From 610bf688a05817b9b3d7bf4244548df931a0cfb6 Mon Sep 17 00:00:00 2001
From: Ming Ming <nkming2@gmail.com>
Date: Sat, 20 Aug 2022 18:51:09 +0800
Subject: [PATCH] Refactor: extract exif function

---
 app/lib/entity/exif_extension.dart     | 43 ++++++++++++++++++++++++++
 app/lib/widget/viewer_detail_pane.dart | 24 +++-----------
 2 files changed, 47 insertions(+), 20 deletions(-)
 create mode 100644 app/lib/entity/exif_extension.dart

diff --git a/app/lib/entity/exif_extension.dart b/app/lib/entity/exif_extension.dart
new file mode 100644
index 00000000..f92bf7ac
--- /dev/null
+++ b/app/lib/entity/exif_extension.dart
@@ -0,0 +1,43 @@
+import 'package:exifdart/exifdart.dart';
+import 'package:nc_photos/entity/exif.dart';
+
+extension ExifExtension on Exif {
+  double? get gpsLatitudeDeg {
+    if (gpsLatitude == null || gpsLatitudeRef == null) {
+      return null;
+    } else if (gpsLatitudeRef != "N" && gpsLatitudeRef != "S") {
+      // invalid value
+      return null;
+    } else if (gpsLatitude!.any((e) => e.denominator == 0)) {
+      // invalid value
+      return null;
+    } else {
+      return _gpsDmsToDouble(gpsLatitude!) * (gpsLatitudeRef == "S" ? -1 : 1);
+    }
+  }
+
+  double? get gpsLongitudeDeg {
+    if (gpsLongitude == null || gpsLongitudeRef == null) {
+      return null;
+    } else if (gpsLongitudeRef != "E" && gpsLongitudeRef != "W") {
+      // invalid value
+      return null;
+    } else if (gpsLongitude!.any((e) => e.denominator == 0)) {
+      // invalid value
+      return null;
+    } else {
+      return _gpsDmsToDouble(gpsLongitude!) * (gpsLongitudeRef == "W" ? -1 : 1);
+    }
+  }
+}
+
+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;
+}
diff --git a/app/lib/widget/viewer_detail_pane.dart b/app/lib/widget/viewer_detail_pane.dart
index e6f1568f..1d24a88f 100644
--- a/app/lib/widget/viewer_detail_pane.dart
+++ b/app/lib/widget/viewer_detail_pane.dart
@@ -1,7 +1,6 @@
 import 'dart:async';
 
 import 'package:android_intent_plus/android_intent.dart';
-import 'package:exifdart/exifdart.dart';
 import 'package:flutter/material.dart';
 import 'package:intl/intl.dart';
 import 'package:kiwi/kiwi.dart';
@@ -15,6 +14,7 @@ import 'package:nc_photos/entity/album.dart';
 import 'package:nc_photos/entity/album/cover_provider.dart';
 import 'package:nc_photos/entity/album/item.dart';
 import 'package:nc_photos/entity/album/provider.dart';
+import 'package:nc_photos/entity/exif_extension.dart';
 import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/notified_action.dart';
@@ -334,14 +334,9 @@ class _ViewerDetailPaneState extends State<ViewerDetailPane> {
     if (exif.isoSpeedRatings != null) {
       _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);
+    final lat = exif.gpsLatitudeDeg;
+    final lng = exif.gpsLongitudeDeg;
+    if (lat != null && lng != null) {
       _log.fine("GPS: ($lat, $lng)");
       _gps = Tuple2(lat, lng);
     }
@@ -494,17 +489,6 @@ class _ViewerDetailPaneState extends State<ViewerDetailPane> {
     });
   }
 
-  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;
-  }
-
   bool _checkCanRemoveFromAlbum() {
     if (widget.album == null ||
         widget.album!.provider is! AlbumStaticProvider) {