var m=0;
var n=0;
var speed = 20;
var text ='-';
var sum = 0;
var totalsum = 0;
var w1 = 0;
var w2 = 0;
var w3 = 0;
var w4 = 0;
var w5= 0;
var w6 = 0;
var w7 = 0;
var w8 = 0;

function calculateWidth() {
if(document.getElementById("pic1")) {
	w1 = document.getElementById("pic1").offsetWidth;
	w1 += 2; //witruimte tussen foto's
}
if(document.getElementById("pic2")) {
	w2 = document.getElementById("pic2").offsetWidth;
	w2 += 2;
}
if(document.getElementById("pic3")) {
	w3 = document.getElementById("pic3").offsetWidth;
	w3 += 2;
}
if(document.getElementById("pic4")) {
	w4 = document.getElementById("pic4").offsetWidth;
	w4 += 2;
}
if(document.getElementById("pic5")) {
	w5 = document.getElementById("pic5").offsetWidth;
	w5 += 2;
}
if(document.getElementById("pic6")) {
	w6 = document.getElementById("pic6").offsetWidth;
	w6 += 2;
}
if(document.getElementById("pic7")) {
	w7 = document.getElementById("pic7").offsetWidth;
	w7 += 2;
}
if(document.getElementById("pic8")) {
	w8 = document.getElementById("pic8").offsetWidth;
	w8 += 2;	
}
totalsum = w1 + w2 + w3 + w4 + w5 + w6 + w7 + w8;
sum = totalsum - 930; //930 is lengte van zichtbaar deel
}

function scrollPics() {	
    document.getElementById('div1').style.left=m+'px';
    document.getElementById('div2').style.left=n+'px';
	if(totalsum > 930) {
		 if (text == '-') {
			   m--;
			   n--;
			if(m==-sum) {
				text = '+';
			 }
			if(n==-sum) {
				text = '+';
			 }
		 }
		 
		 if (text == '+') {
			 m++;
			 n++;
			 if(m==0) {
				text = '-';
			 }
			if(n==0) {
				text = '-';
			 }
	 }
	}
 
setTimeout('scrollPics()',speed);
}