#39 listen to media store changes

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

@@ -16,24 +16,18 @@ 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
 
 class MainActivity : FlutterActivity() {
-    companion object {
+    private lateinit var contentStreamHandler: ContentChangeStreamHandler
-        private val LOG_TAG = LogUtils.createTag(MainActivity::class.java)
+    private lateinit var intentStreamHandler: IntentStreamHandler
-        const val INTENT_CHANNEL = "deckers.thibault/aves/intent"
-        const val VIEWER_CHANNEL = "deckers.thibault/aves/viewer"
-    }
-
-    private val intentStreamHandler = IntentStreamHandler()
     private lateinit var intentDataMap: MutableMap<String, Any?>
 
     override fun onCreate(savedInstanceState: Bundle?) {
         Log.i(LOG_TAG, "onCreate intent=$intent")
         super.onCreate(savedInstanceState)
 
-        intentDataMap = extractIntentData(intent)
-
         val messenger = flutterEngine!!.dartExecutor.binaryMessenger
 
         MethodChannel(messenger, AppAdapterHandler.CHANNEL).setMethodCallHandler(AppAdapterHandler(this))
@@ -48,59 +42,34 @@ class MainActivity : FlutterActivity() {
         StreamsChannel(messenger, MediaStoreStreamHandler.CHANNEL).setStreamHandlerFactory { args -> MediaStoreStreamHandler(this, args) }
         StreamsChannel(messenger, StorageAccessStreamHandler.CHANNEL).setStreamHandlerFactory { args -> StorageAccessStreamHandler(this, args) }
 
+        // Media Store change monitoring
+        contentStreamHandler = ContentChangeStreamHandler(this).apply {
+            EventChannel(messenger, ContentChangeStreamHandler.CHANNEL).setStreamHandler(this)
+        }
+
+        // intent handling
+        intentStreamHandler = IntentStreamHandler().apply {
+            EventChannel(messenger, IntentStreamHandler.CHANNEL).setStreamHandler(this)
+        }
+        intentDataMap = extractIntentData(intent)
         MethodChannel(messenger, VIEWER_CHANNEL).setMethodCallHandler { call, result ->
             when (call.method) {
                 "getIntentData" -> {
                     result.success(intentDataMap)
                     intentDataMap.clear()
                 }
-                "pick" -> {
+                "pick" -> pick(call)
-                    val pickedUri = call.argument<String>("uri")
-                    if (pickedUri != null) {
-                        val intent = Intent().apply {
-                            data = Uri.parse(pickedUri)
-                            addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
-                        }
-                        setResult(RESULT_OK, intent)
-                    } else {
-                        setResult(RESULT_CANCELED)
-                    }
-                    finish()
-                }
-
             }
         }
-        EventChannel(messenger, INTENT_CHANNEL).setStreamHandler(intentStreamHandler)
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N_MR1) {
             setupShortcuts()
         }
     }
 
-    @RequiresApi(Build.VERSION_CODES.N_MR1)
+    override fun onDestroy() {
-    private fun setupShortcuts() {
+        contentStreamHandler.dispose()
-        // do not use 'route' as extra key, as the Flutter framework acts on it
+        super.onDestroy()
-
-        val search = ShortcutInfoCompat.Builder(this, "search")
-            .setShortLabel(getString(R.string.search_shortcut_short_label))
-            .setIcon(IconCompat.createWithResource(this, R.mipmap.ic_shortcut_search))
-            .setIntent(
-                Intent(Intent.ACTION_MAIN, null, this, MainActivity::class.java)
-                    .putExtra("page", "/search")
-            )
-            .build()
-
-        val videos = ShortcutInfoCompat.Builder(this, "videos")
-            .setShortLabel(getString(R.string.videos_shortcut_short_label))
-            .setIcon(IconCompat.createWithResource(this, R.mipmap.ic_shortcut_movie))
-            .setIntent(
-                Intent(Intent.ACTION_MAIN, null, this, MainActivity::class.java)
-                    .putExtra("page", "/collection")
-                    .putExtra("filters", arrayOf("{\"type\":\"mime\",\"mime\":\"video/*\"}"))
-            )
-            .build()
-
-        ShortcutManagerCompat.setDynamicShortcuts(this, listOf(videos, search))
     }
 
     override fun onNewIntent(intent: Intent) {
@@ -109,6 +78,25 @@ class MainActivity : FlutterActivity() {
         intentStreamHandler.notifyNewIntent(extractIntentData(intent))
     }
 
