使相机随着位置的变化而移动（Google Maps Api）

Question

我对谷歌地图 api 有疑问。我想要做的是将相机与 Location 一起移动，以便蓝色指示器始终位于中心。

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

我试图在那里运行这段代码：

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

更新

那么我不能这样做吗？

@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

该代码可用于更新您的相机位置，但无法将 Google 地图蓝色指示器精确居中。这是因为蓝点正在侦听的 locationRequest 与您在代码 sn-p 中创建的 locationRequest 不同（这似乎没有做任何事情）。以下代码sn-p来自here

/* 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，但这应该会为您提供所需的功能。