feat: Add SaveStateDemoActivity. (#431)

ApiDemos/kotlin/app/src/gms/AndroidManifest.xml

@@ -52,6 +52,7 @@
     <activity android:name=".ProgrammaticDemoActivity" />
     <activity android:name=".RawMapViewDemoActivity" />
     <activity android:name=".RetainMapDemoActivity" />
+    <activity android:name=".SaveStateDemoActivity" />
     <activity android:name=".SplitStreetViewPanoramaAndMapDemoActivity" />
     <activity android:name=".StreetViewPanoramaBasicDemoActivity" />
     <activity android:name=".StreetViewPanoramaEventsDemoActivity" />

ApiDemos/kotlin/app/src/gms/java/com/example/kotlindemos/CameraClampingDemoActivity.kt

@@ -23,8 +23,6 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.lifecycle.lifecycleScope
 import com.google.android.gms.maps.CameraUpdateFactory
 import com.google.android.gms.maps.GoogleMap
-import com.google.android.gms.maps.GoogleMap.OnCameraIdleListener
-import com.google.android.gms.maps.OnMapReadyCallback
 import com.google.android.gms.maps.SupportMapFragment
 import com.google.android.gms.maps.model.CameraPosition
 import com.google.android.gms.maps.model.LatLng
@@ -33,7 +31,6 @@ import com.google.maps.android.ktx.CameraIdleEvent
 import com.google.maps.android.ktx.awaitMap
 import com.google.maps.android.ktx.cameraEvents
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.launch
 

ApiDemos/kotlin/app/src/gms/java/com/example/kotlindemos/DemoDetailsList.kt

@@ -86,6 +86,9 @@ class DemoDetailsList {
       DemoDetails(R.string.raw_map_view_demo_label,
                   R.string.raw_map_view_demo_description,
                   RawMapViewDemoActivity::class.java),
+      DemoDetails(R.string.save_state_demo_label,
+                  R.string.save_state_demo_description,
+                  SaveStateDemoActivity::class.java),
       DemoDetails(R.string.street_view_panorama_basic_demo_label,
                   R.string.street_view_panorama_basic_demo_details,
                   StreetViewPanoramaBasicDemoActivity::class.java),

ApiDemos/kotlin/app/src/gms/java/com/example/kotlindemos/SaveStateDemoActivity.kt

