use Photos metadata for pre-sized, blurhashed image placeholders

Signed-off-by: Andrew Backhouse <andrew.backhouse@nextcloud.com>

Author: emberfiend

lib/Controller/AttachmentController.php

@@ -216,13 +216,18 @@ public function getImageFile(string $imageFileName, string $shareToken = '',
 				$userId = $this->getUserId();
 				$imageFile = $this->attachmentService->getImageFile($documentId, $imageFileName, $userId, $preferRawImage === 1);
 			}
-			return $imageFile !== null
-				? new DataDownloadResponse(
+
+			if ($imageFile !== null) {
+				$response = new DataDownloadResponse(
 					$imageFile->getContent(),
 					$imageFile->getName(),
 					$this->getSecureMimeType($imageFile->getMimeType())
-				)
-				: new DataResponse('', Http::STATUS_NOT_FOUND);
+				);
+				$response->cacheFor(3600 * 24, false, true);
+				return $response;
+			}
+
+			return  new DataResponse('', Http::STATUS_NOT_FOUND);
 		} catch (Exception $e) {
 			$this->logger->error('getImageFile error', ['exception' => $e]);
 			return new DataResponse('', Http::STATUS_NOT_FOUND);

lib/Service/AttachmentService.php

@@ -23,6 +23,7 @@
 use OCP\Files\NotFoundException;
 use OCP\Files\NotPermittedException;
 use OCP\Files\SimpleFS\ISimpleFile;
+use OCP\FilesMetadata\IFilesMetadataManager;
 use OCP\IPreview;
 use OCP\IURLGenerator;
 use OCP\Lock\LockedException;
@@ -39,6 +40,7 @@ public function __construct(
 		private IMimeTypeDetector $mimeTypeDetector,
 		private IURLGenerator $urlGenerator,
 		private IFilenameValidator $filenameValidator,
+		private IFilesMetadataManager $filesMetadataManager,
 	) {
 	}
 
@@ -219,21 +221,34 @@ public function getAttachmentList(int $documentId, ?string $userId = null, ?Sess
 
 		$attachments = [];
 		$userFolder = $userId !== null ? $this->rootFolder->getUserFolder($userId) : null;
+
+		$fileNodes = [];
+		$fileIds = [];
 		foreach ($attachmentDir->getDirectoryListing() as $node) {
-			if (!($node instanceof File)) {
-				// Ignore anything but files
-				continue;
+			if ($node instanceof File) {
+				// we only want Files
+				$fileNodes[] = $node;
+				$fileIds[] = $node->getId();
 			}
+		}
+
+		// this is done outside the loop for efficiency
+		$metadataMap = $this->filesMetadataManager->getMetadataForFiles($fileIds);
+
+		foreach ($fileNodes as $node) {
 			$isImage = in_array($node->getMimetype(), AttachmentController::IMAGE_MIME_TYPES, true);
 			$name = $node->getName();
+			$fileId = $node->getId();
+			$metadata = $metadataMap[$fileId] ?? null;
 			$attachments[] = [
-				'fileId' => $node->getId(),
+				'fileId' => $fileId,
 				'name' => $name,
 				'size' => Util::humanFileSize($node->getSize()),
 				'mimetype' => $node->getMimeType(),
 				'mtime' => $node->getMTime(),
 				'isImage' => $isImage,
 				'davPath' => $userFolder?->getRelativePath($node->getPath()),
+				'metadata' => $metadata,
 				'fullUrl' => $isImage
 					? $this->urlGenerator->linkToRouteAbsolute('text.Attachment.getImageFile') . $urlParamsBase . '&imageFileName=' . rawurlencode($name) . '&preferRawImage=1'
 					: $this->urlGenerator->linkToRouteAbsolute('text.Attachment.getMediaFile') . $urlParamsBase . '&mediaFileName=' . rawurlencode($name),

