Show MapView if GPS data exists in exif

android/app/src/main/AndroidManifest.xml

@@ -46,5 +46,9 @@
         <meta-data
             android:name="flutterEmbedding"
             android:value="2" />
+
+        <meta-data
+            android:name="com.google.android.geo.API_KEY"
+            android:value="" />
     </application>
 </manifest>

lib/entity/exif.dart

@@ -89,6 +89,12 @@ class Exif {
   /// 0x920a FocalLength
   Rational get focalLength => data["FocalLength"];
 
+  /// 0x8825 GPS tags
+  String get gpsLatitudeRef => data["GPSLatitudeRef"];
+  List<Rational> get gpsLatitude => data["GPSLatitude"].cast<Rational>();
+  String get gpsLongitudeRef => data["GPSLongitudeRef"];
+  List<Rational> get gpsLongitude => data["GPSLongitude"].cast<Rational>();
+
   static final dateTimeFormat = DateFormat("yyyy:MM:dd HH:mm:ss");
 
   final Map<String, dynamic> data;

lib/platform/features.dart

@@ -0,0 +1,3 @@
+import 'dart:io';
+
+final isSupportMapView = Platform.isAndroid;

lib/widget/viewer_detail_pane.dart

@@ -1,9 +1,12 @@
 import 'dart:io';
 
+import 'package:android_intent/android_intent.dart';
+import 'package:exifdart/exifdart.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
+import 'package:google_maps_flutter/google_maps_flutter.dart';
 import 'package:intl/intl.dart';
 import 'package:logging/logging.dart';
 import 'package:nc_photos/account.dart';
@@ -13,6 +16,7 @@ import 'package:nc_photos/entity/exif.dart';
 import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/exception_util.dart' as exception_util;
 import 'package:nc_photos/k.dart' as k;
+import 'package:nc_photos/platform/features.dart' as features;
 import 'package:nc_photos/snack_bar_manager.dart';
 import 'package:nc_photos/theme.dart';
 import 'package:nc_photos/use_case/remove.dart';
@@ -135,6 +139,36 @@ class _ViewerDetailPaneState extends State<ViewerDetailPane> {
             title: Text(_model),
             subtitle: cameraSubStr.isNotEmpty ? Text(cameraSubStr) : null,
           ),
+        if (features.isSupportMapView && _gps != null)
+          SizedBox(
+            height: 256,
+            child: GoogleMap(
+              compassEnabled: false,
+              mapToolbarEnabled: false,
+              rotateGesturesEnabled: false,
+              scrollGesturesEnabled: false,
+              zoomControlsEnabled: false,
+              zoomGesturesEnabled: false,
+              tiltGesturesEnabled: false,
+              myLocationButtonEnabled: false,
+              buildingsEnabled: false,
+              // liteModeEnabled: true,
+              initialCameraPosition: CameraPosition(
+                target: _gps,
+                zoom: 16,
+              ),
+              markers: {
+                Marker(
+                  markerId: MarkerId("at"),
+                  position: _gps,
+                  // for some reason, GoogleMap's onTap is not triggered if
+                  // tapped on top of the marker
+                  onTap: _onMapTap,
+                ),
+              },
+              onTap: (_) => _onMapTap(),
+            ),
+          ),
       ],
     );
   }
@@ -207,6 +241,16 @@ class _ViewerDetailPaneState extends State<ViewerDetailPane> {
     }
   }
 
+  void _onMapTap() {
+    if (Platform.isAndroid) {
+      final intent = AndroidIntent(
+        action: "action_view",
+        data: Uri.encodeFull("geo:${_gps.latitude},${_gps.longitude}?z=16"),
+      );
+      intent.launch();
+    }
+  }
+
   void _updateMetadata(int imageWidth, int imageHeight, Exif exif) {
     if (imageWidth != null && imageHeight != null) {
       setState(() {
@@ -255,6 +299,30 @@ class _ViewerDetailPaneState extends State<ViewerDetailPane> {
         _isoSpeedRatings = exif.isoSpeedRatings;
       });
     }
+    if (exif.gpsLatitudeRef != null &&
+        exif.gpsLatitude != null &&
+        exif.gpsLongitudeRef != null &&
+        exif.gpsLongitude != null) {
+      final lat = _gpsDmsToDouble(exif.gpsLatitude) *
+          (exif.gpsLatitudeRef == "S" ? -1 : 1);
+      final lng = _gpsDmsToDouble(exif.gpsLongitude) *
+          (exif.gpsLongitudeRef == "W" ? -1 : 1);
+      _log.fine("GPS: ($lat, $lng)");
+      setState(() {
+        _gps = LatLng(lat, lng);
+      });
+    }
+  }
+
+  static double _gpsDmsToDouble(List<Rational> dms) {
+    double product = dms[0].toDouble();
+    if (dms.length > 1) {
+      product += dms[1].toDouble() / 60;
+    }
+    if (dms.length > 2) {
+      product += dms[2].toDouble() / 3600;
+    }
+    return product;
   }
 
   Future<void> _addToAlbum(BuildContext context, Album album) async {
@@ -287,6 +355,7 @@ class _ViewerDetailPaneState extends State<ViewerDetailPane> {
   String _exposureTime;
   double _focalLength;
   int _isoSpeedRatings;
+  LatLng _gps;
 
   static final _log =
       Logger("widget.viewer_detail_pane._ViewerDetailPaneState");

pubspec.lock

@@ -1,6 +1,13 @@
 # Generated by pub
 # See https://dart.dev/tools/pub/glossary#lockfile
 packages:
+  android_intent:
+    dependency: "direct main"
+    description:
+      name: android_intent
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
   archive:
     dependency: transitive
     description:
@@ -153,6 +160,13 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_plugin_android_lifecycle:
+    dependency: transitive
+    description:
+      name: flutter_plugin_android_lifecycle
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.1"
   flutter_staggered_grid_view:
     dependency: "direct main"
     description:
@@ -165,6 +179,20 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  google_maps_flutter:
+    dependency: "direct main"
+    description:
+      name: google_maps_flutter
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.3"
+  google_maps_flutter_platform_interface:
+    dependency: transitive
+    description:
+      name: google_maps_flutter_platform_interface
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.4"
   hashcodes:
     dependency: transitive
     description:
@@ -459,6 +487,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.10.0"
+  stream_transform:
+    dependency: transitive
+    description:
+      name: stream_transform
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
   string_scanner:
     dependency: transitive
     description:

pubspec.yaml

@@ -26,6 +26,7 @@ dependencies:
   flutter_localizations:
     sdk: flutter
 
+  android_intent: ^2.0.0
   bloc: ^7.0.0
   cached_network_image: ^3.0.0
   connectivity: ^3.0.2
@@ -38,6 +39,7 @@ dependencies:
       ref: 1.0.0
   flutter_bloc: ^7.0.0
   flutter_staggered_grid_view: ^0.3.3
+  google_maps_flutter: ^2.0.3
   http: ^0.13.1
   idb_shim: ^2.0.0
   idb_sqflite: ^1.0.0