#51 settings: import/export

android/app/src/main/kotlin/deckers/thibault/aves/MainActivity.kt

@@ -15,11 +15,11 @@ import deckers.thibault.aves.channel.calls.*
 import deckers.thibault.aves.channel.streams.*
 import deckers.thibault.aves.model.provider.MediaStoreImageProvider
 import deckers.thibault.aves.utils.LogUtils
-import deckers.thibault.aves.utils.PermissionManager
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.plugin.common.EventChannel
 import io.flutter.plugin.common.MethodCall
 import io.flutter.plugin.common.MethodChannel
+import java.util.concurrent.ConcurrentHashMap
 
 class MainActivity : FlutterActivity() {
     private lateinit var mediaStoreChangeStreamHandler: MediaStoreChangeStreamHandler
@@ -92,10 +92,10 @@ class MainActivity : FlutterActivity() {
 
     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
         when (requestCode) {
-            VOLUME_ACCESS_REQUEST -> {
+            DOCUMENT_TREE_ACCESS_REQUEST -> {
                 val treeUri = data?.data
                 if (resultCode != RESULT_OK || treeUri == null) {
-                    PermissionManager.onPermissionResult(requestCode, null)
+                    onPermissionResult(requestCode, null)
                     return
                 }
 
@@ -106,7 +106,7 @@ class MainActivity : FlutterActivity() {
                 contentResolver.takePersistableUriPermission(treeUri, takeFlags)
 
                 // resume pending action
-                PermissionManager.onPermissionResult(requestCode, treeUri)
+                onPermissionResult(requestCode, treeUri)
             }
             DELETE_PERMISSION_REQUEST -> {
                 // delete permission may be requested on Android 10+ only
@@ -114,6 +114,9 @@ class MainActivity : FlutterActivity() {
                     MediaStoreImageProvider.pendingDeleteCompleter?.complete(resultCode == RESULT_OK)
                 }
             }
+            CREATE_FILE_REQUEST, OPEN_FILE_REQUEST -> {
+                onPermissionResult(requestCode, data?.data)
+            }
         }
     }
 
@@ -189,7 +192,26 @@ class MainActivity : FlutterActivity() {
     companion object {
         private val LOG_TAG = LogUtils.createTag<MainActivity>()
         const val VIEWER_CHANNEL = "deckers.thibault/aves/viewer"
-        const val VOLUME_ACCESS_REQUEST = 1
+        const val DOCUMENT_TREE_ACCESS_REQUEST = 1
         const val DELETE_PERMISSION_REQUEST = 2
+        const val CREATE_FILE_REQUEST = 3
+        const val OPEN_FILE_REQUEST = 4
+
+        // permission request code to pending runnable
+        val pendingResultHandlers = ConcurrentHashMap<Int, PendingResultHandler>()
+
+        fun onPermissionResult(requestCode: Int, uri: Uri?) {
+            Log.d(LOG_TAG, "onPermissionResult with requestCode=$requestCode, uri=$uri")
+            val handler = pendingResultHandlers.remove(requestCode) ?: return
+            if (uri != null) {
+                handler.onGranted(uri)
+            } else {
+                handler.onDenied()
+            }
+        }
     }
 }
+
+// onGranted: user selected a directory/file (with no guarantee that it matches the requested `path`)
+// onDenied: user cancelled
+data class PendingResultHandler(val path: String?, val onGranted: (uri: Uri) -> Unit, val onDenied: () -> Unit)

android/app/src/main/kotlin/deckers/thibault/aves/channel/streams/ImageByteStreamHandler.kt

@@ -187,12 +187,12 @@ class ImageByteStreamHandler(private val activity: Activity, private val argumen
 
     companion object {
         private val LOG_TAG = LogUtils.createTag<ImageByteStreamHandler>()
-        const val CHANNEL = "deckers.thibault/aves/imagebytestream"
+        const val CHANNEL = "deckers.thibault/aves/image_byte_stream"
 
-        const val BUFFER_SIZE = 2 shl 17 // 256kB
+        private const val BUFFER_SIZE = 2 shl 17 // 256kB
 
         // request a fresh image with the highest quality format
-        val glideOptions = RequestOptions()
+        private val glideOptions = RequestOptions()
             .format(DecodeFormat.PREFER_ARGB_8888)
             .diskCacheStrategy(DiskCacheStrategy.NONE)
             .skipMemoryCache(true)

android/app/src/main/kotlin/deckers/thibault/aves/channel/streams/ImageOpStreamHandler.kt

