android - 使用 MyLocationOverlay 绘制精度圆

Question

我正在开发一个显示带有用户位置的 map 的 Android 应用程序，到目前为止，我能够在线和离线显示 map 。现在我想知道如何使用 MylocationOverlay 在 osmdroid 中绘制与标记一起出现的精度圆？

这是我的代码:

public class AhmedActivity extends Activity 
{
    /** Called when the activity is first created. */
    private MapView mapView;
    private MapController mapController;
    private ScaleBarOverlay mScaleBarOverlay; 
    MyLocationOverlay myLocationOverlay = null;
    private LocationManager locationManager;

    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Initialize the location:
        locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);

        initializemap();

        /* My location overlay */
        /* Create a static Overlay showing a the current location and a compass */                  
        myLocationOverlay = new MyLocationOverlay(this, mapView);
        mapView.getOverlays().add(myLocationOverlay);
        myLocationOverlay.runOnFirstFix( new Runnable() {
            public void run() {
                mapController.animateTo( myLocationOverlay
                                 .getMyLocation());
            }
        });

        //Add Scale Bar
        mScaleBarOverlay = new ScaleBarOverlay(this);                           
        ScaleBarOverlay myScaleBarOverlay = new ScaleBarOverlay(this);
        mScaleBarOverlay.setLineWidth(50); 
        mapView.getOverlays().add(myScaleBarOverlay);
    }

    /** (re-)enable location and compass updates */      
    @Override
    public void onResume() {
        super.onResume();
        myLocationOverlay.enableCompass();
        myLocationOverlay.enableMyLocation();
        //myLocationOverlay.followLocation(true);
        //myLocationOverlay.setDrawAccuracyEnabled(true);
        //myLocationOverlay.isDrawAccuracyEnabled();
    }  

    /** disable compass and location updates */        
    @Override      
    public void onPause() {
        super.onPause();
        myLocationOverlay.disableMyLocation();
        myLocationOverlay.disableCompass();
    }

    public void initializemap()
    {
        mapView = (MapView) this.findViewById(R.id.mapView); 
        mapView.setTileSource(TileSourceFactory.MAPNIK); 
        mapView.setBuiltInZoomControls(true); 
        mapView.setMultiTouchControls(true); 
        mapController = this.mapView.getController();     
        mapController.setZoom(12);
        mapController.setCenter(new GeoPoint(15.610762,32.540345));
    }
}

Answer 1

一个完整的示例，用于在您的位置绘制一个精度圆(这不包括您的位置的标记)。这是基于 OSMDroid 类 DirectedLocationOverlay用方向箭头显示您的位置(我不需要并已删除)。

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;

import org.osmdroid.util.GeoPoint;
import org.osmdroid.views.MapView;
import org.osmdroid.views.Projection;
import org.osmdroid.views.overlay.Overlay;

public class AccuracyOverlay extends Overlay {

    private Paint paint = new Paint();
    private Paint accuracyPaint = new Paint();
    private GeoPoint location;
    private final Point screenCoords = new Point();
    private float accuracy = 0;

    public AccuracyOverlay(GeoPoint location, float accuracyInMeters) {
        super();

        this.location = location;
        this.accuracy = accuracyInMeters;
        this.accuracyPaint.setStrokeWidth(2);
        this.accuracyPaint.setColor(Color.BLUE);
        this.accuracyPaint.setAntiAlias(true);
    }

    @Override
    public void onDetach(MapView view){
        paint = null;
        accuracyPaint = null;
    }

    @Override
    public void draw(final Canvas c, final MapView map, final boolean shadow) {

        if (shadow) {
            return;
        }

        if (location != null) {
            final Projection pj = map.getProjection();
            pj.toPixels(location, screenCoords);

            if (accuracy > 0) {  //Set this to a minimum pixel size to hide if accuracy high enough
                final float accuracyRadius = pj.metersToEquatorPixels(accuracy);

                /* Draw the inner shadow. */
                accuracyPaint.setAntiAlias(false);
                accuracyPaint.setAlpha(30);
                accuracyPaint.setStyle(Paint.Style.FILL);
                c.drawCircle(screenCoords.x, screenCoords.y, accuracyRadius, accuracyPaint);

                /* Draw the edge. */
                accuracyPaint.setAntiAlias(true);
                accuracyPaint.setAlpha(150);
                accuracyPaint.setStyle(Paint.Style.STROKE);
                c.drawCircle(screenCoords.x, screenCoords.y, accuracyRadius, accuracyPaint);
            }
        }
    }
}

然后在你的 Activity 中:

@Override
public void onLocationChanged(Location location) {
    if (accuracyOverlay != null) {
        map.getOverlays().remove(accuracyOverlay);
        map.invalidate();
    }

    accuracyOverlay = new AccuracyOverlay(new GeoPoint(location), location.getAccuracy());
    map.getOverlays().add(accuracyOverlay);
}