function checkForm(theForm) {
var msg='';
// voer automatische een trim uit
// en controleer formulier op juiste waarden
for(i=0; i<theForm.elements.length; i++) {
	fldName=theForm.elements[i].name;
	fldValue=trim(theForm.elements[i].value);

	// zet getrimde waarde terug in form
	theForm.elements[i].value=fldValue;

	// bepaal attributen
	fldAttrDesc=theForm.elements[i].getAttribute('description');
	fldAttrReq=theForm.elements[i].getAttribute('required')!=null;
	fldAttrNumeric=theForm.elements[i].getAttribute('numeric')!=null;
	fldAttrMinVal=theForm.elements[i].getAttribute('minVal');
	fldAttrMaxVal=theForm.elements[i].getAttribute('maxVal');
	fldAttrEmail=theForm.elements[i].getAttribute('email')!=null;

	// valideer op basis van ingestelde attributen
	if (fldAttrReq && fldValue=='') {
		msg+=fldAttrDesc + ' is verplicht\n';
	}
	if (fldAttrMinVal!=null) {
		if (fldValue!='' && fldValue*1<fldAttrMinVal*1) {
			msg+='Minimale waarde van ' + fldAttrDesc + ' is ' + fldAttrMinVal+ '\n';
		}
	}
	if (fldAttrMaxVal!=null) {
		if (fldValue!='' && fldValue*1>fldAttrMaxVal*1) {
			msg+='Maximale waarde van ' + fldAttrDesc + ' is ' + fldAttrMaxVal+ '\n';
		}
	}
	if (fldAttrNumeric) {
		if (!IsNumeric(fldValue) ){
			msg+= fldAttrDesc + ' moet een getal zijn\n';
		}
	}
	if (fldAttrEmail) {
		if (fldValue!='') {
			if (IsValidEmail(fldValue)) {
				msg+=fldAttrDesc + ' bevat geen geldig mailadres\n';
			}
		}
	}


}
}

function IsNumeric(sText) {
   var ValidChars = "0123456789";
   var IsNumber=true;
   var Char;
   for (var i = 0; i < sText.length; i++) 
      { 
      Char = sText.charAt(i); 
      if (ValidChars.indexOf(Char) == -1) 
         {
        	IsNumber = false;
	break;
         }
      }
   return IsNumber;
   }

function trim(str, chars) {
    return ltrim(rtrim(str, chars), chars);
}

function ltrim(str, chars) {
    chars = chars || "\\s";
    return str.replace(new RegExp("^[" + chars + "]+", "g"), "");
}

function rtrim(str, chars) {
    chars = chars || "\\s";
    return str.replace(new RegExp("[" + chars + "]+$", "g"), "");
}

function IsValidEmail(str) {
	var regexp1 = /(@.*@)|(\.\.)|(@\.)|(\.@)|(^\.)/; // not valid
	var regexp2 = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?)$/; //valid
	return !(!regexp1.test(str) && regexp2.test(str));
}

function preload() {
	for (var i=0;i<plaatjes.length;i++) {
		dimages[i]=new Image();
		dimages[i].src='/images/slides/image' + plaatjes[i] +'.jpg';
		d_large_images[i]=new Image();
		d_large_images[i].src='/images/slides/image' + plaatjes[i] +'_groot.jpg';
	}
	numImages=plaatjes.length-1;
}

var dimages=new Array();
var d_large_images=new Array();
var numImages=0;
var curImage=-1;
var secs=4;
 
function swapPicture()
{
  if (document.images)
  {
    var nextImage=curImage+1;
    if (nextImage>=numImages)
      nextImage=0;
    if (dimages[nextImage] && dimages[nextImage].complete)
    {
      var target=0;
      var targetlink=0;

	target=document.getElementById("slideshow");
	targetLink=document.getElementById("slideshowlink");
  
      // make sure target is valid.  It might not be valid
      //   if the page has not finished loading
      if (target) {
        target.src=dimages[nextImage].src;
        curImage=nextImage;
      	if (targetLink) {
        	targetLink.href=d_large_images[nextImage].src;
	}
      }
      setTimeout("swapPicture()", secs * 1000);
 
    }
    else
    {
      setTimeout("swapPicture()", 500);
    }
  }
}
 
function startSwap() {
	preload();
	setTimeout("swapPicture()", 1);
}