fix: don't persist previews used during blurhash generation

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

lib/private/Blurhash/Listener/GenerateBlurhashMetadata.php

@@ -15,12 +15,10 @@ 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;
 
 /**
@@ -34,11 +32,6 @@ class GenerateBlurhashMetadata implements IEventListener {
 	private const COMPONENTS_X = 4;
 	private const COMPONENTS_Y = 3;
 
-	public function __construct(
-		private IPreview $preview,
-	) {
-	}
-
 	/**
 	 * @throws NotPermittedException
 	 * @throws GenericFileException
@@ -67,20 +60,12 @@ class GenerateBlurhashMetadata implements IEventListener {
 			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 (!str_starts_with($file->getMimetype(), 'image/')) {
+			return;
 		}
 
-		if ($image === false) {
+		$image = $this->resizedImageFromFile($file);
+		if (!$image) {
 			return;
 		}