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        if (requestCode == PermissionManager.VOLUME_ACCESS_REQUEST_CODE) {
+            val treeUri = data?.data
+            if (resultCode != RESULT_OK || treeUri == null) {
+                PermissionManager.onPermissionResult(requestCode, null)
+                return
+            }
+
+            // save access permissions across reboots
+            val takeFlags = (data.flags
+                    and (Intent.FLAG_GRANT_READ_URI_PERMISSION
+                    or Intent.FLAG_GRANT_WRITE_URI_PERMISSION))
+            contentResolver.takePersistableUriPermission(treeUri, takeFlags)
+
+            // resume pending action
+            PermissionManager.onPermissionResult(requestCode, treeUri)
+        }
+    }
+
     private fun extractIntentData(intent: Intent?): MutableMap<String, Any?> {
         when (intent?.action) {
             Intent.ACTION_MAIN -> {
@@ -138,22 +126,48 @@ class MainActivity : FlutterActivity() {
         return HashMap()
     }
 
-    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+    private fun pick(call: MethodCall) {
-        if (requestCode == PermissionManager.VOLUME_ACCESS_REQUEST_CODE) {
+        val pickedUri = call.argument<String>("uri")
-            val treeUri = data?.data
+        if (pickedUri != null) {
-            if (resultCode != RESULT_OK || treeUri == null) {
+            val intent = Intent().apply {
-                PermissionManager.onPermissionResult(requestCode, null)
+                data = Uri.parse(pickedUri)
-                return
+                addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
             }
-
+            setResult(RESULT_OK, intent)
-            // save access permissions across reboots
+        } else {
-            val takeFlags = (data.flags
+            setResult(RESULT_CANCELED)
-                    and (Intent.FLAG_GRANT_READ_URI_PERMISSION
-                    or Intent.FLAG_GRANT_WRITE_URI_PERMISSION))
-            contentResolver.takePersistableUriPermission(treeUri, takeFlags)
-
-            // resume pending action
-            PermissionManager.onPermissionResult(requestCode, treeUri)
         }
+        finish()
+    }
+
+    @RequiresApi(Build.VERSION_CODES.N_MR1)
+    private fun setupShortcuts() {
+        // do not use 'route' as extra key, as the Flutter framework acts on it
+
+        val search = ShortcutInfoCompat.Builder(this, "search")
+            .setShortLabel(getString(R.string.search_shortcut_short_label))
+            .setIcon(IconCompat.createWithResource(this, R.mipmap.ic_shortcut_search))
+            .setIntent(
+                Intent(Intent.ACTION_MAIN, null, this, MainActivity::class.java)
+                    .putExtra("page", "/search")
+            )
+            .build()
+
+        val videos = ShortcutInfoCompat.Builder(this, "videos")
+            .setShortLabel(getString(R.string.videos_shortcut_short_label))
+            .setIcon(IconCompat.createWithResource(this, R.mipmap.ic_shortcut_movie))
+            .setIntent(
+                Intent(Intent.ACTION_MAIN, null, this, MainActivity::class.java)
+                    .putExtra("page", "/collection")
+                    .putExtra("filters", arrayOf("{\"type\":\"mime\",\"mime\":\"video/*\"}"))
+            )
+            .build()
+
+        ShortcutManagerCompat.setDynamicShortcuts(this, listOf(videos, search))
+    }
+
+    companion object {
+        private val LOG_TAG = LogUtils.createTag(MainActivity::class.java)
+        const val VIEWER_CHANNEL = "deckers.thibault/aves/viewer"
     }
 }

android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/fetchers/RegionFetcher.kt

@@ -111,11 +111,6 @@ class RegionFetcher internal constructor(
             .submit()
         try {
             val bitmap = target.get()
-//            if (MimeTypes.needRotationAfterGlide(sourceMimeType)) {
-//                bitmap = BitmapUtils.applyExifOrientation(context, bitmap, sourceEntry.rotationDegrees, sourceEntry.isFlipped)
-//            }
-            bitmap ?: throw Exception("failed to get image from uri=$sourceUri page=$pageId")
-
             val tempFile = File.createTempFile("aves", null, context.cacheDir).apply {
                 deleteOnExit()
                 outputStream().use { outputStream ->

