# Areas alarms

Last updated:

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October 18, 2026

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\| 2 minutes read

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Trigger operations when users enter or exit defined geographic areas using the built-in `AlarmService` class.

## Add areas to monitor[​](#add-areas-to-monitor "Direct link to Add areas to monitor")

Define geographic areas and invoke the `monitorArea` method on your `AlarmService` instance. You can monitor three types: `RectangleGeographicArea`, `CircleGeographicArea`, and `PolygonGeographicArea`.

```dart
final RectangleGeographicArea rect = RectangleGeographicArea(
    topLeft: Coordinates(latitude: 1, longitude: 0.5),
    bottomRight: Coordinates(latitude: 0.5, longitude: 1),
);

final CircleGeographicArea circle = CircleGeographicArea(
    centerCoordinates: Coordinates(latitude: 1, longitude: 0.5),
    radius: 100,
);

final PolygonGeographicArea polygon = PolygonGeographicArea(coordinates: [
    Coordinates(latitude: 1, longitude: 0.5),
    Coordinates(latitude: 0.5, longitude: 1),
    Coordinates(latitude: 1, longitude: 1),
    Coordinates(latitude: 1, longitude: 0.5),
]);

alarmService!.monitorArea(rect, id: 'areaRect');
alarmService.monitorArea(circle, id: 'areaCircle');
alarmService.monitorArea(polygon, id: 'areaPolygon');

```

Assign a unique identifier to each area. This lets you determine which zone a user has entered or exited.

## Get monitored areas[​](#get-monitored-areas "Direct link to Get monitored areas")

Access active geofences via the `monitoredAreas` getter. It returns a list of `AlarmMonitoredArea` objects containing the parameters you provided to `monitorArea`.

```dart
List<AlarmMonitoredArea> monitorAreas = alarmService.monitoredAreas;

for (final monitorArea in monitorAreas){
    final GeographicArea area = monitorArea.area;
    final String id = monitorArea.id;
}

```

Tip

When defining a `PolygonGeographicArea`, always "close" the shape by making the first and last coordinates identical. Otherwise, the SDK may return polygons that don't match the one you provided.

## Unmonitor an area[​](#unmonitor-an-area "Direct link to Unmonitor an area")

Remove a monitored area by calling the `unmonitorArea` method with the same `GeographicArea` instance you provided to `monitorArea`.

```dart
final RectangleGeographicArea rect = RectangleGeographicArea(
    topLeft: Coordinates(latitude: 1, longitude: 0.5),
    bottomRight: Coordinates(latitude: 0.5, longitude: 1),
);
alarmService.monitorArea(rect);

alarmService.unmonitorArea(rect);

```

You can also use the `unmonitorAreasByIds` method by passing a list of IDs:

```dart
alarmService.unmonitorAreasByIds(['firstIdToUnmonitor', 'secondIdToUnmonitor']);

```

## Get notified when users enter or exit areass[​](#get-notified-when-users-enter-or-exit-areass "Direct link to Get notified when users enter or exit areass")

Attach an `AlarmListener` with the `onBoundaryCrossed` callback to your `AlarmService`. This callback returns two arrays: entered area IDs and exited area IDs.

```dart
final alarmListener = AlarmListener(
    onBoundaryCrossed: (List<String> entered, List<String> exited) {
        print("ENTERED AREAS: $entered");
        print("EXITED AREAS: $exited");
    },
);

AlarmService alarmService = AlarmService(alarmListener);

```

## Get user location areas[​](#get-user-location-areas "Direct link to Get user location areas")

Retrieve zones the user is currently inside by calling the `insideAreas` getter:

```dart
List<AlarmMonitoredArea> insideAreas = alarmService.insideAreas;

```

info

For the `insideAreas` getter to return a non-empty list, the user must be inside at least one monitored area and must move or change position within that area.

To retrieve exited zones, call the `outsideAreas` getter.

## Relevant examples demonstrating areas alarms related features[​](#relevant-examples-demonstrating-areas-alarms-related-features "Direct link to Relevant examples demonstrating areas alarms related features")

* [Areas Alarms](/docs/flutter/examples/routing-navigation/areas-alarms.md)