var carregar;

function trocarFoto(id) {
	msg = "<div style='height: 244px; width: 344px; float: left; text-align: center;'><img src='images/pre_img.gif' style='margin-top: 118px; margin-left: 168px;'></div>";
	document.getElementById("description_img").innerHTML = msg;
	exibeImg(id);
    carregar = new Image();
    carregar.src = '../fotos/'+id;
}

function exibeImg(id) {
    setTimeout( "abrirImg("+id+")", 100 );
}

function abrirImg(id) {
	if( carregar.complete )
    {
        document.getElementById("description_img").innerHTML = '<img src="'+carregar.src+'" width="344" height="244" alt="">';
    }
    else
    {
        setTimeout( "exibeImg("+id+")", 100 );
    }
}