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

@@ -0,0 +1,61 @@
+package deckers.thibault.aves.channel.streams
+
+import android.content.Context
+import android.database.ContentObserver
+import android.net.Uri
+import android.os.Handler
+import android.os.Looper
+import android.provider.MediaStore
+import android.util.Log
+import deckers.thibault.aves.utils.LogUtils
+import io.flutter.plugin.common.EventChannel
+import io.flutter.plugin.common.EventChannel.EventSink
+
+class ContentChangeStreamHandler(private val context: Context) : EventChannel.StreamHandler {
+    private val contentObserver = object : ContentObserver(null) {
+        override fun onChange(selfChange: Boolean) {
+            this.onChange(selfChange, null)
+        }
+
+        override fun onChange(selfChange: Boolean, uri: Uri?) {
+            // warning: querying the content resolver right after a change
+            // sometimes yields obsolete results
+            success(uri?.toString())
+        }
+    }
+    private lateinit var eventSink: EventSink
+    private lateinit var handler: Handler
+
+    init {
+        context.contentResolver.apply {
+            registerContentObserver(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, true, contentObserver)
+            registerContentObserver(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, true, contentObserver)
+        }
+    }
+
+    override fun onListen(arguments: Any?, eventSink: EventSink) {
+        this.eventSink = eventSink
+        handler = Handler(Looper.getMainLooper())
+    }
+
+    override fun onCancel(arguments: Any?) {}
+
+    fun dispose() {
+        context.contentResolver.unregisterContentObserver(contentObserver)
+    }
+
+    private fun success(uri: String?) {
+        handler.post {
+            try {
+                eventSink.success(uri)
+            } catch (e: Exception) {
+                Log.w(LOG_TAG, "failed to use event sink", e)
+            }
+        }
+    }
+
+    companion object {
+        private val LOG_TAG = LogUtils.createTag(ContentChangeStreamHandler::class.java)
+        const val CHANNEL = "deckers.thibault/aves/contentchange"
+    }
+}

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

@@ -18,4 +18,8 @@ class IntentStreamHandler : EventChannel.StreamHandler {
     fun notifyNewIntent(intentData: MutableMap<String, Any?>?) {
         eventSink?.success(intentData)
     }
+
+    companion object {
+        const val CHANNEL = "deckers.thibault/aves/intent"
+    }
 }

lib/main.dart

@@ -4,7 +4,9 @@ import 'dart:ui';
 import 'package:aves/model/settings/settings.dart';
 import 'package:aves/model/source/collection_source.dart';
 import 'package:aves/model/source/media_store_source.dart';
+import 'package:aves/theme/durations.dart';
 import 'package:aves/theme/icons.dart';
+import 'package:aves/utils/debouncer.dart';
 import 'package:aves/widgets/common/behaviour/route_tracker.dart';
 import 'package:aves/widgets/common/behaviour/routes.dart';
 import 'package:aves/widgets/home_page.dart';
@@ -45,10 +47,14 @@ class AvesApp extends StatefulWidget {
 
 class _AvesAppState extends State<AvesApp> {
   Future<void> _appSetup;
+  final _mediaStoreSource = MediaStoreSource();
+  final Debouncer _contentChangeDebouncer = Debouncer(delay: Durations.contentChangeDebounceDelay);
+  final List<String> changedUris = [];
 
   // observers are not registered when using the same list object with different items
   // the list itself needs to be reassigned
   List<NavigatorObserver> _navigatorObservers = [];
+  final EventChannel _contentChangeChannel = EventChannel('deckers.thibault/aves/contentchange');
   final EventChannel _newIntentChannel = EventChannel('deckers.thibault/aves/intent');
   final GlobalKey<NavigatorState> _navigatorKey = GlobalKey(debugLabel: 'app-navigator');
 
@@ -96,53 +102,18 @@ class _AvesAppState extends State<AvesApp> {
   void initState() {
     super.initState();
     _appSetup = _setup();
+    _contentChangeChannel.receiveBroadcastStream().listen((event) => _onContentChange(event as String));
     _newIntentChannel.receiveBroadcastStream().listen((event) => _onNewIntent(event as Map));
   }
 
