/**
 * Gets the value of a field from an xml file. A field
 * is a structure like <field>value</field>
 *
 * data -> Root DOM element that contains the field
 * field -> Name of the field
 */
function getFieldValue(data, field) {
	var fieldNodes = data.getElementsByTagName(field);
	if (fieldNodes.length > 0) {
		return jQuery(fieldNodes[0]).text();
	} else {
		return "";
	}
}

/**
 * Sets the selected tab in the page view
 *
 * number -> Tab number to set
 */
function setTab(number) {
    var body = document.getElementsByTagName("body")[0];
    body.setAttribute("id", "tab" + number);
}

/**
 * Centers an element on the screen
 *
 * obj -> Element that needs to be centered
 */
function getViewportDimensions() {
result ={};
result['w'] = jQuery(window).width();
result['h'] = jQuery(window).height();
return result;
}

function getElementDimensions(obj) {
result ={};
result['w'] = obj.width();
result['h'] = obj.height();
return result;

}

function centerElement(obj){
      var vpDim = getViewportDimensions();
      var elemDim = getElementDimensions(obj);
      jQuery(obj).css({'left':((vpDim.w - elemDim.w)/2),'top':((vpDim.h - elemDim.h)/2)});
}