Extract XML in PHP

Suppose we have following XML file:
<?xml version="1.0" encoding="UTF-8"?>
<main>
   <config>
  <controlsWidth type="Number">640</controlsWidth>

      <controlsHeight type="Number">480</controlsHeight>

  </config>
</main>

We want to extract  640 in controlsWidth using PHP.
Define a PHP function:
function get_camtasia_width($file){

//call xml2Array class
  $objXML = new xml2Array();
  $data=implode("", file($file));
   $configxml = $objXML->parse($data);
   $lecture_map=$configxml[0]['childNodes'];
 // print_r($lecture_map);
    foreach($lecture_map as $lecture){
           foreach($lecture['childNodes'] as $childNode){

             if ($childNode['name']=="CONTROLSWIDTH") 

             $slide_width = $childNode['text'];
               }
          }
        return        $slide_width;
}

External class xml2Array class as following:
<?php

/* Usage
 Grab some XML data, either from a file, URL, etc. however you want.
Assume storage in $strYourXML;
 $objXML = new xml2Array();
 $arrOutput = $objXML->parse($strYourXML);
 print_r($arrOutput); //print it out, or do whatever!
*/
class xml2Array {
   var $arrOutput = array();
   var $resParser;
   var $strXmlData;
   //var $tag_name;
   function parse($strInputXML) {
           $this->resParser = xml_parser_create ();
           xml_set_object($this->resParser,$this);
           xml_set_element_handler($this->resParser, "tagOpen", "tagClosed");
           xml_set_character_data_handler($this->resParser, "tagData");
           $this->strXmlData = xml_parse($this->resParser,$strInputXML );
           if(!$this->strXmlData) {
               die(sprintf("XML error: %s at line %d",
           xml_error_string(xml_get_error_code($this->resParser)),
           xml_get_current_line_number($this->resParser)));
           }
           xml_parser_free($this->resParser);
           return $this->arrOutput;
   }
   function tagOpen($parser, $name, $attrs) {
       $tag=array("name"=>$name,"attrs"=>$attrs);
       //$tag=array($name=>$attrs);
       //$this->tag_name = $name;
       array_push($this->arrOutput,$tag);
   }
   function tagData($parser, $tagData) {
       if(trim($tagData) != '') {
           if(isset($this->arrOutput[count($this->arrOutput)-1]['text'])) {
               $this->arrOutput[count($this->arrOutput)-1]['text'] .= $tagData;
           }
           else {
               $this->arrOutput[count($this->arrOutput)-1]['text'] = $tagData;
           }
       }
   }
   function tagClosed($parser, $name) {
       $this->arrOutput[count($this->arrOutput)-2]['childNodes'][] =
$this->arrOutput[count($this->arrOutput)-1];
       array_pop($this->arrOutput);
   }
}
?>