使相机随着位置更改而移动(谷歌地图API)

Question

我对谷歌地图API有问题。我想做的是将相机与位置一起移动，使蓝色指示器始终位于中心。

认为放置代码的好地方是OnLocationChanged方法，但事实并非如此。

我尝试在那里运行此代码：

LatLng latlng = new LatLng(mLastLocation.getLatitude(),mLastLocation.getLongitude());
    CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latlng,17);
    mMap.animateCamera(cameraUpdate);

更新

那我不能这样做吗？

@Override
public void onLocationChanged(Location location) {
mLocationRequest = LocationRequest.create()
        .setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY)
        .setInterval(10 * 1000)
        .setFastestInterval(1 * 1000);
    LatLng latLng = new LatLng(location.getLatitude(),location.getLongitude());
    CameraPosition cameraPosition = new CameraPosition.Builder()
            .target(latLng)
            .zoom(ZOOM)
            .bearing(0)
            .tilt(0)
            .build();
    mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
}

Answer 1

该代码将用于更新您的相机位置，但不会精确地将 Google 地图蓝色指示器居中。 这是因为蓝点正在侦听与您在代码片段中创建的位置请求不同的位置请求（似乎没有执行任何操作）。 以下代码片段来自这里

/* Our custom LocationSource. 
 * We register this class to receive location updates from the Location Manager
 * and for that reason we need to also implement the LocationListener interface. */
private class FollowMeLocationSource implements LocationSource, LocationListener {
    private OnLocationChangedListener mListener;
    private LocationManager locationManager;
    private final Criteria criteria = new Criteria();
    private String bestAvailableProvider;
    /* Updates are restricted to one every 10 seconds, and only when
     * movement of more than 10 meters has been detected.*/
    private final int minTime = 10000;     // minimum time interval between location updates, in milliseconds
    private final int minDistance = 10;    // minimum distance between location updates, in meters
    private FollowMeLocationSource() {
        // Get reference to Location Manager
        locationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);
        // Specify Location Provider criteria
        criteria.setAccuracy(Criteria.ACCURACY_FINE);
        criteria.setPowerRequirement(Criteria.POWER_LOW);
        criteria.setAltitudeRequired(true);
        criteria.setBearingRequired(true);
        criteria.setSpeedRequired(true);
        criteria.setCostAllowed(true);
    }
    private void getBestAvailableProvider() {
        /* The preferred way of specifying the location provider (e.g. GPS, NETWORK) to use 
         * is to ask the Location Manager for the one that best satisfies our criteria.
         * By passing the 'true' boolean we ask for the best available (enabled) provider. */
        bestAvailableProvider = locationManager.getBestProvider(criteria, true);
    }
    /* Activates this provider. This provider will notify the supplied listener
     * periodically, until you call deactivate().
     * This method is automatically invoked by enabling my-location layer. */
    @Override
    public void activate(OnLocationChangedListener listener) {
        // We need to keep a reference to my-location layer's listener so we can push forward
        // location updates to it when we receive them from Location Manager.
        mListener = listener;
        // Request location updates from Location Manager
        if (bestAvailableProvider != null) {
            locationManager.requestLocationUpdates(bestAvailableProvider, minTime, minDistance, this);
        } else {
            // (Display a message/dialog) No Location Providers currently available.
        }
    }
    /* Deactivates this provider.
     * This method is automatically invoked by disabling my-location layer. */
    @Override
    public void deactivate() {
        // Remove location updates from Location Manager
        locationManager.removeUpdates(this);
        mListener = null;
    }
    @Override
    public void onLocationChanged(Location location) {
        /* Push location updates to the registered listener..
         * (this ensures that my-location layer will set the blue dot at the new/received location) */
        if (mListener != null) {
            mListener.onLocationChanged(location);
        }
        /* ..and Animate camera to center on that location !
         * (the reason for we created this custom Location Source !) */
        mMap.animateCamera(CameraUpdateFactory.newLatLng(new LatLng(location.getLatitude(), location.getLongitude())));
    }
    @Override
    public void onStatusChanged(String s, int i, Bundle bundle) {
    }
    @Override
    public void onProviderEnabled(String s) {
    }
    @Override
    public void onProviderDisabled(String s) {
    }
}

现在，在您的onMapReady(GoogleMap)回调中，将其放入：

public void onMapReady(GoogleMap map){
    mMap = map;
    FollowMeLocationSource locationSource = new FollowMeLocationSource();
    locationSource.getBestAvailableProvider();
    mMap.setLocationSource(locationSource);
    mMap.setMyLocationEnabled(true);
}

根据需要修改此示例，但这应该可以为您提供所需的功能。