On zoom event for google maps on android

Question

We\'re building an application which is using the google maps api for android.

I have my MapController and MapView, and I enable the built-in zoom controls using:

Answer 1

I think there might another answer to this question. The Overlay class draw method is called after any zoom and I believe this is called after the zoom level changes. Could you not architect your app to take advantage of this? You could even use a dummy overlay just to detect this if you wanted to. Would this not be more efficient than using a runnable with a delay?

@Override
public boolean draw (Canvas canvas, MapView mapView, boolean shadow, long when) {
    int zoomLevel = mapView.getZoomLevel();
    // do what you want with the zoom level
    return super.draw(canvas, mapView, shadow, when);
}

Answer 2

With the Google Maps Android API v2 you can use a GoogleMap.OnCameraChangeListener like this:

mMap.setOnCameraChangeListener(new OnCameraChangeListener() {

    private float currentZoom = -1;

    @Override
    public void onCameraChange(CameraPosition pos) {
        if (pos.zoom != currentZoom){
            currentZoom = pos.zoom;
            // do you action here
        }
    }
});

Answer 3

Here is a clean solution. Simply add this TouchOverlay private class to your activity and a method called onZoom (that is called by this inner class).

Note, you'll have to add this TouchOverlay to your mapView e.g.

mapView.getOverlays().add(new TouchOverlay());

It keeps track of the zoom level whenever the user touches the map e.g. to double-tap or pinch zoom and then fires the onZoom method (with the zoom level) if the zoom level changes.

   private class TouchOverlay extends com.google.android.maps.Overlay {
            int lastZoomLevel = -1;

            @Override
            public boolean onTouchEvent(MotionEvent event, MapView mapview) {
                if (event.getAction() == 1) {
                    if (lastZoomLevel == -1)
                        lastZoomLevel = mapView.getZoomLevel();

                    if (mapView.getZoomLevel() != lastZoomLevel) {
                        onZoom(mapView.getZoomLevel());
                        lastZoomLevel = mapView.getZoomLevel();
                    }
                }
                return false;
            }
        }

        public void onZoom(int level) {
            reloadMapData(); //act on zoom level change event here
        }

Answer 4

The android API suggests you use ZoomControls which has a setOnZoomInClickListener()

To add these zoom controls you would:

ZoomControls mZoom = (ZoomControls) mapView.getZoomControls();

And then add mZoom to your layout.

Answer 5

You Can use

ZoomButtonsController zoomButton = mapView.getZoomButtonsController();
zoomButton.setOnZoomListener(listener);

hope it helps

Answer 6

As the OP said, use the onUserInteractionEvent and do the test yourself.