Add bounds to map to avoid swiping outside a certain region

Question

My app shows a map and i want that users can't swipe over a certain region. So i'm trying to add bounds but it makes the app to crash. Here is the working code:

public class MapViewer extends Activity implements OnInfoWindowClickListener {
    private LatLng defaultLatLng = new LatLng(42.564241, 12.22759);
    private GoogleMap map;
    private int zoomLevel = 5;
    private Database db = new Database(this);

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.mapviewer);

        try {
            map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();
            if (map != null) {
                map.setMyLocationEnabled(true);
                map.setMapType(GoogleMap.MAP_TYPE_NORMAL);
                map.getUiSettings().setRotateGesturesEnabled(false);

                map.moveCamera(CameraUpdateFactory.newLatLngZoom(defaultLatLng, zoomLevel));

                this.addMerchantMarkers(new MarkerOptions());

                map.setOnInfoWindowClickListener(this);
            }
        } catch (NullPointerException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onPause() {
        if (map != null) {
            map.setMyLocationEnabled(false);
            map.setTrafficEnabled(false);
        }
        super.onPause();
    }

    public void addMerchantMarkers(MarkerOptions mo) {
        SQLiteDatabase dbRead = db.getReadableDatabase();
        String[] columns = {"title", "addr", "lat", "lon"};
        Cursor result = dbRead.query("merchants", columns, null, null, null, null, null);

        while(result.moveToNext()) {
            String merchant = result.getString(0);
            String address = result.getString(1);
            float lat = result.getFloat(2);
            float lon = result.getFloat(3);

            LatLng pos = new LatLng(lat, lon);

            map.addMarker(mo.position(pos)
                    .title(merchant)
                    .snippet(address)
                    .icon(BitmapDescriptorFactory.fromResource(R.drawable.marker_50)));;
        }
    }
}

And this is the code i add in onCreate method that cause the crash:

    LatLngBounds.Builder builder = new LatLngBounds.Builder();
    builder.include(new LatLng(47.09194444, 18.52166666));
    builder.include(new LatLng(36.448311, 6.62555555));
    LatLngBounds bounds = builder.build();

    CameraUpdate cu = CameraUpdateFactory.newLatLngBounds(bounds, 30);

    map.animateCamera(cu);

Here is the LogCat:

08-10 20:59:41.689: E/AndroidRuntime(6304): FATAL EXCEPTION: main
08-10 20:59:41.689: E/AndroidRuntime(6304): Process: com.example.myapp, PID: 6304
08-10 20:59:41.689: E/AndroidRuntime(6304): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapp/com.example.myapp.MapViewer}: java.lang.IllegalStateException: Error using newLatLngBounds(LatLngBounds, int): Map size can't be 0. Most likely, layout has not yet occured for the map view.  Either wait until layout has occurred or use newLatLngBounds(LatLngBounds, int, int, int) which allows you to specify the map's dimensions.
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2215)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2264)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.app.ActivityThread.access$800(ActivityThread.java:144)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.os.Handler.dispatchMessage(Handler.java:102)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.os.Looper.loop(Looper.java:136)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.app.ActivityThread.main(ActivityThread.java:5139)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at java.lang.reflect.Method.invokeNative(Native Method)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at java.lang.reflect.Method.invoke(Method.java:515)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at dalvik.system.NativeStart.main(Native Method)
08-10 20:59:41.689: E/AndroidRuntime(6304): Caused by: java.lang.IllegalStateException: Error using newLatLngBounds(LatLngBounds, int): Map size can't be 0. Most likely, layout has not yet occured for the map view.  Either wait until layout has occurred or use newLatLngBounds(LatLngBounds, int, int, int) which allows you to specify the map's dimensions.
08-10 20:59:41.689: E/AndroidRuntime(6304):     at mut.b(Unknown Source)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at oxp.a(Unknown Source)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at oxi.a(Unknown Source)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at oyf.b(Unknown Source)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at grl.onTransact(SourceFile:92)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.os.Binder.transact(Binder.java:361)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at com.google.android.gms.maps.internal.IGoogleMapDelegate$a$a.animateCamera(Unknown Source)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at com.google.android.gms.maps.GoogleMap.animateCamera(Unknown Source)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at com.example.myapp.MapViewer.onCreate(MapViewer.java:59)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.app.Activity.performCreate(Activity.java:5231)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-10 20:59:41.689: E/AndroidRuntime(6304):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2169)
08-10 20:59:41.689: E/AndroidRuntime(6304):     ... 11 more

Answer 1

You can use MapLoadedCallBack;

map.setOnMapLoadedCallback(new GoogleMap.OnMapLoadedCallback() {
  @Override
  public void onMapLoaded() {
      map.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds, 30));
  }
});

and also you can use this event that occurs prier to above.

  map.setOnCameraChangeListener(new GoogleMap.OnCameraChangeListener() {
        @Override
        public void onCameraChange(CameraPosition arg0) {
        map.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds, 30));
  }
});

Answer 2

You can keep the error from occurring by following the advice from the log:

"...use newLatLngBounds(LatLngBounds, int, int, int) which allows you to specify the map's dimensions."

The extra parameters are the width and height of your screen. Here's how your updated code would look:

LatLngBounds.Builder builder = new LatLngBounds.Builder();
builder.include(new LatLng(47.09194444, 18.52166666));
builder.include(new LatLng(36.448311, 6.62555555));
LatLngBounds bounds = builder.build();

// begin new code:
int width = getResources().getDisplayMetrics().widthPixels;
int height = getResources().getDisplayMetrics().heightPixels;
int padding = (int) (width * 0.12); // offset from edges of the map 12% of screen

CameraUpdate cu = CameraUpdateFactory.newLatLngBounds(bounds, width, height, padding);
// end of new code

map.animateCamera(cu);

Answer 3

Documentation for onMapReady() clearly states that you have to wait for both onMapReadyCallback and ViewTreeObserver.OnGlobalLayoutListener:

Note that this does not guarantee that the map has undergone layout. Therefore, the map's size may not have been determined by the time the callback method is called. If you need to know the dimensions or call a method in the API that needs to know the dimensions, get the map's View and register an ViewTreeObserver.OnGlobalLayoutListener as well.

It is quite inconvenient, but one way of doing it would be by using RxJava. You could emit two observables, first one in onMapReady and second one in onGlobalLayout, then zip them together and do whatever you need to do. This way you can be certain that both callbacks were fired.

Answer 4

Caused by: java.lang.IllegalStateException: Map size should not be 0. Most likely, layout has not yet occured for the map view.

The reason Behind this error is because the Map layout has not been completed, You should implement OnMapReadyCallback in your calls, which will ensure that your code will only run after your layout is completed or Implement the below callback

map.setOnCameraChangeListener(new GoogleMap.OnCameraChangeListener() {
    @Override
    public void onCameraChange(CameraPosition arg0) {
    map.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds, 30));
}
});

Duplicate Links

moveCamera with CameraUpdateFactory.newLatLngBounds crashes

IllegalStateException map size should not be 0

I don't if there is a way to merge this link. I Hope i helped