Center the map on collars when possible

app/src/main/java/com/danilafe/fencelessgrazing/CollarDetailActivity.kt

@@ -1,18 +1,14 @@
 package com.danilafe.fencelessgrazing
 
-import android.app.Application
 import android.graphics.Color
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
-import android.util.Log
 import android.widget.TextView
 import android.widget.Toast
-import com.android.volley.Request
 import com.android.volley.RequestQueue
 import com.android.volley.Response
 import com.android.volley.toolbox.Volley
 import com.danilafe.fencelessgrazing.model.CollarPos
-import com.danilafe.fencelessgrazing.model.CollarSummary
 import com.danilafe.fencelessgrazing.model.Polygon
 import com.danilafe.fencelessgrazing.requests.CollarDetailRequest
 import com.danilafe.fencelessgrazing.requests.CollarHistoryRequest
@@ -20,9 +16,7 @@ import org.osmdroid.util.GeoPoint
 import org.osmdroid.views.MapView
 import org.osmdroid.views.overlay.Marker
 import org.osmdroid.views.overlay.Polyline
-import java.sql.Time
 import java.util.*
-import kotlin.collections.ArrayList
 import kotlin.concurrent.timerTask
 
 class CollarDetailActivity : AppCompatActivity() {
@@ -34,6 +28,7 @@ class CollarDetailActivity : AppCompatActivity() {
     private lateinit var queue: RequestQueue
     private var collarId: Int = -1
 
+    private var centerSet: Boolean = false
     private lateinit var map: MapView
 
     private var refreshTimer = Timer()
@@ -67,6 +62,7 @@ class CollarDetailActivity : AppCompatActivity() {
         queue = Volley.newRequestQueue(this)
 
         map = findViewById(R.id.detailMap)
+        map.controller.setZoom(9.5)
         mapPolygon = org.osmdroid.views.overlay.Polygon(map)
         mapMarker = Marker(map)
         mapPolyline = Polyline(map)
@@ -127,11 +123,15 @@ class CollarDetailActivity : AppCompatActivity() {
 
     private fun updateAnimalHistory(points : List<GeoPoint>) {
         val currentPoint = points.first()
-        mapMarker.position = currentPoint
-        mapPolyline.setPoints(points)
         collarPos.text = getString(R.string.collarSummaryLocation, currentPoint.longitude, currentPoint.latitude)
         if(!map.overlays.contains(mapMarker)) map.overlays.add(mapMarker)
         if(!map.overlays.contains(mapPolyline)) map.overlays.add(mapPolyline)
+        mapMarker.position = currentPoint
+        mapPolyline.setPoints(points)
+        if(!centerSet) {
+            centerSet = true
+            map.controller.setCenter(currentPoint)
+        }
         map.invalidate()
     }
 

app/src/main/java/com/danilafe/fencelessgrazing/CollarListActivity.kt

@@ -3,7 +3,6 @@ package com.danilafe.fencelessgrazing
 import android.content.Intent
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
-import android.util.Log
 import android.widget.Toast
 import androidx.preference.PreferenceManager
 import androidx.recyclerview.widget.DividerItemDecoration
@@ -34,6 +33,7 @@ class CollarListActivity : AppCompatActivity() {
     private lateinit var queue: RequestQueue
 
     // The OpenStreetMap map.
+    private var centerSet: Boolean = false
     private lateinit var map: MapView
     private val collarOverlays: MutableMap<Int, Marker> = mutableMapOf()
 
@@ -51,6 +51,7 @@ class CollarListActivity : AppCompatActivity() {
 
         token = intent.getStringExtra("token")!!
         map.setTileSource(TileSourceFactory.MAPNIK)
+        map.controller.setZoom(9.5)
         queue = Volley.newRequestQueue(this)
 
         setupCollarList()
@@ -76,7 +77,7 @@ class CollarListActivity : AppCompatActivity() {
                 summaries.clear()
                 summaries.addAll(it)
                 summaryAdapter.notifyDataSetChanged()
-                updateMapOverlay()
+                updateMap()
             },
             Response.ErrorListener {
                 Toast.makeText(this, "Failed to retrieve collar list!", Toast.LENGTH_SHORT).show()
@@ -111,6 +112,20 @@ class CollarListActivity : AppCompatActivity() {
         collarList.addItemDecoration(DividerItemDecoration(collarList.context, layoutManager.orientation))
     }
 
+    private fun updateMap() {
+        updateMapCenter()
+        updateMapOverlay()
+    }
+
+    private fun updateMapCenter() {
+        if(centerSet) return
+
+        centerSet = true
+        val averageLongitude = summaries.map { it.pos.longitude.toDouble() }.average()
+        val averageLatitude = summaries.map { it.pos.latitude.toDouble() }.average()
+        map.controller.setCenter(GeoPoint(averageLongitude, averageLatitude))
+    }
+
     private fun updateMapOverlay() {
         val currentSet = mutableSetOf<Int>()
         summaries.forEach {
@@ -132,6 +147,7 @@ class CollarListActivity : AppCompatActivity() {
                 collarOverlays.remove(it)
             }
         }
+
         map.invalidate()
     }
 }