/*

   DHTML PNG Snowstorm! OO-style Jascript-based Snow effect

   --------------------------------------------------------

   Version 1.2.20041121a

   Dependencies: GIF/PNG images (0 through 4.gif/png)

   Code by Scott Schiller - www.schillmania.com

   --------------------------------------------------------

   Description:

  

   Initializes after body onload() by default (via addEventHandler() call at bottom.)

  

   Properties:

  

   usePNG

   ---------------

   Enables PNG images if supported ("false" disables all PNG usage)

  

   flakeTypes

   ---------------

   Sets the range of flake images to use (eg. a value of 5

   will use images ranging from 0.png to 4.png.)

  

   flakesMax

   ---------------

   Sets the maximum number of snowflakes that can exist on

   the screen at any given time.

   

   flakesMaxActive

   ---------------

   Sets the limit of "falling" snowflakes (ie. moving, thus

   considered to be "active".)

  

   vMax

   ---------------

   Defines the maximum X and Y velocities for the storm.

   A range up to this value is selected at random.

  

   flakeWidth

   ---------------

   The width (in pixels) of each snowflake image.

  

   flakeHeight

   ---------------

   Height (pixels) of each snowflake image.

   

   flakeBottom

   ---------------

   Limits the "bottom" coordinate of the snow.

  

   snowCollect

   ---------------

   Enables snow to pile up (slowly) at bottom of window.

   Can be very CPU/resource-intensive over time.



*/



var snowStorm = null;



function SnowStorm() {

  var s = this;

  var storm = this;

  this.timers = [];

  this.flakes = [];

  this.disabled = false;

  this.terrain = [];



  // User-configurable variables

  // ---------------------------



  var usePNG = false;

  var imagePath = 'image/snow/'; // relative path to snow images

  var flakeTypes = 5;

  var flakesMax = 0;

  var flakesMaxActive = 25;

  var vMax = 1;

  var flakeWidth = 5;

  var flakeHeight = 5;

  var flakeBottom = null; // Integer for fixed bottom, 0 or null for "full-screen" snow effect

  var snowCollect = false;

  var showStatus = false;



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



  var isIE = (navigator.appName.toLowerCase().indexOf('internet explorer')+1);

  var isWin9X = (navigator.appVersion.toLowerCase().indexOf('windows 98')+1);

  var isOpera = (navigator.userAgent.toLowerCase().indexOf('opera ')+1 || navigator.userAgent.toLowerCase().indexOf('opera/')+1);

  if (isOpera) isIE = false; // Opera (which is sneaky, pretending to be IE by default)

  var screenX = null;

  var screenY = null;

  var scrollY = null;

  var vRndX = null;

  var vRndY = null;



  function rnd(n,min) {

    if (isNaN(min)) min = 0;

    return (Math.random()*n)+min;

  }



  this.randomizeWind = function() { // Changes minimum speed of snowfall

    vRndX = plusMinus(rnd(vMax,4));

    vRndY = rnd(vMax,4);

    if (this.flakes) {

      for (var i=0; i<this.flakes.length; i++) {

        if (this.flakes[i].active) this.flakes[i].setVelocities();

      }

    }

  }



  function plusMinus(n) {

    return (parseInt(rnd(2))==1?n*-1:n);

  }



  this.resizeHandler = function() {

    if (window.innerWidth || window.innerHeight) {

      screenX = window.innerWidth-(!isIE?24:2);

      screenY = (flakeBottom?flakeBottom:window.innerHeight);

    } else {

      screenX = (document.documentElement.clientWidth||document.body.clientWidth||document.body.scrollWidth)-(!isIE?8:0);

      screenY = flakeBottom?flakeBottom:(document.documentElement.clientHeight||document.body.clientHeight||document.body.scrollHeight);

    }

    s.scrollHandler();

