FastImage::getChars PHP Method

    private function getChars($n)
    {
        $response = null;
        // do we need more data?
        if ($this->strpos + $n - 1 >= strlen($this->str)) {
            $end = $this->strpos + $n;
            while (strlen($this->str) < $end && $response !== false) {
                // read more from the file handle
                $need = $end - ftell($this->handle);
                if ($response = fread($this->handle, $need)) {
                    $this->str .= $response;
                } else {
                    return false;
                }
            }
        }
        $result = substr($this->str, $this->strpos, $n);
        $this->strpos += $n;
        return $result;
    }