MediaWiki:Snow.js

/** @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 */ var snowStorm = (function(window, document) { // --- common properties ---  this.autoStart = true;          // Whether the snow should start automatically or not.  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 = '&bull;';  // &bull; = bullet, &middot; 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|opera m(ob|in)/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.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]; // prefix        if (len > 3) {          args.pop; // no capture        }      } 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(s.vMaxX,0.2));    vRndY = rnd(s.vMaxY,0.2);    if (this.flakes) {      for (i=0; i<this.flakes.length; i++) {        if (this.flakes[i].active) {          this.flakes[i].setVelocities;        }      }    }  };  this.scrollHandler = function {    var i;    // "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 (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-16-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 var i;   if (!s.disabled) { s.disabled = 1; } else { return false; }   for (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 { var i;   this.freeze; for (i=this.flakes.length; i--;) { this.flakes[i].o.style.display = 'none'; }   s.events.remove(window,'scroll',s.scrollHandler); s.events.remove(window,'resize',s.resizeHandler); if (s.freezeOnBlur) { if (isIE) { s.events.remove(document,'focusout',s.freeze); s.events.remove(document,'focusin',s.resume); } else { s.events.remove(window,'blur',s.freeze); s.events.remove(window,'focus',s.resume); }   }  };  this.show = function { var i;   for (i=this.flakes.length; i--;) { this.flakes[i].o.style.display = 'block'; } };  this.SnowFlake = function(parent,type,x,y) { var s = this, 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.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)) { // 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, 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 < -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.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++; } 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 (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 = (!isWin98?[setInterval(s.snow,s.animationInterval)]:[setInterval(s.snow,s.animationInterval*3),setInterval(s.snow,s.animationInterval)]); }; this.init = function { var i;   for (i=0; i<s.meltFrameCount; i++) { s.meltFrames.push(1-(i/s.meltFrameCount)); }   s.randomizeWind; s.createSnow(s.flakesMax); // create initial batch s.events.add(window,'resize',s.resizeHandler); s.events.add(window,'scroll',s.scrollHandler); if (s.freezeOnBlur) { if (isIE) { s.events.add(document,'focusout',s.freeze); s.events.add(document,'focusin',s.resume); } else { s.events.add(window,'blur',s.freeze); s.events.add(window,'focus',s.resume); }   }    s.resizeHandler; s.scrollHandler; if (s.followMouse) { s.events.add(isIE?document:window,'mousemove',s.mouseMove); }   s.animationInterval = Math.max(20,s.animationInterval); s.timerInit; }; 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 doDelayedStart { window.setTimeout(function {     s.start(true);    }, 20); // event cleanup s.events.remove(isIE?document:window,'mousemove',doDelayedStart); } function doStart { if (!s.excludeMobile || !isMobile) { if (s.freezeOnBlur) { s.events.add(isIE?document:window,'mousemove',doDelayedStart); } else { doDelayedStart; }   }    // event cleanup s.events.remove(window, 'load', doStart); } // hooks for starting the snow if (s.autoStart) { s.events.add(window, 'load', doStart, false); } return this; }(window, document));