Multiple flutters sample android (#677)

add_to_app/multiple_flutters/multiple_flutters_android/.gitignore

@@ -0,0 +1,15 @@
+*.iml
+.gradle
+/local.properties
+/.idea/caches
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+/.idea/navEditor.xml
+/.idea/assetWizardSettings.xml
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+local.properties

add_to_app/multiple_flutters/multiple_flutters_android/README.md

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+# multiple_flutters_android
+
+This is an add-to-app sample that uses the Flutter engine group API to host
+multiple instances of Flutter in the app.
+
+## Getting Started
+
+```sh
+cd ../multiple_flutters_module
+flutter pub get
+cd -
+open -a "Android Studio" multiple_flutters_android/ # macOS command
+# (build and run)
+```
+
+For more information see
+[multiple_flutters_module](../multiple_flutters_module/README.md).

add_to_app/multiple_flutters/multiple_flutters_android/app/.gitignore

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+/build

add_to_app/multiple_flutters/multiple_flutters_android/app/build.gradle

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+plugins {
+    id 'com.android.application'
+    id 'kotlin-android'
+}
+
+android {
+    signingConfigs {
+        self {
+        }
+    }
+    compileSdkVersion 30
+
+    defaultConfig {
+        applicationId "dev.flutter.multipleflutters"
+        minSdkVersion 24
+        targetSdkVersion 30
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+            signingConfig debug.signingConfig
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+}
+
+dependencies {
+
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    implementation 'androidx.core:core-ktx:1.2.0'
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation 'com.google.android.material:material:1.1.0'
+    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+    testImplementation 'junit:junit:4.+'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
+    implementation project(':flutter')
+}

add_to_app/multiple_flutters/multiple_flutters_android/app/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/AndroidManifest.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="dev.flutter.multipleflutters">
+
+    <application
+        android:name=".App"
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.MultipleFlutters">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+        <activity
+            android:name=".SingleFlutterActivity"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:hardwareAccelerated="true"
+            android:windowSoftInputMode="adjustResize"
+            />
+        <activity
+            android:name=".DoubleFlutterActivity"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:hardwareAccelerated="true"
+            android:windowSoftInputMode="adjustResize"
+            />
+    </application>
+
+</manifest>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/java/dev/flutter/multipleflutters/App.kt

@@ -0,0 +1,18 @@
+package dev.flutter.multipleflutters
+
+import android.app.Application
+import io.flutter.embedding.engine.FlutterEngineGroup
+
+/**
+ * Application class for this app.
+ *
+ * This holds onto our engine group.
+ */
+class App : Application() {
+    lateinit var engines: FlutterEngineGroup
+
+    override fun onCreate() {
+        super.onCreate()
+        engines = FlutterEngineGroup(this)
+    }
+}

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/java/dev/flutter/multipleflutters/DataModel.kt

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+package dev.flutter.multipleflutters
+
+import java.lang.ref.WeakReference
+
+/**
+ * Interface for getting notifications when the DataModel is updated.
+ */
+interface DataModelObserver {
+    fun onCountUpdate(newCount: Int)
+}
+
+/**
+ * A singleton/observable data model for the data shared between Flutter and the host platform.
+ *
+ * This is the definitive source of truth for all data.
+ */
+class DataModel {
+    companion object {
+        val instance = DataModel()
+    }
+
+    private val observers = mutableListOf<WeakReference<DataModelObserver>>()
+
+    public var counter = 0
+        set(value) {
+            field = value
+            for (observer in observers) {
+                observer.get()?.onCountUpdate(value)
+            }
+        }
+
+    fun addObserver(observer: DataModelObserver) {
+        observers.add(WeakReference(observer))
+    }
+
+    fun removeObserver(observer: DataModelObserver) {
+        observers.removeIf {
+            if (it.get() != null) it.get() == observer else true
+        }
+    }
+}

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/java/dev/flutter/multipleflutters/DoubleFlutterActivity.kt

