A simpler way to share photos to other apps

android/app/src/main/kotlin/com/nkming/nc_photos/MainActivity.kt

@@ -17,5 +17,8 @@ class MainActivity : FlutterActivity() {
 		MethodChannel(flutterEngine.dartExecutor.binaryMessenger,
 				SelfSignedCertChannelHandler.CHANNEL).setMethodCallHandler(
 				SelfSignedCertChannelHandler(this))
+		MethodChannel(flutterEngine.dartExecutor.binaryMessenger,
+				ShareChannelHandler.CHANNEL).setMethodCallHandler(
+				ShareChannelHandler(this))
 	}
 }

android/app/src/main/kotlin/com/nkming/nc_photos/ShareChannelHandler.kt

@@ -0,0 +1,56 @@
+package com.nkming.nc_photos
+
+import android.app.Activity
+import android.content.Intent
+import android.net.Uri
+import io.flutter.plugin.common.MethodCall
+import io.flutter.plugin.common.MethodChannel
+
+class ShareChannelHandler(activity: Activity)
+		: MethodChannel.MethodCallHandler {
+	companion object {
+		const val CHANNEL = "com.nkming.nc_photos/share"
+	}
+
+	override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
+		if (call.method == "shareItems") {
+			try {
+				shareItems(call.argument<List<String>>("fileUris")!!,
+						call.argument<List<String?>>("mimeTypes")!!,
+						result)
+			} catch (e: Throwable) {
+				result.error("systemException", e.toString(), null)
+			}
+		} else {
+			result.notImplemented()
+		}
+	}
+
+	private fun shareItems(fileUris: List<String>,
+			mimeTypes: List<String?>, result: MethodChannel.Result) {
+		assert(fileUris.isNotEmpty())
+		assert(fileUris.size == mimeTypes.size)
+		val uris = fileUris.map { Uri.parse(it) }
+
+		val shareIntent = if (uris.size == 1) Intent().apply {
+			action = Intent.ACTION_SEND
+			putExtra(Intent.EXTRA_STREAM, uris[0])
+			type = mimeTypes[0] ?: "*/*"
+			addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+			addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
+		} else Intent().apply {
+			action = Intent.ACTION_SEND_MULTIPLE
+			putParcelableArrayListExtra(Intent.EXTRA_STREAM, ArrayList(uris))
+			type = if (mimeTypes.all { it?.startsWith("image/") == true })
+					"image/*" else "*/*"
+			addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+			addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
+		}
+		val shareChooser = Intent.createChooser(shareIntent, _context.getString(
+				R.string.download_successful_notification_action_share_chooser))
+		_context.startActivity(shareChooser)
+	}
+
+	private val _activity = activity
+	private val _context get() = _activity
+}

lib/l10n/app_en.arb

@@ -555,6 +555,22 @@
 	"@albumAddTextTooltip": {
 		"description": "Add some text that display between photos to an album"
 	},
+	"shareTooltip": "Share",
+	"@shareTooltip": {
+		"description": "Share the current item to other apps"
+	},
+	"shareSelectedTooltip": "Share selected",
+	"@shareSelectedTooltip": {
+		"description": "Share selected items to other apps"
+	},
+	"shareSelectedEmptyNotification": "Select some photos to share",
+	"@shareSelectedEmptyNotification": {
+		"description": "Shown when user pressed the share button with only non-sharable items (e.g., text labels) selected"
+	},
+	"shareDownloadingDialogContent": "Downloading",
+	"@shareDownloadingDialogContent": {
+		"description": "Downloading photos to be shared"
+	},
 
