Excel width calculation

 /**
     * @param mixed $value
     * @param Font  $font
     * @return float
     */
    public function getRenderedCellWidth($value, Font $font)
    {
        $box = imageftbbox($font->getSize(), 0, $this->getFontPath($font), $value);
        $pixels = abs($box[4] - $box[0]);
        $width = round(($pixels + 5) / 7, 3);

        return $width + 0.7;
    }

    /**
     * @param Font $font
     * @return string
     */
    public function getFontPath(Font $font)
    {
        return __DIR__ . '/fonts/' . $this->fontMap[$font->getName()] . '.ttf';
    }