Merge pull request #18911 from owncloud/preview-show-cached-directly

Show cached previews directly

lib/private/preview.php

@@ -772,6 +772,12 @@ class Preview {
 			throw new NotFoundException('File not found.');
 		}
 
+		if ($cachedPath = $this->isCached($this->info->getId())) {
+			header('Content-Type: ' . $this->info->getMimetype());
+			$this->userView->readfile($cachedPath);
+			return;
+		}
+
 		if (is_null($this->preview)) {
 			$this->getPreview();
 		}