Question

I’m making use of the new Android Google Maps API.

I create an activity which includes a MapFragment. In the activity onResume I set the markers into the GoogleMap object and then define a bounding box for the map which includes all of the markers.

This is using the following pseudo code:

LatLngBounds.Builder builder = new LatLngBounds.Builder();
while(data) {
   LatLng latlng = getPosition();
   builder.include(latlng);
}
CameraUpdate cameraUpdate = CameraUpdateFactory
   .newLatLngBounds(builder.build(), 10);
map.moveCamera(cameraUpdate);

The call to map.moveCamera() causes my application to crash with the following stack:

Caused by: java.lang.IllegalStateException: 
    Map size should not be 0. Most likely, layout has not yet 

    at maps.am.r.b(Unknown Source)
    at maps.y.q.a(Unknown Source)
    at maps.y.au.a(Unknown Source)
    at maps.y.ae.moveCamera(Unknown Source)
    at com.google.android.gms.maps.internal.IGoogleMapDelegate$Stub
        .onTransact(IGoogleMapDelegate.java:83)
    at android.os.Binder.transact(Binder.java:310)
    at com.google.android.gms.maps.internal.IGoogleMapDelegate$a$a
        .moveCamera(Unknown Source)
    at com.google.android.gms.maps.GoogleMap.moveCamera(Unknown Source)
    at ShowMapActivity.drawMapMarkers(ShowMapActivity.java:91)
    at ShowMapActivity.onResume(ShowMapActivity.java:58)
    at android.app.Instrumentation
        .callActivityOnResume(Instrumentation.java:1185)
    at android.app.Activity.performResume(Activity.java:5182)
    at android.app.ActivityThread
        .performResumeActivity(ActivityThread.java:2732)

If – instead of the newLatLngBounds() factory method I use newLatLngZoom() method then the same trap does not occur.

Is the onResume the best place to draw the markers onto the GoogleMap object or should I be drawing the markers and setting the camera position somewhere else?

Answer 1

OK I worked this out. As documented here that API can’t be used pre-layout.

The correct API to use is described as:

Note: Only use the simpler method newLatLngBounds(boundary, padding)
to generate a CameraUpdate if it is going to be used to move the
camera after the map has undergone layout. During layout, the API
calculates the display boundaries of the map which are needed to
correctly project the bounding box. In comparison, you can use the
CameraUpdate returned by the more complex method
newLatLngBounds(boundary, width, height, padding) at any time, even
before the map has undergone layout, because the API calculates the
display boundaries from the arguments that you pass.

To fix the problem I calculated my screen size and provided the width and height to

public static CameraUpdate newLatLngBounds(
    LatLngBounds bounds, int width, int height, int padding)

This then allowed me to specify the bounding box pre-layout.