Camera Controls

To create rich experiences on top of the Mappedin Android SDK, it's useful to be able to control the map view programmatically. This guide shows how to focus the map view on targets, how to listen to camera events and how to control the camera.

A complete class that uses the code snippet in this guide can be found in the Mappedin Android Github repo: CameraControls.kt

Focus the Camera on Targets

To focus on a polygon after it has been touched, we use the onPolygonClicked() function in the MPIMapViewListener. In this case, we are targeting only the touched polygon. However, we can also give coordinates or nodes as MPIOptions.CameraTargets.

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override fun onPolygonClicked(polygon: MPINavigatable.MPIPolygon) {
    mapView?.cameraManager?.focusOn(MPIOptions.CameraTargets(polygons = listOf(polygon)))
}

Listening to Camera Events

We can use the onCameraChanged() function in the MPICameraListener to monitor changes to the camera position, rotation, tilt, and zoom.

First, implement the interface on your existing class and assign the listener this. For more information on how to initialize your MPIMapView, read the Getting Started guide

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class MyClass : AppCompatActivity(), MPIMapViewListener, MPICameraListener {
    private var mapView: MPIMapView? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // ... other setup
        mapView?.cameraManager?.listener = this
    }
}

The interface implements the onCameraChanged() function which passes in an MPICameraTransform whenever the camera moves. We can log the values within it to track the camera.

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override fun onCameraChanged(cameraTransform: MPICameraTransform) {
    Log.d("Position", cameraTransform.position.toString())
    Log.d("Rotation", cameraTransform.rotation.toString())
    Log.d("Tilt", cameraTransform.tilt.toString())
    Log.d("Zoom", cameraTransform.zoom.toString())
}

Controlling the Camera

Controlling the camera to set it to a specific tilt, rotation or zoom can be done with mapView.cameraManager.set(). It takes either MPIOptions.CameraTransformNode or MPIOptions.CameraTransformCoordinate which take either an MPINavigatable.MPINode or MPIMap.MPICoordinate respectively as the position. Tilt and rotation are set as radians, where as zoom is in the camera distance in meters from the target.

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mapView?.cameraManager?.set(
  MPIOptions.CameraTransformNode(
    zoom = 1234.0,
    tilt = 0.3,
    rotation = 1.5
  )
)

// or

mapView?.cameraManager?.set(
    MPIOptions.CameraTransformCoordinate(
        zoom = 800.0,
        position = mapView.currentMap?.createCoordinate(
            43.519881426957596,
            -80.53906704663625
        )
    )
)

It is possible to limit the tilting of the camera by listening to the change event and setting it to a desired value in onCameraChanged().

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override fun onCameraChanged(cameraTransform: MPICameraTransform) {
    val tilt = 0.0
    if (cameraTransform.tilt != tilt) {
        mapView?.cameraManager?.set(MPIOptions.CameraTransformNode(tilt = tilt))
    }
}

If you want to be able to zoom in closer than the default limit, use the setter mapView?.cameraManager?.setMinZoom(zoomLevel = 200.0).

A complete class that uses the code snippet in this guide can be found in the Mappedin Android Github repo: CameraControls.kt