@@ -177,6 +177,6 @@ class ImageOpStreamHandler(private val activity: Activity, private val arguments
 
     companion object {
         private val LOG_TAG = LogUtils.createTag<ImageOpStreamHandler>()
-        const val CHANNEL = "deckers.thibault/aves/imageopstream"
+        const val CHANNEL = "deckers.thibault/aves/image_op_stream"
     }
 }

android/app/src/main/kotlin/deckers/thibault/aves/channel/streams/StorageAccessStreamHandler.kt

@@ -1,25 +1,35 @@
 package deckers.thibault.aves.channel.streams
 
 import android.app.Activity
+import android.content.Intent
 import android.os.Build
 import android.os.Handler
 import android.os.Looper
 import android.util.Log
+import deckers.thibault.aves.MainActivity
+import deckers.thibault.aves.PendingResultHandler
 import deckers.thibault.aves.utils.LogUtils
-import deckers.thibault.aves.utils.PermissionManager.requestVolumeAccess
+import deckers.thibault.aves.utils.PermissionManager
 import io.flutter.plugin.common.EventChannel
 import io.flutter.plugin.common.EventChannel.EventSink
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+import java.io.FileOutputStream
 
 // starting activity to give access with the native dialog
 // breaks the regular `MethodChannel` so we use a stream channel instead
 class StorageAccessStreamHandler(private val activity: Activity, arguments: Any?) : EventChannel.StreamHandler {
     private lateinit var eventSink: EventSink
     private lateinit var handler: Handler
-    private var path: String? = null
+
+    private var op: String? = null
+    private lateinit var args: Map<*, *>
 
     init {
         if (arguments is Map<*, *>) {
-            path = arguments["path"] as String?
+            op = arguments["op"] as String?
+            args = arguments
         }
     }
 
@@ -27,6 +37,16 @@ class StorageAccessStreamHandler(private val activity: Activity, arguments: Any?
         this.eventSink = eventSink
         handler = Handler(Looper.getMainLooper())
 
+        when (op) {
+            "requestVolumeAccess" -> requestVolumeAccess()
+            "createFile" -> GlobalScope.launch(Dispatchers.IO) { createFile() }
+            "openFile" -> GlobalScope.launch(Dispatchers.IO) { openFile() }
+            else -> endOfStream()
+        }
+    }
+
+    private fun requestVolumeAccess() {
+        val path = args["path"] as String?
         if (path == null) {
             error("requestVolumeAccess-args", "failed because of missing arguments", null)
             return
@@ -37,12 +57,80 @@ class StorageAccessStreamHandler(private val activity: Activity, arguments: Any?
             return
         }
 
-        requestVolumeAccess(activity, path!!, { success(true) }, { success(false) })
+        PermissionManager.requestVolumeAccess(activity, path, {
+            success(true)
+            endOfStream()
+        }, {
+            success(false)
+            endOfStream()
+        })
+    }
+
+    private fun createFile() {
+        val name = args["name"] as String?
+        val mimeType = args["mimeType"] as String?
+        val bytes = args["bytes"] as ByteArray?
+        if (name == null || mimeType == null || bytes == null) {
+            error("createFile-args", "failed because of missing arguments", null)
+            return
+        }
+
+        val intent = Intent(Intent.ACTION_CREATE_DOCUMENT).apply {
+            addCategory(Intent.CATEGORY_OPENABLE)
+            type = mimeType
+            putExtra(Intent.EXTRA_TITLE, name)
+        }
+        MainActivity.pendingResultHandlers[MainActivity.CREATE_FILE_REQUEST] = PendingResultHandler(null, { uri ->
+            try {
+                activity.contentResolver.openOutputStream(uri)?.use { output ->
+                    output as FileOutputStream
+                    // truncate is necessary when overwriting a longer file
+                    output.channel.truncate(0)
+                    output.write(bytes)
+                }
+                success(true)
+            } catch (e: Exception) {
+                error("createFile-write", "failed to write file at uri=$uri", e.message)
+            }
+            endOfStream()
+        }, {
+            success(null)
+            endOfStream()
+        })
+        activity.startActivityForResult(intent, MainActivity.CREATE_FILE_REQUEST)
+    }
+
+
+    private fun openFile() {
+        val mimeType = args["mimeType"] as String?
+        if (mimeType == null) {
+            error("openFile-args", "failed because of missing arguments", null)
+            return
+        }
+
+        val intent = Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
+            addCategory(Intent.CATEGORY_OPENABLE)
+            type = mimeType
+        }
+        MainActivity.pendingResultHandlers[MainActivity.OPEN_FILE_REQUEST] = PendingResultHandler(null, { uri ->
+            activity.contentResolver.openInputStream(uri)?.use { input ->
+                val buffer = ByteArray(BUFFER_SIZE)
+                var len: Int
+                while (input.read(buffer).also { len = it } != -1) {
+                    success(buffer.copyOf(len))
+                }
+                endOfStream()
+            }
+        }, {
+            success(ByteArray(0))
+            endOfStream()
+        })
+        activity.startActivityForResult(intent, MainActivity.OPEN_FILE_REQUEST)
     }
 
