Allow external definition of additional regions

I'm just about to introduce some regions in the pattern [node_type]_header, [node_type]_payment etc. for some CCK-based forms. If you come up with some code, I'm happy to test a patch, or I might get around to writing a patch next week.

FYI, I have some code like the following:

/**
 * Introduce hook_node_form_regions(). Needs to return array of regions keyed by content type.
 * e.g. 'page' => array('header' => t('Header'));
 */
function nodeformcols_form_regions($type = '') {
  
  $node_form_region_hooks = module_invoke_all('node_form_regions');
  if (!empty($type) && in_array($type, array_keys($node_form_region_hooks))) {
    $regions = $node_form_region_hooks[$type];
    return $regions;
  }

  return array(
    'main' => t('Main column'),
    'right' => t('Right'),
    'footer' => t('Footer'),
  );
}

i.e. pass content type to region definition and if a hook exists, retrieve region definitions from the hook.

Similarly, since each content type can define it's own regions, it also needs to define its own default placements.

/**
 * Gets default placements for standard fields
 *
 * @return array
 */
function _nodeformscols_default_field_placements($type) {

  $node_form_default_field_placements_hooks = module_invoke_all('default_field_placements');
  if (!empty($type) && in_array($type, array_keys($node_form_default_field_placements_hooks))) {
    $default_field_placements = $node_form_default_field_placements_hooks[$type];
    return $default_field_placements;
  }

  return array(
    'title' => array('region' => 'main'),
    'body_field' => array('region' => 'main'),
    'menu' => array('region' => 'right'),
    'revision_information' => array('region' => 'right'),
    'comment_settings' => array('region' => 'right'),
    'path' => array('region' => 'right'),
    'options' => array('region' => 'right'),
    'author' => array('region' => 'right'),
    'buttons' => array('region' => NODEFORMCOLS_DEFAULT_REGION, 'weight' => 100),
  );
}

This isn't quite ideal as if there is no common region between two node types the fields don't show up in the Manage Form list of fields by region.

Perhaps the set of regions returned from the content type need to be merged with the base set defined by nodeformcols?

Agreed, drupal_alter() is a more appropriate solution.

So in nodeformcols.module, I have:

/**
 * Introduce hook_nodeformcols_form_regions_alter().
 */
function nodeformcols_form_regions($type = '') {

  $regions = array(
    'main' => t('Main column'),
    'right' => t('Right'),
    'footer' => t('Footer'),
  );

  drupal_alter('nodeformcols_form_regions', $regions, $type);

  return $regions;
}

/**
 * Gets default placements for standard fields
 *
 * @return array
 */
function _nodeformscols_default_field_placements($type = '') {

  $placements = array(
    'title' => array('region' => 'main'),
    'body_field' => array('region' => 'main'),
    'menu' => array('region' => 'right'),
    'revision_information' => array('region' => 'right'),
    'comment_settings' => array('region' => 'right'),
    'path' => array('region' => 'right'),
    'options' => array('region' => 'right'),
    'author' => array('region' => 'right'),
    'buttons' => array('region' => NODEFORMCOLS_DEFAULT_REGION, 'weight' => 100),
  );

  drupal_alter('nodeformcols_default_field_placements', $placements, $type);

  return $placements;
}

and in template_preprocess_node_form(), pass type:

$form_regions = nodeformcols_form_regions($form['#node']->type);
  foreach ($form_regions as $name => $title) {

Also, in nodeformcols.admin.inc, pass type

Index: modules/nodeformcols/nodeformcols.admin.inc
===================================================================
--- modules/nodeformcols/nodeformcols.admin.inc	(revision 14797)
+++ modules/nodeformcols/nodeformcols.admin.inc	(working copy)
@@ -110,7 +110,7 @@
   $placements = nodeformscols_field_placements($type, $variant);
   nodeformcols_update_placements($type, $variant, $placements);
 
-  $regions = nodeformcols_form_regions();
+  $regions = nodeformcols_form_regions($type);
 
   $form['type'] = array(
     '#type' => 'value',
@@ -197,7 +197,7 @@
   drupal_add_js(drupal_get_path('module', 'nodeformcols') . '/js/nodeformcols.js');
   drupal_add_css(drupal_get_path('module', 'nodeformcols') . '/css/nodeformcols.admin.css');
 
-  $regions = nodeformcols_form_regions();
+  $regions = nodeformcols_form_regions($form['type']['#value']);
   foreach ($regions as $region => $title) {
     if (is_array($form['conf'][$region])) {
       uasort($form['conf'][$region], "element_sort");

The main sticking point is how to pass $type into the context for nodeformcols-configuration.tpl.php? That's not something I've done before...