PHP : trim text function.php

/**
 * Trims text to a space then adds ellipses if desired
 * 
 * @param string $input text to trim
 * @param int $length in characters to trim to
 * @param bool $ellipses if ellipses (...) are to be added
 * @param bool $strip_html if html tags are to be stripped
 * @return string
 */
function trim_text( $input, $length, $ellipses = true, $strip_html = true ) {
 
    //strip tags, if desired
    if ( $strip_html )
        $input = strip_tags( $input );
 
    //no need to trim, already shorter than trim length
    if ( mb_strlen( $input ) <= $length )
        return $input;
 
    //find last space within length
    $last_space = strrpos( substr($input, 0, $length), ' ' );
    $trimmed_text = substr( $input, 0, $last_space );
 
    //add ellipses (...)
    if ( $ellipses )
        $trimmed_text .= '...';
 
    return $trimmed_text;
 
}