snow

/** @license * DHTML Snowstorm! JavaScript-based snow for web pages * Making it snow on the internets since 2003. You're welcome. * ----------------------------------------------------------- * Version 1.44.20131125 (Previous rev: 1.44.20131111) * Copyright (c) 2007, Scott Schiller. All rights reserved. * Code provided under the BSD License * http://schillmania.com/projects/snowstorm/license.txt */ /*jslint nomen: true, plusplus: true, sloppy: true, vars: true, white: true */ /*global window, document, navigator, clearInterval, setInterval */ var snowStorm = (function(window, document) { // --- common properties --- this.autoStart = true; // Whether the snow should start automatically or not. this.excludeMobile = true; // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) Enable at your own risk. this.flakesMax = 356; // Limit total amount of snow made (falling + sticking) this.flakesMaxActive = 328; // Limit amount of snow falling at once (less = lower CPU use) this.animationInterval = 20; // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower this.useGPU = true; // Enable transform-based hardware acceleration, reduce CPU load. this.flakeBottom = null; // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect this.followMouse = false; // 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 = false; // 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 = 1; // Maimum X velocity range for snow this.vMaxY = 1; // Maximum Y velocity range for snow this.zIndex = 9999; // CSS stacking order applied to each snowflake // --- "No user-serviceable parts inside" past this point, yadda yadda --- var storm = this, features, // UA sniffing and backCompat rendering mode checks for fixed position, etc. 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, 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; /** * hat tip: paul irish * http://paulirish.com/2011/requestanimationframe-for-smart-animating/ * https://gist.github.com/838785 */ function timeoutShim(callback) { window.setTimeout(callback, 1000/(storm.animationInterval || 20)); } var _animationFrame = (window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || timeoutShim); // apply to window, avoid "illegal invocation" errors in Chrome getAnimationFrame = _animationFrame ? function() { return _animationFrame.apply(window, arguments); } : null; var testDiv; testDiv = document.createElement('div'); function has(prop) { // test for feature support var result = testDiv.style[prop]; return (result !== undefined ? prop : null); } // note local scope. var localFeatures = { transform: { ie: has('-ms-transform'), moz: has('MozTransform'), opera: has('OTransform'), webkit: has('webkitTransform'), w3: has('transform'), prop: null // the normalized property value }, 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 = (noFixed ? function(o, x, y) { // IE 6 and the like if (o) { o.style.right = (100-(x/screenX*100)) + '%'; // avoid creating vertical scrollbars o.style.top = (Math.min(y, docHeight-storm.flakeHeight)) + 'px'; } } : function(o, x, y) { if (o) { if (!storm.flakeBottom) { // if not using a fixed bottom coordinate... o.style.right = (100-(x/screenX*100)) + '%'; o.style.bottom = (100-(y/screenY*100)) + '%'; } else { // absolute top. 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]; // 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(storm.vMaxX,0.2)); vRndY = rnd(storm.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 = (storm.flakeBottom ? 0 : parseInt(window.scrollY || document.documentElement.scrollTop || (noFixed ? document.body.scrollTop : 0), 10)); if (isNaN(scrollY)) { scrollY = 0; // Netscape 6 scroll fix } if (!fixedForEverything && !storm.flakeBottom && storm.flakes) { for (i=0; i<storm.flakes.length; i++) { 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.offsetLeft + storm.targetElement.offsetWidth - storm.flakeRightOffset; screenY = storm.flakeBottom || (storm.targetElement.offsetTop + storm.targetElement.offsetHeight); screenX2 = parseInt(screenX/2,10); docHeight = document.body.offsetHeight; }; this.freeze = function() { // pause animation 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) { // first run 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++) { 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++) { 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]; // "amplification" for vX/vY (based on flake size/type) 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; this.o.style.color = storm.snowColor; this.o.style.position = (fixedForEverything?'fixed':'absolute'); if (storm.useGPU && features.transform.prop) { // GPU-accelerated snow. 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)) { // safety check 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) { // 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+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) { // ~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 < 0) { if (Math.random() > 0.97) { s.twinkleFrame = parseInt(Math.random() * 8, 10); } } else { s.twinkleFrame--; 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() { // 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, flake = null, i, j; for (i=0, j=storm.flakes.length; i<j; i++) { if (storm.flakes[i].active === 1) { storm.flakes[i].move(); active++; } 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++) { 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++) { storm.meltFrames.push(1-(i/storm.meltFrameCount)); } storm.randomizeWind(); storm.createSnow(storm.flakesMax); // create initial batch 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) { // already loaded and running 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.docuentElement || document.body); } if (storm.targetElement !== document.documentElement && storm.targetElement !== document.body) { storm.resizeHandler = storm.resizeHandlerAlt; // re-map handler to get element instead of screen dimensions } storm.resizeHandler(); // get bounding box elements storm.usePositionFixed = (storm.usePositionFixed && !noFixed && !storm.flakeBottom); // whether or not position:fixed is to be used fixedForEverything = storm.usePositionFixed; if (screenX && screenY && !storm.disabled) { storm.init(); storm.active = true; } }; function doDelayedStart() { window.setTimeout(function() { storm.start(true); }, 20); // event cleanup storm.events.remove(isIE?document:window,'mousemove',doDelayedStart); } function doStart() { if (!storm.excludeMobile || !isMobile) { doDelayedStart(); } // event cleanup storm.events.remove(window, 'load', doStart); } // hooks for starting the snow if (storm.autoStart) { storm.events.add(window, 'load', doStart, false); } return this; }(window, document));