/** @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