有没有办法在Google地图上修复标记的准确半径？

Question

For our application we need to show current user's location with some radius. But when I enabled map.setMyLocationEnabled(true); we've noticed, that accuracy radius changes in very large range (eg from 10m to 50m, then 15m etc), and it may confuse our users. We've decided to fix radius of accuracy circle around marker to give it a different meaning.

Is there a way to fix accuracy radius, in addition to creating your own marker? I don't want create my own marker, because I think that my realization would be much worse than Google's.

Thanks in advance.

Answer 1

Using the My Location layer there is no way you can change the symbology (icon) of the current location.

As a workaround, you can implement this functionality using Location Updates and drawing the location on the map.

To do this, you can use this implementation of LocationListener that draws the current location and accuracy:

import android.graphics.Color;
import android.location.Location;
import android.location.LocationListener;
import android.os.Bundle;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.model.BitmapDescriptor;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.Circle;
import com.google.android.gms.maps.model.CircleOptions;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

public class MyLocationLayer implements LocationListener {
    private GoogleMap map;

    private BitmapDescriptor markerDescriptor;
    private boolean drawAccuracy = true;
    private int accuracyStrokeColor = Color.argb(255, 130, 182, 228);
    private int accuracyFillColor = Color.argb(100, 130, 182, 228);

    private Marker positionMarker;
    private Circle accuracyCircle;

    public MyLocationLayer(GoogleMap map, int markerResource) {
        this.map = map;

        markerDescriptor = BitmapDescriptorFactory.fromResource(markerResource);
    }

    public void setDrawAccuracy(boolean drawAccuracy) {
        this.drawAccuracy = drawAccuracy;
    }

    public void setAccuracyStrokeColor(int color) {
        this.accuracyStrokeColor = color;
    }

    public void setAccuracyFillColor(int color) {
        this.accuracyFillColor = color;
    }

    @Override
    public void onLocationChanged(Location location) {
        double latitude = location.getLatitude();
        double longitude = location.getLongitude();
        float accuracy = location.getAccuracy();

        if (positionMarker != null) {
            positionMarker.remove();
        }
        final MarkerOptions positionMarkerOptions = new MarkerOptions()
                .position(new LatLng(latitude, longitude))
                .icon(markerDescriptor)
                .anchor(0.5f, 0.5f);
        positionMarker = map.addMarker(positionMarkerOptions);

        if (accuracyCircle != null) {
            accuracyCircle.remove();
        }
        if (drawAccuracy) {
            final CircleOptions accuracyCircleOptions = new CircleOptions()
                    .center(new LatLng(latitude, longitude))
                    .radius(accuracy)
                    .fillColor(accuracyFillColor)
                    .strokeColor(accuracyStrokeColor)
                    .strokeWidth(2.0f);
            accuracyCircle = map.addCircle(accuracyCircleOptions);
        }
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {

    }

    @Override
    public void onProviderEnabled(String provider) {

    }

    @Override
    public void onProviderDisabled(String provider) {

    }
}

Improvements to be made

You could rotate your marker based on the direction of the movement using public MarkerOptions rotation (float rotation) https://developers.google.com/android/reference/com/google/android/gms/maps/model/MarkerOptions.html#rotation(float)