function s_picture(g_id, p_id){
	var verificationRequest = createXMLObject();
	
	var requestURL = 'ajax-index.php?content=galleries&action=swap-picture&id_='+g_id+'&pid_='+p_id;
	
	verificationRequest.onreadystatechange = function() { swapPicture(verificationRequest, intVal(g_id), intVal(p_id)); };
	verificationRequest.open('GET', requestURL, true);
	verificationRequest.send(null);
}

function swapPicture(verificationRequest, g_id, p_id){
	if(verificationRequest.readyState == 4){
		if(verificationRequest.status == 200){
			
			var returnedString = verificationRequest.responseText;
		
			var returnedArray = returnedString.split(';');
			
			var p_path = returnedArray[0];
			var n_pictures = intVal(returnedArray[1]);
			
			var c_picture = document.getElementById('c-picture');
			c_picture.src = p_path;
			
			var showEachSide = 16;
			var showTotal = showEachSide*2+1;
			var startNumber = 0;
			var endNumber = 0;
			var toAddToStart = 0;
			var toAddToEnd = 0;
			var differenceFromEnd = 0;
			
			var previous_link = document.getElementById('nav_previous');
			var next_link = document.getElementById('nav_next');
			
			previous_link.href = 'javascript:s_picture(\''+g_id+'\', \''+(p_id !== 1 ? p_id-1 : n_pictures)+'\');';
			next_link.href = 'javascript:s_picture(\''+g_id+'\', \''+(p_id !== n_pictures ? p_id+1 : 1)+'\');';
			
			if(p_id-showEachSide > 1) startNumber = p_id-showEachSide;
			else{
				startNumber = 1;
				toAddToEnd = showEachSide-p_id+1;
			}
			
			if(p_id+showEachSide+toAddToEnd < n_pictures){
				endNumber = p_id+showEachSide+toAddToEnd;
				
				differenceFromEnd = n_pictures-p_id+showEachSide+toAddToEnd;
				if(differenceFromEnd < showEachSide) toAddToStart = differenceFromEnd;
			}
			else{
				endNumber = n_pictures;
				if(startNumber !== 1){
					toAddToStart = startNumber-1 < showEachSide-(endNumber-p_id) ? startNumber-1 : showEachSide-(endNumber-p_id);
				}
			}
			startNumber += -toAddToStart;
			
			var pagesList = '';
			
			for(var i = startNumber; i <= endNumber; i++){
				
				pagesList += '<li><a'+(i == p_id ? ' class="selectedLink"' : ' href="javascript:s_picture(\''+g_id+'\', \''+i+'\');"')+'>'+i+'</a></li>';
			}
			
			pagesList += '<br clear="left" />';
			
			var p_ul = document.getElementById('list-pages');
			
			p_ul.innerHTML = pagesList;
			
		}
	}
}