在这里，我创建了一个跟踪当前位置的项目。 但我编码时出了问题...我不确切知道如何使用OVERLAY类以及何时调用它。
我已发布我的代码..请帮帮我
package com.techno.gps;
import java.io.IOException;
import java.util.List;
import java.util.Locale;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.Projection;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.RectF;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.TextView;
public class gps extends MapActivity{
MapController mapController;
Location location;
MyPositionOverlay positionOverlay;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Get a reference to the MapView
MapView myMapView = (MapView)findViewById(R.id.mapView);
// Get the Map View’s controller
mapController = myMapView.getController();
// Configure the map display options
myMapView.setSatellite(true);
myMapView.setStreetView(true);
myMapView.displayZoomControls(false);
// Zoom in
mapController.setZoom(17);
//add postionoverlay
positionOverlay = new MyPositionOverlay();
List<Overlay> overlays = myMapView.getOverlays();
overlays.add(positionOverlay);
LocationManager locationManager;
String context = Context.LOCATION_SERVICE;
locationManager = (LocationManager)getSystemService(context);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(true);
criteria.setPowerRequirement(Criteria.POWER_LOW);
String provider = locationManager.getBestProvider(criteria, true);
location = locationManager.getLastKnownLocation(provider);
updateWithNewLocation(location);
locationManager.requestLocationUpdates(provider, 2000, 10,locationListener);
}
@Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
private void updateWithNewLocation(Location location)
{
String latLongString;
TextView myLocationText;
myLocationText = (TextView)findViewById(R.id.myLocationText);
String addressString = "No address found";
if (location != null) {
// Update the map location.
positionOverlay.setLocation(location);
Double geoLat = location.getLatitude()*1E6;
Double geoLng = location.getLongitude()*1E6;
GeoPoint point = new GeoPoint(geoLat.intValue(),
geoLng.intValue());
mapController.animateTo(point);
double lat = location.getLatitude();
double lng = location.getLongitude();
latLongString = "Lat: "+ lat + " Long:" + lng;
double latitude = location.getLatitude();
double longitude = location.getLongitude();
Geocoder gc = new Geocoder(this, Locale.getDefault());
try
{
List<Address> addresses = gc.getFromLocation(latitude, longitude, 1);
StringBuilder sb = new StringBuilder();
if (addresses.size() > 0)
{
Address address = addresses.get(0);
for (int i = 0; i < address.getMaxAddressLineIndex(); i++)
{
sb.append(address.getAddressLine(i)).append("\n");
}
sb.append(address.getLocality()).append("\n");
sb.append(address.getPostalCode()).append("\n");
sb.append(address.getCountryName());
}
addressString = sb.toString();
}
catch (IOException e)
{
}
}
else
{
latLongString = "No location found";
}
myLocationText.setText("Your Current Position is:\n" +latLongString + "\n" + addressString);
}
private final LocationListener locationListener = new LocationListener()
{
public void onLocationChanged(Location location) {
updateWithNewLocation(location);
}
public void onProviderDisabled(String provider)
{
updateWithNewLocation(null);
}
public void onProviderEnabled(String provider)
{
}
public void onStatusChanged(String provider, int status,Bundle extras)
{
}
};
public class MyPositionOverlay extends Overlay
{
Location location;
@Override
public void draw(Canvas canvas, MapView mapView, boolean shadow)
{
Projection projection = mapView.getProjection();
if (shadow == false) {
// Get the current location
Double latitude = location.getLatitude()*1E6;
Double longitude = location.getLongitude()*1E6;
GeoPoint geoPoint;
geoPoint = new GeoPoint(latitude.intValue(),longitude.intValue());
// Convert the location to screen pixels
int mRadius=5;
Point point = new Point();
projection.toPixels(geoPoint, point);
RectF oval = new RectF(point.x - mRadius, point.y - mRadius,
point.x + mRadius, point.y + mRadius);
// Setup the paint
Paint paint = new Paint();
paint.setARGB(250, 255, 0, 0);
paint.setAntiAlias(true);
paint.setFakeBoldText(true);
Paint backPaint = new Paint();
backPaint.setARGB(175, 50, 50, 50);
backPaint.setAntiAlias(true);
RectF backRect = new RectF(point.x + 2 + mRadius,
point.y - 3*mRadius,
point.x + 65, point.y + mRadius);
// Draw the marker
canvas.drawOval(oval, paint);
canvas.drawRoundRect(backRect, 5, 5, backPaint);
canvas.drawText("Here I Am", point.x + 2*mRadius, point.y, paint);
}
super.draw(canvas, mapView, shadow);
}
@Override
public boolean onTap(GeoPoint point, MapView mapView)
{
// Return true if screen tap is handled by this overlay
return false;
}
public Location getLocation() {
return location;
}
public void setLocation(Location location) {
this.location = location;
}
}
}
感谢...
答案 0 :(得分：2)
很遗憾你不知道自己的代码。你应该尝试自己写。复制粘贴始终不起作用。
回答你的问题。 Overlay是可绘制对象，可以在MapView上方的不同图层上显示在地图的顶部。
这是将该绘图添加到MapView的代码的一部分。
positionOverlay = new MyPositionOverlay();
List<Overlay> overlays = myMapView.getOverlays();
overlays.add(positionOverlay);
您正在OnCreate（）中执行此操作。哪个没有意义，因为你还没有定位。
答案 1 :(得分：1)
我有相同的示例代码，2.2安卓，工作，但不要卓越覆盖，我的位置，否则，使用debuggin你可以看到代码正常工作。真奇怪。
我认为代码是正确的，因为在onCreate中，代码已初始化，然后在updateWithNewLocation中，覆盖图将使用positionOverlay.setLocation(location);更新