在我的代码中，我在 Android 屏幕的上半部分用一张图片显示了我当前的位置。所以我需要以我当前的位置为圆心，在我当前的位置周围画一个像上图一样的圆圈。我需要绘制四个半径分别为 10m、20m、30m、40m 的圆。下面是我的代码，它显示了谷歌地图上的当前位置。
@Override
protected void onCreate(Bundle icicle) {
try {
super.onCreate(icicle);
setContentView(R.layout.activity_main);
initComponents();
mapView.setBuiltInZoomControls(true);
mapView.setSatellite(false);
mapController = mapView.getController();
mapController.setZoom(16);
locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
if (locationManager == null) {
Toast.makeText(getApplicationContext(),
"Location Manager Not Available", Toast.LENGTH_SHORT)
.show();
return;
}
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location == null)
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
double lat = location.getLatitude();
double lng = location.getLongitude();
Toast.makeText(getApplicationContext(),
"Location Are" + lat + ":" + lng, Toast.LENGTH_SHORT)
.show();
GeoPoint point = new GeoPoint((int) (lat * 1E6), (int) (lng * 1E6));
mapController.animateTo(point, new Message());
mapOverlay.setPointToDraw(point);
List<Overlay> listOfOverlays = mapView.getOverlays();
listOfOverlays.clear();
listOfOverlays.add(mapOverlay);
}
locationListener = new LocationListener() {
@Override
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
}
@Override
public void onProviderEnabled(String arg0) {
}
@Override
public void onProviderDisabled(String arg0) {
}
@Override
public void onLocationChanged(Location l) {
location = l;
locationManager.removeUpdates(this);
if (l.getLatitude() == 0 || l.getLongitude() == 0) {
} else {
double lat = l.getLatitude();
double lng = l.getLongitude();
Toast.makeText(getApplicationContext(),
"Location Are" + lat + ":" + lng,
Toast.LENGTH_SHORT).show();
}
}
};
if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER))
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER, 1000, 10f, locationListener);
if (locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)){
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER, 1000, 10f, locationListener);
}
locationtimer = new CountDownTimer(30000, 5000) {
@Override
public void onTick(long millisUntilFinished) {
if (location != null)
locationtimer.cancel();
}
@Override
public void onFinish() {
if (location == null) {
}
}
};
locationtimer.start();
}
catch(Exception e) {
System.out.println(e);
}
}
public MapView getMapView() {
return this.mapView;
}
private void initComponents() {
mapView = (MapView) findViewById(R.id.mapView);
}
@Override
protected boolean isRouteDisplayed() {
return false;
}
下面的类是上面的延续。在下面的课程中，我在谷歌地图上显示了我当前的位置。所以我认为我需要在这个类中进行更改，只需要以当前位置为圆心来绘制四个圆。
class MapOverlay extends Overlay {
private GeoPoint pointToDraw;
public void setPointToDraw(GeoPoint point) {
pointToDraw = point;
}
public GeoPoint getPointToDraw() {
return pointToDraw;
}
@Override
public boolean draw(Canvas canvas, MapView mapView, boolean shadow,
long when) {
super.draw(canvas, mapView, shadow);
Point screenPts = new Point();
mapView.getProjection().toPixels(pointToDraw, screenPts);
Bitmap bmp = BitmapFactory.decodeResource(getResources(),
R.drawable.current_user);
canvas.drawBitmap(bmp, screenPts.x, screenPts.y - 24, null);
return true;
}
}
}