function bp_friends_filter_activity_scope( $retval = array(), $filter = array() ) {

	// Determine the user_id.
	if ( ! empty( $filter['user_id'] ) ) {
		$user_id = $filter['user_id'];
	} else {
		$user_id = bp_displayed_user_id()
			? bp_displayed_user_id()
			: bp_loggedin_user_id();
	}

	// Determine friends of user.
	$friends = friends_get_friend_user_ids( $user_id );
	if ( empty( $friends ) ) {
		$friends = array( 0 );
	}

	$retval = array(
		'relation' => 'AND',
		array(
			'column'  => 'user_id',
			'compare' => 'IN',
			'value'   => (array) $friends
		),

		// We should only be able to view sitewide activity content for friends.
		array(
			'column' => 'hide_sitewide',
			'value'  => 0
		),

		// Overrides.
		'override' => array(
			'filter'      => array( 'user_id' => 0 ),
			'show_hidden' => true
		),
	);

	return $retval;
}