Getting map zoom level for given bounds on Android

问题:

I have a cluster marker that defines a bounding rectangle containing a group of markers. The cluster has a center (lat,lon), a marker count and a latitude and longitude span to calculate the bounds.

The Google Maps API (JS) has a function called "getBoundsZoomLevel(bounds)" but I cannot find an equivalent method in the Google Maps SDK for Android. How can I estimate the zoom level for given bounds (especially on different devices with different resolutions/densitys)?

I've planned that an user can touch a cluster marker and the map view will be centered to the center and the bounds of that cluster.

Has anybody a working code snippet or some suggestions for me?

Thanks in advance Regards Thorsten.

回答1:

Thank you for your answer Solvek. Meanwhile I found a solution that I've adapted slightly and it works. The method computes the bounds of a set of geo points, computes the span of these points and finally uses zoomToSpan and animateTo for zooming into and centering the given area:

 public static void zoomInBounds(final MapView view, final GeoPoint.. bounds) {

    int minLat = Integer.MAX_VALUE;
    int minLong = Integer.MAX_VALUE;
    int maxLat = Integer.MIN_VALUE;
    int maxLong = Integer.MIN_VALUE;

    for (GeoPoint point : bounds) {
        minLat = Math.min(point.getLatitudeE6(), minLat);
        minLong = Math.min(point.getLongitudeE6(), minLong);
        maxLat = Math.max(point.getLatitudeE6(), maxLat);
        maxLong = Math.max(point.getLongitudeE6(), maxLong);
    }

    final MapController controller = view.getController();
    controller.zoomToSpan(
                       Math.abs(minLat - maxLat), Math.abs(minLong - maxLong));
    controller.animateTo(new GeoPoint((maxLat + minLat) / 2,
        (maxLong + minLong) / 2));
}

回答2:

Now you could zoom to bounds with .newLatLngBounds() method:

map.animateCamera(CameraUpdateFactory.newLatLngBounds(place.getViewport(), 10)); // 10 is padding

It will move and zoom to given bounds, so they all visible on a screen (e.g. different zoom for city or country). It works perfectly with location search.

回答3:

I didn't tried this but maybe it will work for you. Imagine you have a rectangle (x1,y1)-(x2,y2)

    MapController c = mapView.getController();
    c.setCenter(new GeoPoint((x1+x2)/2,(y1+y2)/2));
    c.zoomToSpan(x2, y2);