@@ -0,0 +1,160 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.example.kotlindemos
+
+import android.os.Bundle
+import android.os.Parcelable
+import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.lifecycleScope
+import com.google.android.gms.maps.CameraUpdateFactory
+import com.google.android.gms.maps.GoogleMap.OnMarkerClickListener
+import com.google.android.gms.maps.GoogleMap.OnMarkerDragListener
+import com.google.android.gms.maps.SupportMapFragment
+import com.google.android.gms.maps.model.BitmapDescriptorFactory
+import com.google.android.gms.maps.model.LatLng
+import com.google.android.gms.maps.model.Marker
+import com.google.maps.android.ktx.CameraEvent
+import com.google.maps.android.ktx.addMarker
+import com.google.maps.android.ktx.awaitMap
+import com.google.maps.android.ktx.cameraEvents
+import kotlinx.android.parcel.Parcelize
+import kotlinx.coroutines.flow.collect
+import java.util.Random
+
+/**
+ * This activity shows how to save the state of a MapFragment when the activity is recreated, like
+ * after rotation of the device.
+ */
+class SaveStateDemoActivity : AppCompatActivity() {
+
+  @Parcelize
+  internal data class MarkerInfo(var hue: Float) : Parcelable
+
+  /**
+   * Example of a custom `MapFragment` showing how the position of a marker and other
+   * custom
+   * [Parcelable]s objects can be saved after rotation of the device.
+   *
+   *
+   * Storing custom [Parcelable] objects directly in the [Bundle] provided by the
+   * [.onActivityCreated] method will throw a `ClassNotFoundException`. This
+   * is due to the fact that this Bundle is parceled (thus losing its ClassLoader attribute at
+   * this moment) and unparceled later in a different ClassLoader.
+   * <br></br>
+   * A workaround to store these objects is to wrap the custom [Parcelable] objects in a
+   * new
+   * [Bundle] object.
+   *
+   *
+   * However, note that it is safe to store [Parcelable] objects from the Maps API (eg.
+   * MarkerOptions, LatLng, etc.) directly in the Bundle provided by the
+   * [.onActivityCreated] method.
+   */
+  class SaveStateMapFragment : SupportMapFragment(), OnMarkerClickListener, OnMarkerDragListener {
+
+    private lateinit var mMarkerPosition: LatLng
+    private lateinit var mMarkerInfo: MarkerInfo
+    private var mMoveCameraToMarker = false
+
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+      super.onCreate(savedInstanceState)
+
+      // Extract the state of the MapFragment:
+      // - Objects from the API (eg. LatLng, MarkerOptions, etc.) were stored directly in
+      //   the savedInsanceState Bundle.
+      // - Custom Parcelable objects were wrapped in another Bundle.
+      mMarkerPosition =
+        savedInstanceState?.getParcelable(MARKER_POSITION) ?: DEFAULT_MARKER_POSITION
+      mMarkerInfo =
+        savedInstanceState?.getBundle(OTHER_OPTIONS)?.getParcelable(MARKER_INFO) ?: MarkerInfo(
+          BitmapDescriptorFactory.HUE_RED)
+      mMoveCameraToMarker = savedInstanceState == null
+
+      lifecycleScope.launchWhenCreated {
+        val map = awaitMap()
+        map.addMarker {
+          icon(BitmapDescriptorFactory.defaultMarker(mMarkerInfo.hue))
+          position(mMarkerPosition)
+          draggable(true)
+        }
+
+        map.setOnMarkerDragListener(this@SaveStateMapFragment)
+        map.setOnMarkerClickListener(this@SaveStateMapFragment)
+
+        if (mMoveCameraToMarker) {
+          map.animateCamera(CameraUpdateFactory.newLatLng(mMarkerPosition))
+        }
+      }
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+      super.onSaveInstanceState(outState)
+
+      // All Parcelable objects of the API  (eg. LatLng, MarkerOptions, etc.) can be set
+      // directly in the given Bundle.
+      outState.putParcelable(MARKER_POSITION, mMarkerPosition)
+
+      // All other custom Parcelable objects must be wrapped in another Bundle. Indeed,
+      // failing to do so would throw a ClassNotFoundException. This is due to the fact that
+      // this Bundle is being parceled (losing its ClassLoader at this time) and unparceled
+      // later in a different ClassLoader.
+      val bundle = Bundle()
+      bundle.putParcelable(MARKER_INFO, mMarkerInfo)
+      outState.putBundle(OTHER_OPTIONS, bundle)
+    }
+
+    override fun onMarkerClick(marker: Marker): Boolean {
+      val newHue = MARKER_HUES[Random()
+        .nextInt(MARKER_HUES.size)]
+      mMarkerInfo.hue = newHue
+      marker.setIcon(BitmapDescriptorFactory.defaultMarker(newHue))
+      return true
+    }
+
+    override fun onMarkerDragStart(marker: Marker) {}
+    override fun onMarkerDrag(marker: Marker) {}
+    override fun onMarkerDragEnd(marker: Marker) {
+      mMarkerPosition = marker.position
+    }
+  }
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    setContentView(R.layout.save_state_demo)
+  }
+
+  companion object {
+    /** Default marker position when the activity is first created.  */
+    private val DEFAULT_MARKER_POSITION = LatLng(48.858179, 2.294576)
+
+    /** List of hues to use for the marker  */
+    private val MARKER_HUES = floatArrayOf(
+      BitmapDescriptorFactory.HUE_RED,
+      BitmapDescriptorFactory.HUE_ORANGE,
+      BitmapDescriptorFactory.HUE_YELLOW,
+      BitmapDescriptorFactory.HUE_GREEN,
+      BitmapDescriptorFactory.HUE_CYAN,
+      BitmapDescriptorFactory.HUE_AZURE,
+      BitmapDescriptorFactory.HUE_BLUE,
+      BitmapDescriptorFactory.HUE_VIOLET,
+      BitmapDescriptorFactory.HUE_MAGENTA,
+      BitmapDescriptorFactory.HUE_ROSE)
+
+    // Bundle keys.
+    private const val OTHER_OPTIONS = "options"
+    private const val MARKER_POSITION = "markerPosition"
+    private const val MARKER_INFO = "markerInfo"
+  }
+}

ApiDemos/kotlin/app/src/gms/res/layout/save_state_demo.xml

@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+     Copyright (C) 2012 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <TextView
+        android:id="@+id/instructions"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/save_state_instructions" />
+
+    <fragment
+        android:id="@+id/map"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        class="com.example.kotlindemos.SaveStateDemoActivity$SaveStateMapFragment" />
+
+</LinearLayout>

ApiDemos/kotlin/app/src/main/res/values/strings.xml

@@ -310,4 +310,9 @@
     <string name="retain_map_demo_label">Retain map</string>
     <string name="retain_map_demo_description">Demonstrates how to reuse a MapFragment.</string>
 
+    <!-- Saved State -->
+    <string name="save_state_demo_label">Save the state of a MapFragment.</string>
+    <string name="save_state_demo_description">Demonstrates how to save the state of a MapFragment upon rotation of the device.</string>
+    <string name="save_state_instructions">Drag the marker, tap on it to change its color and rotate the device to check that the state of the map is preserved.</string>
+
 </resources>