如何检查 lat , long 是否在我的地理围栏内 lat,long,radius

Question

我正在尝试在城市内制作圆形地理围栏，我希望这个地理围栏的圆形宽度为 2 公里，我想知道用户是否在这个地理围栏内

我做了什么

 private fun checkIfInsideGeoFence(){
        geofenceList.add(Geofence.Builder()
                // Set the request ID of the geofence. This is a string to identify this
                // geofence.
                .setRequestId("New York")

                // Set the circular region of this geofence.
                .setCircularRegion(
                    40.6882657,
                    -73.9398756,
                    2000F)

                // Create the geofence.
                .build())

        geofencingClient.addGeofences(getGeofencingRequest(),geofencePendingIntent).addOnSuccessListener {
            fusedLocationClient.lastLocation
                .addOnSuccessListener { location : Location? ->

                    // Got last known location, here I need to check if its inside the geofence
                }
        }.addOnFailureListener{

        }

    }

    private fun getGeofencingRequest(): GeofencingRequest {
        return GeofencingRequest.Builder().apply {
            setInitialTrigger(GeofencingRequest.INITIAL_TRIGGER_ENTER)
            addGeofences(geofenceList)
        }.build()
    }

    private val geofencePendingIntent: PendingIntent by lazy {
        //Here I dont use a brodcast receiver since I dont need to know if the user enters or leaves the area, just if its inside
        PendingIntent.getBroadcast(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
    }

我需要了解内部

 fusedLocationClient.lastLocation
                    .addOnSuccessListener { location : Location? ->

                        // Got last known location, here I need to check if its inside the geofence
                    }

如何知道用户是否处于该特定比例

Answer 1

最简单的方法是检查中心经纬度到当前经度经度之间的距离，看看距离是否

 fusedLocationClient.lastLocation
            .addOnSuccessListener { location : Location? ->

                val results = FloatArray(1)
                Location.distanceBetween(
                    40.6882657,
                    -73.9398756,
                    location!!.latitude,
                    location.longitude,
                    results
                )
                val distanceInMeters = results[0]
                val isWithin2km = distanceInMeters < 2000
                if(isWithin2km){
                    navigateTo()
                }else{
                    startActivity(Intent(this,ActivityGeoFenceError::class.java))
                    finish()
                }
            }

Answer 2

基于@CoffeeBreak 的方法，也可以使用实例方法distanceTo 以使其不那么冗长。类似这样的扩展函数形式：

fun Location.checkIsInBound(radius: Int,center:Location):Boolean
        =  this.distanceTo(center)<radius

fusedLocationClient.lastLocation
        .addOnSuccessListener { location : Location? ->
        val isWithin2km = location?.checkIsInBound(2000,center) }

除了使用 Location API 的 distanceTo，您还可以使用 Google Map Utility Library 的 SphericalUtil 的 computeDistanceBetween，但它需要 LatLng 作为输入。