     override fun onCancel(arguments: Any?) {}
 
-    private fun success(result: Boolean) {
+    private fun success(result: Any?) {
         handler.post {
             try {
                 eventSink.success(result)
@@ -50,7 +138,6 @@ class StorageAccessStreamHandler(private val activity: Activity, arguments: Any?
                 Log.w(LOG_TAG, "failed to use event sink", e)
             }
         }
-        endOfStream()
     }
 
     @Suppress("SameParameterValue")
@@ -62,6 +149,7 @@ class StorageAccessStreamHandler(private val activity: Activity, arguments: Any?
                 Log.w(LOG_TAG, "failed to use event sink", e)
             }
         }
+        endOfStream()
     }
 
     private fun endOfStream() {
@@ -76,6 +164,7 @@ class StorageAccessStreamHandler(private val activity: Activity, arguments: Any?
 
     companion object {
         private val LOG_TAG = LogUtils.createTag<StorageAccessStreamHandler>()
-        const val CHANNEL = "deckers.thibault/aves/storageaccessstream"
+        const val CHANNEL = "deckers.thibault/aves/storage_access_stream"
+        private const val BUFFER_SIZE = 2 shl 17 // 256kB
     }
 }

android/app/src/main/kotlin/deckers/thibault/aves/utils/PermissionManager.kt

@@ -9,22 +9,19 @@ import android.os.Environment
 import android.os.storage.StorageManager
 import android.util.Log
 import androidx.annotation.RequiresApi
-import deckers.thibault.aves.MainActivity.Companion.VOLUME_ACCESS_REQUEST
+import deckers.thibault.aves.MainActivity
+import deckers.thibault.aves.PendingResultHandler
 import deckers.thibault.aves.utils.StorageUtils.PathSegments
 import java.io.File
 import java.util.*
-import java.util.concurrent.ConcurrentHashMap
 import kotlin.collections.ArrayList
 
 object PermissionManager {
     private val LOG_TAG = LogUtils.createTag<PermissionManager>()
 
-    // permission request code to pending runnable
-    private val pendingPermissionMap = ConcurrentHashMap<Int, PendingPermissionHandler>()
-
     @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
-    fun requestVolumeAccess(activity: Activity, path: String, onGranted: () -> Unit, onDenied: () -> Unit) {
+    fun requestVolumeAccess(activity: Activity, path: String, onGranted: (uri: Uri) -> Unit, onDenied: () -> Unit) {
-        Log.i(LOG_TAG, "request user to select and grant access permission to volume=$path")
+        Log.i(LOG_TAG, "request user to select and grant access permission to path=$path")
 
         var intent: Intent? = null
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
@@ -38,20 +35,14 @@ object PermissionManager {
         }
 
         if (intent.resolveActivity(activity.packageManager) != null) {
-            pendingPermissionMap[VOLUME_ACCESS_REQUEST] = PendingPermissionHandler(path, onGranted, onDenied)
+            MainActivity.pendingResultHandlers[MainActivity.DOCUMENT_TREE_ACCESS_REQUEST] = PendingResultHandler(path, onGranted, onDenied)
-            activity.startActivityForResult(intent, VOLUME_ACCESS_REQUEST, null)
+            activity.startActivityForResult(intent, MainActivity.DOCUMENT_TREE_ACCESS_REQUEST)
         } else {
             Log.e(LOG_TAG, "failed to resolve activity for intent=$intent")
             onDenied()
         }
     }
 