 	"changelogTitle": "Changelog",
 	"@changelogTitle": {

lib/mobile/android/share.dart

@@ -0,0 +1,12 @@
+import 'package:flutter/services.dart';
+
+class Share {
+  static Future<void> shareItems(
+          List<String> fileUris, List<String> mimeTypes) =>
+      _channel.invokeMethod("shareItems", <String, dynamic>{
+        "fileUris": fileUris,
+        "mimeTypes": mimeTypes,
+      });
+
+  static const _channel = const MethodChannel("com.nkming.nc_photos/share");
+}

lib/mobile/share.dart

@@ -0,0 +1,14 @@
+import 'package:nc_photos/mobile/android/share.dart';
+import 'package:nc_photos/platform/share.dart' as itf;
+
+class AndroidShare extends itf.Share {
+  AndroidShare(this.fileUris, this.mimeTypes);
+
+  @override
+  Future<void> share() {
+    return Share.shareItems(fileUris, mimeTypes);
+  }
+
+  final List<String> fileUris;
+  final List<String> mimeTypes;
+}

lib/platform/share.dart

@@ -0,0 +1,3 @@
+abstract class Share {
+  Future<void> share();
+}

lib/share_handler.dart

@@ -0,0 +1,60 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_gen/gen_l10n/app_localizations.dart';
+import 'package:logging/logging.dart';
+import 'package:nc_photos/account.dart';
+import 'package:nc_photos/entity/file.dart';
+import 'package:nc_photos/exception.dart';
+import 'package:nc_photos/exception_util.dart' as exception_util;
+import 'package:nc_photos/k.dart' as k;
+import 'package:nc_photos/mobile/platform.dart'
+    if (dart.library.html) 'package:nc_photos/web/platform.dart' as platform;
+import 'package:nc_photos/mobile/share.dart';
+import 'package:nc_photos/platform/k.dart' as platform_k;
+import 'package:nc_photos/snack_bar_manager.dart';
+import 'package:nc_photos/widget/processing_dialog.dart';
+import 'package:tuple/tuple.dart';
+
+/// Handle sharing to other apps
+class ShareHandler {
+  Future<void> shareFiles(
+      BuildContext context, Account account, List<File> files) async {
+    assert(platform_k.isAndroid);
+    showDialog(
+      context: context,
+      builder: (context) => ProcessingDialog(
+          text: AppLocalizations.of(context).shareDownloadingDialogContent),
+    );
+    final results = <Tuple2<File, dynamic>>[];
+    for (final f in files) {
+      try {
+        results.add(
+            Tuple2(f, await platform.Downloader().downloadFile(account, f)));
+      } on PermissionException catch (_) {
+        _log.warning("[shareFiles] Permission not granted");
+        SnackBarManager().showSnackBar(SnackBar(
+          content: Text(AppLocalizations.of(context)
+              .downloadFailureNoPermissionNotification),
+          duration: k.snackBarDurationNormal,
+        ));
+        // dismiss the dialog
+        Navigator.of(context).pop();
+        rethrow;
+      } catch (e, stacktrace) {
+        _log.shout("[shareFiles] Failed while downloadFile", e, stacktrace);
+        SnackBarManager().showSnackBar(SnackBar(
+          content: Text(exception_util.toUserString(e, context)),
+          duration: k.snackBarDurationNormal,
+        ));
+      }
+    }
+    // dismiss the dialog
+    Navigator.of(context).pop();
+
+    final share = AndroidShare(results.map((e) => e.item2 as String).toList(),
+        results.map((e) => e.item1.contentType).toList());
+    share.share();
+  }
+
+  static final _log = Logger("share_handler.ShareHandler");
+}

lib/widget/album_viewer.dart

@@ -15,7 +15,9 @@ import 'package:nc_photos/entity/file_util.dart' as file_util;
 import 'package:nc_photos/exception_util.dart' as exception_util;
 import 'package:nc_photos/iterable_extension.dart';
 import 'package:nc_photos/k.dart' as k;
+import 'package:nc_photos/platform/k.dart' as platform_k;
 import 'package:nc_photos/session_storage.dart';
+import 'package:nc_photos/share_handler.dart';
 import 'package:nc_photos/snack_bar_manager.dart';
 import 'package:nc_photos/theme.dart';
 import 'package:nc_photos/use_case/resync_album.dart';
@@ -222,6 +224,14 @@ class _AlbumViewerState extends State<AlbumViewer>
 
