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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.

RectangleGeographicArea rect = RectangleGeographicArea(
    { 40.71713, -74.00396 }, // top-left
    { 40.71357, -73.99925 }  // bottom-right
    );

CircleGeographicArea circle = CircleGeographicArea(
    { 40.77430, -73.97085 }, // center
    100 		     // radius in meters
    );

PolygonGeographicArea polygon = PolygonGeographicArea({
    { 40.77158, -73.97833 }, // point 1
    { 40.76882, -73.98061 }, // point 2
    { 40.76659, -73.97666 }, // point 3
    { 40.76945, -73.97441 }  // point 4
    });

alarmService->monitorArea(rect, "areaRect");
alarmService->monitorArea(circle, "areaCircle");
alarmService->monitorArea(polygon, "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 getMonitoredAreas method. It returns a list of AlarmMonitoredArea objects containing the parameters you provided to monitorArea.

List<AlarmMonitoredArea> monitorAreas = alarmService->getMonitoredAreas();

for (auto  monitorArea : monitorAreas)
{
    GeographicArea area = monitorArea.area;
    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.

RectangleGeographicArea rect = RectangleGeographicArea(
    { 40.71713, -74.00396 }, // top-left
    { 40.71357, -73.99925 }  // bottom-right
    );
alarmService->monitorArea(rect);

alarmService->unmonitorArea(rect);

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

alarmService->unmonitorAreas({"firstIdToUnmonitor", "secondIdToUnmonitor"});

Get notified when users enter or exit areas​

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

class MyAlarmListener : public IAlarmListener
{
    void onBoundaryCrossed( const AlarmMonitoredAreaList &enteredAreas, const AlarmMonitoredAreaList &exitedAreas ) override
    {
        for (auto area : enteredAreas)
        {
            GEM_INFO_LOG("ENTERED AREA: %s", area.id);
        }

        for (auto area : exitedAreas)
        {
            GEM_INFO_LOG("EXITED AREA: %s", area.id);
        }
    }
};

auto myListener = StrongPointerFactory<MyAlarmListener>();

alarmService = AlarmService::produce(myListener);

Get user location areas​

Retrieve zones the user is currently inside by calling the getInsideAreas method:

auto insideAreas = alarmService->getInsideAreas();
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 getOutsideAreas method.

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