var speed = 13;
var timer = "";
var currentPage = 1;

function viewNextPage() {
	viewPage(currentPage+1,currentPage);	
	currentPage++;
}

function viewPrevPage() {
	viewPage(currentPage-1,currentPage);
	currentPage--;
}

function viewPage(targetPage,currentpage) {
	var container = document.getElementById("page_container");
	var cp = document.getElementById("page_" + currentpage);
	var np = document.getElementById("page_" + targetPage);	
	//cp.style.width = np.style.width = (parseInt(container.style.width)-5) + "px";
	//cp.style.height = np.style.height = (parseInt(container.style.height)-50) + "px";
	cp.style.position = np.style.position = "absolute";	
	cp.style.zIndex = currentPage;
	np.style.zIndex = targetPage;
	var isNext = true;	
	var el;		
	np.style.display = "block";
	if(targetPage < currentPage) {
		np.style.left = "0px";
		cp.style.left = "0px";
		isNext = false;		
		el = cp;
	}
	else {			
		np.style.width = np.clientWidth + "px";
		np.style.height = np.clientHeight + "px";		
		np.style.left = (parseInt(np.clientWidth) + 1) + "px";	
		el = np;
	}			
	timer = setInterval(function(){animatepage(el,isNext);},1);
}

function animatepage(el,isNext) {
	var currentSpeed = speed;
	if(isNext) {
		if(parseInt(el.style.left) <= 0) {				
			clearInterval(timer);
		} else {					
			if(parseInt(el.style.left) < currentSpeed && parseInt(el.style.left) > 0) 
				currentSpeed = parseInt(el.style.left);											
			el.style.left = (parseInt(el.style.left) - currentSpeed) + "px";		
		}
	} else {
		if(parseInt(el.style.left) >= (parseInt(el.offsetWidth) + 1)) {		
			el.style.display = "none";
			clearInterval(timer);
		} else {						
			el.style.left = (parseInt(el.style.left) + currentSpeed) + "px";
		}
	}
}