Return additional theme engines provided by modules.
This hook is invoked from _system_rebuild_theme_data() and allows modules to register additional theme engines outside of the regular 'themes/engines' directories of a Drupal installation.
An associative array. Each key is the system name of a theme engine and each value is the corresponding path to the theme engine's .engine file.
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_system_theme_engine_info() {
$theme_engines['izumi'] = drupal_get_path('module', 'mymodule') . '/izumi/izumi.engine';
return $theme_engines;
}