@@ -0,0 +1,81 @@
+package dev.flutter.multipleflutters
+
+import android.content.Intent
+import android.os.Bundle
+import android.widget.FrameLayout
+import android.widget.LinearLayout
+import androidx.fragment.app.FragmentActivity
+import androidx.fragment.app.FragmentManager
+import io.flutter.embedding.android.FlutterFragment
+import io.flutter.embedding.engine.FlutterEngineCache
+
+/**
+ * An activity that displays 2 FlutterFragments vertically.
+ */
+class DoubleFlutterActivity : FragmentActivity(), EngineBindingsDelegate {
+    private val topBindings: EngineBindings by lazy {
+        EngineBindings(activity = this, delegate = this, entrypoint = "topMain")
+    }
+    private val bottomBindings: EngineBindings by lazy {
+        EngineBindings(activity = this, delegate = this, entrypoint = "bottomMain")
+    }
+    private val numberOfFlutters = 2
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        val root = LinearLayout(this)
+        root.layoutParams = LinearLayout.LayoutParams(
+            LinearLayout.LayoutParams.MATCH_PARENT,
+            LinearLayout.LayoutParams.MATCH_PARENT
+        )
+        root.orientation = LinearLayout.VERTICAL
+        root.weightSum = numberOfFlutters.toFloat()
+
+        val fragmentManager: FragmentManager = supportFragmentManager
+
+        setContentView(root)
+
+        val app = applicationContext as App
+
+        for (i in 0 until numberOfFlutters) {
+            val flutterContainer = FrameLayout(this)
+            root.addView(flutterContainer)
+            flutterContainer.id = 12345 + i
+            flutterContainer.layoutParams = LinearLayout.LayoutParams(
+                FrameLayout.LayoutParams.MATCH_PARENT,
+                FrameLayout.LayoutParams.MATCH_PARENT,
+                1.0f
+            )
+            val engine = if (i == 0) topBindings.engine else bottomBindings.engine
+            FlutterEngineCache.getInstance().put(i.toString(), engine)
+            val flutterFragment =
+                FlutterFragment.withCachedEngine(i.toString()).build<FlutterFragment>()
+            fragmentManager
+                .beginTransaction()
+                .add(
+                    12345 + i,
+                    flutterFragment
+                )
+                .commit()
+        }
+
+        topBindings.attach()
+        bottomBindings.attach()
+    }
+
+    override fun onDestroy() {
+        for (i in 0 until numberOfFlutters) {
+            FlutterEngineCache.getInstance().remove(i.toString())
+        }
+
+        super.onDestroy()
+
+        bottomBindings.detach()
+        topBindings.detach()
+    }
+
+    override fun onNext() {
+        val flutterIntent = Intent(this, MainActivity::class.java)
+        startActivity(flutterIntent)
+    }
+}

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/java/dev/flutter/multipleflutters/EngineBindings.kt

@@ -0,0 +1,86 @@
+package dev.flutter.multipleflutters
+
+import android.app.Activity
+import io.flutter.FlutterInjector
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.embedding.engine.dart.DartExecutor
+import io.flutter.plugin.common.MethodChannel
+
+/**
+ * This interface represents the notifications an EngineBindings may be receiving from the Flutter
+ * instance.
+ *
+ * What methods this interface has depends on the messages that are sent over the EngineBinding's
+ * channel in `main.dart`.  Messages that interact with the DataModel are handled automatically
+ * by the EngineBindings.
+ *
+ * @see main.dart for what messages are getting sent from Flutter.
+ */
+interface EngineBindingsDelegate {
+    fun onNext()
+}
+
+/**
+ * This binds a FlutterEngine instance with the DataModel and a channel for communicating with that
+ * engine.
+ *
+ * Messages involving the DataModel are handled by the EngineBindings, other messages are forwarded
+ * to the EngineBindingsDelegate.
+ *
+ * @see main.dart for what messages are getting sent from Flutter.
+ */
+class EngineBindings(activity: Activity, delegate: EngineBindingsDelegate, entrypoint: String) :
+    DataModelObserver {
+    val channel: MethodChannel
+    val engine: FlutterEngine
+    val delegate: EngineBindingsDelegate
+
+    init {
+        val app = activity.applicationContext as App
+        // This has to be lazy to avoid creation before the FlutterEngineGroup.
+        val dartEntrypoint =
+            DartExecutor.DartEntrypoint(
+                FlutterInjector.instance().flutterLoader().findAppBundlePath(), entrypoint
+            )
+        engine = app.engines.createAndRunEngine(activity, dartEntrypoint)
+        this.delegate = delegate
+        channel = MethodChannel(engine.dartExecutor.binaryMessenger, "multiple-flutters")
+    }
+
+    /**
+     * This setups the messaging connections on the platform channel and the DataModel.
+     */
+    fun attach() {
+        DataModel.instance.addObserver(this)
+        channel.invokeMethod("setCount", DataModel.instance.counter)
+        channel.setMethodCallHandler { call, result ->
+            when (call.method) {
+                "incrementCount" -> {
+                    DataModel.instance.counter = DataModel.instance.counter + 1
+                    result.success(null)
+                }
+                "next" -> {
+                    this.delegate.onNext()
+                    result.success(null)
+                }
+                else -> {
+                    result.notImplemented()
+                }
+            }
+        }
+    }
+
+    /**
+     * This tears down the messaging connections on the platform channel and the DataModel.
+     */
+    fun detach() {
+        // TODO: Uncomment after https://github.com/flutter/engine/pull/24644 is on stable.
+        // engine.destroy();
+        DataModel.instance.removeObserver(this)
+        channel.setMethodCallHandler(null)
+    }
+
+    override fun onCountUpdate(newCount: Int) {
+        channel.invokeMethod("setCount", newCount)
+    }
+}

