var imgcur='';

function imgnext(){
	var o=document.getElementById('photos'),os=o.getElementsByTagName('img'),n=-1,l=os.length;
	for(var i=0;i<l;i++){
		if(os[i].getAttribute('_url')==imgcur) {
			n=i; break;
		}
	}
	n+=1;
	if(n>=l) n=0;
	imgto(os[n]);
}

function imgto(o){
	var url=o.getAttribute('_url'), txt=o.getAttribute('_txt');
	llamarasincrono(url, txt);
}

function llamarasincrono (url, txt) {
	var os=document.getElementById('photoImgSrc');
	os.src=url;
	imgcur=url;
	os.onclick=function(){
		imgnext();
	}
	document.getElementById('imgText').innerHTML = txt;
	window.setTimeout( function() {
		os.src=url;
	}, 500 );
}