-  Future<void> _setup() async {
-    await Firebase.initializeApp().then((app) {
-      final crashlytics = FirebaseCrashlytics.instance;
-      FlutterError.onError = crashlytics.recordFlutterError;
-      crashlytics.setCustomKey('locales', window.locales.join(', '));
-      final now = DateTime.now();
-      crashlytics.setCustomKey('timezone', '${now.timeZoneName} (${now.timeZoneOffset})');
-      crashlytics.setCustomKey(
-          'build_mode',
-          kReleaseMode
-              ? 'release'
-              : kProfileMode
-                  ? 'profile'
-                  : 'debug');
-    });
-    await settings.init();
-    await settings.initFirebase();
-    _navigatorObservers = [
-      FirebaseAnalyticsObserver(analytics: FirebaseAnalytics()),
-      CrashlyticsRouteTracker(),
-    ];
-  }
-
-  void _onNewIntent(Map intentData) {
-    debugPrint('$runtimeType onNewIntent with intentData=$intentData');
-
-    // do not reset when relaunching the app
-    if (AvesApp.mode == AppMode.main && (intentData == null || intentData.isEmpty == true)) return;
-
-    FirebaseCrashlytics.instance.log('New intent');
-    _navigatorKey.currentState.pushReplacement(DirectMaterialPageRoute(
-      settings: RouteSettings(name: HomePage.routeName),
-      builder: (_) => getFirstPage(intentData: intentData),
-    ));
-  }
-
   @override
   Widget build(BuildContext context) {
     // place the settings provider above `MaterialApp`
     // so it can be used during navigation transitions
     return ChangeNotifierProvider<Settings>.value(
       value: settings,
-      child: Provider<CollectionSource>(
+      child: Provider<CollectionSource>.value(
-        create: (context) => MediaStoreSource(),
+        value: _mediaStoreSource,
         child: OverlaySupport(
           child: FutureBuilder<void>(
             future: _appSetup,
@@ -181,4 +152,48 @@ class _AvesAppState extends State<AvesApp> {
       ),
     );
   }
+
+  Future<void> _setup() async {
+    await Firebase.initializeApp().then((app) {
+      final crashlytics = FirebaseCrashlytics.instance;
+      FlutterError.onError = crashlytics.recordFlutterError;
+      crashlytics.setCustomKey('locales', window.locales.join(', '));
+      final now = DateTime.now();
+      crashlytics.setCustomKey('timezone', '${now.timeZoneName} (${now.timeZoneOffset})');
+      crashlytics.setCustomKey(
+          'build_mode',
+          kReleaseMode
+              ? 'release'
+              : kProfileMode
+                  ? 'profile'
+                  : 'debug');
+    });
+    await settings.init();
+    await settings.initFirebase();
+    _navigatorObservers = [
+      FirebaseAnalyticsObserver(analytics: FirebaseAnalytics()),
+      CrashlyticsRouteTracker(),
+    ];
+  }
+
+  void _onNewIntent(Map intentData) {
+    debugPrint('$runtimeType onNewIntent with intentData=$intentData');
+
+    // do not reset when relaunching the app
+    if (AvesApp.mode == AppMode.main && (intentData == null || intentData.isEmpty == true)) return;
+
+    FirebaseCrashlytics.instance.log('New intent');
+    _navigatorKey.currentState.pushReplacement(DirectMaterialPageRoute(
+      settings: RouteSettings(name: HomePage.routeName),
+      builder: (_) => getFirstPage(intentData: intentData),
+    ));
+  }
+
+  void _onContentChange(String uri) {
+    changedUris.add(uri);
+    _contentChangeDebouncer(() {
+      _mediaStoreSource.refreshUris(List.of(changedUris));
+      changedUris.clear();
+    });
+  }
 }

lib/model/entry.dart

@@ -268,12 +268,13 @@ class AvesEntry {
     }
   }
 
-  // The additional comparison of width to height is a workaround for badly registered entries.
+  // Media Store size/rotation is inaccurate, e.g. a portrait FHD video is rotated according to its metadata,
-  // e.g. a portrait FHD video should be registered as width=1920, height=1080, orientation=90,
+  // so it should be registered as width=1920, height=1080, orientation=90,
-  // but is incorrectly registered in the Media Store as width=1080, height=1920, orientation=0
+  // but is incorrectly registered as width=1080, height=1920, orientation=0.
-  // Double-checking the width/height during loading or cataloguing is the proper solution,
+  // Double-checking the width/height during loading or cataloguing is the proper solution, but it would take space and time.
-  // but it would take space and time, so a basic workaround will do.
+  // Comparing width and height can help with the portrait FHD video example,
-  bool get isPortrait => rotationDegrees % 180 == 90 && (catalogMetadata?.rotationDegrees == null || width > height);
+  // but it fails for a portrait screenshot rotated, which is landscape with width=1080, height=1920, orientation=90
+  bool get isRotated => rotationDegrees % 180 == 90;
 
