class.assOrderingQuestion.php

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<?php
 /*
   +----------------------------------------------------------------------------+
   | ILIAS open source                                                          |
   +----------------------------------------------------------------------------+
   | Copyright (c) 1998-2001 ILIAS open source, University of Cologne           |
   |                                                                            |
   | This program is free software; you can redistribute it and/or              |
   | modify it under the terms of the GNU General Public License                |
   | as published by the Free Software Foundation; either version 2             |
   | of the License, or (at your option) any later version.                     |
   |                                                                            |
   | This program is distributed in the hope that it will be useful,            |
   | but WITHOUT ANY WARRANTY; without even the implied warranty of             |
   | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the              |
   | GNU General Public License for more details.                               |
   |                                                                            |
   | You should have received a copy of the GNU General Public License          |
   | along with this program; if not, write to the Free Software                |
   | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
   +----------------------------------------------------------------------------+
*/

include_once "./Modules/TestQuestionPool/classes/class.assQuestion.php";
include_once "./Modules/Test/classes/inc.AssessmentConstants.php";

class assOrderingQuestion extends assQuestion
{
        var $answers;

        var $ordering_type;

        var $thumb_geometry = 100;

        var $element_height;

        function __construct(
                $title = "",
                $comment = "",
                $author = "",
                $owner = -1,
                $question = "",
                $ordering_type = OQ_TERMS
        )
        {
                parent::__construct($title, $comment, $author, $owner, $question);
                $this->answers = array();
                $this->ordering_type = $ordering_type;
        }

        function isComplete()
        {
                if (($this->title) and ($this->author) and ($this->question) and (count($this->answers)) and ($this->getMaximumPoints() > 0))
                {
                        return true;
                }
                        else
                {
                        return false;
                }
        }

        function saveToDb($original_id = "")
        {
                global $ilDB;

                $this->saveQuestionDataToDb($original_id);

                // save additional data
                $affectedRows = $ilDB->manipulateF("DELETE FROM " . $this->getAdditionalTableName() . " WHERE question_fi = %s", 
                        array("integer"),
                        array($this->getId())
                );

                $affectedRows = $ilDB->manipulateF("INSERT INTO " . $this->getAdditionalTableName() . " (question_fi, ordering_type, thumb_geometry, element_height) VALUES (%s, %s, %s, %s)", 
                        array("integer", "text","integer","integer"),
                        array(
                                $this->getId(),
                                $this->ordering_type,
                                $this->getThumbGeometry(),
                                ($this->getElementHeight() > 20) ? $this->getElementHeight() : NULL
                        )
                );

                $affectedRows = $ilDB->manipulateF("DELETE FROM qpl_a_ordering WHERE question_fi = %s",
                        array('integer'),
                        array($this->getId())
                );

                // Anworten wegschreiben
                foreach ($this->answers as $key => $value)
                {
                        $answer_obj = $this->answers[$key];
                        $next_id = $ilDB->nextId('qpl_a_ordering');
                        $affectedRows = $ilDB->manipulateF("INSERT INTO qpl_a_ordering (answer_id, question_fi, answertext, solution_order, ".
                                "random_id, tstamp) VALUES (%s, %s, %s, %s, %s, %s)",
                                array('integer','integer','text','integer','integer','integer'),
                                array(
                                        $next_id,
                                        $this->getId(),
                                        ilRTE::_replaceMediaObjectImageSrc($answer_obj->getAnswertext(), 0),
                                        $key,
                                        $answer_obj->getRandomID(),
                                        time()
                                )
                        );
                }

                if ($this->getOrderingType() == OQ_PICTURES)
                {
                        $this->rebuildThumbnails();
                }

                $this->cleanImagefiles();
                parent::saveToDb($original_id);
        }

        function loadFromDb($question_id)
        {
                global $ilDB;

