builds, has camera cache

lib/services/camera_cache.dart

@@ -0,0 +1,40 @@
+import 'package:latlong2/latlong.dart';
+import '../models/osm_camera_node.dart';
+import 'package:flutter_map/flutter_map.dart' show LatLngBounds;
+
+class CameraCache {
+  // Singleton instance
+  static final CameraCache instance = CameraCache._internal();
+  factory CameraCache() => instance;
+  CameraCache._internal();
+
+  final Map<int, OsmCameraNode> _nodes = {};
+
+  /// Add or update a batch of camera nodes in the cache.
+  void addOrUpdate(List<OsmCameraNode> nodes) {
+    for (var node in nodes) {
+      _nodes[node.id] = node;
+    }
+  }
+
+  /// Query for all cached cameras currently within the given LatLngBounds.
+  List<OsmCameraNode> queryByBounds(LatLngBounds bounds) {
+    return _nodes.values
+        .where((node) => _inBounds(node.coord, bounds))
+        .toList();
+  }
+
+  /// Retrieve all cached cameras.
+  List<OsmCameraNode> getAll() => _nodes.values.toList();
+
+  /// Optionally clear the cache (rarely needed)
+  void clear() => _nodes.clear();
+
+  /// Utility: point-in-bounds for coordinates
+  bool _inBounds(LatLng coord, LatLngBounds bounds) {
+    return coord.latitude >= bounds.southWest.latitude &&
+        coord.latitude <= bounds.northEast.latitude &&
+        coord.longitude >= bounds.southWest.longitude &&
+        coord.longitude <= bounds.northEast.longitude;
+  }
+}