feat: implement modal to select location and save map state

solution/app/src/main/java/com/google/codelabs/maps/placesdemo/CurrentPlaceActivity.kt

@@ -20,15 +20,15 @@ import android.Manifest
 import android.Manifest.permission.ACCESS_COARSE_LOCATION
 import android.Manifest.permission.ACCESS_FINE_LOCATION
 import android.annotation.SuppressLint
+import android.content.DialogInterface
 import android.content.pm.PackageManager
 import android.os.Bundle
 import android.text.method.ScrollingMovementMethod
 import android.util.Log
-import android.view.View
 import android.widget.Button
-import android.widget.FrameLayout
 import android.widget.TextView
 import androidx.annotation.RequiresPermission
+import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.app.ActivityCompat
 import androidx.core.content.ContextCompat
@@ -38,7 +38,6 @@ import com.google.android.gms.maps.GoogleMap
 import com.google.android.gms.maps.OnMapReadyCallback
 import com.google.android.gms.maps.SupportMapFragment
 import com.google.android.gms.maps.model.LatLng
-import com.google.android.gms.maps.model.Marker
 import com.google.android.gms.maps.model.MarkerOptions
 import com.google.android.libraries.places.api.Places
 import com.google.android.libraries.places.api.model.Place
@@ -58,10 +57,21 @@ class CurrentPlaceActivity : AppCompatActivity(), OnMapReadyCallback {
     private var map: GoogleMap? = null
     private val defaultLocation = LatLng(-33.8523341, 151.2106085)
 
+    private var likelyPlaceNames = mutableListOf<String>()
+    private var likelyPlaceAddresses = mutableListOf<String>()
+    private var likelyPlaceAttributions = mutableListOf<MutableList<String?>?>()
+    private var likelyPlaceLatLngs = mutableListOf<LatLng>()
+
+    private var lastKnownLocation: LatLng? = null
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_current)
 
+        if (savedInstanceState != null) {
+            lastKnownLocation = savedInstanceState.getParcelable(KEY_LOCATION)
+        }
+
         val apiKey = BuildConfig.PLACES_API_KEY
 
         // Log an error if apiKey is not set.
@@ -87,6 +97,14 @@ class CurrentPlaceActivity : AppCompatActivity(), OnMapReadyCallback {
 
     }
 
+    /**
+     * Saves the state of the map when the activity is paused.
+     */
+    override fun onSaveInstanceState(outState: Bundle) {
+        outState.putParcelable(KEY_LOCATION, lastKnownLocation)
+        super.onSaveInstanceState(outState)
+    }
+
     /**
      * Checks that the user has granted permission for fine or coarse location.
      * If granted, finds current Place.
@@ -171,12 +189,25 @@ class CurrentPlaceActivity : AppCompatActivity(), OnMapReadyCallback {
             // Retrieve likely places based on the device's current location
             lifecycleScope.launch {
                 val response = placesClient.awaitFindCurrentPlace(placeFields)
-                val place = if (!response.placeLikelihoods.isEmpty()) {
-                    response.placeLikelihoods[0].place
-                } else {
-                    null
+
+                val locations = response
+                    .placeLikelihoods
+                    .take(M_MAX_ENTRIES)
+
+                likelyPlaceNames.clear()
+                likelyPlaceAddresses.clear()
+                likelyPlaceAttributions.clear()
+                likelyPlaceLatLngs.clear()
+
+                for (location in locations) {
+                    likelyPlaceNames.add(location.place.name)
+                    likelyPlaceAddresses.add(location.place.address)
+                    likelyPlaceAttributions.add(location.place.attributions)
+                    likelyPlaceLatLngs.add(location.place.latLng)
                 }
-                setPlaceOnMap(place)
+
+                openPlacesDialog()
+
                 responseView.text = response.prettyPrint()
 
                 // Enable scrolling on the long list of likely places
@@ -190,11 +221,54 @@ class CurrentPlaceActivity : AppCompatActivity(), OnMapReadyCallback {
         }
     }
 
+    /**
+     * Displays a form allowing the user to select a place from a list of likely places.
+     */
+    private fun openPlacesDialog() {
+        // Ask the user to choose the place where they are now.
+        val listener =
+            DialogInterface.OnClickListener { _, which -> // The "which" argument contains the position of the selected item.
+                val markerLatLng: LatLng = likelyPlaceLatLngs.get(which)
+                var markerSnippet: String = likelyPlaceAddresses.get(which)
+                if (likelyPlaceAttributions.get(which) != null) {
+                    markerSnippet = """
+                        $markerSnippet
+                        ${likelyPlaceAttributions.get(which)}
+                    """.trimIndent()
+                }
+
+                lastKnownLocation = markerLatLng
+
+                var place = Place.builder().apply {
+                    name = likelyPlaceNames.get(which)
+                    latLng = markerLatLng
+                }.build()
+
+                map!!.clear()
+
+                setPlaceOnMap(place, markerSnippet)
+            }
+
+        // Display the dialog.
+        AlertDialog.Builder(this)
+            .setTitle(R.string.pick_place)
+            .setItems(likelyPlaceNames.toTypedArray(), listener)
+            .show()
+    }
+
     override fun onMapReady(map: GoogleMap) {
         this.map = map
+        if (lastKnownLocation != null) {
+            map.moveCamera(
+                CameraUpdateFactory.newLatLngZoom(
+                    lastKnownLocation!!,
+                    DEFAULT_ZOOM
+                )
+            )
+        }
     }
 
-    private fun setPlaceOnMap(place: Place?) {
+    private fun setPlaceOnMap(place: Place?, markerSnippet: String?) {
         val latLng = place?.latLng ?: defaultLocation
         map?.moveCamera(
             CameraUpdateFactory.newLatLngZoom(
@@ -206,13 +280,20 @@ class CurrentPlaceActivity : AppCompatActivity(), OnMapReadyCallback {
             MarkerOptions()
             .position(latLng)
             .title(place?.name)
+            .snippet(markerSnippet)
         )
     }
 
     companion object {
         private val TAG = "CurrentPlaceActivity"
         private const val PERMISSION_REQUEST_CODE = 9
         private const val DEFAULT_ZOOM = 15f
+
+        // Key for storing activity state.
+        private const val KEY_LOCATION = "location"
+
+        private const val M_MAX_ENTRIES = 5
+
     }
 }
 

solution/app/src/main/res/values/strings.xml

@@ -27,4 +27,5 @@
     <string name="details_input_default">ChIJ-fIL2vnvTxkRaNUY32NGBYs</string>
     <string name="current_button">Get Current Place</string>
     <string name="showing_most_likely_place">Showing most likely place</string>
+    <string name="pick_place">Choose a place</string>
 </resources>