ユーザーに続くマップビュー-Android Maps API v2のMyLocationOverlayタイプの機能
Maps for Androidのv2に切り替え、次の機能を移植しようとしています。
MyLocationOverlayを使用すると、デバイスの現在の場所（青い点）を表示できます。ユーザーの位置が変わり、ドットが可視領域の端に到達すると、マップがアニメーション表示され、ドットがリアルタイムでビューの中心になります。
V2では、getMap（）。setMyLocationEnabled（true）でSupportMapFragmentを使用しています。現在の場所は青い点（矢印）で表示されますが、デバイスが場所を変更しても、マップビューは移動せず、ドットは最終的にビューを離れます。
何か案は？
[〜＃〜] update [〜＃〜]：Googleが新しい LocationClient を導入し、関連付けられました- LocationListener （OnMyLocationChangeListenerインターフェースは廃止されました）。したがって、カメラの自動センタリングは簡単な作業です。
Spotdogはすでに自分の例を共有したいという質問に答えましたが、これが仲間のAndroid初心者がカスタムLocationSourceを作成するために必要なことをよりよく理解するのに役立つと思いますロケーションレイヤー。うまくいけば、コードが十分に文書化/コメントされていることがわかります。
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) {
}
}
}
LocationSourceをGoogleMapに追加して、onLocationChangedイベントに応答する必要があります。以下は、ユーザーの位置を尋ね、ユーザーの位置が利用可能になるまで待機し、マップをアニメーション化してユーザーの位置を中心とする単純なクラスです。
public class MyLocationMapFragmentActivity extends FragmentActivity implements LocationListener, LocationSource
{
/**
* Note that this may be null if the Google Play services APK is not available.
*/
private GoogleMap mMap;
private OnLocationChangedListener mListener;
private LocationManager locationManager;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.basic_map);
locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
if(locationManager != null)
{
boolean gpsIsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
boolean networkIsEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if(gpsIsEnabled)
{
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 5000L, 10F, this);
}
else if(networkIsEnabled)
{
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 5000L, 10F, this);
}
else
{
//Show an error dialog that GPS is disabled.
}
}
else
{
//Show a generic error dialog since LocationManager is null for some reason
}
setUpMapIfNeeded();
}
@Override
public void onPause()
{
if(locationManager != null)
{
locationManager.removeUpdates(this);
}
super.onPause();
}
@Override
public void onResume()
{
super.onResume();
setUpMapIfNeeded();
if(locationManager != null)
{
mMap.setMyLocationEnabled(true);
}
}
/**
* 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
* call {@link #setUpMap()} once when {@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.
* <p>
* A user can return to this Activity after following the Prompt and correctly
* installing/updating/enabling the Google Play services. Since the Activity may not have been
* completely destroyed during this process (it is likely that it would only be stopped or
* paused), {@link #onCreate(Bundle)} may not be called again so we should call this method in
* {@link #onResume()} to guarantee that it will be called.
*/
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mMap == null)
{
// Try to obtain the map from the SupportMapFragment.
mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.basicMap)).getMap();
// Check if we were successful in obtaining the map.
if (mMap != null)
{
setUpMap();
}
//This is how you register the LocationSource
mMap.setLocationSource(this);
}
}
/**
* This is where we can add markers or lines, add listeners or move the camera. In this case, we
* just add a marker near Africa.
* <p>
* This should only be called once and when we are sure that {@link #mMap} is not null.
*/
private void setUpMap()
{
mMap.setMyLocationEnabled(true);
}
@Override
public void activate(OnLocationChangedListener listener)
{
mListener = listener;
}
@Override
public void deactivate()
{
mListener = null;
}
@Override
public void onLocationChanged(Location location)
{
if( mListener != null )
{
mListener.onLocationChanged( location );
//Move the camera to the user's location once it's available!
mMap.animateCamera(CameraUpdateFactory.newLatLng(new LatLng(location.getLatitude(), location.getLongitude())));
}
}
@Override
public void onProviderDisabled(String provider)
{
// TODO Auto-generated method stub
Toast.makeText(this, "provider disabled", Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderEnabled(String provider)
{
// TODO Auto-generated method stub
Toast.makeText(this, "provider enabled", Toast.LENGTH_SHORT).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras)
{
// TODO Auto-generated method stub
Toast.makeText(this, "status changed", Toast.LENGTH_SHORT).show();
}
}
これは、ユーザーに追従し、変更に応じて地図の位置を中央に維持する必要があります。ユーザーが「画面外」に移動したときにのみユーザーの地図を中央に配置する場合は、ユーザーの位置が範囲内にあるかどうかを確認できます。マップの可視境界
@Override
public void onLocationChanged(Location location)
{
if( mListener != null )
{
mListener.onLocationChanged( location );
LatLngBounds bounds = this.mMap.getProjection().getVisibleRegion().latLngBounds;
if(!bounds.contains(new LatLng(location.getLatitude(), location.getLongitude())))
{
//Move the camera to the user's location if they are off-screen!
mMap.animateCamera(CameraUpdateFactory.newLatLng(new LatLng(location.getLatitude(), location.getLongitude())));
}
}
}
トピックに関する簡単な説明を以下に示します。 Google Maps Android API V2 MyLocation LocationSourceおよびイベント処理
[〜＃〜]更新[〜＃〜]
ユーザーの場所を取得する方法を編集しました（onCreateのlocationManagerコードを参照）。 「getBestProvider」メソッドを使用すると信頼性が低く、いくつかのデバイスでは機能しないことがわかりました。いくつものユーザーが、基準をどのように緩和したとしても、デバイスが自分の位置を見つけることができないと不平を言っていました。 GPSまたはネットワークを手動で選択することは、普遍的に機能するようです。
OnMyLocationChangeListenerを使用し、メソッドpublic void onMyLocationChange(Location location)をオーバーライドするだけです。リスナーを登録するには、GoogleMap.setOnMyLocationChangeListener(your listener)を使用します。
public void onMyLocationChange(Location location) {
changeMapLocation(location);
}
private void changeMapLocation(Location location) {
LatLng latlong = new LatLng(location.getLatitude(),
location.getLongitude());
map.moveCamera(CameraUpdateFactory.newLatLngZoom(latlong, 15));
// Zoom in, animating the camera.
map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);
}