  }



  this.scrollHandler = function() {

    // "attach" snowflakes to bottom of window if no absolute bottom value was given

    scrollY = (flakeBottom?0:parseInt(window.scrollY||document.documentElement.scrollTop||document.body.scrollTop));

    if (isNaN(scrollY)) scrollY = 0; // Netscape 6 scroll fix

    if (!flakeBottom && s.flakes) {

      for (var i=0; i<s.flakes.length; i++) {

        if (s.flakes[i].active == 0) s.flakes[i].stick();

      }

    }

  }



  this.freeze = function() {

    // pause animation

    if (!s.disabled) {

      s.disabled = 1;

    } else {

      return false;

    }

    if (!isWin9X) {

      clearInterval(s.timers);

    } else {

      for (var i=0; i<s.timers.length; i++) {

        clearInterval(s.timers[i]);

      }

    }

  }



  this.resume = function() {

    if (s.disabled) {

       s.disabled = 0;

    } else {

      return false;

    }

    s.timerInit();

  }



  this.stop = function() {

    this.freeze();

    for (var i=0; i<this.flakes.length; i++) {

      this.flakes[i].o.style.display = 'none';

    }

    removeEventHandler(window,'scroll',this.scrollHandler,false);

    removeEventHandler(window,'resize',this.resizeHandler,false);

  }



  this.SnowFlake = function(parent,type,x,y) {

    var s = this;

    var storm = parent;

    this.type = type;

    this.x = x||parseInt(rnd(screenX-12));

    this.y = (!isNaN(y)?y:-12);

    this.vX = null;

    this.vY = null;

    this.vAmpTypes = [2.0,1.0,1.25,1.0,1.5,1.75]; // "amplification" for vX/vY (based on flake size/type)

    this.vAmp = this.vAmpTypes[this.type];



    this.active = 1;

    this.o = document.createElement('img');

    this.o.style.position = 'absolute';

    this.o.style.width = flakeWidth+'px';

    this.o.style.height = flakeHeight+'px';

    this.o.style.fontSize = '1px'; // so IE keeps proper size

    this.o.style.zIndex = 2;

    this.o.src = imagePath+this.type+(pngHandler.supported && usePNG?'.png':'.gif');

    document.body.appendChild(this.o);

    if (pngHandler.supported && usePNG) pngHandler.transform(this.o);



    this.refresh = function() {

      this.o.style.left = this.x+'px';

      this.o.style.top = this.y+'px';

    }



    this.stick = function() {

      s.o.style.top = (screenY+scrollY-flakeHeight-storm.terrain[Math.floor(this.x)])+'px';

      // called after relative left has been called

    }



    this.vCheck = function() {

      if (this.vX>=0 && this.vX<0.2) {

        this.vX = 0.2;

      } else if (this.vX<0 && this.vX>-0.2) {

        this.vX = -0.2;

      }

      if (this.vY>=0 && this.vY<0.2) {

        this.vY = 0.2;

      }

    }



    this.move = function() {

      this.x += this.vX;

      this.y += (this.vY*this.vAmp);

      this.refresh();



      if (this.vX && screenX-this.x<flakeWidth+this.vX) { // X-axis scroll check

        this.x = 0;

      } else if (this.vX<0 && this.x<0-flakeWidth) {

        this.x = screenX-flakeWidth; // flakeWidth;

      }

      var yDiff = screenY+scrollY-this.y-storm.terrain[Math.floor(this.x)];

      if (yDiff<flakeHeight) {

        this.active = 0;

        if (snowCollect) {

          var height = [0.75,1.5,0.75];

          for (var i=0; i<2; i++) {

            storm.terrain[Math.floor(this.x)+i+2] += height[i];

          }

        }

        this.o.style.left = ((this.x-(!isIE?flakeWidth:0))/screenX*100)+'%'; // set "relative" left (change with resize)

        if (!flakeBottom) {

          this.stick();

        }

      }

    }



    this.animate = function() {

      // main animation loop

      // move, check status, die etc.

      this.move();

    }



    this.setVelocities = function() {

      this.vX = vRndX+rnd(vMax*0.12,0.1);

      this.vY = vRndY+rnd(vMax*0.12,0.1);

