/* Smooth scrolling
   Changes links that link to other parts of this page to scroll
   smoothly to those links rather than jump to them directly, which
   can be a little disorienting.
   sil, http://www.kryogenix.org/

   v1.0 2003-11-11
   v1.1 2005-06-16 wrap it up in an object
*/

var ss = {
  fixAllLinks: function() {
    // Get a list of all links in the page
    var allLinks = document.getElementsByTagName('a');
    // Walk through the list
    for (var i=0;i<allLinks.length;i++) {
      var lnk = allLinks[i];
      if ((lnk.href && lnk.href.indexOf('#t') != -1) && 
          ( (lnk.pathname == location.pathname) ||
	    ('/'+lnk.pathname == location.pathname) ) && 
          (lnk.search == location.search)) {
        // If the link is internal to the page (begins in #)
        // then attach the smoothScroll function as an onclick
        // event handler
        ss.addEvent(lnk,'click',ss.smoothScroll);
      }
    }
  },

  smoothScroll: function(e) {
    // This is an event handler; get the clicked on element,
    // in a cross-browser fashion
    if (window.event) {
      target = window.event.srcElement;
    } else if (e) {
      target = e.target;
    } else return;

    // Make sure that the target is an element, not a text node
    // within an element
    if (target.nodeName.toLowerCase() != 'a') {
      target = target.parentNode;
    }

    // Paranoia; check this is an A tag
    if (target.nodeName.toLowerCase() != 'a') return;

    // Find the <a name> tag corresponding to this href
    // First strip off the hash (first character)
    anchor = target.hash.substr(1);
    // Now loop all A tags until we find one with that name
    var allLinks = document.getElementsByTagName('a');
    var destinationLink = null;

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

      var lnk = allLinks[i];

      if (lnk.name && (lnk.name == anchor)) {

        destinationLink = lnk;

        break;

      }

    }

    if (!destinationLink) destinationLink = document.getElementById(anchor);



    // If we didn't find a destination, give up and let the browser do

    // its thing

    if (!destinationLink) return true;

  

    // Find the destination's position

    var destx = destinationLink.offsetLeft; 

    var desty = destinationLink.offsetTop;

    var thisNode = destinationLink;

    while (thisNode.offsetParent && 

          (thisNode.offsetParent != document.body)) {

      thisNode = thisNode.offsetParent;

      destx += thisNode.offsetLeft;

      desty += thisNode.offsetTop;

    }

  

    // Stop any current scrolling

    clearInterval(ss.INTERVAL);

  

    cypos = ss.getCurrentYPos();

  

    ss_stepsize = parseInt((desty-cypos)/ss.STEPS);

    ss.INTERVAL =

setInterval('ss.scrollWindow('+ss_stepsize+','+desty+',"'+anchor+'")',10);

  

    // And stop the actual click happening

    if (window.event) {

      window.event.cancelBubble = true;

      window.event.returnValue = false;

    }

    if (e && e.preventDefault && e.stopPropagation) {

      e.preventDefault();

      e.stopPropagation();

    }

  },



  scrollWindow: function(scramount,dest,anchor) {

    wascypos = ss.getCurrentYPos();

    isAbove = (wascypos < dest);

    window.scrollTo(0,wascypos + scramount);

    iscypos = ss.getCurrentYPos();

    isAboveNow = (iscypos < dest);

    if ((isAbove != isAboveNow) || (wascypos == iscypos)) {

      // if we've just scrolled past the destination, or

      // we haven't moved from the last scroll (i.e., we're at the

      // bottom of the page) then scroll exactly to the link

      window.scrollTo(0,dest);

      // cancel the repeating timer

      clearInterval(ss.INTERVAL);

      // and jump to the link directly so the URL's right

      location.hash = anchor;

    }

  },



  getCurrentYPos: function() {

    if (document.body && document.body.scrollTop)

      return document.body.scrollTop;

    if (document.documentElement && document.documentElement.scrollTop)

      return document.documentElement.scrollTop;

    if (window.pageYOffset)
      return window.pageYOffset;
    return 0;
  },



  addEvent: function(elm, evType, fn, useCapture) {

    // addEvent and removeEvent

    // cross-browser event handling for IE5+,  NS6 and Mozilla

    // By Scott Andrew

    if (elm.addEventListener){

      elm.addEventListener(evType, fn, useCapture);

      return true;

    } else if (elm.attachEvent){

      var r = elm.attachEvent("on"+evType, fn);

      return r;

    } else {

      alert("Handler could not be removed");

    }

  } 

}



ss.STEPS = 15;



ss.addEvent(window,"load",ss.fixAllLinks);