                $result = $ilDB->queryF("SELECT qpl_questions.*, " . $this->getAdditionalTableName() . ".* FROM qpl_questions LEFT JOIN " . $this->getAdditionalTableName() . " ON " . $this->getAdditionalTableName() . ".question_fi = qpl_questions.question_id WHERE qpl_questions.question_id = %s",
                        array("integer"),
                        array($question_id)
                );
                if ($result->numRows() == 1)
                {
                        $data = $ilDB->fetchAssoc($result);
                        $this->setId($question_id);
                        $this->setObjId($data["obj_fi"]);
                        $this->setTitle($data["title"]);
                        $this->setComment($data["description"]);
                        $this->setOriginalId($data["original_id"]);
                        $this->setAuthor($data["author"]);
                        $this->setNrOfTries($data['nr_of_tries']);
                        $this->setPoints($data["points"]);
                        $this->setOwner($data["owner"]);
                        include_once("./Services/RTE/classes/class.ilRTE.php");
                        $this->setQuestion(ilRTE::_replaceMediaObjectImageSrc($data["question_text"], 1));
                        $this->ordering_type = strlen($data["ordering_type"]) ? $data["ordering_type"] : OQ_TERMS;
                        $this->thumb_geometry = $data["thumb_geometry"];
                        $this->element_height = $data["element_height"];
                        $this->setEstimatedWorkingTime(substr($data["working_time"], 0, 2), substr($data["working_time"], 3, 2), substr($data["working_time"], 6, 2));
                }

                $result = $ilDB->queryF("SELECT * FROM qpl_a_ordering WHERE question_fi = %s ORDER BY solution_order ASC",
                        array('integer'),
                        array($question_id)
                );

                include_once "./Modules/TestQuestionPool/classes/class.assAnswerOrdering.php";
                if ($result->numRows() > 0)
                {
                        while ($data = $ilDB->fetchAssoc($result))
                        {
                                include_once("./Services/RTE/classes/class.ilRTE.php");
                                $data["answertext"] = ilRTE::_replaceMediaObjectImageSrc($data["answertext"], 1);
                                array_push($this->answers, new ASS_AnswerOrdering($data["answertext"], $data["random_id"]));
                        }
                }
                parent::loadFromDb($question_id);
        }
        
        function duplicate($for_test = true, $title = "", $author = "", $owner = "")
        {
                if ($this->id <= 0)
                {
                        // The question has not been saved. It cannot be duplicated
                        return;
                }
                // duplicate the question in database
                $this_id = $this->getId();
                $clone = $this;
                include_once ("./Modules/TestQuestionPool/classes/class.assQuestion.php");
                $original_id = assQuestion::_getOriginalId($this->id);
                $clone->id = -1;
                if ($title)
                {
                        $clone->setTitle($title);
                }
                if ($author)
                {
                        $clone->setAuthor($author);
                }
                if ($owner)
                {
                        $clone->setOwner($owner);
                }
                if ($for_test)
                {
                        $clone->saveToDb($original_id);
                }
                else
                {
                        $clone->saveToDb();
                }

                // copy question page content
                $clone->copyPageOfQuestion($this_id);
                // copy XHTML media objects
                $clone->copyXHTMLMediaObjectsOfQuestion($this_id);
                // duplicate the generic feedback
                $clone->duplicateFeedbackGeneric($this_id);

                // duplicate the image
                $clone->duplicateImages($this_id);
                $clone->onDuplicate($this_id);
                return $clone->id;
        }

        function copyObject($target_questionpool, $title = "")
        {
                if ($this->id <= 0)
                {
                        // The question has not been saved. It cannot be duplicated
                        return;
                }
                // duplicate the question in database
                $clone = $this;
                include_once ("./Modules/TestQuestionPool/classes/class.assQuestion.php");
                $original_id = assQuestion::_getOriginalId($this->id);
                $clone->id = -1;
                $source_questionpool = $this->getObjId();
                $clone->setObjId($target_questionpool);
                if ($title)
                {
                        $clone->setTitle($title);
                }
                
                $clone->saveToDb();

                // copy question page content
                $clone->copyPageOfQuestion($original_id);
                // copy XHTML media objects
                $clone->copyXHTMLMediaObjectsOfQuestion($original_id);
                // duplicate the generic feedback
                $clone->duplicateFeedbackGeneric($original_id);

