protected function createCanvas()
    {
        $this->canvas['canvas'] = imagecreatetruecolor($this->canvas['width'], $this->canvas['height']);
        if ($this->canvas['canvas'] === false) {
            throw new \Exception(Helper::ERROR_CALL_IMAGECREATETRUECOLOR);
        }

        $fill_color = imagecolorallocate($this->canvas['canvas'], $this->canvas['color']['r'],
            $this->canvas['color']['g'], $this->canvas['color']['b']);
        if ($fill_color === false) {
            throw new \Exception(Helper::ERROR_CALL_IMAGECOLORALLOCATE);
        }

        if (imagefill($this->canvas['canvas'], 0, 0, $fill_color) === false) {
            throw new \Exception(Helper::ERROR_CALL_IMAGEFILL);
        };
    }