--- /dev/null
+<?php
+
+declare(strict_types=1);
+/**
+ * @copyright 2024 Maxence Lange <maxence@artificial-owl.com>
+ *
+ * @author Maxence Lange <maxence@artificial-owl.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Blurhash\Listener;
+
+use GdImage;
+use kornrunner\Blurhash\Blurhash;
+use OC\Files\Node\File;
+use OCP\EventDispatcher\Event;
+use OCP\EventDispatcher\IEventDispatcher;
+use OCP\EventDispatcher\IEventListener;
+use OCP\Files\GenericFileException;
+use OCP\Files\NotFoundException;
+use OCP\Files\NotPermittedException;
+use OCP\FilesMetadata\AMetadataEvent;
+use OCP\FilesMetadata\Event\MetadataBackgroundEvent;
+use OCP\FilesMetadata\Event\MetadataLiveEvent;
+use OCP\IPreview;
+use OCP\Lock\LockedException;
+
+/**
+ * Generate a Blurhash string as metadata when image file is uploaded/edited.
+ *
+ * @template-implements IEventListener<AMetadataEvent>
+ */
+class GenerateBlurhashMetadata implements IEventListener {
+ private const RESIZE_BOXSIZE = 300;
+
+ private const COMPONENTS_X = 4;
+ private const COMPONENTS_Y = 3;
+
+ public function __construct(
+ private IPreview $preview,
+ ) {
+ }
+
+ /**
+ * @throws NotPermittedException
+ * @throws GenericFileException
+ * @throws LockedException
+ */
+ public function handle(Event $event): void {
+ if (!($event instanceof MetadataLiveEvent)
+ && !($event instanceof MetadataBackgroundEvent)) {
+ return;
+ }
+
+ $file = $event->getNode();
+ if (!($file instanceof File)) {
+ return;
+ }
+
+ // too heavy to run on the live thread, request a rerun as a background job
+ if ($event instanceof MetadataLiveEvent) {
+ $event->requestBackgroundJob();
+ return;
+ }
+
+ $image = false;
+ try {
+ // using preview image to generate the blurhash
+ $preview = $this->preview->getPreview($file, 256, 256);
+ $image = imagecreatefromstring($preview->getContent());
+ } catch (NotFoundException $e) {
+ // https://github.com/nextcloud/server/blob/9d70fd3e64b60a316a03fb2b237891380c310c58/lib/private/legacy/OC_Image.php#L668
+ // The preview system can fail on huge picture, in that case we use our own image resizer.
+ if (str_starts_with($file->getMimetype(), 'image/')) {
+ $image = $this->resizedImageFromFile($file);
+ }
+ }
+
+ if ($image === false) {
+ return;
+ }
+
+ $metadata = $event->getMetadata();
+ $metadata->setString('blurhash', $this->generateBlurHash($image));
+ }
+
+ /**
+ * @param File $file
+ *
+ * @return GdImage|false
+ * @throws GenericFileException
+ * @throws NotPermittedException
+ * @throws LockedException
+ */
+ private function resizedImageFromFile(File $file): GdImage|false {
+ $image = imagecreatefromstring($file->getContent());
+ if ($image === false) {
+ return false;
+ }
+
+ $currX = imagesx($image);
+ $currY = imagesy($image);
+
+ if ($currX > $currY) {
+ $newX = self::RESIZE_BOXSIZE;
+ $newY = intval($currY * $newX / $currX);
+ } else {
+ $newY = self::RESIZE_BOXSIZE;
+ $newX = intval($currX * $newY / $currY);
+ }
+
+ $newImage = imagescale($image, $newX, $newY);
+ return ($newImage !== false) ? $newImage : $image;
+ }
+
+ /**
+ * @param GdImage $image
+ *
+ * @return string
+ */
+ public function generateBlurHash(GdImage $image): string {
+ $width = imagesx($image);
+ $height = imagesy($image);
+
+ $pixels = [];
+ for ($y = 0; $y < $height; ++$y) {
+ $row = [];
+ for ($x = 0; $x < $width; ++$x) {
+ $index = imagecolorat($image, $x, $y);
+ $colors = imagecolorsforindex($image, $index);
+ $row[] = [$colors['red'], $colors['green'], $colors['blue']];
+ }
+
+ $pixels[] = $row;
+ }
+
+ return Blurhash::encode($pixels, self::COMPONENTS_X, self::COMPONENTS_Y);
+ }
+
+ /**
+ * @param IEventDispatcher $eventDispatcher
+ *
+ * @return void
+ */
+ public static function loadListeners(IEventDispatcher $eventDispatcher): void {
+ $eventDispatcher->addServiceListener(MetadataLiveEvent::class, self::class);
+ $eventDispatcher->addServiceListener(MetadataBackgroundEvent::class, self::class);
+ }
+}
projects / nextcloud-server.git / commitdiff