ViewUI::getOverrideValues

public ViewUI::getOverrideValues($form, FormStateInterface $form_state)

public function getOverrideValues($form, FormStateInterface $form_state) {
  // Make sure the dropdown exists in the first place.
  if ($form_state->hasValue(array('override', 'dropdown'))) {
    // #default_value is used to determine whether it was the default value or not.
    // So the available options are: $display, 'default' and 'default_revert', not 'defaults'.
    $was_defaulted = ($form['override']['dropdown']['#default_value'] === 'defaults');
    $dropdown = $form_state->getValue(array('override', 'dropdown'));
    $is_defaulted = ($dropdown === 'default');
    $revert = ($dropdown === 'default_revert');

    if ($was_defaulted !== $is_defaulted && isset($form['#section'])) {
      // We're changing which display these values apply to.
      // Update the #section so it knows what to mark changed.
      $form['#section'] = str_replace('default-', $form_state->get('display_id') . '-', $form['#section']);
    }
  }
  else {
    // The user didn't get the dropdown for overriding the default display.
    $was_defaulted = FALSE;
    $is_defaulted = FALSE;
    $revert = FALSE;
  }

  return array($was_defaulted, $is_defaulted, $revert);
}