var exibido = false;
var janelaBlog = document.getElementById('janela_blog');
var objeto = null; /*VARIÁVEL A SER UTILIZADA PARA ASSUMIR O ELEMENTO A SER MANIPULADO PELA FUNÇÃO	changeOpac() */
var xmlHttp;
var velocidadeFade = 500;
var htmlo = document.documentElement.style.overflow;
var bodyo = document.body.style.overflow;

function ajaxFunction()
{
	try
	{
		// Firefox, Opera 8.0+, Safari
		xmlHttp=new XMLHttpRequest();
	}
	catch (e)
	{
		// Internet Explorer
		try
		{
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e)
		{
			try
			{
				xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
			}
			catch (e)
			{
				alert("Seu browser não é compatível com AJAX!");
				return false;
			}
		}
	}
}

function ajaxExec()
{
	if(xmlHttp.readyState == 4)
	{
		janelaBlog.innerHTML = '<div id="fechar"><a id="bt_fechar" href="#">X Fechar</a></div><div id="iframe_div">' + xmlHttp.responseText + '</div>';

		document.getElementById('bt_fechar').onclick = new Function('esconderBlog();');

		exibido = true;
	}
}


function exibirBlog()
{
	objeto = janelaBlog.style;
	changeOpac(0);
	janelaBlog.style.display = "block";
	document.body.style.overflow = 'hidden';
	document.documentElement.style.overflow = 'hidden';
	opacity(janelaBlog.id, 0, 100, velocidadeFade);

	if(!exibido)
	{
		xmlHttp.onreadystatechange = new Function('ajaxExec();');
		
		xmlHttp.open("GET","iframe.php?endereco=blog",true);
		xmlHttp.send(null);
	}
}

function esconderBlog()
{
	opacity(janelaBlog.id, 100, 0, velocidadeFade);
	setTimeout("document.getElementById('janela_blog').style.display = 'none';", velocidadeFade+1);
	document.body.style.overflow = bodyo;
	document.documentElement.style.overflow = htmlo;
}

function opacity(id, opacStart, opacEnd, millisec)
{
    //speed for each frame
    var speed = Math.round(millisec / 100);
    var timer = 0;
	objeto = document.getElementById(id).style;

    //determine the direction for the blending, if start and end are the same nothing happens
    if(opacStart > opacEnd) {
        for(i = opacStart; i >= opacEnd; i--) {
            setTimeout("changeOpac(" + i + ")",(timer * speed));
            timer++;
        }
    } else if(opacStart < opacEnd) {
        for(i = opacStart; i <= opacEnd; i++)
            {
            setTimeout("changeOpac(" + i + ")",(timer * speed));
            timer++;
        }
    }
}

//change the opacity for different browsers
function changeOpac(opacity)
{
    objeto.opacity = (opacity/100);
    objeto.MozOpacity = (opacity/100);
    objeto.KhtmlOpacity = (opacity/100);
    objeto.filter = "alpha(opacity=" + opacity + ")";
} 

ajaxFunction();

document.getElementById('bt_blog').onclick = new Function('exibirBlog();');
document.getElementById('link_blog').onclick = new Function('exibirBlog();');