src/nodes/ImageView.vue

@@ -6,6 +6,7 @@
 <template>
 	<NodeViewWrapper :contenteditable="isEditable">
 		<figure
+			ref="wrapper"
 			class="image image-view"
 			data-component="image-view"
 			:data-attachment-type="attachmentType"
@@ -105,6 +106,12 @@
 						@close="showImageModal = false" />
 				</div>
 			</div>
+			<div v-else-if="canDisplayPlaceholder" class="image__placeholder">
+				<NcBlurHash
+					:hash="imageBlurhash"
+					:style="blurhashSize"
+					aria-hidden="true" />
+			</div>
 			<div v-else class="image-view__cant_display">
 				<transition name="fade">
 					<div v-show="loaded" class="image__caption">
@@ -128,6 +135,7 @@
 <script>
 import ClickOutside from 'vue-click-outside'
 import NcButton from '@nextcloud/vue/components/NcButton'
+import NcBlurHash from '@nextcloud/vue/components/NcBlurHash'
 import { showError } from '@nextcloud/dialogs'
 import ShowImageModal from '../components/ImageView/ShowImageModal.vue'
 import { useAttachmentResolver } from '../components/Editor.provider.js'
@@ -149,6 +157,7 @@ export default {
 		ImageIcon,
 		DeleteIcon,
 		NcButton,
+		NcBlurHash,
 		ShowImageModal,
 		NodeViewWrapper,
 	},
@@ -160,7 +169,13 @@ export default {
 	data() {
 		return {
 			attachment: null,
+			attachmentPromise: null,
 			imageLoaded: false,
+			imageWidth: 0,
+			imageHeight: 0,
+			wrapperWidth: 0,
+			resizeObserver: null,
+			imageBlurhash: null,
 			loaded: false,
 			failed: false,
 			showIcons: false,
@@ -199,6 +214,25 @@ export default {
 
 			return this.loaded && this.imageLoaded
 		},
+		canDisplayPlaceholder() {
+			return this.imageHeight > 0
+		},
+		blurhashSize() {
+			if (this.imageWidth > 0 && this.imageHeight > 0) {
+				const ratio = this.imageWidth / this.imageHeight
+				const newWidth =
+					this.wrapperWidth - 12 > this.imageWidth
+						? this.imageWidth
+						: this.wrapperWidth - 12
+				const newHeight = newWidth / ratio
+
+				return {
+					width: `${newWidth}px`,
+					height: `${newHeight}px`,
+				}
+			}
+			return {}
+		},
 		src: {
 			get() {
 				return this.node.attrs.src || ''
@@ -233,6 +267,10 @@ export default {
 		})
 	},
 	mounted() {
+		this.attachmentPromise = this.$attachmentResolver.resolve(this.src)
+		this.loadAttachmentMetadata()
+		this.setupResizeObserver()
+
 		this.$nextTick(() => {
 			// nextTick is necessary, intersection detection is slightly unreliable without it
 			const options = {
@@ -254,10 +292,38 @@ export default {
 	},
 	beforeUnmount() {
 		this.loadIntersectionObserver?.disconnect()
+		this.resizeObserver?.disconnect()
 	},
 	methods: {
+		setupResizeObserver() {
+			if (!this.$refs.wrapper) return
+
+			this.resizeObserver = new ResizeObserver((entries) => {
+				const width = entries[0].contentRect.width
+				if (width > 0) {
+					this.wrapperWidth = width
+				}
+			})
+
+			this.resizeObserver.observe(this.$refs.wrapper)
+		},
+		async loadAttachmentMetadata() {
+			try {
+				this.attachment = await this.attachmentPromise
+
+				const size = this.attachment?.metadata?.['photos-size']?.value
+				this.imageWidth = size.width
+				this.imageHeight = size.height
+
+				this.imageBlurhash = this.attachment?.metadata?.blurhash?.value
+			} catch (err) {
+				throw new Error('Failed to load attachment metadata')
+			}
+		},
 		async loadPreview() {
-			this.attachment = await this.$attachmentResolver.resolve(this.src)
+			if (!this.attachment) {
+				this.attachment = await this.attachmentPromise
+			}
 			if (!this.attachment.previewUrl) {
 				throw new Error('Attachment source was not resolved')
 			}
@@ -268,6 +334,9 @@ export default {
 					this.imageLoaded = true
 					this.loaded = true
 					this.attachmentSize = this.attachment.size
+					// once the image is loaded, we can stop tracking the container width
+					//  since we only use it for sizing the placeholder
+					this.resizeObserver?.disconnect()
 				}
 				img.onerror = (e) => {
 					reject(new LoadImageError(e, this.attachment.previewUrl))
@@ -426,6 +495,12 @@ export default {
 	height: 100px;
 }
 
+.image__placeholder {
+	padding: 7px 6px;
+	margin-bottom: 26px;
+	position: relative;
+}
+
 .image__main {
 	max-height: calc(100vh - 50px - 50px);
 }