var current = 1;
var itemid = 0;
var attachid = 0;
var global_total = 0;

function fix() {
	
	// mostrar atras
	if (current != 1) {
		document.getElementById('anterior').style.display = '';
	} else {
		document.getElementById('anterior').style.display = 'none';
	}
	
	// mostrar siguiente
	if (current == global_total) {
		document.getElementById('siguiente').style.display = 'none';
	} else {
		document.getElementById('siguiente').style.display = '';
	}
	
	document.getElementById('thumblink').href = 'verImagen/' + itemid + '_' + current + '_' + attachid;
	
}

function dostart(item,id,total) {
	var next = current+1;
	document.getElementById('thumb').src = 'verThumb/' + item + '_' + next + '_' + id + '';
	document.getElementById('siguiente').onclick = '';
	document.getElementById('anterior').style.display = '';
	document.getElementById('siguiente').href = 'javascript:donext();';
	global_total = total;
	itemid = item;
	attachid = id;
}

function donext() {
	var next = current+1;
	document.getElementById('thumb').src = 'verThumb/' + itemid + '_' + next + '_' + attachid + '';
	current = current+1;
	fix();
}

function doprev() {
	var prev = current-1;
	document.getElementById('thumb').src = 'verThumb/' + itemid + '_' + prev + '_' + attachid + '';
	current = current-1;
	fix();
}