    }



    this.recycle = function() {

      this.setVelocities();

      this.vCheck();

      this.x = parseInt(rnd(screenX-flakeWidth-1));

      this.y = parseInt(rnd(640)*-1)-flakeHeight;

      this.active = 1;

    }



    this.recycle(); // set up x/y coords etc.

    this.refresh();



  }



  this.snow = function() {

    var active = 0;

    var used = 0;

    var waiting = 0;

    for (var i=this.flakes.length-1; i>0; i--) {

      if (this.flakes[i].active == 1) {

        this.flakes[i].animate();

        active++;

      } else if (this.flakes[i].active == 0) {

        used++;

      } else {

        waiting++;

      }

    }

    if (snowCollect && !waiting) { // !active && !waiting

      // create another batch of snow

      this.createSnow(flakesMaxActive,true);

    }

    if (active<flakesMaxActive) {

      with (this.flakes[parseInt(rnd(this.flakes.length))]) {

        if (!snowCollect && active == 0) {

          recycle();

        } else if (active == -1) {

          active = 1;

        }

      }

    }

  }



  this.createSnow = function(limit,allowInactive) {

    if (showStatus) window.status = 'Creating snow...';

    for (var i=0; i<limit; i++) {

      this.flakes[this.flakes.length] = new this.SnowFlake(this,parseInt(rnd(flakeTypes)));

      if (allowInactive || i>flakesMaxActive) this.flakes[this.flakes.length-1].active = -1;

    }

    if (showStatus) window.status = '';

  }



  this.timerInit = function() {

    this.timers = (!isWin9X?setInterval("snowStorm.snow()",20):[setInterval("snowStorm.snow()",75),setInterval("snowStorm.snow()",25)]);

  }



  this.init = function() {

    for (var i=0; i<8192; i++) {

      this.terrain[i] = 0;

    }

    this.randomizeWind();

    this.createSnow(snowCollect?flakesMaxActive:flakesMaxActive*2); // create initial batch

    addEventHandler(window,'resize',this.resizeHandler,false);

    addEventHandler(window,'scroll',this.scrollHandler,false);

    // addEventHandler(window,'scroll',this.resume,false); // scroll does not cause window focus. (odd)

    // addEventHandler(window,'blur',this.freeze,false);

    // addEventHandler(window,'focus',this.resume,false);

    this.timerInit();

  }



  this.resizeHandler(); // get screen coordinates



  if (screenX && screenY && !this.disabled) {

    this.init();

  }



}



function snowStormInit() {

  setTimeout("snowStorm = new SnowStorm()",500);

}



// Generic addEventHandler() wrapper

// ---------------------------------

// A generic interface for adding DOM event handlers

// Version 1.2.20040404

//

// Code by Scott Schiller | schillmania.com

//

// Revision history:

// ---------------------------------

// v1.1.20031218: initial deploy

// v1.2.20040404: added post-load event check



var addEventHandler = null;

var removeEventHandler = null;



function postLoadEvent(eventType) {

  // test for adding an event to the body (which has already loaded) - if so, fire immediately

  return ((eventType.toLowerCase().indexOf('load')>=0) && document.body);

}



function addEventHandlerDOM(o,eventType,eventHandler,eventBubble) {

  if (!postLoadEvent(eventType)) {

    o.addEventListener(eventType,eventHandler,eventBubble);

  } else {

    eventHandler();

  }

}



function removeEventHandlerDOM(o,eventType,eventHandler,eventBubble) {

  o.removeEventListener(eventType,eventHandler,eventBubble);

}

  

function addEventHandlerIE(o,eventType,eventHandler) { // IE workaround

  if (!eventType.indexOf('on')+1) eventType = 'on'+eventType;

  if (!postLoadEvent(eventType)) {

    o.attachEvent(eventType,eventHandler); // Note addition of "on" to event type

  } else {

    eventHandler();

