public function upload_preview()
 {
     global $CFG;
     $imagefolder = $CFG->dataroot . '/temp/assignsubmission_pdf/img';
     if (!check_dir_exists($imagefolder, true, true)) {
         echo "Unable to create temporary image folder";
         die;
     }
     $mform = new edit_templates_form();
     $fname = $mform->save_temp_file('preview');
     if (!$fname) {
         return;
     }
     $pdf = new AssignPDFLib();
     $pdf->load_pdf($fname);
     $pdf->set_image_folder($imagefolder);
     $imgname = $pdf->get_image(1);
     $context = context_course::instance($this->courseid);
     $fs = get_file_storage();
     if ($oldfile = $fs->get_file($context->id, 'assignsubmission_pdf', 'previewimage', 0, '/', 'preview.png')) {
         $oldfile->delete();
     }
     $imginfo = array('contextid' => $context->id, 'component' => 'assignsubmission_pdf', 'filearea' => 'previewimage', 'itemid' => 0, 'filepath' => '/', 'filename' => 'preview.png');
     $fs->create_file_from_pathname($imginfo, $imagefolder . '/' . $imgname);
     // Copy the image into the file storage.
     // Delete the temporary files.
     unlink($fname);
     unlink($imagefolder . '/' . $imgname);
     $this->imagetime = time();
 }
 function upload_preview()
 {
     global $CFG;
     $imagefolder = $CFG->dataroot . '/temp/uploadpdf/img';
     if (!file_exists($imagefolder)) {
         if (!mkdir($imagefolder, 0777, true)) {
             echo "Unable to create temporary image folder";
             die;
         }
     }
     $mform = new edit_templates_form();
     $fname = $mform->save_temp_file('preview');
     if (!$fname) {
         return;
     }
     $pdf = new MyPDFLib();
     $pdf->load_pdf($fname);
     $pdf->set_image_folder($imagefolder);
     $imgname = $pdf->get_image(1);
     $context = get_context_instance(CONTEXT_COURSE, $this->courseid);
     $fs = get_file_storage();
     if ($oldfile = $fs->get_file($context->id, 'mod_assignment', 'previewimage', 0, '/', 'preview.png')) {
         $oldfile->delete();
     }
     $imginfo = array('contextid' => $context->id, 'component' => 'mod_assignment', 'filearea' => 'previewimage', 'itemid' => 0, 'filepath' => '/', 'filename' => 'preview.png');
     $file = $fs->create_file_from_pathname($imginfo, $imagefolder . '/' . $imgname);
     // Copy the image into the file storage
     //Delete the temporary files
     unlink($fname);
     unlink($imagefolder . '/' . $imgname);
     $this->imagetime = time();
 }