   Widget _buildSelectionAppBar(BuildContext context) {
     return buildSelectionAppBar(context, [
+      if (platform_k.isAndroid)
+        IconButton(
+          icon: const Icon(Icons.share),
+          tooltip: AppLocalizations.of(context).shareSelectedTooltip,
+          onPressed: () {
+            _onSelectionAppBarSharePressed(context);
+          },
+        ),
       IconButton(
         icon: const Icon(Icons.remove),
         tooltip: AppLocalizations.of(context).removeSelectedFromAlbumTooltip,
@@ -261,6 +271,27 @@ class _AlbumViewerState extends State<AlbumViewer>
         arguments: ViewerArguments(widget.account, _backingFiles, fileIndex));
   }
 
+  void _onSelectionAppBarSharePressed(BuildContext context) {
+    assert(platform_k.isAndroid);
+    final selected = selectedListItems
+        .whereType<_FileListItem>()
+        .map((e) => e.file)
+        .toList();
+    if (selected.isEmpty) {
+      SnackBarManager().showSnackBar(SnackBar(
+        content:
+            Text(AppLocalizations.of(context).shareSelectedEmptyNotification),
+        duration: k.snackBarDurationNormal,
+      ));
+      return;
+    }
+    ShareHandler().shareFiles(context, widget.account, selected).then((_) {
+      setState(() {
+        clearSelectedItems();
+      });
+    });
+  }
+
   void _onSelectionAppBarRemovePressed() {
     final selectedIndexes =
         selectedListItems.map((e) => (e as _ListItem).index).toList();
@@ -526,6 +557,7 @@ class _AlbumViewerState extends State<AlbumViewer>
           } else if (file_util.isSupportedVideoFormat(item.file)) {
             yield _VideoListItem(
               index: i,
+              file: item.file,
               account: widget.account,
               previewUrl: previewUrl,
               onTap: () => _onItemTap(i),
@@ -677,10 +709,31 @@ abstract class _ListItem implements SelectableItem, DraggableItem {
   final VoidCallback _onDragEndedAny;
 }
 
-class _ImageListItem extends _ListItem {
+abstract class _FileListItem extends _ListItem {
-  _ImageListItem({
+  _FileListItem({
     @required int index,
     @required this.file,
+    VoidCallback onTap,
+    DragTargetAccept<DraggableItem> onDropBefore,
+    DragTargetAccept<DraggableItem> onDropAfter,
+    VoidCallback onDragStarted,
+    VoidCallback onDragEndedAny,
+  }) : super(
+          index: index,
+          onTap: onTap,
+          onDropBefore: onDropBefore,
+          onDropAfter: onDropAfter,
+          onDragStarted: onDragStarted,
+          onDragEndedAny: onDragEndedAny,
+        );
+
+  final File file;
+}
+
+class _ImageListItem extends _FileListItem {
+  _ImageListItem({
+    @required int index,
+    @required File file,
     @required this.account,
     @required this.previewUrl,
     VoidCallback onTap,
@@ -690,6 +743,7 @@ class _ImageListItem extends _ListItem {
     VoidCallback onDragEndedAny,
   }) : super(
           index: index,
+          file: file,
           onTap: onTap,
           onDropBefore: onDropBefore,
           onDropAfter: onDropAfter,
@@ -706,14 +760,14 @@ class _ImageListItem extends _ListItem {
     );
   }
 
