private function getCharacterWidth($fontName, $fontSize, $char)
    {
        if (!isset($this->sizes[$fontName][$fontSize][$char])) {
            $this->sizes[$fontName][$fontSize][$char] =
                $this->calculateCharacterWith($fontName, $fontSize, $char);
        }

        return $this->sizes[$fontName][$fontSize][$char];
    }