Keep contact GPS location saved

lib/services/route_hash_preferences.dart

@@ -0,0 +1,26 @@
+import 'package:shared_preferences/shared_preferences.dart';
+
+class RouteHashPreferences {
+  static const String _hashSizeKey = 'route_hash_size';
+  static const int defaultHashSize = 1;
+
+  static Future<int> getHashSize() async {
+    final prefs = await SharedPreferences.getInstance();
+    final value = prefs.getInt(_hashSizeKey) ?? defaultHashSize;
+    return _normalize(value);
+  }
+
+  static Future<void> setHashSize(int value) async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setInt(_hashSizeKey, _normalize(value));
+  }
+
+  static int normalizeSync(int value) => _normalize(value);
+
+  static int _normalize(int value) {
+    if (value < 1 || value > 3) {
+      return defaultHashSize;
+    }
+    return value;
+  }
+}