                // duplicate the image
                $clone->copyImages($original_id, $source_questionpool);
                $clone->onCopy($this->getObjId(), $this->getId());
                return $clone->id;
        }
        
        function duplicateImages($question_id)
        {
                global $ilLog;
                if ($this->getOrderingType() == OQ_PICTURES)
                {
                        $imagepath = $this->getImagePath();
                        $imagepath_original = str_replace("/$this->id/images", "/$question_id/images", $imagepath);
                        if (!file_exists($imagepath)) {
                                ilUtil::makeDirParents($imagepath);
                        }
                        foreach ($this->answers as $answer)
                        {
                                $filename = $answer->getAnswertext();
                                if (!@copy($imagepath_original . $filename, $imagepath . $filename)) 
                                {
                                        $ilLog->write("image could not be duplicated!!!!");
                                }
                                if (@file_exists($imagepath_original. $this->getThumbPrefix(). $filename))
                                {
                                        if (!@copy($imagepath_original . $this->getThumbPrefix() . $filename, $imagepath . $this->getThumbPrefix() . $filename)) 
                                        {
                                                $ilLog->write("image thumbnail could not be duplicated!!!!");
                                        }
                                }
                        }
                }
        }

        function copyImages($question_id, $source_questionpool)
        {
                global $ilLog;
                if ($this->getOrderingType() == OQ_PICTURES)
                {
                        $imagepath = $this->getImagePath();
                        $imagepath_original = str_replace("/$this->id/images", "/$question_id/images", $imagepath);
                        $imagepath_original = str_replace("/$this->obj_id/", "/$source_questionpool/", $imagepath_original);
                        if (!file_exists($imagepath)) {
                                ilUtil::makeDirParents($imagepath);
                        }
                        foreach ($this->answers as $answer)
                        {
                                $filename = $answer->getAnswertext();
                                if (!@copy($imagepath_original . $filename, $imagepath . $filename)) 
                                {
                                        $ilLog->write("Ordering Question image could not be copied: $imagepath_original$filename");
                                }
                                if (@file_exists($imagepath_original. $this->getThumbPrefix(). $filename))
                                {
                                        if (!@copy($imagepath_original . $this->getThumbPrefix() . $filename, $imagepath . $this->getThumbPrefix() . $filename)) 
                                        {
                                                $ilLog->write("Ordering Question image thumbnail could not be copied: $imagepath_original" . $this->getThumbPrefix() . $filename);
                                        }
                                }
                        }
                }
        }

        function setOrderingType($ordering_type = OQ_TERMS)
        {
                $this->ordering_type = $ordering_type;
        }
        
        function getOrderingType()
        {
                return $this->ordering_type;
        }

        function addAnswer(
                $answertext = "",
                $solution_order = -1
        )
        {
                include_once "./Modules/TestQuestionPool/classes/class.assAnswerOrdering.php";
                $answer = new ASS_AnswerOrdering($answertext, $this->getRandomID());
                if (($solution_order >= 0) && ($solution_order < count($this->answers)))
                {
                        $part1 = array_slice($this->answers, 0, $solution_order);
                        $part2 = array_slice($this->answers, $solution_order);
                        $this->answers = array_merge($part1, array($answer), $part2);
                }
                else
                {
                        array_push($this->answers, $answer);
                }
        }
        
        public function moveAnswerUp($position)
        {
                if ($position > 0)
                {
                        $temp = $this->answers[$position-1];
                        $this->answers[$position-1] = $this->answers[$position];
                        $this->answers[$position] = $temp;
                }
        }
        
        public function moveAnswerDown($position)
        {
                if ($position < count($this->answers)-1)
                {
                        $temp = $this->answers[$position+1];
                        $this->answers[$position+1] = $this->answers[$position];
                        $this->answers[$position] = $temp;
                }
        }