   static const ratioSeparator = '\u2236';
   static const resolutionSeparator = ' \u00D7 ';
@@ -281,7 +282,7 @@ class AvesEntry {
   String get resolutionText {
     final ws = width ?? '?';
     final hs = height ?? '?';
-    return isPortrait ? '$hs$resolutionSeparator$ws' : '$ws$resolutionSeparator$hs';
+    return isRotated ? '$hs$resolutionSeparator$ws' : '$ws$resolutionSeparator$hs';
   }
 
   String get aspectRatioText {
@@ -289,7 +290,7 @@ class AvesEntry {
       final gcd = width.gcd(height);
       final w = width ~/ gcd;
       final h = height ~/ gcd;
-      return isPortrait ? '$h$ratioSeparator$w' : '$w$ratioSeparator$h';
+      return isRotated ? '$h$ratioSeparator$w' : '$w$ratioSeparator$h';
     } else {
       return '?$ratioSeparator?';
     }
@@ -297,13 +298,13 @@ class AvesEntry {
 
   double get displayAspectRatio {
     if (width == 0 || height == 0) return 1;
-    return isPortrait ? height / width : width / height;
+    return isRotated ? height / width : width / height;
   }
 
   Size get displaySize {
     final w = width.toDouble();
     final h = height.toDouble();
-    return isPortrait ? Size(h, w) : Size(w, h);
+    return isRotated ? Size(h, w) : Size(w, h);
   }
 
   int get megaPixels => width != null && height != null ? (width * height / 1000000).round() : null;
@@ -636,7 +637,10 @@ class AvesEntry {
   // 1) date descending
   // 2) name descending
   static int compareByDate(AvesEntry a, AvesEntry b) {
-    final c = (b.bestDate ?? _epoch).compareTo(a.bestDate ?? _epoch);
+    var c = (b.bestDate ?? _epoch).compareTo(a.bestDate ?? _epoch);
-    return c != 0 ? c : -compareByName(a, b);
+    if (c != 0) return c;
+    c = (b.dateModifiedSecs ?? 0).compareTo(a.dateModifiedSecs ?? 0);
+    if (c != 0) return c;
+    return -compareByName(a, b);
   }
 }

lib/model/source/album.dart

@@ -53,7 +53,7 @@ mixin AlbumMixin on SourceBase {
   Map<String, AvesEntry> getAlbumEntries() {
     final entries = sortedEntriesForFilterList;
     final regularAlbums = <String>[], appAlbums = <String>[], specialAlbums = <String>[];
-    for (var album in sortedAlbums) {
+    for (final album in sortedAlbums) {
       switch (androidFileUtils.getAlbumType(album)) {
         case AlbumType.regular:
           regularAlbums.add(album);

lib/model/source/collection_lens.dart

@@ -19,6 +19,7 @@ class CollectionLens with ChangeNotifier, CollectionActivityMixin, CollectionSel
   EntryGroupFactor groupFactor;
   EntrySortFactor sortFactor;
   final AChangeNotifier filterChangeNotifier = AChangeNotifier();
+  bool listenToSource;
 