-    fun onPermissionResult(requestCode: Int, treeUri: Uri?) {
-        Log.d(LOG_TAG, "onPermissionResult with requestCode=$requestCode, treeUri=$treeUri")
-        val handler = pendingPermissionMap.remove(requestCode) ?: return
-        (if (treeUri != null) handler.onGranted else handler.onDenied)()
-    }
-
     fun getGrantedDirForPath(context: Context, anyPath: String): String? {
         return getAccessibleDirs(context).firstOrNull { anyPath.startsWith(it) }
     }
@@ -167,8 +158,4 @@ object PermissionManager {
         }
         return accessibleDirs
     }
-
-    // onGranted: user gave access to a directory, with no guarantee that it matches the specified `path`
-    // onDenied: user cancelled
-    internal data class PendingPermissionHandler(val path: String, val onGranted: () -> Unit, val onDenied: () -> Unit)
 }

lib/l10n/app_en.arb

@@ -538,6 +538,11 @@
   "settingsSystemDefault": "System",
   "@settingsSystemDefault": {},
 
+  "settingsActionExport": "Export",
+  "@settingsActionExport": {},
+  "settingsActionImport": "Import",
+  "@settingsActionImport": {},
+
   "settingsSectionNavigation": "Navigation",
   "@settingsSectionNavigation": {},
   "settingsHome": "Home",

lib/l10n/app_ko.arb

@@ -250,6 +250,9 @@
   "settingsPageTitle": "설정",
   "settingsSystemDefault": "시스템",
 
+  "settingsActionExport": "내보내기",
+  "settingsActionImport": "가져오기",
+
   "settingsSectionNavigation": "탐색",
   "settingsHome": "홈",
   "settingsKeepScreenOnTile": "화면 자동 꺼짐 방지",

lib/model/actions/entry_actions.dart

@@ -113,7 +113,7 @@ extension ExtraEntryAction on EntryAction {
       case EntryAction.delete:
         return AIcons.delete;
       case EntryAction.export:
-        return AIcons.export;
+        return AIcons.saveAs;
       case EntryAction.info:
         return AIcons.info;
       case EntryAction.rename:

lib/model/actions/settings_actions.dart

@@ -0,0 +1,4 @@
+enum SettingsAction {
+  export,
+  import,
+}

lib/model/filters/filters.dart

@@ -26,22 +26,24 @@ abstract class CollectionFilter implements Comparable<CollectionFilter> {
 
   static CollectionFilter? fromJson(String jsonString) {
     final jsonMap = jsonDecode(jsonString);
-    final type = jsonMap['type'];
+    if (jsonMap is Map<String, dynamic>) {
-    switch (type) {
+      final type = jsonMap['type'];
-      case AlbumFilter.type:
+      switch (type) {
-        return AlbumFilter.fromMap(jsonMap);
+        case AlbumFilter.type:
-      case FavouriteFilter.type:
+          return AlbumFilter.fromMap(jsonMap);
-        return FavouriteFilter.instance;
+        case FavouriteFilter.type:
-      case LocationFilter.type:
+          return FavouriteFilter.instance;
-        return LocationFilter.fromMap(jsonMap);
+        case LocationFilter.type:
-      case TypeFilter.type:
+          return LocationFilter.fromMap(jsonMap);
-        return TypeFilter.fromMap(jsonMap);
+        case TypeFilter.type:
-      case MimeFilter.type:
+          return TypeFilter.fromMap(jsonMap);
-        return MimeFilter.fromMap(jsonMap);
+        case MimeFilter.type:
-      case QueryFilter.type:
+          return MimeFilter.fromMap(jsonMap);
-        return QueryFilter.fromMap(jsonMap);
+        case QueryFilter.type:
-      case TagFilter.type:
+          return QueryFilter.fromMap(jsonMap);
-        return TagFilter.fromMap(jsonMap);
+        case TagFilter.type:
+          return TagFilter.fromMap(jsonMap);
+      }
     }
     debugPrint('failed to parse filter from json=$jsonString');
     return null;

lib/model/settings/settings.dart

@@ -1,3 +1,5 @@
+import 'dart:convert';
+
 import 'package:aves/model/actions/entry_actions.dart';
 import 'package:aves/model/actions/video_actions.dart';
 import 'package:aves/model/filters/filters.dart';
@@ -25,6 +27,14 @@ class Settings extends ChangeNotifier {
     _platformSettingsChangeChannel.receiveBroadcastStream().listen((event) => _onPlatformSettingsChange(event as Map?));
   }
 