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/java/dev/flutter/multipleflutters/MainActivity.kt

@@ -0,0 +1,61 @@
+package dev.flutter.multipleflutters
+
+import android.content.Intent
+import androidx.appcompat.app.AppCompatActivity
+import android.os.Bundle
+import android.view.View
+import android.widget.TextView
+
+/**
+ * The activity that uses standard platform UI APIs.
+ *
+ * This doesn't talk directly to or render Flutter content and represents a part of your app that
+ * would potentially already be written that wants to interface with Flutter.
+ */
+class MainActivity : AppCompatActivity(), DataModelObserver {
+    private lateinit var countView: TextView
+    private val mainActivityIdentifier: Int
+
+    private companion object {
+        /** A count that makes every other MainActivity have 1 or 2 Flutter instances. */
+        var mainActivityCount = 0
+    }
+
+    init {
+        mainActivityIdentifier = mainActivityCount
+        mainActivityCount += 1
+    }
+
+    /** Implemented from AppCompactActivity. */
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+        DataModel.instance.addObserver(this)
+        countView = findViewById(R.id.count)
+        countView.text = DataModel.instance.counter.toString()
+    }
+
+    /** Implemented from AppCompactActivity. */
+    override fun onDestroy() {
+        super.onDestroy()
+        DataModel.instance.removeObserver(this)
+    }
+
+    /** Event from `activity_main.xml`. */
+    fun onClickNext(view: View) {
+        val nextClass =
+            if (mainActivityIdentifier % 2 == 0) SingleFlutterActivity::class.java else DoubleFlutterActivity::class.java
+        val flutterIntent = Intent(this, nextClass)
+        startActivity(flutterIntent)
+    }
+
+    /** Event from `activity_main.xml`. */
+    fun onClickAdd(view: View) {
+        DataModel.instance.counter = DataModel.instance.counter + 1
+    }
+
+    /** Implemented from DataModelObserver. */
+    override fun onCountUpdate(newCount: Int) {
+        countView.text = newCount.toString()
+    }
+}

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/java/dev/flutter/multipleflutters/SingleFlutterActivity.kt

@@ -0,0 +1,37 @@
+package dev.flutter.multipleflutters
+
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+
+/**
+ * This is an Activity that displays one instance of Flutter.
+ *
+ * EngineBindings is used to bridge communication between the Flutter instance and the DataModel.
+ */
+class SingleFlutterActivity : FlutterActivity(), EngineBindingsDelegate {
+    private val engineBindings: EngineBindings by lazy {
+        EngineBindings(activity = this, delegate = this, entrypoint = "main")
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        engineBindings.attach()
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        engineBindings.detach()
+    }
+
+    override fun provideFlutterEngine(context: Context): FlutterEngine? {
+        return engineBindings.engine
+    }
+
+    override fun onNext() {
+        val flutterIntent = Intent(this, MainActivity::class.java)
+        startActivity(flutterIntent)
+    }
+}

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/drawable-v24/ic_launcher_foreground.xml