        protected function getRandomID()
        {
                $random_number = mt_rand(1, 100000);
                $found = true;
                while ($found)
                {
                        $found = false;
                        foreach ($this->getAnswers() as $answer)
                        {
                                if ($answer->getRandomID() == $random_number)
                                {
                                        $found = true;
                                        $random_number++;
                                }
                        }
                }
                return $random_number;
        }

        function getAnswer($index = 0)
        {
                if ($index < 0) return NULL;
                if (count($this->answers) < 1) return NULL;
                if ($index >= count($this->answers)) return NULL;
                return $this->answers[$index];
        }

        function deleteAnswer($index = 0)
        {
                if ($index < 0)
                {
                        return;
                }
                if (count($this->answers) < 1)
                {
                        return;
                }
                if ($index >= count($this->answers))
                {
                        return;
                }
                unset($this->answers[$index]);
                $this->answers = array_values($this->answers);
                for ($i = 0; $i < count($this->answers); $i++)
                {
                        if ($this->answers[$i]->getOrder() > $index)
                        {
                                $this->answers[$i]->setOrder($i);
                        }
                }
        }

        function flushAnswers()
        {
                $this->answers = array();
        }

        function getAnswerCount()
        {
                return count($this->answers);
        }

        function getMaxSolutionOrder()
        {
                if (count($this->answers) == 0)
                {
                        $max = 0;
                }
                else
                {
                        $max = $this->answers[0]->getSolutionOrder();
                }
                foreach ($this->answers as $key => $value)
                {
                        if ($value->getSolutionOrder() > $max)
                        {
                                $max = $value->getSolutionOrder();
                        }
                }
                return $max;
        }

        function calculateReachedPoints($active_id, $pass = NULL)
        {
                global $ilDB;
                
                $found_value1 = array();
                $found_value2 = array();
                if (is_null($pass))
                {
                        $pass = $this->getSolutionMaxPass($active_id);
                }
                $result = $ilDB->queryF("SELECT * FROM tst_solutions WHERE active_fi = %s AND question_fi = %s AND pass = %s",
                        array('integer','integer','integer'),
                        array($active_id, $this->getId(), $pass)
                );
                $user_order = array();
                while ($data = $ilDB->fetchAssoc($result))
                {
                        if ((strcmp($data["value1"], "") != 0) && (strcmp($data["value2"], "") != 0))
                        {
                                $user_order[$data["value2"]] = $data["value1"];
                        }
                }
                ksort($user_order);
                $user_order = array_values($user_order);
                $points = 0;
                $correctcount = 0;
                foreach ($this->answers as $index => $answer)
                {
                        if ($index == $user_order[$index])
                        {
                                $correctcount++;
                        }
                }
                if ($correctcount == count($this->answers))
                {
                        $points = $this->getPoints();
                }

                $points = parent::calculateReachedPoints($active_id, $pass = NULL, $points);
                return $points;
        }

        public function getMaximumPoints()
        {
                return $this->getPoints();
        }

        /*
        * Returns the encrypted save filename of a matching picture
        * Images are saved with an encrypted filename to prevent users from
        * cheating by guessing the solution from the image filename
        * 
        * @param string $filename Original filename
        * @return string Encrypted filename
        */
        public function getEncryptedFilename($filename)
        {
                $extension = "";
                if (preg_match("/.*\\.(\\w+)$/", $filename, $matches))
                {
                        $extension = $matches[1];
                }
                return md5($filename) . "." . $extension;
        }
        
        protected function cleanImagefiles()
        {
                if ($this->getOrderingType() == OQ_PICTURES)
                {
                        if (@file_exists($this->getImagePath()))
                        {
                                $contents = ilUtil::getDir($this->getImagePath());
                                foreach ($contents as $f)
                                {
                                        if (strcmp($f['type'], 'file') == 0)
                                        {
                                                $found = false;
                                                foreach ($this->getAnswers() as $answer)
                                                {
                                                        if (strcmp($f['entry'], $answer->getAnswertext()) == 0) $found = true;
                                                        if (strcmp($f['entry'], $this->getThumbPrefix() . $answer->getAnswertext()) == 0) $found = true;
                                                }
                                                if (!$found)
                                                {
                                                        if (@file_exists($this->getImagePath() . $f['entry'])) @unlink($this->getImagePath() . $f['entry']);
                                                }
                                        }
                                }
                        }
                }
                else
                {
                        if (@file_exists($this->getImagePath()))
                        {
                                ilUtil::delDir($this->getImagePath());
                        }
                }
        }

