移动相机时移动以相机为中心的谷歌地图标记

Question

The goal is to capture the lat/long of where ever the user navigates in the map. There is a marker right on the center of it.

Here's what I got so far:

    myMap.setOnCameraMoveListener(new GoogleMap.OnCameraMoveListener() {
        @Override
        public void onCameraMove() {
            CameraPosition test = myMap.getCameraPosition();
            myMap.addMarker(new MarkerOptions().position(myMap.getCameraPosition().target).anchor(0.5f, .05f).title("Test"));
            Log.d(TAG, "Map Coordinate: " + String.valueOf(test));
        }
    });

It works, but it creates thousands of markers as you might have guessed. I'm thinking the marker should be created outside the move listener and animated to the center every time the camera moves.

So, how can I achieve that?

Answer 1

Simply keep one Marker reference that will always point to the current center. Then, when placing a new one, remove the old one if necessary:

//Instance variable:
Marker mCenterMarker;

myMap.setOnCameraMoveListener(new GoogleMap.OnCameraMoveListener() {
    @Override
    public void onCameraMove() {

        //Remove previous center if it exists
        if (mCenterMarker != null) {
            mCenterMarker.remove();
        }

        CameraPosition test = myMap.getCameraPosition();
        //Assign mCenterMarker reference:
        mCenterMarker = myMap.addMarker(new MarkerOptions().position(myMap.getCameraPosition().target).anchor(0.5f, .05f).title("Test"));
        Log.d(TAG, "Map Coordinate: " + String.valueOf(test));
    }
});

Answer 2

The goal is to capture the lat/long of where ever the user navigates in the map. There is a marker right on the center of it.

Here's what I got so far:

    myMap.setOnCameraMoveListener(new GoogleMap.OnCameraMoveListener() {
        @Override
        public void onCameraMove() {
            CameraPosition test = myMap.getCameraPosition();
            myMap.addMarker(new MarkerOptions().position(myMap.getCameraPosition().target).anchor(0.5f, .05f).title("Test"));
            Log.d(TAG, "Map Coordinate: " + String.valueOf(test));
        }
    });

It works, but it creates thousands of markers as you might have guessed. I'm thinking the marker should be created outside the move listener and animated to the center every time the camera moves.

So, how can I achieve that?

Answer 3

You could create a universal marker variable, and just change it's location based on the camera using setPosition(myMap.getCameraPosition().target)

//Instance variable:
Marker mCenterMarker;

myMap.setOnCameraMoveListener(new GoogleMap.OnCameraMoveListener() {
@Override
public void onCameraMove() {

    //Remove previous center if it exists

    CameraPosition test = myMap.getCameraPosition();
    //Assign mCenterMarker reference:
    mCenterMarker = setPosition(myMap.getCameraPosition().target)
    Log.d(TAG, "Map Coordinate: " + String.valueOf(test));
}

then define mCenterMarker somewhere else.