function apercu(id){
    var xhr=null;
    if (window.XMLHttpRequest){ 
        xhr = new XMLHttpRequest();
    }else if (window.ActiveXObject){
        xhr = new ActiveXObject("Microsoft.XMLHTTP");
    }
    xhr.onreadystatechange = function() { alert_apercu(xhr,id);};
    xhr.open("GET", "recupererphoto.php?id=" + id, true);
    xhr.send(null);
}

function alert_apercu(xhr,id){
    if (xhr.readyState == 4  && xhr.status == 200){
		var docXML = xhr.responseXML;
		var fic = docXML.getElementsByTagName("fichier");
		var altern = docXML.getElementsByTagName("alternatif");
		var text = docXML.getElementsByTagName("texte");
		document.getElementById('photo_apercu').src = "galerie/" + fic[0].firstChild.nodeValue + "-" + id + ".jpg";
		if(altern[0]) document.getElementById('photo_apercu').alt = altern[0].firstChild.nodeValue;
		else document.getElementById('photo_apercu').alt = "";
		if(text[0]) document.getElementById('texte_photo').innerHTML = text[0].firstChild.nodeValue;
		else document.getElementById('texte_photo').innerHTML = "";
    }
}