islandora/islandora_basic_image/islandora_basic_image.install

<?php

function islandora_basic_image_install() {
  $t = get_t();

  $basic_image_content_type = array(
    'type' => 'basic_image',
    'name' => $t('Basic Image'),
    'base' => 'node_content',
    'description' => $t('An image object in Fedora'),
  );

  $basic_image_content_type = node_type_set_defaults($basic_image_content_type);

  $status = node_type_save($basic_image_content_type);

  $t_args = array('%name' => $basic_image_content_type->name);

  if ($status == SAVED_UPDATED) {
    drupal_set_message($t('Updated %name content type.', $t_args));
  }
  elseif ($status == SAVED_NEW) {
    drupal_set_message($t('Created %name content type.', $t_args));
  }

  $tn_field_name = 'field_tn';
  if (field_info_field($tn_field_name)) {
    $tn_field_instance = array(
      'field_name' => $tn_field_name,
      'entity_type' => 'node',
      'bundle' => 'basic_image',
      'label' => $t("Thumbnail"),
      'description' => $t("A thumbnail for the Fedora resource"),
      'required' => FALSE,
      'settings' => array(
        'file_extensions' => 'png jpg jpeg gif',
        'max_filesize' => '1 MB',
      ),
    );
    field_create_instance($tn_field_instance);
    drupal_set_message($t('Field %name was created successfully', array('%name' => $tn_field_name))); 
  }
}

function islandora_basic_image_uninstall() {
  field_delete_instance(field_info_instance('node_content', 'field_tn', 'basic_image'));
  node_type_delete('basic_image');
}