   List<AvesEntry> _filteredEntries;
   List<StreamSubscription> _subscriptions = [];
@@ -30,13 +31,16 @@ class CollectionLens with ChangeNotifier, CollectionActivityMixin, CollectionSel
     Iterable<CollectionFilter> filters,
     @required EntryGroupFactor groupFactor,
     @required EntrySortFactor sortFactor,
+    this.listenToSource = true,
   })  : filters = {if (filters != null) ...filters.where((f) => f != null)},
         groupFactor = groupFactor ?? EntryGroupFactor.month,
         sortFactor = sortFactor ?? EntrySortFactor.date {
-    _subscriptions.add(source.eventBus.on<EntryAddedEvent>().listen((e) => _refresh()));
+    if (listenToSource) {
-    _subscriptions.add(source.eventBus.on<EntryRemovedEvent>().listen((e) => onEntryRemoved(e.entries)));
+      _subscriptions.add(source.eventBus.on<EntryAddedEvent>().listen((e) => _refresh()));
-    _subscriptions.add(source.eventBus.on<EntryMovedEvent>().listen((e) => _refresh()));
+      _subscriptions.add(source.eventBus.on<EntryRemovedEvent>().listen((e) => onEntryRemoved(e.entries)));
-    _subscriptions.add(source.eventBus.on<CatalogMetadataChangedEvent>().listen((e) => _refresh()));
+      _subscriptions.add(source.eventBus.on<EntryMovedEvent>().listen((e) => _refresh()));
+      _subscriptions.add(source.eventBus.on<CatalogMetadataChangedEvent>().listen((e) => _refresh()));
+    }
     _refresh();
   }
 
@@ -49,15 +53,6 @@ class CollectionLens with ChangeNotifier, CollectionActivityMixin, CollectionSel
     super.dispose();
   }
 
-  CollectionLens derive(CollectionFilter filter) {
-    return CollectionLens(
-      source: source,
-      filters: filters,
-      groupFactor: groupFactor,
-      sortFactor: sortFactor,
-    )..addFilter(filter);
-  }
-
   bool get isEmpty => _filteredEntries.isEmpty;
 
   int get entryCount => _filteredEntries.length;
@@ -82,7 +77,7 @@ class CollectionLens with ChangeNotifier, CollectionActivityMixin, CollectionSel
     return true;
   }
 
-  Object heroTag(AvesEntry entry) => '$hashCode${entry.uri}';
+  Object heroTag(AvesEntry entry) => entry.uri;
 
   void addFilter(CollectionFilter filter) {
     if (filter == null || filters.contains(filter)) return;

lib/model/source/collection_source.dart

@@ -56,6 +56,7 @@ abstract class CollectionSource with SourceBase, AlbumMixin, LocationMixin, TagM
   }
 
   void addAll(Iterable<AvesEntry> entries) {
+    if (entries.isEmpty) return;
     if (_rawEntries.isNotEmpty) {
       final newContentIds = entries.map((entry) => entry.contentId).toList();
       _rawEntries.removeWhere((entry) => newContentIds.contains(entry.contentId));

lib/model/source/media_store_source.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:math';
 
 import 'package:aves/model/entry.dart';
@@ -40,6 +41,7 @@ class MediaStoreSource extends CollectionSource {
 
   @override
   Future<void> refresh() async {
+    assert(_initialized);
     debugPrint('$runtimeType refresh start');
     final stopwatch = Stopwatch()..start();
     stateNotifier.value = SourceState.loading;
@@ -47,8 +49,8 @@ class MediaStoreSource extends CollectionSource {
 
     final oldEntries = await metadataDb.loadEntries(); // 400ms for 5500 entries
     final knownEntryMap = Map.fromEntries(oldEntries.map((entry) => MapEntry(entry.contentId, entry.dateModifiedSecs)));
-    final obsoleteEntries = (await ImageFileService.getObsoleteEntries(knownEntryMap.keys.toList())).toSet();
+    final obsoleteContentIds = (await ImageFileService.getObsoleteEntries(knownEntryMap.keys.toList())).toSet();
-    oldEntries.removeWhere((entry) => obsoleteEntries.contains(entry.contentId));
+    oldEntries.removeWhere((entry) => obsoleteContentIds.contains(entry.contentId));
 
     // show known entries
     addAll(oldEntries);
@@ -57,9 +59,10 @@ class MediaStoreSource extends CollectionSource {
     debugPrint('$runtimeType refresh loaded ${oldEntries.length} known entries, elapsed=${stopwatch.elapsed}');
 
     // clean up obsolete entries
-    metadataDb.removeIds(obsoleteEntries, updateFavourites: true);
+    metadataDb.removeIds(obsoleteContentIds, updateFavourites: true);
 
     // fetch new entries
+    // refresh after the first 10 entries, then after 100 more, then every 1000 entries
     var refreshCount = 10;
     const refreshCountMax = 1000;
     final allNewEntries = <AvesEntry>[], pendingNewEntries = <AvesEntry>[];
@@ -102,6 +105,45 @@ class MediaStoreSource extends CollectionSource {
     );
   }
 
