var index = 0;
f = 0;

function showDia(img){
	loadImg(img);
	document.getElementById('aufhellen').style.visibility='visible';
	document.getElementById('diashow').style.visibility='visible';
}


function hideDia(){
	document.getElementById('aufhellen').style.visibility='hidden';
	document.getElementById('diashow').style.visibility='hidden';	
}


function showImg(){
	document.getElementById('dia').style.background = 'url(' + document.getElementById('diaImg').src + ') no-repeat top left';
	document.getElementById('diaImg').src = imgArr[index];
	
	document.getElementById('diaImg').style.filter = 'alpha(opacity=0)';
	document.getElementById('diaImg').style.opacity = '0.0';
	//document.getElementById('diaImg').style.-moz-opacity = '0.85';
	f = 0;
	setTimeout(fadein, 2);
}


function fadein(){
	if(f == 100){
		f = 0;	
		document.getElementById('dia').style.background = 'url(' + document.getElementById('diaImg').src + ') no-repeat top left';
	}
	else if(f < 100){
		document.getElementById('diaImg').style.filter = 'alpha(opacity=' + f + ')';
		document.getElementById('diaImg').style.opacity = f/100.0;
		f += 5;
		setTimeout(fadein, 8);
	}
}

function loadImg(img){
	index = img - 1;
	showImg();
}

function next(){
	index = (index + 1) % imgArr.length;	
	showImg();
}

function prev(){
	index = (imgArr.length + index - 1) % imgArr.length;	
	showImg();
}



function preloadDiaImages(){
	for(i=0; i<imgArr.length; i++){
		pic = new Image();
		pic.src = imgArr[i];
	}
}