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Areas alarms

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

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.

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​

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

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​

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

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:

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

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.

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​

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

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.

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