+  static const Set<String> internalKeys = {
+    hasAcceptedTermsKey,
+    catalogTimeZoneKey,
+    videoShowRawTimedTextKey,
+    searchHistoryKey,
+    lastVersionCheckDateKey,
+  };
+
   // app
   static const hasAcceptedTermsKey = 'has_accepted_terms';
   static const isCrashlyticsEnabledKey = 'is_crashlytics_enabled';
@@ -109,8 +119,12 @@ class Settings extends ChangeNotifier {
     await FirebaseCrashlytics.instance.setCrashlyticsCollectionEnabled(isCrashlyticsEnabled);
   }
 
-  Future<void> reset() {
+  Future<void> reset({required bool includeInternalKeys}) async {
-    return _prefs!.clear();
+    if (includeInternalKeys) {
+      await _prefs!.clear();
+    } else {
+      await Future.forEach(_prefs!.getKeys().whereNot(internalKeys.contains), _prefs!.remove);
+    }
   }
 
   // app
@@ -398,4 +412,98 @@ class Settings extends ChangeNotifier {
   bool _isRotationLocked = false;
 
   bool get isRotationLocked => _isRotationLocked;
+
+  // import/export
+
+  String toJson() => jsonEncode(Map.fromEntries(
+        _prefs!.getKeys().whereNot(internalKeys.contains).map((k) => MapEntry(k, _prefs!.get(k))),
+      ));
+
+  Future<void> fromJson(String jsonString) async {
+    final jsonMap = jsonDecode(jsonString);
+    if (jsonMap is Map<String, dynamic>) {
+      // clear to restore defaults
+      await reset(includeInternalKeys: false);
+
+      // apply user modifications
+      jsonMap.forEach((key, value) {
+        if (key.startsWith(tileExtentPrefixKey)) {
+          if (value is double) {
+            _prefs!.setDouble(key, value);
+          } else {
+            debugPrint('failed to import key=$key, value=$value is not a double');
+          }
+        } else {
+          switch (key) {
+            case subtitleTextColorKey:
+            case subtitleBackgroundColorKey:
+              if (value is int) {
+                _prefs!.setInt(key, value);
+              } else {
+                debugPrint('failed to import key=$key, value=$value is not an int');
+              }
+              break;
+            case subtitleFontSizeKey:
+            case infoMapZoomKey:
+              if (value is double) {
+                _prefs!.setDouble(key, value);
+              } else {
+                debugPrint('failed to import key=$key, value=$value is not a double');
+              }
+              break;
+            case isCrashlyticsEnabledKey:
+            case mustBackTwiceToExitKey:
+            case showThumbnailLocationKey:
+            case showThumbnailRawKey:
+            case showThumbnailVideoDurationKey:
+            case showOverlayMinimapKey:
+            case showOverlayInfoKey:
+            case showOverlayShootingDetailsKey:
+            case enableVideoHardwareAccelerationKey:
+            case enableVideoAutoPlayKey:
+            case subtitleShowOutlineKey:
+            case saveSearchHistoryKey:
+              if (value is bool) {
+                _prefs!.setBool(key, value);
+              } else {
+                debugPrint('failed to import key=$key, value=$value is not a bool');
+              }
+              break;
+            case localeKey:
+            case keepScreenOnKey:
+            case homePageKey:
+            case collectionGroupFactorKey:
+            case collectionSortFactorKey:
+            case albumGroupFactorKey:
+            case albumSortFactorKey:
+            case countrySortFactorKey:
+            case tagSortFactorKey:
+            case videoLoopModeKey:
+            case subtitleTextAlignmentKey:
+            case infoMapStyleKey:
+            case coordinateFormatKey:
+            case rasterBackgroundKey:
+            case vectorBackgroundKey:
+              if (value is String) {
+                _prefs!.setString(key, value);
+              } else {
+                debugPrint('failed to import key=$key, value=$value is not a string');
+              }
+              break;
+            case pinnedFiltersKey:
+            case hiddenFiltersKey:
+            case viewerQuickActionsKey:
+            case videoQuickActionsKey:
+              if (value is List) {
+                _prefs!.setStringList(key, value.cast<String>());
+              } else {
+                debugPrint('failed to import key=$key, value=$value is not a list');
+              }
+              break;
+          }
+        }
+      });
+      notifyListeners();
+    }
+  }
 }

lib/ref/mime_types.dart

@@ -44,6 +44,8 @@ class MimeTypes {
   static const mp2t = 'video/mp2t'; // .m2ts
   static const mp4 = 'video/mp4';
 
