Extract GPS data from EXIF

Signed-off-by: Louis Chemineau <louis@chmn.me>

1 files changed, 72 insertions, 14 deletions

diff --git a/lib/private/Metadata/Provider/ExifProvider.php b/lib/private/Metadata/Provider/ExifProvider.php
index 892671556b3..aa0b5464682 100644
--- a/lib/private/Metadata/Provider/ExifProvider.php
+++ b/lib/private/Metadata/Provider/ExifProvider.php
@@ -5,10 +5,19 @@ namespace OC\Metadata\Provider;
 use OC\Metadata\FileMetadata;
 use OC\Metadata\IMetadataProvider;
 use OCP\Files\File;
+use Psr\Log\LoggerInterface;
 
 class ExifProvider implements IMetadataProvider {
+	private LoggerInterface $logger;
+
+	public function __construct(
+		LoggerInterface $logger
+	) {
+		$this->logger = $logger;
+	}
+
 	public static function groupsProvided(): array {
-		return ['size'];
+		return ['size', 'gps'];
 	}
 
 	public static function isAvailable(): bool {
@@ -16,8 +25,21 @@ class ExifProvider implements IMetadataProvider {
 	}
 
 	public function execute(File $file): array {
+		$exifData = [];
 		$fileDescriptor = $file->fopen('rb');
-		$data = exif_read_data($fileDescriptor, 'COMPUTED', true);
+
+		$data = null;
+		try {
+			// Needed to make reading exif data reliable.
+			// This is to trigger this condition: https://github.com/php/php-src/blob/d64aa6f646a7b5e58359dc79479860164239580a/main/streams/streams.c#L710
+			// But I don't understand why 1 as a special meaning.
+			// Revert right after reading the exif data.
+			$oldBufferSize = stream_set_chunk_size($fileDescriptor, 1);
+			$data = exif_read_data($fileDescriptor, 'ANY_TAG', true);
+			stream_set_chunk_size($fileDescriptor, $oldBufferSize);
+		} catch (\Exception $ex) {
+			$this->logger->warning("Couldn't extract metadata for ".$file->getId(), ['exception' => $ex]);
+		}
 
 		$size = new FileMetadata();
 		$size->setGroupName('size');
@@ -31,29 +53,65 @@ class ExifProvider implements IMetadataProvider {
 					'width' => $sizeResult[0],
 					'height' => $sizeResult[1],
 				]);
+
+				$exifData['size'] = $size;
 			}
+		} elseif (array_key_exists('COMPUTED', $data)) {
+			if (array_key_exists('Width', $data['COMPUTED']) && array_key_exists('Height', $data['COMPUTED'])) {
+				$size->setMetadata([
+					'width' => $data['COMPUTED']['Width'],
+					'height' => $data['COMPUTED']['Height'],
+				]);
 
-			return [
-				'size' => $size,
-			];
+				$exifData['size'] = $size;
+			}
 		}
 
-		if (array_key_exists('COMPUTED', $data)
-			&& array_key_exists('Width', $data['COMPUTED'])
-			&& array_key_exists('Height', $data['COMPUTED'])
+		if ($data && array_key_exists('GPS', $data)
+			&& array_key_exists('GPSLatitude', $data['GPS']) && array_key_exists('GPSLatitudeRef', $data['GPS'])
+			&& array_key_exists('GPSLongitude', $data['GPS']) && array_key_exists('GPSLongitudeRef', $data['GPS'])
 		) {
-			$size->setMetadata([
-				'width' => $data['COMPUTED']['Width'],
-				'height' => $data['COMPUTED']['Height'],
+			$gps = new FileMetadata();
+			$gps->setGroupName('gps');
+			$gps->setId($file->getId());
+			$gps->setMetadata([
+				'latitude' => $this->gpsDegreesToDecimal($data['GPS']['GPSLatitude'], $data['GPS']['GPSLatitudeRef']),
+				'longitude' => $this->gpsDegreesToDecimal($data['GPS']['GPSLongitude'], $data['GPS']['GPSLongitudeRef']),
 			]);
+
+			$exifData['gps'] = $gps;
 		}
 
-		return [
-			'size' => $size,
-		];
+		return $exifData;
 	}
 
 	public static function getMimetypesSupported(): string {
 		return '/image\/.*/';
 	}
+
+	/**
+	 * @param array|string $coordinates
+	 */
+	private static function gpsDegreesToDecimal($coordinates, ?string $hemisphere): float {
+		if (is_string($coordinates)) {
+			$coordinates = array_map("trim", explode(",", $coordinates));
+		}
+
+		if (count($coordinates) !== 3) {
+			throw new \Exception('Invalid coordinate format: ' . json_encode($coordinates));
+		}
+
+		[$degrees, $minutes, $seconds] = array_map(function (string $rawDegree) {
+			$parts = explode('/', $rawDegree);
+
+			if ($parts[1] === '0') {
+				return 0;
+			}
+
+			return floatval($parts[0]) / floatval($parts[1] ?? 1);
+		}, $coordinates);
+
+		$sign = ($hemisphere === 'W' || $hemisphere === 'S') ? -1 : 1;
+		return $sign * ($degrees + $minutes / 60 + $seconds / 3600);
+	}
 }