BookStack\Services\ExportService::containHtml PHP Метод

    protected function containHtml($htmlContent)
    {
        $imageTagsOutput = [];
        preg_match_all("/\\<img.*src\\=(\\'|\")(.*?)(\\'|\").*?\\>/i", $htmlContent, $imageTagsOutput);
        // Replace image src with base64 encoded image strings
        if (isset($imageTagsOutput[0]) && count($imageTagsOutput[0]) > 0) {
            foreach ($imageTagsOutput[0] as $index => $imgMatch) {
                $oldImgString = $imgMatch;
                $srcString = $imageTagsOutput[2][$index];
                $isLocal = strpos(trim($srcString), 'http') !== 0;
                if ($isLocal) {
                    $pathString = public_path(trim($srcString, '/'));
                } else {
                    $pathString = $srcString;
                }
                if ($isLocal && !file_exists($pathString)) {
                    continue;
                }
                $imageContent = file_get_contents($pathString);
                $imageEncoded = 'data:image/' . pathinfo($pathString, PATHINFO_EXTENSION) . ';base64,' . base64_encode($imageContent);
                $newImageString = str_replace($srcString, $imageEncoded, $oldImgString);
                $htmlContent = str_replace($oldImgString, $newImageString, $htmlContent);
            }
        }
        $linksOutput = [];
        preg_match_all("/\\<a.*href\\=(\\'|\")(.*?)(\\'|\").*?\\>/i", $htmlContent, $linksOutput);
        // Replace image src with base64 encoded image strings
        if (isset($linksOutput[0]) && count($linksOutput[0]) > 0) {
            foreach ($linksOutput[0] as $index => $linkMatch) {
                $oldLinkString = $linkMatch;
                $srcString = $linksOutput[2][$index];
                if (strpos(trim($srcString), 'http') !== 0) {
                    $newSrcString = url($srcString);
                    $newLinkString = str_replace($srcString, $newSrcString, $oldLinkString);
                    $htmlContent = str_replace($oldLinkString, $newLinkString, $htmlContent);
                }
            }
        }
        // Replace any relative links with system domain
        return $htmlContent;
    }