Overriding admin settings form from bootstrap sub theme

Question

I need a little help here. I am creating a sub theme of bootstrap theme and I need to add an additional fieldset under "Bootstrap Settings" form (similar to Components, Advanced etc which are currently present) which appears under Appearance->Settings-><THEME NAME> page. I think we can use hook_form_alter() for this but the problem is that hook_form_alter() is being always invoked with $form_id set to "search_form" and never "system_theme_settings". Thus any form updates I am making under this hook are getting applied to search box instead of admin settings form.

I referred code under bootstrap_form_alter() in alter.inc file in bootstrap theme and tried to replicate it in sub theme but it doesn't seem to work. In order to ensure that I am not making any mistakes while creating subtheme I also tried using other available subtheme such as one created by Adam Balsam (he has provided details on this in response to a question here.

Any help/pointers would be greatly appreciated.

I am listing below my code from template.php file of the bootstrap_ignitor sub theme

function bootstrap_ignitor_form_alter(&$form, &$form_state, $form_id) {
  drupal_set_message('<pre>'.print_r($form_id,TRUE).'</pre>'); ***<= this always prints as search_block_form***
  $form['actions']['submit']['#attributes']['class'][] = 'btn';
  _bootstrap_ignitor_settings_form($form, $form_state);
}

function _bootstrap_ignitor_settings_form(&$form, $form_state) {

  // Advanced settings.
  $form['themealter'] = array(
    '#type' => 'fieldset',
    '#title' => t('Theme Alter'),
    '#group' => 'bootstrap',
  );

  $form['themealter']['local_cdn'] = array(
    '#type' => 'fieldset',
    '#title' => t('NewBootstrapCDN'),
    '#description' => t('Testing...'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
  );  

}

Answer 1

You need to create theme-settings.php in your theme directory & add following function in that to add new fields as shown in code below:

<?php
function <THEME_NAME>_form_system_theme_settings_alter(&$form, &$form_state) {
    $form['campaign_pages'] = array(
        '#title' => t('Campaign Pages'),
        '#type' => 'textarea',
        '#description' => t('Specify pages by using their paths. Enter one path per line.'),
        '#default_value' => theme_get_setting('campaign_pages'),
    );

}

Here theme_get_setting stores the value of your field.