Android的地图API V2 MyLocationOverlay类型的功能 - 以下用户地图视图 [英] Map view following user - MyLocationOverlay type functionality for Android Maps API v2
问题描述
我切换到地图的Android v2和我想的端口在以下功能：
I switched to v2 of Maps for Android, and I am trying to port over the following functionality:
使用MyLocationOverlay我可以显示设备的当前位置（蓝点）。当用户的位置改变和点达到可见区域的边缘，在地图上动画出这样的点变成视图的中心，在实时
With MyLocationOverlay I can show the devices current location (Blue Dot). When the user's location changes and the dot reaches the edge of the visible area, the map animates out so the dot becomes the center of the view, in real time.
在v2中，我使用SupportMapFragment用的GetMap（）。setMyLocationEnabled（真）。当前位置显示为蓝色点（箭头），但是当该装置改变位置，地图视图不移位和点最终离开图。
In v2, I am using SupportMapFragment with getMap().setMyLocationEnabled(true). The current location appears as a blue dot(arrow), but when the device changes location, the map view does not shift and the dot eventually leaves the view.
任何想法？
推荐答案
更新：谷歌推出新的<一个href="https://developer.android.com/reference/com/google/android/gms/location/LocationClient.html"><$c$c>LocationClient和相关的<一个href="https://developer.android.com/reference/com/google/android/gms/location/LocationListener.html"><$c$c>LocationListener （在 OnMyLocationChangeListener 接口现在是很precated）。相机的所以现在自动居中是一个简单的任务。
UPDATE: Google introduced the new LocationClient and associated LocationListener (the OnMyLocationChangeListener interface is now deprecated). So now automatic centering of the camera is a trivial task.
虽然spotdog已经回答了，我想分享一下我自己的例子，我希望能帮助其他的Android的初学者更好地理解如何才能做一个自定义的 LocationSource 的问题我的定位层。希望你会发现，code是有据可查/评论道。
Although spotdog already answered the question I wanted to share my own example, which I hope will help fellow Android beginners better understand what it takes to make a custom LocationSource for the my-location layer. Hopefully you will find that the code is well documented/commented.
public class PlaceMapFragment extends SupportMapFragment {
// Note that this may be null if the Google Play services APK is not available.
private GoogleMap mMap;
protected PlaceActivity activity;
private FollowMeLocationSource followMeLocationSource;
private Context mContext;
/* We need the Context in order to get a reference to the Location Manager
* (when instantiating this fragment from your activity use:
* PlaceMapFragment mapFragment = new PlaceMapFragment(this); ) */
public PlaceMapFragment(Context context) {
this.mContext = context;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
activity = (PlaceActivity)getActivity();
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// creates our custom LocationSource and initializes some of its members
followMeLocationSource = new FollowMeLocationSource();
/* We can't be guaranteed that the map is available because Google Play services might not be available.
* (un-comment the following line when using this code in a FragmentActivity / Activity
* to try get a reference to the map here !) */
//setUpMapIfNeeded();
}
@Override
public void onResume() {
super.onResume();
/* We query for the best Location Provider everytime this fragment is displayed
* just in case a better provider might have become available since we last displayed it */
followMeLocationSource.getBestAvailableProvider();
// Get a reference to the map/GoogleMap object
setUpMapIfNeeded();
/* Enable the my-location layer (this causes our LocationSource to be automatically activated.)
* While enabled, the my-location layer continuously draws an indication of a user's
* current location and bearing, and displays UI controls that allow a user to interact
* with their location (for example, to enable or disable camera tracking of their location and bearing).*/
mMap.setMyLocationEnabled(true);
}
@Override
public void onPause() {
/* Disable the my-location layer (this causes our LocationSource to be automatically deactivated.) */
mMap.setMyLocationEnabled(false);
super.onPause();
}
/**
* Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
* installed) and the map has not already been instantiated. This will ensure that we only ever
* manipulate the map once when it {@link #mMap} is not null.
* <p>
* If it isn't installed {@link SupportMapFragment} (and {@link com.google.android.gms.maps.MapView
* MapView}) will show a prompt for the user to install/update the Google Play services APK on their device.
*/
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mMap == null) {
mMap = getMap();
// Check if we were successful in obtaining the map.
if (mMap != null) {
// The Map is verified. It is now safe to manipulate the map:
// Replace the (default) location source of the my-location layer with our custom LocationSource
mMap.setLocationSource(followMeLocationSource);
// Set default zoom
mMap.moveCamera(CameraUpdateFactory.zoomTo(15f));
}
}
}
/* 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 preffered 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) {
}
}
}
这篇关于Android的地图API V2 MyLocationOverlay类型的功能 - 以下用户地图视图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
