gistfile1.txt

/**
   * Overrides parent::render_grouping().
   */
  function render_grouping($records, $groupings = array(), $group_rendered = NULL) {
    $sets = parent::render_grouping($records, $groupings, $group_rendered);
    // Apply the offset and limit.
    array_walk($sets, array($this, 'group_limit_recursive'));
    return $sets;
  }

  /**
   * Recursively limits the number of rows in nested groups.
   *
   * @param array $group_data
   *   A single level of grouped records.
   *
   * @param mixed $key
   *   The key of the array being passed in. Used for when this function is
   *   called from array_walk() and the like. Do not set directly.
   *
   * @params int $level
   *   The current level we are gathering results for. Used for recursive
   *   operations; do not set directly.
   *
   * @return array
   *   An array with a "rows" property that is recursively grouped by the
   *   grouping fields.
   */
  function group_limit_recursive(&$group_data, $key = NULL, $level = 0) {
    $settings = $this->grouping_limit_settings($level);

    // Slice up the rows according to the offset and limit.
    $group_data['rows'] = array_slice($group_data['rows'], $settings['grouping-offset'], $settings['grouping-limit'], TRUE);
   
    // For each row, if it appears to be another grouping, recurse again.
    foreach ($group_data['rows'] as &$data) {
      if (is_array($data) && isset($data['group']) && isset($data['rows'])) {
        $this->group_limit_recursive($data, NULL, $level + 1);
      }
    }
  }