var fileviewer = new Hash();
var flipindex = new Hash();

function addFile(rahmenid,filename) {
    var files = fileviewer.get(rahmenid);
    if(files==null) {
        files = new Array();
    }
    var index = files.length;
    files[index]  = filename;
    fileviewer.set(rahmenid,files);
}

function startPresentation(rahmenid) {    
	$('L'+rahmenid).update('<img src=\''+fileviewer.get(rahmenid)[0]+'\' style=\'width:100%; height:100%\'/>');
    new PeriodicalExecuter( function() {
        var index = flipindex.get(rahmenid);
        var files = fileviewer.get(rahmenid);
        if(files!=null) {			
            if(index==null) index=0;
			var ustr = '<img src=\''+files[index]+'\' style=\'position:absolute; top:0px; left:0px; width:100%; height:100%\'/>';
            index+=1;            
            if(index>=files.length) index=0;
			ustr = ustr + '<img src=\''+files[index]+'\' style=\'position:absolute; top:0px; left:0px; opacity:0; width:100%; height:100%\'/>';
            $('L'+rahmenid).update(ustr);
			fade($('L'+rahmenid),0);			
        }		
        flipindex.set(rahmenid,index);
    },8);    
}

function fade(objid, step) {	
	var image0 = objid.down('img',0);
	var image = objid.down('img',1);	
	step = step || 0;

	image.style.opacity=step/100;	
	image.style.filter="alpha(opacity=" + step + ")";
	image0.style.opacity=(100-step)/100;
	image0.style.filter="alpha(opacity=" + (100-step) + ")";
	step+=4;
	if(step<=100)
		window.setTimeout(function() { fade(objid, step); }, 1);
	
}