  }

}

  

function removeEventHandlerIE(o,eventType,eventHandler) {

  if (!eventType.indexOf('on')+1) eventType = 'on'+eventType;

  o.detachEvent(eventType,eventHandler);

}



function addEventHandlerOpera(o,eventType,eventHandler,eventBubble) {

  if (!postLoadEvent(eventType)) {

    (o==window?document:o).addEventListener(eventType,eventHandler,eventBubble);

  } else {

    eventHandler();

  }

}



function removeEventHandlerOpera(o,eventType,eventHandler,eventBubble) {

  (o==window?document:o).removeEventListener(eventType,eventHandler,eventBubble);

}



if (navigator.userAgent.toLowerCase().indexOf('opera ')+1 || navigator.userAgent.toLowerCase().indexOf('opera/')+1) {

  // opera is dumb at times.

  addEventHandler = addEventHandlerOpera;

  removeEventHandler = removeEventHandlerOpera;

} else if (document.addEventListener) { // DOM event handler method

  addEventHandler = addEventHandlerDOM;

  removeEventHandler = removeEventHandlerDOM;

} else if (document.attachEvent) { // IE event handler method

  addEventHandler = addEventHandlerIE;

  removeEventHandler = removeEventHandlerIE;

} else { // Neither "DOM level 2" (?) methods supported

  addEventHandler = function(o,eventType,eventHandler,eventBubble) {

    o['on'+eventType] = eventHandler;

    // Multiple events could be added here via array etc.

  }

  removeEventHandler = function(o,eventType,eventHandler,eventBubble) {}

}



// Safari 1.0 does not support window.scroll events - apparently netscape 6.0/6.2 and mozilla 1.4 also.

// Refer to events support table at http://www.quirksmode.org/js/events_compinfo.html



// -- end addEventHandler definition --



/*

   PNGHandler: Object-Oriented Javascript-based PNG wrapper

   --------------------------------------------------------

   Version 1.2.20040803

   Code by Scott Schiller - www.schillmania.com

   --------------------------------------------------------

   Description:

   Provides gracefully-degrading PNG functionality where

   PNG is supported natively or via filters (Damn you, IE!)

   Should work with PNGs as images and DIV background images.

   --------------------------------------------------------

   Revision history

   --------------------------------------------------------

   1.2

   - Added refresh() for changing PNG images under IE

   - Class extension: "scale" causes PNG to scale under IE

   --------------------------------------------------------

   Known bugs

   --------------------------------------------------------

   - ie:mac doesn't support PNG background images.

   - Safari doesn't support currentStyle() - can't parse BG

     via CSS (ie. for a DIV with a PNG background by class)



*/



function PNGHandler() {

  var self = this;



  this.na = navigator.appName.toLowerCase();

  this.nv = navigator.appVersion.toLowerCase();

  this.isIE = this.na.indexOf('internet explorer')+1?1:0;

  this.isWin = this.nv.indexOf('windows')+1?1:0;

  this.isIEMac = (this.isIE&&!this.isWin);

  this.isIEWin = (this.isIE&&this.isWin);

  this.ver = this.isIE?parseFloat(this.nv.split('msie ')[1]):parseFloat(this.nv);

  this.isMac = this.nv.indexOf('mac')+1?1:0;

  this.isOpera = (navigator.userAgent.toLowerCase().indexOf('opera ')+1 || navigator.userAgent.toLowerCase().indexOf('opera/')+1);

  if (this.isOpera) this.isIE = false; // Opera filter catch (which is sneaky, pretending to be IE by default)

  this.filterID = 'DXImageTransform.Microsoft.AlphaImageLoader';

  this.supported = false;

  this.transform = self.doNothing;



  this.filterMethod = function(o) {

    // IE 5.5+ proprietary filter garbage (boo!)

    // Create new element based on old one. Doesn't seem to render properly otherwise (due to filter?)