+  static const json = 'application/json';
+
   // groups
 
   // formats that support transparency

lib/services/image_file_service.dart

@@ -1,10 +1,10 @@
 import 'dart:async';
-import 'dart:convert';
 import 'dart:math';
 import 'dart:typed_data';
 
 import 'package:aves/model/entry.dart';
 import 'package:aves/services/image_op_events.dart';
+import 'package:aves/services/output_buffer.dart';
 import 'package:aves/services/service_policy.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
@@ -96,8 +96,8 @@ abstract class ImageFileService {
 
 class PlatformImageFileService implements ImageFileService {
   static const platform = MethodChannel('deckers.thibault/aves/image');
-  static final StreamsChannel _byteStreamChannel = StreamsChannel('deckers.thibault/aves/imagebytestream');
+  static final StreamsChannel _byteStreamChannel = StreamsChannel('deckers.thibault/aves/image_byte_stream');
-  static final StreamsChannel _opStreamChannel = StreamsChannel('deckers.thibault/aves/imageopstream');
+  static final StreamsChannel _opStreamChannel = StreamsChannel('deckers.thibault/aves/image_op_stream');
   static const double thumbnailDefaultSize = 64.0;
 
   static Map<String, dynamic> _toPlatformEntryMap(AvesEntry entry) {
@@ -157,7 +157,7 @@ class PlatformImageFileService implements ImageFileService {
   }) {
     try {
       final completer = Completer<Uint8List>.sync();
-      final sink = _OutputBuffer();
+      final sink = OutputBuffer();
       var bytesReceived = 0;
       _byteStreamChannel.receiveBroadcastStream(<String, dynamic>{
         'uri': uri,
@@ -405,40 +405,3 @@ class PlatformImageFileService implements ImageFileService {
     return {};
   }
 }
-
-// cf flutter/foundation `consolidateHttpClientResponseBytes`
-typedef BytesReceivedCallback = void Function(int cumulative, int? total);
-
-// cf flutter/foundation `consolidateHttpClientResponseBytes`
-class _OutputBuffer extends ByteConversionSinkBase {
-  List<List<int>>? _chunks = <List<int>>[];
-  int _contentLength = 0;
-  Uint8List? _bytes;
-
-  @override
-  void add(List<int> chunk) {
-    assert(_bytes == null);
-    _chunks!.add(chunk);
-    _contentLength += chunk.length;
-  }
-
-  @override
-  void close() {
-    if (_bytes != null) {
-      // We've already been closed; this is a no-op
-      return;
-    }
-    _bytes = Uint8List(_contentLength);
-    var offset = 0;
-    for (final chunk in _chunks!) {
-      _bytes!.setRange(offset, offset + chunk.length, chunk);
-      offset += chunk.length;
-    }
-    _chunks = null;
-  }
-
-  Uint8List get bytes {
-    assert(_bytes != null);
-    return _bytes!;
-  }
-}

lib/services/output_buffer.dart

@@ -0,0 +1,36 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+// cf flutter/foundation `consolidateHttpClientResponseBytes`
+class OutputBuffer extends ByteConversionSinkBase {
+  List<List<int>>? _chunks = <List<int>>[];
+  int _contentLength = 0;
+  Uint8List? _bytes;
+
+  @override
+  void add(List<int> chunk) {
+    assert(_bytes == null);
+    _chunks!.add(chunk);
+    _contentLength += chunk.length;
+  }
+
+  @override
+  void close() {
+    if (_bytes != null) {
+      // We've already been closed; this is a no-op
+      return;
+    }
+    _bytes = Uint8List(_contentLength);
+    var offset = 0;
+    for (final chunk in _chunks!) {
+      _bytes!.setRange(offset, offset + chunk.length, chunk);
+      offset += chunk.length;
+    }
+    _chunks = null;
+  }
+
+  Uint8List get bytes {
+    assert(_bytes != null);
+    return _bytes!;
+  }
+}

lib/services/storage_service.dart

@@ -1,5 +1,7 @@
 import 'dart:async';
+import 'dart:typed_data';
 
+import 'package:aves/services/output_buffer.dart';
 import 'package:aves/utils/android_file_utils.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
@@ -26,11 +28,16 @@ abstract class StorageService {
 
