/**
  * Unmarshall a DOMElement object corresponding to a DrawingInteraction element.
  * 
  * @param DOMElement $element A DOMElement object.
  * @return QtiComponent A DrawingInteraction object.
  * @throws UnmarshallingException
  */
 protected function unmarshall(DOMElement $element)
 {
     if (($responseIdentifier = self::getDOMElementAttributeAs($element, 'responseIdentifier')) !== null) {
         $objectElts = self::getChildElementsByTagName($element, 'object');
         if (count($objectElts) > 0) {
             $objectElt = $objectElts[0];
             $object = $this->getMarshallerFactory()->createMarshaller($objectElt)->unmarshall($objectElt);
             $component = new DrawingInteraction($responseIdentifier, $object);
             $promptElts = self::getChildElementsByTagName($element, 'prompt');
             if (count($promptElts) > 0) {
                 $promptElt = $promptElts[0];
                 $prompt = $this->getMarshallerFactory()->createMarshaller($promptElt)->unmarshall($promptElt);
                 $component->setPrompt($prompt);
             }
             if (($xmlBase = self::getXmlBase($element)) !== false) {
                 $component->setXmlBase($xmlBase);
             }
             self::fillBodyElement($component, $element);
             return $component;
         } else {
             $msg = "A 'drawingInteraction' element must contain exactly one 'object' element, none given.";
             throw new UnmarshallingException($msg, $element);
         }
     } else {
         $msg = "The mandatory 'responseIdentifier' attribute is missing from the 'drawingInteraction' element.";
         throw new UnmarshallingException($msg, $element);
     }
 }
 public function testMarshall()
 {
     $object = new Object('my-canvas.png', 'image/png');
     $drawingInteraction = new DrawingInteraction('RESPONSE', $object, 'my-drawings', 'draw-it');
     $prompt = new Prompt();
     $prompt->setContent(new FlowStaticCollection(array(new TextRun('Prompt...'))));
     $drawingInteraction->setPrompt($prompt);
     $element = $this->getMarshallerFactory('2.1.0')->createMarshaller($drawingInteraction)->marshall($drawingInteraction);
     $dom = new DOMDocument('1.0', 'UTF-8');
     $element = $dom->importNode($element, true);
     $this->assertEquals('<drawingInteraction id="my-drawings" class="draw-it" responseIdentifier="RESPONSE"><prompt>Prompt...</prompt><object data="my-canvas.png" type="image/png"/></drawingInteraction>', $dom->saveXML($element));
 }