var leftmost_visible = 0;
var rightmost_visible = 3;


function portfolio_left() {

	var elements = portfolio_getElementsByClass(document, "portfolio_item", "*");  

	if (leftmost_visible == 0)
		return;
	else {
		//elements[leftmost_visible - 1].style.display = "block";
		$(elements[leftmost_visible - 1]).show("slow");
		$(elements[rightmost_visible]).hide("slow");
		leftmost_visible--;
		rightmost_visible--;
	}
}

function portfolio_right() {

	var elements = portfolio_getElementsByClass(document, "portfolio_item", "*");  

	if (rightmost_visible == elements.length - 1)
		return;
	else {
		$(elements[leftmost_visible]).hide("slow");
		$(elements[rightmost_visible + 1]).show("slow");
		leftmost_visible++;
		rightmost_visible++;
	}

}

 function portfolio_getElementsByClass(node,searchClass,tag) {  
     var classElements = new Array();  
	 if ( node == null )  
	     node = document;  
	 if ( tag == null )  
	     tag = '*';  
     var els = node.getElementsByTagName(tag); // use "*" for all elements  
     var elsLen = els.length;  
     var pattern = new RegExp("\\b"+searchClass+"\\b");  
     for (kk = 0, rr = 0; kk < elsLen; kk++) {  
	  if ( pattern.test(els[kk].className) ) {  
	  classElements[rr] = els[kk];  
	  rr++;  
	  }  
     }  
     return classElements;  
   }