+  Future<void> refreshUris(List<String> changedUris) async {
+    assert(_initialized);
+    debugPrint('$runtimeType refreshUris uris=$changedUris');
+
+    final uriByContentId = Map.fromEntries(changedUris.map((uri) {
+      if (uri == null) return null;
+      final idString = Uri.parse(uri).pathSegments.last;
+      return MapEntry(int.tryParse(idString), uri);
+    }).where((kv) => kv != null));
+
+    // clean up obsolete entries
+    final obsoleteContentIds = (await ImageFileService.getObsoleteEntries(uriByContentId.keys.toList())).toSet();
+    uriByContentId.removeWhere((contentId, _) => obsoleteContentIds.contains(contentId));
+    metadataDb.removeIds(obsoleteContentIds, updateFavourites: true);
+
+    // add new entries
+    final newEntries = <AvesEntry>[];
+    for (final kv in uriByContentId.entries) {
+      final contentId = kv.key;
+      final uri = kv.value;
+      final sourceEntry = await ImageFileService.getEntry(uri, null);
+      final existingEntry = rawEntries.firstWhere((entry) => entry.contentId == contentId, orElse: () => null);
+      if (existingEntry == null || sourceEntry.dateModifiedSecs > existingEntry.dateModifiedSecs) {
+        newEntries.add(sourceEntry);
+      }
+    }
+    addAll(newEntries);
+    await metadataDb.saveEntries(newEntries);
+    updateAlbums();
+
+    stateNotifier.value = SourceState.cataloguing;
+    await catalogEntries();
+
+    stateNotifier.value = SourceState.locating;
+    await locateEntries();
+
+    stateNotifier.value = SourceState.ready;
+  }
+
   @override
   Future<void> refreshMetadata(Set<AvesEntry> entries) {
     final contentIds = entries.map((entry) => entry.contentId).toSet();

lib/theme/durations.dart

@@ -48,4 +48,5 @@ class Durations {
   static const doubleBackTimerDelay = Duration(milliseconds: 1000);
   static const softKeyboardDisplayDelay = Duration(milliseconds: 300);
   static const searchDebounceDelay = Duration(milliseconds: 250);
+  static const contentChangeDebounceDelay = Duration(milliseconds: 1000);
 }

lib/widgets/collection/grid/thumbnail.dart

@@ -55,7 +55,13 @@ class InteractiveThumbnail extends StatelessWidget {
       TransparentMaterialPageRoute(
         settings: RouteSettings(name: EntryViewerPage.routeName),
         pageBuilder: (c, a, sa) => EntryViewerPage(
-          collection: collection,
+          collection: CollectionLens(
+            source: collection.source,
+            filters: collection.filters,
+            groupFactor: collection.groupFactor,
+            sortFactor: collection.sortFactor,
+            listenToSource: false,
+          ),
           initialEntry: entry,
         ),
       ),

lib/widgets/viewer/debug_page.dart

@@ -77,8 +77,8 @@ class ViewerDebugPage extends StatelessWidget {
           'height': '${entry.height}',
           'sourceRotationDegrees': '${entry.sourceRotationDegrees}',
           'rotationDegrees': '${entry.rotationDegrees}',
+          'isRotated': '${entry.isRotated}',
           'isFlipped': '${entry.isFlipped}',
-          'portrait': '${entry.isPortrait}',
           'displayAspectRatio': '${entry.displayAspectRatio}',
           'displaySize': '${entry.displaySize}',
         }),

lib/widgets/viewer/entry_action_delegate.dart

@@ -16,11 +16,11 @@ import 'package:aves/widgets/dialogs/aves_dialog.dart';
 import 'package:aves/widgets/dialogs/rename_entry_dialog.dart';
 import 'package:aves/widgets/filter_grids/album_pick.dart';
 import 'package:aves/widgets/viewer/debug_page.dart';
+import 'package:aves/widgets/viewer/info/notifications.dart';
 import 'package:aves/widgets/viewer/printer.dart';
 import 'package:aves/widgets/viewer/source_viewer_page.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/services.dart';
 import 'package:intl/intl.dart';
 import 'package:pedantic/pedantic.dart';
 import 'package:provider/provider.dart';
@@ -139,15 +139,11 @@ class EntryActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAwareMix
 
     if (!await entry.delete()) {
       showFeedback(context, 'Failed');
-    } else if (hasCollection) {
-      // update collection
-      collection.source.removeEntries([entry]);
-      if (collection.sortedEntries.isEmpty) {
-        Navigator.pop(context);
-      }
     } else {
-      // leave viewer
+      if (hasCollection) {
-      unawaited(SystemNavigator.pop());
+        collection.source.removeEntries([entry]);
+      }
+      EntryDeletedNotification(entry).dispatch(context);
     }
   }
 
