function getXMLHTTPRequest()
{
	var xmlhttp=false;
	try {
		xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");
	} catch(e) {
		try {
			xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
		} catch(E) { xmlhttp=false; }
	}
	if (!xmlhttp && typeof XMLHttpRequest!='undefined')
	{
		xmlhttp=new XMLHttpRequest();
	}
	return xmlhttp;
}
//---------------------------------------------------------------------------------------------------------------
function d(tag){ return document.getElementById(tag); }
//---------------------------------------------------------------------------------------------------------------
function c(tag){ return document.createElement(tag); }
//---------------------------------------------------------------------------------------------------------------
function e(evt){ return (!evt) ? event : evt; }
//---------------------------------------------------------------------------------------------------------------
function f(evt){ return evt.srcElement ?  evt.srcElement : evt.target; }
//---------------------------------------------------------------------------------------------------------------
function getResolucion()
{
	var height=0; var width=0; var resolucion="";
	if (self.screen)
	{
		// for NN4 and IE4
		width = screen.width;
		height = screen.height
	}
	else if (self.java)
	{
		// for NN3 with enabled Java
		var jkit = java.awt.Toolkit.getDefaultToolkit();
		var scrsize = jkit.getScreenSize();
		width = scrsize.width;
		height = scrsize.height;
	}
	document.getElementById("resolucion").value = (width > 0 && height > 0) ? width+"x"+height : "No determinada";
}
//---------------------------------------------------------------------------------------------------------------
function validar_categoria()
{
	if(!document.getElementById('sicategoria'))
	{
		var nombre_ct = document.getElementById('select_id_categoria').options[document.getElementById('select_id_categoria').selectedIndex].innerHTML;
		if(nombre_ct!='') alert('Seleccione una categorķa de '+nombre_ct);
		else alert('Seleccione una categorķa');
		return false;
	}
	validar_caracteres()
	return false;
}
//---------------------------------------------------------------------------------------------------------------
function validar_caracteres()
{
	ajax=nuevo_ajax();
	ajax.onreadystatechange = enviar_formulario;

	var caracter = document.getElementById('caracter').value;
	if(caracter == '') { alert('Vuelva a escribir los caracteres que ve en la imagen.'); return false; }

	ajax.open("GET", URL_BASE+'zonaAjax/validar_caracteres.php?caracter='+caracter , true);
	ajax.send(null);
}
//---------------------------------------------------------------------------------------------------------------
function enviar_formulario()
{
	if (ajax.readyState == 4)
	{
		if (ajax.status == 200)
		{
			if(ajax.responseText=='ok') document.getElementById('ingreso').submit();
			else alert('Vuelva a escribir los caracteres que ve en la imagen.');
		}
	}
}