Auto-size zoom on Google Maps in java? (depending

问题:

I've got 2 GeoPoints given to show them on the map with markers.

How can I get the optimum zoom level for the MapController in order to focus the middle of both points, but also have them on the map.

The whole thing should work at different screen resolutions.

回答1:

You can do this using the MapView's MapController. You get the MapController using MapView.getController(), then you can attempt to set the correct zoom using MapController.zoomToSpan(). I also tend to use ItemizedOverlay's getLatSpanE6() and getLonSpanE6() to make this simpler. An example:

MapView map = (MapView) findViewById(R.id.Map);
MapController mc = map.getController();
mc.zoomToSpan(overlay.getLatSpanE6(), overlay.getLonSpanE6());

It is important to note their caveat:

Because the zoom can only achieve discrete levels, and because the aspect ratio of the map may not match the ratio given, the quality of the fit may vary. The only thing we guarantee is that, after the zoom, at least one of the new latitude or the new longitude will be within a factor of 2 from the corresponding parameter.

Edit: In order to also get the map to zoom on the correct place, you have to use MapController.setCenter().

回答2:

This is how it should be done:

private void loadMarkerPositions() {


    for (Stores store : storeList) {
        latlong1 = new LatLng(store.getLatitude(), store.getLongtitude());
        array.add(latlong1);
    }

     List<LatLng> points = array; 

     final LatLngBounds.Builder bc = new LatLngBounds.Builder();

        for (LatLng item : points) {
            bc.include(item);
        }

    googleMap.setOnCameraChangeListener(new OnCameraChangeListener() {

        @Override
        public void onCameraChange(CameraPosition arg0) {
            // Move camera.
            googleMap.moveCamera(CameraUpdateFactory.newLatLngBounds(bc.build(), 30));
            // Remove listener to prevent position reset on camera move.
            googleMap.setOnCameraChangeListener(null);
        }
    });

}

Reference: moveCamera with CameraUpdateFactory.newLatLngBounds crashes

There is another easy way, you can use this project to accomplish all map related activities:

https://github.com/girishnair12345/Google-Maps-V2-library