Google Maps two finger pinch/stretch callbacks - android-maps-v2

Question

In my map, I am trying to capture zoom in/out using ScaleGestureDetector but I am never receiving any callbacks to either of onScale or onScaleBegin or onScaleEnd.
In my Fragment's onCreateView, I initialize:
scaleGestureDetector = new ScaleGestureDetector(getContext(), new simpleOnScaleGestureListener());
And I implement the callbacks like so:
public class simpleOnScaleGestureListener extends
SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
// TODO Auto-generated method stub
startScale = detector.getScaleFactor();
Log.d(TAG, "::onScale:: " + detector.getScaleFactor());
return true;
}
#Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
// TODO Auto-generated method stub
Log.d(TAG, "::onScaleBegin:: " + detector.getScaleFactor());
return true;
}
#Override
public void onScaleEnd(ScaleGestureDetector detector) {
// TODO Auto-generated method stub
Log.d(TAG, "::onScaleEnd:: " + detector.getScaleFactor());
endScale = detector.getScaleFactor();
}
Also, is it fair to assume that the callbacks will be called continuously whenever the user zooms in/out?

Answer 1

I was able to get past the issue of getting callbacks. Essentially, two things:
In your activity/fragment, implement, GoogleMap.OnCameraIdleListener
In onMapReady(), call mMap.setOnCameraIdleListener(this);
Hence, override onCameraIdle():
#Override
public void onCameraIdle() {
Log.i(TAG, "::onCameraIdle::" + mMap.getCameraPosition().toString());
}
to get lat/long, zoom, tilt and bearing, essentially CameraPosition.
I found a way to get radius in meters by referring to this response
VisibleRegion vr = map.getProjection().getVisibleRegion();
Location center = new Location("center");
center.setLatitude(vr.latLngBounds.getCenter().latitude);
center.setLongitude(vr.latLngBounds.getCenter().longitude);
//Location("radiusLatLng") as mentioned in google maps sample
Location farVisiblePoint = new Location("radiusLatLng");
farVisiblePoint.setLatitude(vr.farLeft.latitude);
farVisiblePoint.setLongitude(vr.farLeft.longitude);
radius = center.distanceTo(farVisiblePoint);