java 如何从Google Maps android中的当前位置不断检测附近的标记位置？
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How to constantly detect nearby marker locations from current location in Google Maps android?
提问by Pangu
I am trying to display a TextViewat the top left corner of Google Maps that inform users if they are x distances from particular marker point locations, i.e. "You are close to location A", but only display the TextViewif within range. If they move out of range, the TextViewwill disappear.
我试图TextView在谷歌地图的左上角显示一个，通知用户他们是否距离特定标记点位置 x 距离，即“您靠近位置 A”，但只显示TextView如果在范围内。如果它们超出范围，则TextView将消失。
I understand that the Google Places API shows you all the nearby locations, but I only want to show nearby locations of the markers I have on the map if users are x distances close to them.
我知道 Google Places API 会向您显示所有附近的位置，但我只想显示我在地图上的标记的附近位置，如果用户与他们相距 x 距离。
How can I achieve this? Would I still need to use Google Places API?
我怎样才能做到这一点？我还需要使用 Google Places API 吗？
my class .java:
我的类.java：
private GoogleMap mMap;
private LatLng currLocation;
private static final LatLng POINTA = new LatLng(32.820193, -117.232568);
private static final LatLng POINTB = new LatLng(32.829129, -117.232204);
private static final LatLng POINTC = new LatLng(32.821114, -117.231534);
private static final LatLng POINTD = new LatLng(32.825157, -117.232003);
// Array to store hotspot coordinates
private ArrayList<LatLng> markerCoords = new ArrayList<LatLng>();
private static final int POINTS = 4;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
setUpMapIfNeeded();
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Create MenuInflater object to insert ActionBar buttons
MenuInflater inflater = getMenuInflater();
// Display the ActionBar buttons from .xml
inflater.inflate(R.menu.menu_map, menu);
return true;
}
@Override
protected void onResume()
{
super.onResume();
setUpMapIfNeeded();
}
private void setUpMapIfNeeded()
{
if (mMap == null)
{
mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
// Check if we were successful in obtaining the map.
if (mMap != null)
{
markerCoords.add(POINTA);
markerCoords.add(POINTB);
markerCoords.add(POINTC);
markerCoords.add(POINTD);
setUpMap();
}
}
}
private void setUpMap()
{
// Set My Location blue dot
mMap.setMyLocationEnabled(true);
LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
String provider = locationManager.getBestProvider(criteria, true);
Location myLocation = locationManager.getLastKnownLocation(provider);
if (myLocation != null)
{
double latitude = myLocation.getLatitude();
double longitude = myLocation.getLongitude();
currLocation = new LatLng(latitude, longitude);
}
for (int i = 0; i < POINTS; i++)
{
mMap.addMarker(new MarkerOptions()
.position(markerCoords.get(i))
.icon(BitmapDescriptorFactory.fromResource(R.drawable.post_it_marker)));
}
}
map.xml
地图文件
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<fragment
xmlns:map="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
map:cameraTargetLat="32.881416"
map:cameraTargetLng="-117.237428"
map:cameraZoom="15"
map:mapType="normal" />
</RelativeLayout>
Can someone point me in the right direction? Thanks
有人可以指出我正确的方向吗？谢谢
回答by Stas Parshin
Short answer location.distanceTo(anotherLocation)
简答 location.distanceTo(anotherLocation)
In setupMap i recommend to add additional listener, to get all location changes in a simple way.
在 setupMap 中，我建议添加额外的侦听器，以简单的方式获取所有位置更改。
mMap.setMyLocationEnabled(true);
mMap.setOnMyLocationChangeListener(this);
Then in this listener you just take distance between current location and your targets. Distance in meters.
然后在这个侦听器中，您只需计算当前位置和目标之间的距离。以米为单位的距离。
@Override
public void onMyLocationChange(Location location) {
Location target = new Location("target");
for(LatLng point : new LatLng[]{POINTA, POINTB, POINTC, POINTD}) {
target.setLatitude(point.latitude);
target.setLongitude(point.longitude);
if(location.distanceTo(target) < METERS_100) {
// bingo!
}
}
}
Of course, you should make your activity implements GoogleMap.OnMyLocationChangeListener
当然，你应该让你的活动 implements GoogleMap.OnMyLocationChangeListener
