public function getRulers($line = 10)
    {
        if ($line == 0) {
            return [];
        }
        $data = [0];
        $percent = ($this->panel->duration / 100);
        $row = $this->panel->duration / $line;
        $precision = $row > 100 ? -2 : -1;
        for ($i = 1; $i < $line; $i++) {
            $ms = round($i * $row, $precision);
            $data[$ms] = $ms / $percent;
        }
        return $data;
    }