I have build simple module form using form api to upload a txt document.
The txt document then process and convert to pdf document, a link to download pdf is given

here my code

function modulku_menu() {
  $items = array();
  $items['module/form'] = array(
    'title' => t('My form'),
    'page callback' => 'modulku_form',
    'access arguments' => array('access content'),
    'description' => t('My form'),
    'type' => MENU_CALLBACK,
  );
  return $items;
}

function modulku_form() {
  return drupal_get_form('myform');
}
function myform() {
  $form = array();
  // If this #attribute is not present, upload will fail on submit
  $form['#attributes']['enctype'] = 'multipart/form-data';
  $form['file_upload'] = array(
    '#title' => t('Upload file'),
    '#type'  => 'file',
  );
  $form['submit_upload'] = array(
    '#type'  =>  'submit',
    '#value'  =>  'Submit'
  );
  return $form;
}

function myform_submit($form, &$form_state) {
  $validators = array();
  $dest = 'upload_directory';
  $file = file_save_upload('file_upload', $validators, $dest);
  if ($file != 0) {
        $random_digit=rand(0,9);
        $new_file_name=$random_digit.$file->filename;
        $dest_path = $new_file_name;
    $result = file_copy($file, $dest_path, FILE_EXISTS_RENAME);
    if ($result == 1) {
        $path= $new_file_name;
        //process and convert in here
$filepdf="$PATH/$name.pdf";

        if (file_exists($filepdf)) {
                echo "$filepdf created <BR/>";
                echo "$filepdfF can be download it <a href=$name.pdf>here</a> <BR/>";
        } else {
                echo "The file $filepdf does not exist";}
    }
    else {
      //Failure
    }
  }
  else {
    form_set_error('myform', t("Failed to save the file."));
  }
}
?>

The upload process is running well, and the converting process also work,
the question is how can I make the download link result is better than just plain hmtl
     echo "$filepdf created <BR/>";
                echo "$filepdfF can be download it <a href=$name.pdf>here</a> <BR/>";
       

I mean, the result page also "inside" the drupal theme not only the plain html page

Regards
wa2nlinux