Mike42\Escpos\EscposImage::getRasterFormatFromFile PHP Метод

getRasterFormatFromFile() защищенный Метод

protected getRasterFormatFromFile ( string $filename = null ) : string | null
$filename string Filename to load from
Результат string | null Raster format data, or NULL if no optimised renderer is available in this implementation.
    protected function getRasterFormatFromFile($filename = null)
    {
        // No optimised implementation to provide
        return null;
    }