iframe formatter

Here is my code that adds an iframe formatter. I haven't figured out how to add this formatter without modifying the link.module file.

/**
 * Implements hook_theme(). (modified)
 */
function link_theme() {
  return array(
    /*'link_field_settings' => array(
      'variables' => array('element' => NULL),
    ),*/
    'link_formatter_link_default' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_plain' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_title_plain' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_url' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_short' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_label' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_separate' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_iframe' => array(
      'variables' => array('element' => NULL),
    ),
    'link_field' => array(
      'render element' => 'element',
    ),
  );
}

/**
 * Implementation of hook_field_formatter_info(). (modified)
 */
function link_field_formatter_info() {
  return array(
    'link_default' => array(
      'label' => t('Title, as link (default)'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_title_plain' => array(
      'label' => t('Title, as plain text'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_url' => array(
      'label' => t('URL, as link'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_plain' => array(
      'label' => t('URL, as plain text'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_short' => array(
      'label' => t('Short, as link with title "Link"'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_label' => array(
      'label' => t('Label, as link with label as title'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_separate' => array(
      'label' => t('Separate title and URL'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_iframe' => array(
      'label' => t('Embedded iframe'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
      'settings' => array(
        'width' => '400',
        'height' => '300',
      ),
    ),
  );
}

/**
 * Implements hook_field_formatter_settings_form(). (new)
 */
function link_field_formatter_settings_form($field, $instance, $view_mode, $form, &$form_state) {
  $display = $instance['display'][$view_mode];
  $settings = $display['settings'];
  $element = array();
  if ($display['type'] == 'link_iframe') {
    $element['width'] = array(
      '#title' => t('Width'),
      '#type' => 'textfield',
      '#size' => 10,
      '#default_value' => $settings['width'],
      '#element_validate' => array('element_validate_integer_positive'),
      '#required' => TRUE,
    );
    $element['height'] = array(
      '#title' => t('Height'),
      '#type' => 'textfield',
      '#size' => 10,
      '#default_value' => $settings['height'],
      '#element_validate' => array('element_validate_integer_positive'),
      '#required' => TRUE,
    );
  }
  return $element;
}

/**
 * Implements hook_field_formatter_settings_summary(). (new)
 */
function link_field_formatter_settings_summary($field, $instance, $view_mode) {
  $display = $instance['display'][$view_mode];
  $settings = $display['settings'];
  $summary = $display['type'] == 'link_iframe' ?
  	'width='. $settings['width'] .' height='. $settings['height'] : '';
  return $summary;
}

/**
 * Theme function for 'iframe' link field formatter. (new)
 */
function theme_link_formatter_link_iframe($vars) {
	//see($vars['field']['display']);
	return '<iframe width="'. $vars['field']['display']['default']['settings']['width'] .' "height="' .
		$vars['field']['display']['default']['settings']['height'] .'" src="'. $vars['element']['url']
		.'" frameborder="0" allowfullscreen></iframe><br />'. $vars['element']['title'];
}

Just talk about problem.