safe. document.addEventListener('DOMContentLoaded',doStart,false); window.addEventListener('load',doStart,false); } else { addEvent(window,'load',doStart); }

}

snowStorm = new SnowStorm;