-  final File file;
   final Account account;
   final String previewUrl;
 }
 
-class _VideoListItem extends _ListItem {
+class _VideoListItem extends _FileListItem {
   _VideoListItem({
     @required int index,
+    @required File file,
     @required this.account,
     @required this.previewUrl,
     VoidCallback onTap,
@@ -723,6 +777,7 @@ class _VideoListItem extends _ListItem {
     VoidCallback onDragEndedAny,
   }) : super(
           index: index,
+          file: file,
           onTap: onTap,
           onDropBefore: onDropBefore,
           onDropAfter: onDropAfter,

lib/widget/dynamic_album_viewer.dart

@@ -17,6 +17,8 @@ import 'package:nc_photos/exception_util.dart' as exception_util;
 import 'package:nc_photos/iterable_extension.dart';
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/list_extension.dart';
+import 'package:nc_photos/platform/k.dart' as platform_k;
+import 'package:nc_photos/share_handler.dart';
 import 'package:nc_photos/snack_bar_manager.dart';
 import 'package:nc_photos/theme.dart';
 import 'package:nc_photos/use_case/populate_album.dart';
@@ -229,6 +231,14 @@ class _DynamicAlbumViewerState extends State<DynamicAlbumViewer>
 
   Widget _buildSelectionAppBar(BuildContext context) {
     return buildSelectionAppBar(context, [
+      if (platform_k.isAndroid)
+        IconButton(
+          icon: const Icon(Icons.share),
+          tooltip: AppLocalizations.of(context).shareSelectedTooltip,
+          onPressed: () {
+            _onSelectionAppBarSharePressed(context);
+          },
+        ),
       PopupMenuButton(
         tooltip: MaterialLocalizations.of(context).moreButtonTooltip,
         itemBuilder: (context) => [
@@ -313,6 +323,19 @@ class _DynamicAlbumViewerState extends State<DynamicAlbumViewer>
     });
   }
 
+  void _onSelectionAppBarSharePressed(BuildContext context) {
+    assert(platform_k.isAndroid);
+    final selected = selectedListItems
+        .whereType<_FileListItem>()
+        .map((e) => e.file)
+        .toList();
+    ShareHandler().shareFiles(context, widget.account, selected).then((_) {
+      setState(() {
+        clearSelectedItems();
+      });
+    });
+  }
+
   void _onSelectionAppBarDeletePressed() async {
     SnackBarManager().showSnackBar(SnackBar(
       content: Text(AppLocalizations.of(context)
@@ -392,6 +415,7 @@ class _DynamicAlbumViewerState extends State<DynamicAlbumViewer>
           );
         } else if (file_util.isSupportedVideoFormat(f)) {
           yield _VideoListItem(
+            file: f,
             account: widget.account,
             previewUrl: previewUrl,
             onTap: () => _onItemTap(i),
@@ -433,13 +457,27 @@ abstract class _ListItem implements SelectableItem {
   final VoidCallback _onTap;
 }
 
-class _ImageListItem extends _ListItem {
+abstract class _FileListItem extends _ListItem {
-  _ImageListItem({
+  _FileListItem({
     @required this.file,
+    VoidCallback onTap,
+  }) : super(
+          onTap: onTap,
+        );
+
+  final File file;
+}
+
+class _ImageListItem extends _FileListItem {
+  _ImageListItem({
+    @required File file,
     @required this.account,
     @required this.previewUrl,
     VoidCallback onTap,
-  }) : super(onTap: onTap);
+  }) : super(
+          file: file,
+          onTap: onTap,
+        );
 
   @override
   buildWidget(BuildContext context) {
@@ -450,17 +488,20 @@ class _ImageListItem extends _ListItem {
     );
   }
 
-  final File file;
   final Account account;
   final String previewUrl;
 }
 
-class _VideoListItem extends _ListItem {
+class _VideoListItem extends _FileListItem {
   _VideoListItem({
+    @required File file,
     @required this.account,
     @required this.previewUrl,
     VoidCallback onTap,
-  }) : super(onTap: onTap);
+  }) : super(
+          file: file,
+          onTap: onTap,
+        );
 
