How to move camera when marker goes outside of the screen?

Question

I am working on map base application to animate marker. There are one marker which is updated against 30 sec interval from server. Marker always move to center of the Map ,so i close moveCamera marker but when marker move outside the map then marker is not come in map view. so i want to camera move when marker goes from map view

Answer 1

Before setting new position of the marker, check it's new position and current bounds of map view.

LatLng newPosition = new LatLng(...);

boolean contains = mMap.getProjection()
    .getVisibleRegion()
    .latLngBounds
    .contains(newPosition);

if(!contains){
    // MOVE CAMERA
}
// UPDATE MARKER POSITION

• During the marker's each new position inside map view, marker moves(not center of map)
• Just If next position goes out of view, camera and marker will be centered.

Edit

I created a sample route to simulate each point on map periodically. Route gist

public class SampleRoute {
    public static List<LatLng> GetPoints() {
        return new ArrayList<>(Arrays.asList(
            new LatLng(38.4670419, 27.1647131),
            new LatLng(38.4667244, 27.1648277),
            new LatLng(38.4666633, 27.1649079),
            new LatLng(38.4665983, 27.1648022),
            new LatLng(38.4665958, 27.1647843),
            new LatLng(38.4665958, 27.1647843),
            new LatLng(38.4665809, 27.1646429),
            new LatLng(38.4665704, 27.1645506),
            new LatLng(38.4665529, 27.1644067),
            ...
        }
    }
}

Then i create a method in sample activity that calculates current region's bounds and marker's X, Y points on this region. Activity gist

private void moveCamera(LatLng destination){
    Projection projection =  mMap.getProjection();

    LatLngBounds bounds = projection.getVisibleRegion().latLngBounds;
    int boundsTopY = projection.toScreenLocation(bounds.northeast).y;
    int boundsBottomY = projection.toScreenLocation(bounds.southwest).y;
    int boundsTopX = projection.toScreenLocation(bounds.northeast).x;
    int boundsBottomX = projection.toScreenLocation(bounds.southwest).x;

    int offsetY = (boundsBottomY - boundsTopY) / 10;
    int offsetX = (boundsTopX - boundsBottomX ) / 10;

    Point destinationPoint = projection.toScreenLocation(destination);
    int destinationX = destinationPoint.x;
    int destinationY = destinationPoint.y;

    int scrollX = 0;
    int scrollY = 0;

    if(destinationY <= (boundsTopY + offsetY)){
        scrollY = -(Math.abs((boundsTopY + offsetY) - destinationY));
    }
    else if(destinationY >= (boundsBottomY - offsetY)){
        scrollY = (Math.abs(destinationY - (boundsBottomY - offsetY)));
    }
    if(destinationX >= (boundsTopX - offsetX)){
        scrollX = (Math.abs(destinationX - (boundsTopX - offsetX)));
    }
    else if(destinationX <= (boundsBottomX + offsetX)){
        scrollX = -(Math.abs((boundsBottomX + offsetX) - destinationX));
    }
    mMap.animateCamera(CameraUpdateFactory.scrollBy(scrollX, scrollY));
    mMarker.setPosition(destination);
}

And then started to simulate points

mHandler.postDelayed(new Runnable() {
    @Override
    public void run() {
        moveCamera(mPoints.get(mCurrentPos));
        if(++mCurrentPos < mPoints.size()){
            mHandler.postDelayed(this, 1500);
        }
    }
}, 1500);

I tried and it's working well on me

So, if i understand you correctly and it works for you too then i could explain.

Answer 2

When marker location is updated you can animate the camera to the marker position. Following sample code may help you

  LatLng definedLoc = new LatLng(latitudeValue, longitudeValue);
  CameraPosition cameraPosition = new CameraPosition.Builder().target(definedLoc).zoom(13.0F).build();
  map.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));

Answer 3

You can animate the camera to the Marker position if the map bounds does not contain the marker using a GoogleMap.OnCameraChangeListener:

private Marker marker;

// ...

@Override
public void onCameraChange(final CameraPosition cameraPosition) {
    ensureMarkerOnBounds();
}

private void ensureMarkerOnBounds() {
    if (marker != null) {
        if (!mMap.getProjection().getVisibleRegion().latLngBounds.contains(marker.getPosition())) {
            mMap.animateCamera(CameraUpdateFactory.newLatLng(marker.getPosition()));
        }
    }
}

// This is the function that you use to move your marker
private void moveMarker (Marker marker) {
    // ... Your code to move your marker
    ensureMarkerOnBounds();
}