function getImage()
{
  tfWidthTxt = document.getElementById('tfWidth').value;
  tfHeightTxt = document.getElementById('tfHeight').value;
  if(tfWidthTxt == ""){
    alert("Prosz poda szeroko.");
    return;
  }
  if(tfHeightTxt == ""){
    alert("Prosz poda wysoko.");
    return;
  }

  url = "http://localhost/dane.php?width=" + tfWidthTxt;
  url += "&height=" + tfHeightTxt;
  url = encodeURI(url);

  var btnWykonaj = document.getElementById('btnWykonaj');
  btnWykonaj.disabled = true;
  startGETRequest(url, onComplete, onEnd);
}
