Android getbearing只返回0.0.尝试使用旋转当前位置图标

这部分是前一个问题的扩展：Android programming, mapview locationoverlay: how to change the default blue location dot, with another image

我一直在努力让设备位置显示在地图上(使用enablemylocation很容易),但我需要更换默认图标(很容易,排序),然后旋转它以对应当前设备轴承 – 从GPS获取,因为它需要是运动方向,而不是手机朝向的方向.

我使用’getbearing()’的方式与我成功使用’getlatitude()’和’getaltitude()’相同,但getbearing总是返回0.(以确保它不是旋转的代码问题的图标轴承的变量在其他任何事情发生之前打印在textview中)

非常奇怪的是它现在已经工作了两次,持续5秒,然后又回到了0 – 所以理论上代码似乎是正确的？

代码如下.

亲切的问候

缺口

主要活动：

package com.nick.kestrel;

import android.content.Context;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.TextView;

import com.google.android.maps.MapActivity;
import com.google.android.maps.MapView;


public class KestrelActivity extends MapActivity {
/** Called when the activity is first created. */

static TextView LocationText;
MapView mapView;


@Override
protected boolean isRouteDisplayed() {
        return false;
}

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

  //Identifies the textview 'locationtext' as the variable LocationText. Planned usage just for debugging
    LocationText = (TextView)findViewById(R.id.locationtext);

  //defines the mapview as variable 'mapView' and enables zoom controls
    mapView = (MapView) findViewById(R.id.mapview);
    mapView.setBuiltInZoomControls(true);

    /**
     * Code required to receive gps location. Activates GPS provider, and is set to update only after
     * at least 10 seconds and a position change of at least 10 metres
     */
    LocationListener locationListener = new MyLocationListener();

    //setting up the location manager
    LocationManager locman = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

    locman.requestLocationUpdates(LocationManager.GPS_PROVIDER, 500, (float) 0.01, locationListener); 

    //Adds a current location overlay to the map 'mapView' and turns on the map's compass

    MyLocation myLocationOverlay = new MyLocation(this, mapView);
    myLocationOverlay.enableMyLocation();
    myLocationOverlay.enableCompass();

    mapView.getOverlays().add(myLocationOverlay);
    mapView.postInvalidate();
}

}

mylocationlistener

package com.nick.kestrel;

import android.location.Location;
import android.location.LocationListener;
import android.os.Bundle;


public class MyLocationListener implements LocationListener {

private boolean hasbearing;

/**
 * Code to run when the listener receives a new location
 */



@Override
public void onLocationChanged(Location locFromGps) {



    //Toast.makeText(getApplicationContext(), "Location changed, Lat: "+locFromGps.getLatitude()+" Long: "+ locFromGps.getLongitude(), Toast.LENGTH_SHORT).show();

    //LocationText.setText("Your Location: Latitude " +locFromGps.getLatitude() + " Longitude: " +locFromGps.getLongitude());

    double dbllatitude = locFromGps.getLatitude();
    double dbllongitude = locFromGps.getLongitude();
    double dblaltitude = locFromGps.getAltitude();
    float bearing = locFromGps.getBearing(); 

    KestrelActivity.LocationText.setText("Your Location: Latitude " + dbllatitude + " Longitude: " +dbllongitude + " Altitude " + dblaltitude + " Bearing: " + bearing);



    hasbearing = locFromGps.hasBearing();


    if (hasbearing =  false) {

        //Toast.makeText(getApplicationContext(), "No bearing", Toast.LENGTH_SHORT).show();

    }
    else
    {
        //Toast.makeText(getApplicationContext(), "I HAZ bearing: " + locFromGps.getBearing(), Toast.LENGTH_SHORT).show();
    }


}

@Override
public void onProviderDisabled(String provider) {
   // called when the GPS provider is turned off (user turning off the GPS on the phone)
}

@Override
public void onProviderEnabled(String provider) {
   // called when the GPS provider is turned on (user turning on the GPS on the phone)
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
   // called when the status of the GPS provider changes

}

}

我的位置

package com.nick.kestrel;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Point;
import android.location.Location;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapView;
import com.google.android.maps.MyLocationOverlay;



public class MyLocation extends MyLocationOverlay {
private Context mContext;
static float   mOrientation;

public MyLocation(Context context, MapView mapView) {
    super(context, mapView);
    mContext = context;
}

@Override 
protected void drawMyLocation(Canvas canvas, MapView mapView, Location lastFix, GeoPoint myLocation, long when) {
    // translate the GeoPoint to screen pixels
    Point screenPts = mapView.getProjection().toPixels(myLocation, null);

    // create a rotated copy of the marker
    Bitmap arrowBitmap = BitmapFactory.decodeResource( mContext.getResources(), R.drawable.pin_icon);
    Matrix matrix = new Matrix();
    matrix.postRotate(mOrientation);
    Bitmap rotatedBmp = Bitmap.createBitmap(
        arrowBitmap, 
        0, 0, 
        arrowBitmap.getWidth(), 
        arrowBitmap.getHeight(), 
        matrix, 
        true
    );
    // add the rotated marker to the canvas
    canvas.drawBitmap(
        rotatedBmp, 
        screenPts.x - (rotatedBmp.getWidth()  / 2), 
        screenPts.y - (rotatedBmp.getHeight() / 2), 

        null

    );
    mapView.postInvalidate();

}

public void setOrientation(float newOrientation) {
     mOrientation = newOrientation;
}

}

解决方法:

什么是位置提供商？如果是NETWORK_PROVIDER,那么你就不会受到影响,因为它的精度要低,要检测轴承.

在外面和GPS_PROVIDER上试试你的应用程序？

标签：android,google-maps-api-3,gps,location,android-mapview
来源： https://codeday.me/bug/20191007/1868077.html