        /*
        * Deletes an imagefile from the system if the file is deleted manually
        * 
        * @param string $filename Image file filename
        * @return boolean Success
        */
        public function deleteImagefile($filename)
        {
                $deletename = $$filename;
                $result = @unlink($this->getImagePath().$deletename);
                $result = $result & @unlink($this->getImagePath().$this->getThumbPrefix() . $deletename);
                return $result;
        }

        function setImageFile($image_tempfilename, $image_filename, $previous_filename)
        {
                $result = TRUE;
                if (strlen($image_tempfilename))
                {
                        $image_filename = str_replace(" ", "_", $image_filename);
                        $imagepath = $this->getImagePath();
                        if (!file_exists($imagepath))
                        {
                                ilUtil::makeDirParents($imagepath);
                        }
                        $savename = $image_filename;
                        if (!ilUtil::moveUploadedFile($image_tempfilename, $savename, $imagepath.$savename))
                        {
                                $result = FALSE;
                        }
                        else
                        {
                                // create thumbnail file
                                $thumbpath = $imagepath . $this->getThumbPrefix() . $savename;
                                ilUtil::convertImage($imagepath.$savename, $thumbpath, "JPEG", $this->getThumbGeometry());
                        }
                        if ($result && (strcmp($image_filename, $previous_filename) != 0) && (strlen($previous_filename)))
                        {
                                $this->deleteImagefile($previous_filename);
                        }
                }
                return $result;
        }

        function checkSaveData()
        {
                $result = true;
                if ($this->getOutputType() == OUTPUT_JAVASCRIPT)
                {
                        if (strlen($_POST["orderresult"]))
                        {
                                return $result;
                        }
                }
                $order_values = array();
                foreach ($_POST as $key => $value)
                {
                        if (preg_match("/^order_(\d+)/", $key, $matches))
                        {
                                if (strcmp($value, "") != 0)
                                {
                                        array_push($order_values, $value);
                                }
                        }
                }
                $check_order = array_flip($order_values);
                if (count($check_order) != count($order_values))
                {
                        // duplicate order values!!!
                        $result = false;
                        ilUtil::sendInfo($this->lng->txt("duplicate_order_values_entered"), TRUE);
                }
                return $result;
        }

        function saveWorkingData($active_id, $pass = NULL)
        {
                global $ilDB;
                global $ilUser;

                $saveWorkingDataResult = $this->checkSaveData();
                $entered_values = 0;
                if ($saveWorkingDataResult)
                {
                        if (is_null($pass))
                        {
                                include_once "./Modules/Test/classes/class.ilObjTest.php";
                                $pass = ilObjTest::_getPass($active_id);
                        }

