MediaWiki:Snowstorm.js

var snowStorm = null;

function SnowStorm { this.flakesMax = 60; this.flakesMaxActive = 60; this.animationInterval = 40; this.flakeBottom = null; this.targetElement = null; this.followMouse = true; this.snowColor = '#fff'; this.snowCharacter = '&bull;'; this.snowStick = false; this.useMeltEffect = true; this.useTwinkleEffect = false; this.usePositionFixed = false; this.flakeLeftOffset = 0; this.flakeRightOffset = 0; this.flakeWidth = 5; this.flakeHeight = 5; this.vMaxX = 2.5; this.vMaxY = 2.5; this.zIndex = 10000; 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 { scrollY = (s.flakeBottom ? 0 : parseInt(window.scrollY || document.documentElement.scrollTop || document.body.scrollTop, 10)); if (isNaN(scrollY)) { scrollY = 0; }       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 { 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) { 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]; 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)) { 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) { s.x = 0; } else if (vX < 0 && s.x - storm.flakeLeftOffset < 0 - storm.flakeWidth) { s.x = screenX - storm.flakeWidth - 1; }           s.refresh; var yDiff = screenY + scrollY - s.y;           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) { s.melting = true; s.melt; }               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 { 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; 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 (x < screenX2) { windOffset = -windMultiplier + (x / screenX2 * windMultiplier); } else { x -= screenX2; windOffset = (x / screenX2) * windMultiplier; }   };    this.createSnow = function(limit, allowInactive) { for (var i = 0; i < limit; i++) { s.flakes[s.flakes.length] = new s.SnowFlake(s, parseInt(rnd(flakeTypes), 10)); if (allowInactive || i > s.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); 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) { 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; }       s.resizeHandler; s.usePositionFixed = (s.usePositionFixed && !noFixed); fixedForEverything = s.usePositionFixed; if (screenX && screenY && !s.disabled) { s.init; s.active = true; }   };

function doStart { s.start(true); }   if (document.addEventListener) { document.addEventListener('DOMContentLoaded', doStart, false); window.addEventListener('load', doStart, false); } else { addEvent(window, 'load', doStart); } } snowStorm = new SnowStorm;