   // returns media URI
   Future<Uri?> scanFile(String path, String mimeType);
+
+  // return whether operation succeeded (`null` if user cancelled)
+  Future<bool?> createFile(String name, String mimeType, Uint8List bytes);
+
+  Future<Uint8List> openFile(String mimeType);
 }
 
 class PlatformStorageService implements StorageService {
   static const platform = MethodChannel('deckers.thibault/aves/storage');
-  static final StreamsChannel storageAccessChannel = StreamsChannel('deckers.thibault/aves/storageaccessstream');
+  static final StreamsChannel storageAccessChannel = StreamsChannel('deckers.thibault/aves/storage_access_stream');
 
   @override
   Future<Set<StorageVolume>> getStorageVolumes() async {
@@ -113,9 +120,10 @@ class PlatformStorageService implements StorageService {
     try {
       final completer = Completer<bool>();
       storageAccessChannel.receiveBroadcastStream(<String, dynamic>{
+        'op': 'requestVolumeAccess',
         'path': volumePath,
       }).listen(
-        (data) => completer.complete(data as bool?),
+        (data) => completer.complete(data as bool),
         onError: completer.completeError,
         onDone: () {
           if (!completer.isCompleted) completer.complete(false);
@@ -158,4 +166,55 @@ class PlatformStorageService implements StorageService {
     }
     return null;
   }
+
+  @override
+  Future<bool?> createFile(String name, String mimeType, Uint8List bytes) async {
+    try {
+      final completer = Completer<bool>();
+      storageAccessChannel.receiveBroadcastStream(<String, dynamic>{
+        'op': 'createFile',
+        'name': name,
+        'mimeType': mimeType,
+        'bytes': bytes,
+      }).listen(
+        (data) => completer.complete(data as bool?),
+        onError: completer.completeError,
+        onDone: () {
+          if (!completer.isCompleted) completer.complete(false);
+        },
+        cancelOnError: true,
+      );
+      return completer.future;
+    } on PlatformException catch (e) {
+      debugPrint('createFile failed with code=${e.code}, exception=${e.message}, details=${e.details}}');
+    }
+    return false;
+  }
+
+  @override
+  Future<Uint8List> openFile(String mimeType) async {
+    try {
+      final completer = Completer<Uint8List>.sync();
+      final sink = OutputBuffer();
+      storageAccessChannel.receiveBroadcastStream(<String, dynamic>{
+        'op': 'openFile',
+        'mimeType': mimeType,
+      }).listen(
+        (data) {
+          final chunk = data as Uint8List;
+          sink.add(chunk);
+        },
+        onError: completer.completeError,
+        onDone: () {
+          sink.close();
+          completer.complete(sink.bytes);
+        },
+        cancelOnError: true,
+      );
+      return completer.future;
+    } on PlatformException catch (e) {
+      debugPrint('openFile failed with code=${e.code}, exception=${e.message}, details=${e.details}}');
+    }
+    return Uint8List(0);
+  }
 }

lib/theme/icons.dart

@@ -39,13 +39,14 @@ class AIcons {
   static const IconData createAlbum = Icons.add_circle_outline;
   static const IconData debug = Icons.whatshot_outlined;
   static const IconData delete = Icons.delete_outlined;
-  static const IconData export = Icons.save_alt_outlined;
+  static const IconData export = MdiIcons.fileExportOutline;
   static const IconData flip = Icons.flip_outlined;
   static const IconData favourite = Icons.favorite_border;
   static const IconData favouriteActive = Icons.favorite;
   static const IconData goUp = Icons.arrow_upward_outlined;
   static const IconData group = Icons.group_work_outlined;
   static const IconData hide = Icons.visibility_off_outlined;
+  static const IconData import = MdiIcons.fileImportOutline;
   static const IconData info = Icons.info_outlined;
   static const IconData layers = Icons.layers_outlined;
   static const IconData openOutside = Icons.open_in_new_outlined;
@@ -57,6 +58,7 @@ class AIcons {
   static const IconData rotateLeft = Icons.rotate_left_outlined;
   static const IconData rotateRight = Icons.rotate_right_outlined;
   static const IconData rotateScreen = Icons.screen_rotation_outlined;
+  static const IconData saveAs = Icons.save_alt_outlined;
   static const IconData search = Icons.search_outlined;
   static const IconData select = Icons.select_all_outlined;
   static const IconData setCover = MdiIcons.imageEditOutline;