                        $affectedRows = $ilDB->manipulateF("DELETE FROM tst_solutions WHERE active_fi = %s AND question_fi = %s AND pass = %s",
                                array('integer','integer','integer'),
                                array($active_id, $this->getId(), $pass)
                        );
                        if (array_key_exists("orderresult", $_POST))
                        {
                                $orderresult = $_POST["orderresult"];
                                if (strlen($orderresult))
                                {
                                        $orderarray = explode(":", $orderresult);
                                        $ordervalue = 1;
                                        foreach ($orderarray as $index)
                                        {
                                                if (preg_match("/id_(\\d+)/", $index, $idmatch))
                                                {
                                                        $randomid = $idmatch[1];
                                                        foreach ($this->getAnswers() as $answeridx => $answer)
                                                        {
                                                                if ($answer->getRandomID() == $randomid)
                                                                {
                                                                        $next_id = $ilDB->nextId('tst_solutions');
                                                                        $affectedRows = $ilDB->insert("tst_solutions", array(
                                                                                "solution_id" => array("integer", $next_id),
                                                                                "active_fi" => array("integer", $active_id),
                                                                                "question_fi" => array("integer", $this->getId()),
                                                                                "value1" => array("clob", $answeridx),
                                                                                "value2" => array("clob", trim($ordervalue)),
                                                                                "pass" => array("integer", $pass),
                                                                                "tstamp" => array("integer", time())
                                                                        ));
                                                                        $ordervalue++;
                                                                        $entered_values++;
                                                                }
                                                        }
                                                }
                                        }
                                }
                        }
                        else
                        {
                                foreach ($_POST as $key => $value)
                                {
                                        if (preg_match("/^order_(\d+)/", $key, $matches))
                                        {
                                                if (!(preg_match("/initial_value_\d+/", $value)))
                                                {
                                                        if (strlen($value))
                                                        {
                                                                foreach ($this->getAnswers() as $answeridx => $answer)
                                                                {
                                                                        if ($answer->getRandomID() == $matches[1])
                                                                        {
                                                                                $next_id = $ilDB->nextId('tst_solutions');
                                                                                $affectedRows = $ilDB->insert("tst_solutions", array(
                                                                                        "solution_id" => array("integer", $next_id),
                                                                                        "active_fi" => array("integer", $active_id),
                                                                                        "question_fi" => array("integer", $this->getId()),
                                                                                        "value1" => array("clob", $answeridx),
                                                                                        "value2" => array("clob", $value),
                                                                                        "pass" => array("integer", $pass),
                                                                                        "tstamp" => array("integer", time())
                                                                                ));
                                                                                $entered_values++;
                                                                        }
                                                                }
                                                        }
                                                }
                                        }
                                }
                        }
                }
                if ($entered_values)
                {
                        include_once ("./Modules/Test/classes/class.ilObjAssessmentFolder.php");
                        if (ilObjAssessmentFolder::_enabledAssessmentLogging())
                        {
                                $this->logAction($this->lng->txtlng("assessment", "log_user_entered_values", ilObjAssessmentFolder::_getLogLanguage()), $active_id, $this->getId());
                        }
                }
                else
                {
                        include_once ("./Modules/Test/classes/class.ilObjAssessmentFolder.php");
                        if (ilObjAssessmentFolder::_enabledAssessmentLogging())
                        {
                                $this->logAction($this->lng->txtlng("assessment", "log_user_not_entered_values", ilObjAssessmentFolder::_getLogLanguage()), $active_id, $this->getId());
                        }
                }
    parent::saveWorkingData($active_id, $pass);
                return $saveWorkingDataResult;
        }

        function getQuestionType()
        {
                return "assOrderingQuestion";
        }

        function getAdditionalTableName()
        {
                return "qpl_qst_ordering";
        }

        function getAnswerTableName()
        {
                return "qpl_a_ordering";
        }

        function getRTETextWithMediaObjects()
        {
                $text = parent::getRTETextWithMediaObjects();
                foreach ($this->answers as $index => $answer)
                {
                        $answer_obj = $this->answers[$index];
                        $text .= $answer_obj->getAnswertext();
                }
                return $text;
        }
        
        function &getAnswers()
        {
                return $this->answers;
        }

        function supportsJavascriptOutput()
        {
                return TRUE;
        }

        public function setExportDetailsXLS(&$adapter, $startrow, $active_id, $pass)
        {
                $solutions = $this->getSolutionValues($active_id, $pass);
                $sol = array();
                foreach ($solutions as $solution)
                {
                        $sol[$solution["value1"]] = $solution["value2"];
                }
                asort($sol);
                $sol = array_keys($sol);
                $adapter->setCellValue($startrow, 0, $this->lng->txt($this->getQuestionType()), CELL_FORMAT_TITLE);
                $adapter->setCellValue($startrow, 1, $this->getTitle(), CELL_FORMAT_TITLE);
                $i = 1;
                $answers = $this->getAnswers();
                foreach ($sol as $idx)
                {
                        foreach ($solutions as $solution)
                        {
                                if ($solution["value1"] == $idx) $adapter->setCellValue($startrow+$i, 0, $solution["value2"]);
                        }
                        $adapter->setCellValue($startrow+$i, 1, $answers[$idx]->getAnswertext());
                        $i++;
                }
                return $startrow + $i + 1;
        }

