Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Html.php
private function writeChartInCell(Worksheet $pSheet, $coordinates)
    {
        // Construct HTML
        $html = '';

        // Write charts
        foreach ($pSheet->getChartCollection() as $chart) {
            if ($chart instanceof Chart) {
                $chartCoordinates = $chart->getTopLeftPosition();
                if ($chartCoordinates['cell'] == $coordinates) {
                    $chartFileName = File::sysGetTempDir() . '/' . uniqid('', true) . '.png';
                    if (!$chart->render($chartFileName)) {
                        return;
                    }

                    $html .= PHP_EOL;
                    $imageDetails = getimagesize($chartFileName);
                    if ($fp = fopen($chartFileName, 'rb', 0)) {
                        $picture = fread($fp, filesize($chartFileName));
                        fclose($fp);
                        // base64 encode the binary data, then break it
                        // into chunks according to RFC 2045 semantics
                        $base64 = chunk_split(base64_encode($picture));
                        $imageData = 'data:' . $imageDetails['mime'] . ';base64,' . $base64;

                        $html .= '<div style="position: relative;">';
                        $html .= '<img style="position: absolute; z-index: 1; left: ' . $chartCoordinates['xOffset'] . 'px; top: ' . $chartCoordinates['yOffset'] . 'px; width: ' . $imageDetails[0] . 'px; height: ' . $imageDetails[1] . 'px;" src="' . $imageData . '" border="0" />' . PHP_EOL;
                        $html .= '</div>';

                        unlink($chartFileName);
                    }
                }
            }
        }

        // Return
        return $html;
    }
private function writeChartInCell(Worksheet $pSheet, $coordinates)
    {
        // Construct HTML
        $html = '';

        // Write charts
        foreach ($pSheet->getChartCollection() as $chart) {
            if ($chart instanceof Chart) {
                $chartCoordinates = $chart->getTopLeftPosition();
                if ($chartCoordinates['cell'] == $coordinates) {
                    $chartFileName = File::sysGetTempDir() . '/' . uniqid('', true) . '.png';
                    if (!$chart->render($chartFileName)) {
                        return;
                    }

                    $html .= PHP_EOL;
                    $imageDetails = getimagesize($chartFileName);
                    if ($fp = fopen($chartFileName, 'rb', 0)) {
                        $picture = fread($fp, filesize($chartFileName));
                        fclose($fp);
                        // base64 encode the binary data, then break it
                        // into chunks according to RFC 2045 semantics
                        $base64 = chunk_split(base64_encode($picture));
                        $imageData = 'data:' . $imageDetails['mime'] . ';base64,' . $base64;

                        $html .= '<div style="position: relative;">';
                        $html .= '<img style="position: absolute; z-index: 1; left: ' . $chartCoordinates['xOffset'] . 'px; top: ' . $chartCoordinates['yOffset'] . 'px; width: ' . $imageDetails[0] . 'px; height: ' . $imageDetails[1] . 'px;" src="' . $imageData . '" border="0" />' . PHP_EOL;
                        $html .= '</div>';

                        unlink($chartFileName);
                    }
                }
            }
        }

        // Return
        return $html;
    }
Generate chart tag in cell.

@param Worksheet $pSheet \PhpOffice\PhpSpreadsheet\Worksheet\Worksheet
@param string $coordinates Cell coordinates

@return string