function toonImg(boxId, imgNum, evt) {
  if (!evt) {
    var evt = (evt) ? evt : window.event;
  }
  evt.cancelBubble = true;
  var height = $("#" + boxId).height();
  $("#" + boxId).css("background-position", "left " + (-(height * imgNum)) + "px")
}

function verbergContent() {
  $("#content").hide();
}

function controleerContactFormulier() {
  //Controleer verplichte velden of ze niet leeg zijn
  var inputs = new Array("ctl00_ContentPlaceHolder1_tbxContactpersoon","ctl00_ContentPlaceHolder1_tbxAdres", "ctl00_ContentPlaceHolder1_tbxPostcode", "ctl00_ContentPlaceHolder1_tbxPlaats","ctl00_ContentPlaceHolder1_tbxOnderwerp");
  var divs = new Array("divContactpersoon", "divAdres", "divPostcode", "divPlaats", "divOnderwerp");
  var blnCheck = true;  
  for (var i=0; i<inputs.length; i++) {
    if (isEmpty(inputs[i], divs[i], true)) {
      blnCheck = false;
    }
  }
  //Controleer overige velden met extra voorwaarden
  if (isEmpty("ctl00_ContentPlaceHolder1_tbxEmail", "divEmail", true) || !regCheck(/\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*/, "ctl00_ContentPlaceHolder1_tbxEmail", "divEmail")) {
    blnCheck = false;
  }
  if (isEmpty("ctl00_ContentPlaceHolder1_tbxTelefoon", "divTelefoon", true) || !regCheck(/^[0-9]{2,4}[-]?[0-9]{6,8}$/, "ctl00_ContentPlaceHolder1_tbxTelefoon", "divTelefoon")) {
    blnCheck = false;
  }
  if (!isEmpty("ctl00_ContentPlaceHolder1_tbxMobiel", "divTelefoonMobiel", false)) {
    if (!regCheck(/^[0-9]{2,4}[-]?[0-9]{6,8}$/, "ctl00_ContentPlaceHolder1_tbxMobiel", "divTelefoonMobiel")) {
      blnCheck = false;
    }
  }
  if (!blnCheck) {
    document.getElementById("pMelding").style.display = "block";
  }
  return blnCheck;
}

function isEmpty(formID, divId, foutmelding) {
  document.getElementById(divId).className = document.getElementById(divId).className.replace(/regel_fout/, "");
  if (document.getElementById(formID).value == "") {
    if (foutmelding) {
      document.getElementById(divId).className += " regel_fout";
    }
    return true
  }
  return false
}

function regCheck(regex, docId, divId){
  document.getElementById(divId).className = document.getElementById(divId).className.replace(/regel_fout/, "");
  if (document.getElementById(docId).value.search(regex)==-1) {
    document.getElementById(divId).className += " regel_fout";
    return false;    
  }
  return true;
}