/* Tiny Scrolling - a smooth navigation between internal links and their destinations
by Marco Rosella - http://www.centralscrutinizer.it/en/design/js-php/tiny-scrolling
based on the works by Travis Beckham and Brian McAllister.
                v0.3 - March 27, 2006
*/

var tinyScrolling = {
	
	speed : 20,		// scroll speed
	maxStep: 200,	// max speed
	brakeK: 3,		// slowdown timing
	
	hash:null,		
	currentBlock:null,
	requestedY:0,
	
	init: function() {
		var lnks = document.getElementsByTagName('a');
		for(var i = 0, lnk; lnk = lnks[i]; i++) {
			if ((lnk.href && lnk.href.indexOf('#') != -1 && lnk.href != "#") &&  ( (lnk.pathname == location.pathname) ||
			('/'+lnk.pathname == location.pathname) ) && (lnk.search == location.search)) {
			lnk.onclick = tinyScrolling.initScroll;
			}
		}
	},
	
	getElementYpos: function(el){
		var y = 0;
		while(el.offsetParent){
			y += el.offsetTop;
			el = el.offsetParent;
		}
		return y;
	},
	
	getScrollTop: function(){
		if(document.all) return (document.documentElement.scrollTop) ? document.documentElement.scrollTop : document.body.scrollTop;
		else return window.pageYOffset;   
	},
	
	getWindowHeight: function(){
		if (window.innerHeight)	return window.innerHeight;
		if(document.documentElement && document.documentElement.clientHeight) return document.documentElement.clientHeight;
	},
	
	getDocumentHeight: function(){
		if (document.height) return document.height;
		if(document.body.offsetHeight) return document.body.offsetHeight;
	},
	
	getFirstAncestorAnchor: function(el){
		var found = false;
		while(!found){
			el = el.parentNode;
			found = (el.href)? true : false;
		}
		return el;
	},
	
	initScroll: function(e){
		
		// get clicked element from event
		
			var targ;  
			if (!e) var e = window.event;
			if (e.target) targ = e.target;
			else if (e.srcElement) targ = e.srcElement;
			if(!targ.href || (targ.src == targ.href)){ // ie handle img element's src as href...
				targ = tinyScrolling.getFirstAncestorAnchor(targ);
			 }
			
		// prepare for scroll
			
			tinyScrolling.hash = targ.href.substr(targ.href.indexOf('#')+1,targ.href.length); 
			tinyScrolling.currentBlock = document.getElementById(tinyScrolling.hash);   
			if(!tinyScrolling.currentBlock) return;
			tinyScrolling.requestedY = tinyScrolling.getElementYpos(tinyScrolling.currentBlock); 
			
		// start scroll
			
			tinyScrolling.scroll();  
			return false;
	},
	
	scroll: function(){
		var top  = tinyScrolling.getScrollTop();
		if(tinyScrolling.requestedY > top) {  
			var endDistance = Math.round((tinyScrolling.getDocumentHeight() - (top + tinyScrolling.getWindowHeight())) / tinyScrolling.brakeK);
			endDistance = Math.min(Math.round((tinyScrolling.requestedY-top)/ tinyScrolling.brakeK), endDistance);
			var offset = Math.max(2, Math.min(endDistance, tinyScrolling.maxStep));
		} else { var offset = - Math.min(Math.abs(Math.round((tinyScrolling.requestedY-top)/ tinyScrolling.brakeK)), tinyScrolling.maxStep);
		} window.scrollTo(0, top + offset);  
		if(Math.abs(top-tinyScrolling.requestedY) <= 1 || tinyScrolling.getScrollTop() == top) {
			window.scrollTo(0, tinyScrolling.requestedY);
			if(!document.all || window.opera) location.hash = tinyScrolling.hash;
			tinyScrolling.hash = null;
		} else 	setTimeout(tinyScrolling.scroll,tinyScrolling.speed);
	}
	
}