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<?php
namespace Zotlabs\Thumbs;
use DOMDocument;
use DOMElement;
use DOMXPath;
use GdImage;
use ZipArchive;
/**
* Thumbnail creation for epub files.
*/
class Epubthumb {
/**
* Match for application/epub+zip.
*
* @param string $type MimeType
* @return boolean
*/
function Match(string $type): bool {
return $type === 'application/epub+zip';
}
/**
* Create the thumbnail if the Epub has a cover.
*
* @param array $attach
* @param int $preview_style unused
* @param int $height (optional) default 300
* @param int $width (optional) default 300
*
* @SuppressWarnings(PHPMD.UnusedFormalParameter)
* phpcs:disable Generic.CodeAnalysis.UnusedFunctionParameter.FoundBeforeLastUsed
*/
function Thumb($attach, $preview_style, $height = 300, $width = 300): void {
$file = dbunescbin($attach['content']);
if (!$file) {
return;
}
$image = $this->getCoverFromEpub($file);
if ($image) {
$srcwidth = imagesx($image);
$srcheight = imagesy($image);
$dest = imagecreatetruecolor($width, $height);
imagealphablending($dest, false);
imagesavealpha($dest, true);
imagecopyresampled($dest, $image, 0, 0, 0, 0, $width, $height, $srcwidth, $srcheight);
imagejpeg($dest, "{$file}.thumb");
imagedestroy($image);
imagedestroy($dest);
}
}
/**
* Fetch the cover from the epub archive, if it's present.
*
* There's a few limitations here: This will only work if the cover
* is a raster image of a supported format. SVG does not work, neither
* will other schemes sometimes used for cover/front page.
*
* @param string $filename The local filename of the epub archive.
*
* @return GdImage|false If a cover is found, it is returned as a
* GdImage object. Otherwise return false.
*/
private function getCoverFromEpub(string $filename): GdImage|false {
$epub = new ZipArchive();
$rc = $epub->open($filename, ZipArchive::RDONLY);
if ($rc !== true) {
logger("Error opening file '{$filename}': rc = ${rc}.", LOGGER_DEBUG, LOG_DEBUG);
return false;
}
$cover = false;
$cover_name = $this->parseEpub($epub);
if ($cover_name !== false) {
$cover = $epub->getFromName($cover_name);
if ($cover === false) {
logger("File '{$cover_name}' not found in EPUB.", LOGGER_DEBUG, LOG_DEBUG);
}
}
$epub->close();
if ($cover !== false && !empty($cover)) {
return imagecreatefromstring($cover);
} else {
return false;
}
}
/**
* Parse the epub to find the path of the cover image.
*
* @param ZipArchive $epub An opened epub ZipArchive.
*
* @return string|false The path to the cover image or false.
*/
private function parseEpub(ZipArchive $epub): string|false {
$packagePath = $this->getEpubPackagePath($epub);
if ($packagePath !== false) {
$package = $epub->getFromName($packagePath);
if ($package === false || empty($package)) {
logger("Package file '${packagePath}' not found in EPUB", LOGGER_DEBUG, LOG_DEBUG);
return false;
}
$domdoc = new DOMDocument();
$domdoc->loadXML($package);
$xpath = new DOMXPath($domdoc);
$xpath->registerNamespace("n", "http://www.idpf.org/2007/opf");
$nodes = $xpath->query('/n:package/n:manifest/n:item[@properties="cover-image"]');
if ($nodes->count() === 0) {
logger('No cover found in EPUB manifest.', LOGGER_DEBUG, LOG_DEBUG);
return false;
}
$node = $nodes->item(0);
if ($node === null) {
logger('No nodes in non-empty node list?', LOGGER_DEBUG, LOG_DEBUG);
return false;
}
if (is_a($node, DOMElement::class)) {
// The URL's in the package file is relative to the subdirectory
// within the epub archive where it is located. See
// https://www.w3.org/TR/epub-33/#sec-parsing-urls-metainf
return dirname($packagePath) . '/' . $node->getAttribute('href');
}
}
return false;
}
/**
* Locate the package file within the epub.
*
* The package file in an epub archive contains the manifest
* that again may contain a reference to the cover for the
* epub.
*
* @param ZipArchive $epub An opened epub archive.
*
* @return string|false The full pathname of the package file or false.
*/
private function getEpubPackagePath(ZipArchive $epub): string|false {
//
// The only mandatory known file within the archive is the
// container file, so we fetch it to find the reference to
// the package file.
//
// See: https://www.w3.org/TR/epub-33/#sec-container-metainf
//
$container = $epub->getFromName('META-INF/container.xml');
if ($container === false || empty($container)) {
logger('No container in archive, probably not an EPUB.', LOGGER_DEBUG, LOG_DEBUG);
return false;
}
$domdoc = new DOMDocument();
$domdoc->loadXML($container);
$nodes = $domdoc->getElementsByTagName('rootfile');
if ($nodes->count() == 0) {
logger('EPUB rootfile not found, is this an epub?', LOGGER_DEBUG, LOG_DEBUG);
return false;
}
$packageNode = $nodes->item(0);
if ($packageNode === null || !is_a($packageNode, DOMElement::class)) {
logger('EPUB rootfile element missing or invalid.', LOGGER_DEBUG, LOG_DEBUG);
return false;
}
$packagePath = $packageNode->getAttribute('full-path');
$packageMediaType = $packageNode->getAttribute('media-type');
if (empty($packagePath) || $packageMediaType !== 'application/oebps-package+xml') {
logger('EPUB package path missing or incorrect media type.', LOGGER_DEBUG, LOG_DEBUG);
return false;
}
return $packagePath;
}
}
|
