Support loading metadata from local file

app/lib/file_extension.dart

@@ -0,0 +1,15 @@
+import 'dart:io';
+
+import 'package:path/path.dart' as path_lib;
+import 'package:mime/mime.dart';
+
+extension FileExtension on File {
+  Future<String?> readMime() async {
+    final header = await openRead(0, defaultMagicNumbersMaxLength)
+        .expand((element) => element)
+        .toList();
+    return lookupMimeType(path, headerBytes: header);
+  }
+
+  String get filename => path_lib.basename(path);
+}

app/lib/use_case/load_metadata.dart

@@ -1,19 +1,23 @@
+import 'dart:io' as io;
 import 'dart:typed_data';
 
 import 'package:exifdart/exifdart.dart' as exifdart;
+import 'package:exifdart/exifdart_io.dart';
 import 'package:exifdart/exifdart_memory.dart';
 import 'package:image_size_getter/image_size_getter.dart';
 import 'package:logging/logging.dart';
 import 'package:nc_photos/account.dart';
 import 'package:nc_photos/debug_util.dart';
 import 'package:nc_photos/entity/exif.dart';
-import 'package:nc_photos/entity/file.dart';
+import 'package:nc_photos/entity/file.dart' as app;
 import 'package:nc_photos/entity/file_util.dart' as file_util;
+import 'package:nc_photos/file_extension.dart';
 import 'package:nc_photos/image_size_getter_util.dart';
 
 class LoadMetadata {
   /// Load metadata of [binary], which is the content of [file]
-  Future<Metadata> loadRemote(Account account, File file, Uint8List binary) {
+  Future<app.Metadata> loadRemote(
+      Account account, app.File file, Uint8List binary) {
     return _loadMetadata(
       mime: file.contentType ?? "",
       exifdartReaderBuilder: () => MemoryBlobReader(binary),
@@ -22,7 +26,20 @@ class LoadMetadata {
     );
   }
 
-  Future<Metadata> _loadMetadata({
+  Future<app.Metadata> loadLocal(
+    io.File file, {
+    String? mime,
+  }) async {
+    mime = mime ?? await file.readMime();
+    return _loadMetadata(
+      mime: mime ?? "",
+      exifdartReaderBuilder: () => FileReader(file),
+      imageSizeGetterInputBuilder: () => AsyncFileInput(file),
+      filename: file.path,
+    );
+  }
+
+  Future<app.Metadata> _loadMetadata({
     required String mime,
     required exifdart.AbstractBlobReader Function() exifdartReaderBuilder,
     required AsyncImageInput Function() imageSizeGetterInputBuilder,
@@ -86,7 +103,7 @@ class LoadMetadata {
     return _buildMetadata(map);
   }
 
-  Metadata _buildMetadata(Map<String, dynamic> map) {
+  app.Metadata _buildMetadata(Map<String, dynamic> map) {
     int? imageWidth, imageHeight;
     Exif? exif;
     if (map.containsKey("resolution")) {
@@ -96,7 +113,7 @@ class LoadMetadata {
     if (map.containsKey("exif")) {
       exif = Exif(map["exif"]);
     }
-    return Metadata(
+    return app.Metadata(
       imageWidth: imageWidth,
       imageHeight: imageHeight,
       exif: exif,

app/pubspec.lock

@@ -620,7 +620,7 @@ packages:
     source: hosted
     version: "2.0.0"
   mime:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: mime
       url: "https://pub.dartlang.org"

app/pubspec.yaml

@@ -71,6 +71,7 @@ dependencies:
   intl: ^0.17.0
   kiwi: ^4.0.1
   logging: ^1.0.1
+  mime: ^1.0.1
   mutex: ^3.0.0
   native_device_orientation: ^1.0.0
   nc_photos_plugin: