Example of pre hook_islandora_derivative derivative generation in Islandora

gistfile1.php

<?php

/**
 * Implements hook_CMODEL_PID_islandora_object_ingested().
 */

function islandora_pdf_islandora_sp_pdf_islandora_object_ingested($object) {
  module_load_include('inc', 'islandora_pdf', 'includes/derivatives');
  islandora_pdf_create_all_derivatives($object);
}


function islandora_pdf_create_all_derivatives(AbstractObject $object) {
  if (!isset($object['OBJ'])) {
    drupal_set_message(t('Could not create image derivatives for %s. No image file was uploaded.',
      array('%s' => $object->id)), 'error');
    return FALSE;
  }
  $success = TRUE;
  $file_uri = islandora_pdf_get_derivative_source_as_unmanaged_file($object);
  $success &= islandora_pdf_add_tn_derivative($object, $file_uri);
  $success &= islandora_pdf_add_preview_derivative($object, $file_uri);

  if (!isset($object['FULL_TEXT']) && variable_get('islandora_pdf_create_fulltext', FALSE)) {
    $success &= islandora_pdf_add_fulltext_derivative($object, $file_uri);
  }
  file_unmanaged_delete($file_uri);
  return $success;
}


?>