Robin Royal Robin Royal - 6 months ago 133
Android Question

Android Google Map show markers on zoom change

Guys I have to show markers on google maps with zoom.When user zoom in or zoom out markers will be visible covering the map area which is on the screen.How can I do this using Android google map?

Answer

Okay so you can use a CameraChangeListener:

private HashMap<Integer, Marker> courseMarkers = new HashMap<Integer, Marker>();
//all your visible markers
ArrayList<Item> yourMarkerList = new ArrayList<Item>();
//method to add all your markers with unique ids
addItemsToMap(); //first call to initially show the markers you want

googleMap.setOnCameraChangeListener(new OnCameraChangeListener() {

private float currentZoom = -1; //keep track of your current zoom level

@Override
public void onCameraChange(CameraPosition camera) {
    if (camera.zoom != currentZoom){
        currentZoom = camera.zoom;
        //here you will then check your markers
        addItemsToMap(yourMarkerList);
    }
}
});

You will need a class Item that has a variable for a unique int id and a MarkerOptions

private void addItemsToMap(List<Item> items)
{
if(this.mMap != null)
{
    //This is the current user-viewable region of the map
    LatLngBounds bounds = this.mMap.getProjection().getVisibleRegion().latLngBounds;

    //Loop through all the items that are available to be placed on the map
    for(Item m : item) 
    {

        //If the item is within the the bounds of the screen
        if(bounds.contains(item.getMarker().getPosition()))
        {
            //If the item isn't already being displayed
            if(!courseMarkers.containsKey(item.getId()))
            {
                //Add the Marker to the Map and keep track of it with the HashMap
                //getMarkerForItem just returns a MarkerOptions object
                this.courseMarkers.put(item.getId(), this.googleMap.addMarker(item.getMarker())); //getmarkerforitem
            }
        }

        //If the marker is off screen
        else
        {
            //If the course was previously on screen
            if(courseMarkers.containsKey(item.getId()))
            {
                //1. Remove the Marker from the GoogleMap
                courseMarkers.get(item.getId()).remove();

                //2. Remove the reference to the Marker from the HashMap
                courseMarkers.remove(item.getId());
            }
        }
    }
}

}

This should do it

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