    // use DOM "currentStyle" method, so rules inherited via CSS are picked up.

    if (o.nodeName != 'IMG') {

      var b = o.currentStyle.backgroundImage.toString(); // parse out background image URL

      o.style.backgroundImage = 'none';

      // Parse out background image URL from currentStyle.

      var i1 = b.indexOf('url("')+5;

      var newSrc = b.substr(i1,b.length-i1-2).replace('.gif','.png'); // find first instance of ") after (", chop from string

      o.style.writingMode = 'lr-tb'; // Has to be applied so filter "has layout" and is displayed. Seriously. Refer to http://msdn.microsoft.com/workshop/author/filter/reference/filters/alphaimageloader.asp?frame=true

      o.style.filter = "progid:"+self.filterID+"(src='"+newSrc+"',sizingMethod='"+(o.className.indexOf('scale')+1?'scale':'crop')+"')";

    } else if (o.nodeName == 'IMG') {

      var newSrc = o.getAttribute('src').replace('.gif','.png');

      // apply filter

      o.src = 'image/none.gif'; // get rid of image

      o.style.filter = "progid:"+self.filterID+"(src='"+newSrc+"',sizingMethod="+(o.className.indexOf('scale')+1?'scale':'crop')+"')";

      o.style.writingMode = 'lr-tb'; // Has to be applied so filter "has layout" and is displayed. Seriously. Refer to http://msdn.microsoft.com/workshop/author/filter/reference/filters/alphaimageloader.asp?frame=true

    }

  }



  this.pngMethod = function(o) {

    // Native transparency support. Easy to implement. (woo!)

    bgImage = this.getBackgroundImage(o);

    if (bgImage) {

      // set background image, replacing .gif

      o.style.backgroundImage = 'url('+bgImage.replace('.gif','.png')+')';

    } else if (o.nodeName == 'IMG') {

      o.src = o.src.replace('.gif','.png');

    } else if (!bgImage) {

      // no background image

    }

  }



  this.getBackgroundImage = function(o) {

    var b, i1; // background-related variables

    var bgUrl = null;

    if (o.nodeName != 'IMG' && !(this.isIE && this.isMac)) { // ie:mac PNG support broken for DIVs with PNG backgrounds

      if (document.defaultView) {

        if (document.defaultView.getComputedStyle) {

          b = document.defaultView.getComputedStyle(o,'').getPropertyValue('background-image');

          i1 = b.indexOf('url(')+4;

          bgUrl = b.substr(i1,b.length-i1-1);

        } else {

          // no computed style

          return false;

        }

      } else {

        // no default view

        return false;

      }

    }

    return bgUrl;

  }



  this.doNothing = function() {}

  

  this.supportTest = function() {

    // Determine method to use.

    // IE 5.5+/win32: filter



    if (this.isIE && this.isWin && this.ver >= 5.5) {

      // IE proprietary filter method (via DXFilter)

      self.transform = self.filterMethod;

    } else if (!this.isIE && this.ver < 5) {

      // No PNG support or broken support

      // Leave existing content as-is

      self.transform = null;

      return false;

    } else if (!this.isIE && this.ver >= 5 || (this.isIE && this.isMac && this.ver >= 5)) { // version 5+ browser (not IE), or IE:mac 5+

      self.transform = self.pngMethod;

    } else {

      // Presumably no PNG support. GIF used instead.

      self.transform = null;

      return false;

    }

    return true;

  }



  this.init = function() {

    this.supported = this.supportTest();

  }



}



function getElementsByClassName(className,oParent) {

  var doc = (oParent||document);

  var matches = [];

  var nodes = doc.all||doc.getElementsByTagName('*');

  for (var i=0; i<nodes.length; i++) {

    if (nodes[i].className == className || nodes[i].className.indexOf(className)+1 || nodes[i].className.indexOf(className+' ')+1 || nodes[i].className.indexOf(' '+className)+1) {

      matches[matches.length] = nodes[i];

    }

  }

  return matches; // kids, don't play with fire. ;)

}



// Instantiate and initialize PNG Handler



var pngHandler = new PNGHandler();



pngHandler.init();





addEventHandler(window,'load',snowStormInit,false);