@@ -199,7 +195,6 @@ class EntryActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAwareMix
         } else {
           showFeedback(context, 'Done!');
         }
-        source.refresh();
       },
     );
   }

lib/widgets/viewer/entry_viewer_page.dart

@@ -20,17 +20,10 @@ class EntryViewerPage extends StatelessWidget {
   Widget build(BuildContext context) {
     return MediaQueryDataProvider(
       child: Scaffold(
-        body: collection != null
+        body: EntryViewerStack(
-            ? AnimatedBuilder(
+          collection: collection,
-                animation: collection,
+          initialEntry: initialEntry,
-                builder: (context, child) => EntryViewerStack(
+        ),
-                  collection: collection,
-                  initialEntry: initialEntry,
-                ),
-              )
-            : EntryViewerStack(
-                initialEntry: initialEntry,
-              ),
         backgroundColor: Navigator.canPop(context) ? Colors.transparent : Colors.black,
         resizeToAvoidBottomInset: false,
       ),

lib/widgets/viewer/entry_viewer_stack.dart

@@ -164,6 +164,8 @@ class _EntryViewerStackState extends State<EntryViewerStack> with SingleTickerPr
             _goToCollection(notification.filter);
           } else if (notification is ViewStateNotification) {
             _updateViewState(notification.uri, notification.viewState);
+          } else if (notification is EntryDeletedNotification) {
+            _onEntryDeleted(context, notification.entry);
           }
           return false;
         },
@@ -324,7 +326,14 @@ class _EntryViewerStackState extends State<EntryViewerStack> with SingleTickerPr
       context,
       MaterialPageRoute(
         settings: RouteSettings(name: CollectionPage.routeName),
-        builder: (context) => CollectionPage(collection.derive(filter)),
+        builder: (context) => CollectionPage(
+          CollectionLens(
+            source: collection.source,
+            filters: collection.filters,
+            groupFactor: collection.groupFactor,
+            sortFactor: collection.sortFactor,
+          )..addFilter(filter),
+        ),
       ),
       (route) => false,
     );
@@ -356,6 +365,21 @@ class _EntryViewerStackState extends State<EntryViewerStack> with SingleTickerPr
     _updateEntry();
   }
 
+  void _onEntryDeleted(BuildContext context, AvesEntry entry) {
+    if (hasCollection) {
+      final entries = collection.sortedEntries;
+      entries.remove(entry);
+      if (entries.isEmpty) {
+        Navigator.pop(context);
+      } else {
+        _onCollectionChange();
+      }
+    } else {
+      // leave viewer
+      SystemNavigator.pop();
+    }
+  }
+
   void _updateEntry() {
     if (_currentHorizontalPage != null && entries.isNotEmpty && _currentHorizontalPage >= entries.length) {
       // as of Flutter v1.22.2, `PageView` does not call `onPageChanged` when the last page is deleted

lib/widgets/viewer/info/notifications.dart

@@ -11,6 +11,12 @@ class FilterNotification extends Notification {
   const FilterNotification(this.filter);
 }
 
+class EntryDeletedNotification extends Notification {
+  final AvesEntry entry;
+
+  const EntryDeletedNotification(this.entry);
+}
+
 class OpenTempEntryNotification extends Notification {
   final AvesEntry entry;
 

lib/widgets/viewer/printer.dart

@@ -32,8 +32,9 @@ class EntryPrinter {
 
     void _addPdfPage(pdf.Widget pdfChild) {
       if (pdfChild == null) return;
+      final displaySize = entry.displaySize;
       pages.add(pdf.Page(
-        orientation: entry.isPortrait ? pdf.PageOrientation.portrait : pdf.PageOrientation.landscape,
+        orientation: displaySize.height > displaySize.width ? pdf.PageOrientation.portrait : pdf.PageOrientation.landscape,
         build: (context) => pdf.FullPage(
           ignoreMargins: true,
           child: pdf.Center(