如何从Google Maps android中的当前位置不断检测附近的标记位置? [英] How to constantly detect nearby marker locations from current location in Google Maps android?

问题描述

我试图在 Google 地图的左上角显示一个 TextView，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"，但是如果在范围内，则仅显示 TextView.如果它们超出范围，TextView 将消失.

I am trying to display a TextView at 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 TextView if within range. If they move out of range, the TextView will disappear.

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).

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.

我怎样才能做到这一点?我还需要使用 Google Places API 吗?

How can I achieve this? Would I still need to use Google Places API?

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)));
    }
}

地图.xml

<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>

有人能指出我正确的方向吗?谢谢

Can someone point me in the right direction? Thanks

推荐答案

Short answer location.distanceTo(anotherLocation)

Short answer location.distanceTo(anotherLocation)

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.

In setupMap i recommend to add additional listener, to get all location changes in a simple way.

mMap.setMyLocationEnabled(true);
mMap.setOnMyLocationChangeListener(this);

然后在此侦听器中，您只需计算当前位置与目标之间的距离即可.以米为单位的距离.

Then in this listener you just take distance between current location and your targets. Distance in meters.

@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!
        }
    }
}

当然，你应该让你的 Activity 实现 GoogleMap.OnMyLocationChangeListener

Of course, you should make your activity implements GoogleMap.OnMyLocationChangeListener

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