fix: sync theme updates with the map-ready message

CHANGELOG_UNRELEASED.md

@@ -8,4 +8,8 @@
   actions such as selecting a POI or starting navigation from outside the map screen (e.g., from a
   list or a notification). Since the MapViewController is only available once the MapView has fully
   loaded, this helper provides a simple, awaitable ensureMapViewController() method—powered by a
-  Dart Completer—that resolves automatically when the controller becomes ready.
+  Dart Completer—that resolves automatically when the controller becomes ready.
+
+### Added
+
+- Added new message to let map-viewer know what's the current device preferred color scheme.

lib/src/controller.dart

@@ -114,6 +114,15 @@ class MapViewController {
     _webViewController.reload();
   }
 
+  /// Sets the viewer `preferredTheme` according to the current platform brightness.
+  ///
+  /// This does not override a theme already selected by the user inside the
+  /// webview; it only provides the preferred theme when the viewer applies system
+  /// preferences.
+  void _setPreferredTheme(Brightness brightness) {
+    _sendPreferredTheme(brightness);
+  }
+
   /// Selects the given Building in the map.
   /// To set the initial Building use [MapViewConfiguration].
   void selectBuilding(String identifier) async {
@@ -272,7 +281,8 @@ class MapViewController {
   /// Select a floor of the current building by its [Floor.identifier].
   ///
   /// **NOTE**: introducing an invalid identifier may result in unexpected behaviours.
-  void selectFloor(String identifier, {SelectCartographyOptions? options}) async {
+  void selectFloor(String identifier,
+      {SelectCartographyOptions? options}) async {
     int floorId = int.tryParse(identifier) ?? 0;
     final message = {
       "identifier": floorId,
@@ -347,6 +357,17 @@ class MapViewController {
     _sendMessage(WV_APP_CONFIG, jsonEncode(configItems));
   }
 
+  void _sendPreferredTheme(Brightness brightness) {
+    dynamic message = {
+      "theme": brightness == Brightness.dark ? 'dark' : 'light'
+    };
+
+    _sendMessage(
+      WV_MESSAGE_UI_SET_PREFERRED_THEME,
+      jsonEncode(message),
+    );
+  }
+
   void _setRoute(
       DirectionsMessage directionsMessage, SitumRoute situmRoute) async {
     situmRoute.rawContent["identifier"] = directionsMessage.identifier;

lib/src/situm_map_view.dart

@@ -31,7 +31,7 @@ class MapView extends StatefulWidget {
   State<StatefulWidget> createState() => _MapViewState();
 }
 
-class _MapViewState extends State<MapView> {
+class _MapViewState extends State<MapView> with WidgetsBindingObserver {
   static MapViewController? wyfController;
   static PlatformWebViewController? webViewController;
   static PlatformWebViewWidget? webViewWidget;
@@ -44,6 +44,7 @@ class _MapViewState extends State<MapView> {
   @override
   void initState() {
     super.initState();
+    WidgetsBinding.instance.addObserver(this);
     mapViewConfiguration = widget.configuration;
 
     // Avoid re-initializations of the underlying WebView (PlatformView) if
@@ -176,6 +177,12 @@ class _MapViewState extends State<MapView> {
         ?.loadRequest(LoadRequestParams(uri: Uri.parse(mapViewUrl)));
   }
 
+  void _syncPlatformPreferredTheme() {
+    wyfController?._setPreferredTheme(
+      WidgetsBinding.instance.platformDispatcher.platformBrightness,
+    );
+  }
+
   void _displayBlankScreen(bool value) {
     if (mounted) {
       setState(() {
@@ -221,16 +228,22 @@ class _MapViewState extends State<MapView> {
     }
   }
 
+  @override
+  void didChangePlatformBrightness() {
+    _syncPlatformPreferredTheme();
+  }
+
   @override
   void dispose() {
-    super.dispose();
+    WidgetsBinding.instance.removeObserver(this);
     // IMPORTANT: We use a static reference to support the
     // "persistUnderlyingWidget" feature. Because of that, this state must be
     // explicitly unregistered when disposed; otherwise it may continue receiving
     // WebView messages through _onMapViewerMessageUpdateInternalState, causing
     // unwanted rebuilds in an inconsistent state.
     _InternalMessageBridge.unregister();
     // wyfController?.onWidgetDisposed();
+    super.dispose();
   }
 
   void _onErrorRetryLoad() {
@@ -255,6 +268,7 @@ class _MapViewState extends State<MapView> {
           _shouldDisplayMainFrameError = false;
         }
       });
+      _syncPlatformPreferredTheme();
     }
   }
 }

lib/wayfinding.dart

@@ -60,6 +60,7 @@ const WV_MESSAGE_CALIBRATION_STOPPED = "calibration.stopped";
 
 // Configuration
 const WV_APP_CONFIG = "app.set_config_item";
+const WV_MESSAGE_UI_SET_PREFERRED_THEME = "ui.set_preferred_theme";
 const WV_APP_CONFIG_ITEM_TTS_ENGINE = "internal.tts.engine";
 
 // Location actions