lib/widgets/debug/settings.dart

@@ -22,8 +22,15 @@ class DebugSettingsSection extends StatelessWidget {
             Padding(
               padding: const EdgeInsets.symmetric(horizontal: 8),
               child: ElevatedButton(
-                onPressed: () => settings.reset(),
+                onPressed: () => settings.reset(includeInternalKeys: true),
-                child: const Text('Reset'),
+                child: const Text('Reset (all store)'),
+              ),
+            ),
+            Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 8),
+              child: ElevatedButton(
+                onPressed: () => settings.reset(includeInternalKeys: false),
+                child: const Text('Reset (user preferences)'),
               ),
             ),
             SwitchListTile(

lib/widgets/settings/settings_page.dart

@@ -1,4 +1,14 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:aves/model/actions/settings_actions.dart';
+import 'package:aves/model/settings/settings.dart';
+import 'package:aves/ref/mime_types.dart';
+import 'package:aves/services/services.dart';
 import 'package:aves/theme/durations.dart';
+import 'package:aves/theme/icons.dart';
+import 'package:aves/widgets/common/action_mixins/feedback.dart';
+import 'package:aves/widgets/common/basic/menu_row.dart';
 import 'package:aves/widgets/common/extensions/build_context.dart';
 import 'package:aves/widgets/common/providers/media_query_data_provider.dart';
 import 'package:aves/widgets/settings/language/language.dart';
@@ -8,7 +18,9 @@ import 'package:aves/widgets/settings/thumbnails.dart';
 import 'package:aves/widgets/settings/video/video.dart';
 import 'package:aves/widgets/settings/viewer/viewer.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:flutter_staggered_animations/flutter_staggered_animations.dart';
+import 'package:intl/intl.dart';
 
 class SettingsPage extends StatefulWidget {
   static const routeName = '/settings';
@@ -19,7 +31,7 @@ class SettingsPage extends StatefulWidget {
   _SettingsPageState createState() => _SettingsPageState();
 }
 
-class _SettingsPageState extends State<SettingsPage> {
+class _SettingsPageState extends State<SettingsPage> with FeedbackMixin {
   final ValueNotifier<String?> _expandedNotifier = ValueNotifier(null);
 
   @override
@@ -29,6 +41,26 @@ class _SettingsPageState extends State<SettingsPage> {
       child: Scaffold(
         appBar: AppBar(
           title: Text(context.l10n.settingsPageTitle),
+          actions: [
+            PopupMenuButton<SettingsAction>(
+              itemBuilder: (context) {
+                return [
+                  PopupMenuItem(
+                    value: SettingsAction.export,
+                    child: MenuRow(text: context.l10n.settingsActionExport, icon: AIcons.export),
+                  ),
+                  PopupMenuItem(
+                    value: SettingsAction.import,
+                    child: MenuRow(text: context.l10n.settingsActionImport, icon: AIcons.import),
+                  ),
+                ];
+              },
+              onSelected: (action) {
+                // wait for the popup menu to hide before proceeding with the action
+                Future.delayed(Durations.popupMenuAnimation * timeDilation, () => _onActionSelected(action));
+              },
+            ),
+          ],
         ),
         body: Theme(
           data: theme.copyWith(
@@ -66,4 +98,35 @@ class _SettingsPageState extends State<SettingsPage> {
       ),
     );
   }
+
+  void _onActionSelected(SettingsAction action) async {
+    switch (action) {
+      case SettingsAction.export:
+        final success = await storageService.createFile(
+          'aves-settings-${DateFormat('yyyyMMdd_HHmmss').format(DateTime.now())}.json',
+          MimeTypes.json,
+          Uint8List.fromList(utf8.encode(settings.toJson())),
+        );
+        if (success != null) {
+          if (success) {
+            showFeedback(context, context.l10n.genericSuccessFeedback);
+          } else {
+            showFeedback(context, context.l10n.genericFailureFeedback);
+          }
+        }
+        break;
+      case SettingsAction.import:
+        final bytes = await storageService.openFile(MimeTypes.json);
+        if (bytes.isNotEmpty) {
+          try {
+            await settings.fromJson(utf8.decode(bytes));
+            showFeedback(context, context.l10n.genericSuccessFeedback);
+          } catch (error) {
+            debugPrint('failed to import settings, error=$error');
+            showFeedback(context, context.l10n.genericFailureFeedback);
+          }
+        }
+        break;
+    }
+  }
 }