By default, Drupal Form API would render each element per row. To alter the presentation, we have several ways. The simplest one is by defining #suffix, #prefix attributes in the form elements. The prefered one is by defining the theme function that would override the default presentation. Consider the following form definition:-

function customer_form($customer) {
  $form = array();
  $form['name'] = array('#type' => 'textfield',
    '#default_value' => $customer->name,
    '#title' => 'Nama');
  $form['address'] = array('#type' => 'textarea',
    '#default_value' => $customer->address,
    '#size' => 30,
    '#title' => 'Alamat');
  $form['postcode'] = array('#type' => 'textfield',
    '#title' => t('Poskod'),
    '#size' => 5,
    '#maxlength' => 5,
    '#default_value' => $customer->postcode);
  $form['city'] = array('#type' => 'textfield',
    '#title' => t('Bandar'),
    '#size' => 30,
    '#default_value' => $customer->city);
}

The form is build by the following function:-

function customer_new($customer) {
  return drupal_get_form('customer_new', customer_form($customer));
}

So to override the default presentation, we define the theme function as `theme_form_id`:-

function theme_customer_new($form) {
  $output = new Container;
  $output->add(form_render($form['name']));
  $table = html_table();
  $table->add_row(form_render($form['address']), form_render($form['city']), form_render($form['postcode']));
  $output->add($table);
  // render the rest of the elements
  $output->add(form_render($form));
  return $output->render();
}

References:- http://drupal.org/node/47582

Notes:- This example make use PHPHtmllib library to build the HTML table.

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