Merge pull request #19495 from nextcloud/preview-generate-batch

optimize batch generation of previews

1 files changed, 71 insertions, 41 deletions

diff --git a/lib/private/Preview/Generator.php b/lib/private/Preview/Generator.php
index f945849c276..650c3a6ba9f 100644
--- a/lib/private/Preview/Generator.php
+++ b/lib/private/Preview/Generator.php
@@ -91,22 +91,37 @@ class Generator {
 	 * @throws \InvalidArgumentException if the preview would be invalid (in case the original image is invalid)
 	 */
 	public function getPreview(File $file, $width = -1, $height = -1, $crop = false, $mode = IPreview::MODE_FILL, $mimeType = null) {
+		$specification = [
+			'width' => $width,
+			'height' => $height,
+			'crop' => $crop,
+			'mode' => $mode,
+		];
+		$this->eventDispatcher->dispatch(
+			IPreview::EVENT,
+			new GenericEvent($file, $specification)
+		);
+
+		// since we only ask for one preview, and the generate method return the last one it created, it returns the one we want
+		return $this->generatePreviews($file, [$specification], $mimeType);
+	}
+
+	/**
+	 * Generates previews of a file
+	 *
+	 * @param File $file
+	 * @param array $specifications
+	 * @param string $mimeType
+	 * @return ISimpleFile the last preview that was generated
+	 * @throws NotFoundException
+	 * @throws \InvalidArgumentException if the preview would be invalid (in case the original image is invalid)
+	 */
+	public function generatePreviews(File $file, array $specifications, $mimeType = null) {
 		//Make sure that we can read the file
 		if (!$file->isReadable()) {
 			throw new NotFoundException('Cannot read file');
 		}
 
-
-		$this->eventDispatcher->dispatch(
-			IPreview::EVENT,
-			new GenericEvent($file, [
-				'width' => $width,
-				'height' => $height,
-				'crop' => $crop,
-				'mode' => $mode
-			])
-		);
-
 		if ($mimeType === null) {
 			$mimeType = $file->getMimeType();
 		}
@@ -123,41 +138,57 @@ class Generator {
 
 		// Get the max preview and infer the max preview sizes from that
 		$maxPreview = $this->getMaxPreview($previewFolder, $file, $mimeType, $previewVersion);
+		$maxPreviewImage = null; // only load the image when we need it
 		if ($maxPreview->getSize() === 0) {
 			$maxPreview->delete();
 			throw new NotFoundException('Max preview size 0, invalid!');
 		}
 
-		list($maxWidth, $maxHeight) = $this->getPreviewSize($maxPreview, $previewVersion);
+		[$maxWidth, $maxHeight] = $this->getPreviewSize($maxPreview, $previewVersion);
 
-		// If both width and heigth are -1 we just want the max preview
-		if ($width === -1 && $height === -1) {
-			$width = $maxWidth;
-			$height = $maxHeight;
-		}
+		$preview = null;
 
-		// Calculate the preview size
-		list($width, $height) = $this->calculateSize($width, $height, $crop, $mode, $maxWidth, $maxHeight);
+		foreach ($specifications as $specification) {
+			$width = $specification['width'] ?? -1;
+			$height = $specification['height'] ?? -1;
+			$crop = $specification['crop'] ?? false;
+			$mode = $specification['mode'] ?? IPreview::MODE_FILL;
 
-		// No need to generate a preview that is just the max preview
-		if ($width === $maxWidth && $height === $maxHeight) {
-			return $maxPreview;
-		}
+			// If both width and heigth are -1 we just want the max preview
+			if ($width === -1 && $height === -1) {
+				$width = $maxWidth;
+				$height = $maxHeight;
+			}
 
-		// Try to get a cached preview. Else generate (and store) one
-		try {
+			// Calculate the preview size
+			[$width, $height] = $this->calculateSize($width, $height, $crop, $mode, $maxWidth, $maxHeight);
+
+			// No need to generate a preview that is just the max preview
+			if ($width === $maxWidth && $height === $maxHeight) {
+				// ensure correct return value if this was the last one
+				$preview = $maxPreview;
+				continue;
+			}
+
+			// Try to get a cached preview. Else generate (and store) one
 			try {
-				$preview = $this->getCachedPreview($previewFolder, $width, $height, $crop, $maxPreview->getMimeType(), $previewVersion);
-			} catch (NotFoundException $e) {
-				$preview = $this->generatePreview($previewFolder, $maxPreview, $width, $height, $crop, $maxWidth, $maxHeight, $previewVersion);
+				try {
+					$preview = $this->getCachedPreview($previewFolder, $width, $height, $crop, $maxPreview->getMimeType(), $previewVersion);
+				} catch (NotFoundException $e) {
+					if ($maxPreviewImage === null) {
+						$maxPreviewImage = $this->helper->getImage($maxPreview);
+					}
+
+					$preview = $this->generatePreview($previewFolder, $maxPreviewImage, $width, $height, $crop, $maxWidth, $maxHeight, $previewVersion);
+				}
+			} catch (\InvalidArgumentException $e) {
+				throw new NotFoundException("", 0, $e);
 			}
-		} catch (\InvalidArgumentException $e) {
-			throw new NotFoundException();
-		}
 
-		if ($preview->getSize() === 0) {
-			$preview->delete();
-			throw new NotFoundException('Cached preview size 0, invalid!');
+			if ($preview->getSize() === 0) {
+				$preview->delete();
+				throw new NotFoundException('Cached preview size 0, invalid!');
+			}
 		}
 
 		return $preview;
@@ -360,9 +391,8 @@ class Generator {
 	 * @throws NotFoundException
 	 * @throws \InvalidArgumentException if the preview would be invalid (in case the original image is invalid)
 	 */
-	private function generatePreview(ISimpleFolder $previewFolder, ISimpleFile $maxPreview, $width, $height, $crop, $maxWidth, $maxHeight, $prefix) {
-		$preview = $this->helper->getImage($maxPreview);
-
+	private function generatePreview(ISimpleFolder $previewFolder, IImage $maxPreview, $width, $height, $crop, $maxWidth, $maxHeight, $prefix) {
+		$preview = $maxPreview;
 		if (!$preview->valid()) {
 			throw new \InvalidArgumentException('Failed to generate preview, failed to load image');
 		}
@@ -380,13 +410,13 @@ class Generator {
 					$scaleH = $maxHeight / $widthR;
 					$scaleW = $width;
 				}
-				$preview->preciseResize((int)round($scaleW), (int)round($scaleH));
+				$preview = $preview->preciseResizeCopy((int)round($scaleW), (int)round($scaleH));
 			}
 			$cropX = (int)floor(abs($width - $preview->width()) * 0.5);
 			$cropY = (int)floor(abs($height - $preview->height()) * 0.5);
-			$preview->crop($cropX, $cropY, $width, $height);
+			$preview = $preview->cropCopy($cropX, $cropY, $width, $height);
 		} else {
-			$preview->resize(max($width, $height));
+			$preview = $maxPreview->resizeCopy(max($width, $height));
 		}
 
 
@@ -448,7 +478,7 @@ class Generator {
 			case 'image/gif':
 				return 'gif';
 			default:
-				throw new \InvalidArgumentException('Not a valid mimetype');
+				throw new \InvalidArgumentException('Not a valid mimetype: "' . $mimeType . '"');
 		}
 	}
 }