source: sipes/modules_contrib/captcha/image_captcha/image_captcha.install @ 92213c1

<?php

/*
 * @file
 * Installation/uninstallation related functions for the image_captcha module.
 */

/**
 * Implementation of hook_requirements().
 */
function image_captcha_requirements($phase) {
  $requirements = array();
  $t = get_t();
  if ($phase == 'install') {
    // _image_captcha_check_setup() is defined in image_captcha.module.
    // We use a trick based on __FILE__ instead of a call to
    // module_load_include(), because the latter is not available when
    // this module is installed as part of an installation profile.
    include_once(dirname(__FILE__) .'/image_captcha.module');
    // Check if the GD library is available and raise an error when not.
    if (_image_captcha_check_setup(FALSE) & IMAGE_CAPTCHA_ERROR_NO_GDLIB) {
      $requirements['image_captcha_requires_gd'] = array(
        'title' => $t('Image CAPTCHA requires GD library'),
        'description' =>
          $t('The Image CAPTCHA module can not be installed because your PHP setup does not provide the <a href="!gddoc">GD library</a>, which is required to generate images.',
            array('!gddoc' => 'http://www.php.net/manual/en/book.image.php',)
          ),
        'severity' => REQUIREMENT_ERROR,
      );
    }
  }
  return $requirements;
}

/**
 * On uninstall: remove module variables and clear variable cache
 */
function image_captcha_uninstall() {
  db_query("DELETE FROM {variable} WHERE name LIKE 'image_captcha_%'");
  cache_clear_all('variables', 'cache');
}

/**
 * Implementation of hook_update_N()
 */
function image_captcha_update_6201() {
  // Fixing a typo in a variable.
  $old = 'image_captcha_bilinair_interpolation';
  $new = 'image_captcha_bilinear_interpolation';
  variable_set($new, variable_get($old, FALSE));
  variable_del($old);
  $items = array();
  return $items;
}

/**
 * Implementation of hook_update_N().
 *
 * Translate single font variable to multiple font variable.
 */
function image_captcha_update_6203() {
  // Old single font variable.
  $font = variable_get('image_captcha_font', NULL);
  // If there was a valid value,
  // save it as an array to the new multiple fonts variable.
  if ($font != NULL) {
    variable_set('image_captcha_fonts', array($font));
  }
  return array();
}