        /*
        * Get the thumbnail geometry
        *
        * @return integer Geometry
        */
        public function getThumbGeometry()
        {
                return $this->thumb_geometry;
        }
        
        public function getThumbSize()
        {
                return $this->getThumbGeometry();
        }

        /*
        * Set the thumbnail geometry
        *
        * @param integer $a_geometry Geometry
        */
        public function setThumbGeometry($a_geometry)
        {
                $this->thumb_geometry = ($a_geometry < 1) ? 100 : $a_geometry;
        }

        /*
        * Get the minimum element height
        *
        * @return integer Height
        */
        public function getElementHeight()
        {
                return $this->element_height;
        }
        
        /*
        * Set the minimum element height
        *
        * @param integer $a_height Height
        */
        public function setElementHeight($a_height)
        {
                $this->element_height = ($a_height < 20) ? "" : $a_height;
        }

        /*
        * Rebuild the thumbnail images with a new thumbnail size
        */
        public function rebuildThumbnails()
        {
                if ($this->getOrderingType() == OQ_PICTURES)
                {
                        foreach ($this->getAnswers() as $answer)
                        {
                                $this->generateThumbForFile($this->getImagePath(), $answer->getAnswertext());
                        }
                }
        }
        
        public function getThumbPrefix()
        {
                return "thumb.";
        }
        
        protected function generateThumbForFile($path, $file)
        {
                $filename = $path . $file;
                if (@file_exists($filename))
                {
                        $thumbpath = $path . $this->getThumbPrefix() . $file;
                        $path_info = @pathinfo($filename);
                        $ext = "";
                        switch (strtoupper($path_info['extension']))
                        {
                                case 'PNG':
                                        $ext = 'PNG';
                                        break;
                                case 'GIF':
                                        $ext = 'GIF';
                                        break;
                                default:
                                        $ext = 'JPEG';
                                        break;
                        }
                        ilUtil::convertImage($filename, $thumbpath, $ext, $this->getThumbGeometry());
                }
        }
        
        public function toJSON()
        {
                include_once("./Services/RTE/classes/class.ilRTE.php");
                $result = array();
                $result['id'] = (int) $this->getId();
                $result['type'] = (string) $this->getQuestionType();
                $result['title'] = (string) $this->getTitle();
                $result['question'] =  (string) ilRTE::_replaceMediaObjectImageSrc($this->getQuestion(), 0);
                $result['nr_of_tries'] = (int) $this->getNrOfTries();
                $result['shuffle'] = (bool) true;
                $result['points'] = (bool) $this->getPoints();
                $result['feedback'] = array(
                        "onenotcorrect" => nl2br(ilRTE::_replaceMediaObjectImageSrc($this->getFeedbackGeneric(0), 0)),
                        "allcorrect" => nl2br(ilRTE::_replaceMediaObjectImageSrc($this->getFeedbackGeneric(1), 0))
                        );
                $counter = 1;
                $answers = array();
                foreach ($this->getAnswers() as $answer_obj)
                {
                        $answers[$counter] = $answer_obj->getAnswertext();
                        $counter++;
                }
                $answers = $this->pcArrayShuffle($answers);
                $arr = array();
                foreach ($answers as $order => $answer)
                {
                        array_push($arr, array(
                                "answertext" => (string) $answer,
                                "order" => (int) $order
                        ));
                }
                $result['answers'] = $arr;
                $mobs = ilObjMediaObject::_getMobsOfObject("qpl:html", $this->getId());
                $result['mobs'] = $mobs;
                return json_encode($result);
        }

        public function removeAnswerImage($index)
        {
                $answer = $this->answers[$index];
                if (is_object($answer))
                {
                        $this->deleteImagefile($answer->getAnswertext());
                        $answer->setAnswertext('');
                }
        }

}

?>