   @override
   buildWidget(BuildContext context) {

lib/widget/home_photos.dart

@@ -21,8 +21,10 @@ import 'package:nc_photos/exception_util.dart' as exception_util;
 import 'package:nc_photos/iterable_extension.dart';
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/metadata_task_manager.dart';
+import 'package:nc_photos/platform/k.dart' as platform_k;
 import 'package:nc_photos/pref.dart';
 import 'package:nc_photos/primitive.dart';
+import 'package:nc_photos/share_handler.dart';
 import 'package:nc_photos/snack_bar_manager.dart';
 import 'package:nc_photos/theme.dart';
 import 'package:nc_photos/use_case/remove.dart';
@@ -159,6 +161,14 @@ class _HomePhotosState extends State<HomePhotos>
         title: Text(AppLocalizations.of(context)
             .selectionAppBarTitle(selectedListItems.length)),
         actions: [
+          if (platform_k.isAndroid)
+            IconButton(
+              icon: const Icon(Icons.share),
+              tooltip: AppLocalizations.of(context).shareSelectedTooltip,
+              onPressed: () {
+                _onSelectionAppBarSharePressed(context);
+              },
+            ),
           IconButton(
             icon: const Icon(Icons.playlist_add),
             tooltip: AppLocalizations.of(context).addSelectedToAlbumTooltip,
@@ -260,6 +270,19 @@ class _HomePhotosState extends State<HomePhotos>
         arguments: ViewerArguments(widget.account, _backingFiles, index));
   }
 
+  void _onSelectionAppBarSharePressed(BuildContext context) {
+    assert(platform_k.isAndroid);
+    final selected = selectedListItems
+        .whereType<_FileListItem>()
+        .map((e) => e.file)
+        .toList();
+    ShareHandler().shareFiles(context, widget.account, selected).then((_) {
+      setState(() {
+        clearSelectedItems();
+      });
+    });
+  }
+
   void _onSelectionAppBarAddToAlbumPressed(BuildContext context) {
     showDialog(
       context: context,
@@ -699,4 +722,5 @@ class _VideoListItem extends _FileListItem {
 
 enum _SelectionAppBarMenuOption {
   archive,
+  delete,
 }

lib/widget/viewer.dart

@@ -18,6 +18,7 @@ import 'package:nc_photos/mobile/notification.dart';
 import 'package:nc_photos/mobile/platform.dart'
     if (dart.library.html) 'package:nc_photos/web/platform.dart' as platform;
 import 'package:nc_photos/platform/k.dart' as platform_k;
+import 'package:nc_photos/share_handler.dart';
 import 'package:nc_photos/snack_bar_manager.dart';
 import 'package:nc_photos/theme.dart';
 import 'package:nc_photos/use_case/remove.dart';
@@ -298,6 +299,18 @@ class _ViewerState extends State<Viewer> {
               mainAxisAlignment: MainAxisAlignment.center,
               mainAxisSize: MainAxisSize.max,
               children: <Widget>[
+                if (platform_k.isAndroid)
+                  Expanded(
+                    flex: 1,
+                    child: IconButton(
+                      icon: Icon(
+                        Icons.share_outlined,
+                        color: Colors.white.withOpacity(.87),
+                      ),
+                      tooltip: AppLocalizations.of(context).shareTooltip,
+                      onPressed: () => _onSharePressed(context),
+                    ),
+                  ),
                 Expanded(
                   flex: 1,
                   child: IconButton(
@@ -543,6 +556,12 @@ class _ViewerState extends State<Viewer> {
     }
   }
 
+  void _onSharePressed(BuildContext context) {
+    assert(platform_k.isAndroid);
+    final file = widget.streamFiles[_pageController.page.round()];
+    ShareHandler().shareFiles(context, widget.account, [file]);
+  }
+
   void _onDownloadPressed(BuildContext context) async {
     final file = widget.streamFiles[_pageController.page.round()];
     _log.info("[_onDownloadPressed] Downloading file: ${file.path}");