/* 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('#') != -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 = 25;

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