@@ -0,0 +1,30 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path android:pathData="M31,63.928c0,0 6.4,-11 12.1,-13.1c7.2,-2.6 26,-1.4 26,-1.4l38.1,38.1L107,108.928l-32,-1L31,63.928z">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="85.84757"
+                android:endY="92.4963"
+                android:startX="42.9492"
+                android:startY="49.59793"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M65.3,45.828l3.8,-6.6c0.2,-0.4 0.1,-0.9 -0.3,-1.1c-0.4,-0.2 -0.9,-0.1 -1.1,0.3l-3.9,6.7c-6.3,-2.8 -13.4,-2.8 -19.7,0l-3.9,-6.7c-0.2,-0.4 -0.7,-0.5 -1.1,-0.3C38.8,38.328 38.7,38.828 38.9,39.228l3.8,6.6C36.2,49.428 31.7,56.028 31,63.928h46C76.3,56.028 71.8,49.428 65.3,45.828zM43.4,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2c-0.3,-0.7 -0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C45.3,56.528 44.5,57.328 43.4,57.328L43.4,57.328zM64.6,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2s-0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C66.5,56.528 65.6,57.328 64.6,57.328L64.6,57.328z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/drawable/ic_launcher_background.xml

@@ -0,0 +1,170 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#3DDC84"
+        android:pathData="M0,0h108v108h-108z" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M9,0L9,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,0L19,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,0L29,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,0L39,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,0L49,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,0L59,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,0L69,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,0L79,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M89,0L89,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M99,0L99,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,9L108,9"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,19L108,19"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,29L108,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,39L108,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,49L108,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,59L108,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,69L108,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,79L108,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,89L108,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,99L108,99"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,29L89,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,39L89,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,49L89,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,59L89,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,69L89,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,79L89,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,19L29,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,19L39,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,19L49,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,19L59,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,19L69,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,19L79,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+</vector>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/layout/activity_main.xml

@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".MainActivity">
+
+    <TextView
+        android:id="@+id/count"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="1dp"
+        android:layout_marginRight="260dp"
+        android:text="Hello World!"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintRight_toRightOf="parent"
+        app:layout_constraintStart_toEndOf="@+id/countLabel"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <TextView
+        android:id="@+id/countLabel"
+        android:layout_width="58dp"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="16dp"
+        android:text="Count:"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <Button
+        android:id="@+id/button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginEnd="16dp"
+        android:layout_marginBottom="16dp"
+        android:onClick="onClickNext"
+        android:text="Next"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent" />
+
+    <Button
+        android:id="@+id/button2"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginEnd="16dp"
+        android:onClick="onClickAdd"
+        android:text="Add"
+        app:layout_constraintBottom_toTopOf="@+id/button"
+        app:layout_constraintEnd_toEndOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/values-night/themes.xml

@@ -0,0 +1,16 @@
+<resources xmlns:tools="http://schemas.android.com/tools">
+    <!-- Base application theme. -->
+    <style name="Theme.MultipleFlutters" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/purple_200</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/black</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_200</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+</resources>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/values/colors.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="purple_200">#FFBB86FC</color>
+    <color name="purple_500">#FF6200EE</color>
+    <color name="purple_700">#FF3700B3</color>
+    <color name="teal_200">#FF03DAC5</color>
+    <color name="teal_700">#FF018786</color>
+    <color name="black">#FF000000</color>
+    <color name="white">#FFFFFFFF</color>
+</resources>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">Multiple Flutters</string>
+</resources>

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/res/values/themes.xml

@@ -0,0 +1,16 @@
+<resources xmlns:tools="http://schemas.android.com/tools">
+    <!-- Base application theme. -->
+    <style name="Theme.MultipleFlutters" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/purple_500</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/white</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_700</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+</resources>

add_to_app/multiple_flutters/multiple_flutters_android/build.gradle

@@ -0,0 +1,26 @@
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+buildscript {
+    ext.kotlin_version = "1.3.72"
+    repositories {
+        google()
+        jcenter()
+    }
+    dependencies {
+        classpath "com.android.tools.build:gradle:4.1.2"
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+
+        // NOTE: Do not place your application dependencies here; they belong
+        // in the individual module build.gradle files
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}

add_to_app/multiple_flutters/multiple_flutters_android/gradle.properties

@@ -0,0 +1,21 @@
+# Project-wide Gradle settings.
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+# org.gradle.parallel=true
+# AndroidX package structure to make it clearer which packages are bundled with the
+# Android operating system, and which are packaged with your app"s APK
+# https://developer.android.com/topic/libraries/support-library/androidx-rn
+android.useAndroidX=true
+# Automatically convert third-party libraries to use AndroidX
+android.enableJetifier=true
+# Kotlin code style for this project: "official" or "obsolete":
+kotlin.code.style=official

add_to_app/multiple_flutters/multiple_flutters_android/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Wed Jan 27 11:54:04 PST 2021
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.5-all.zip

add_to_app/multiple_flutters/multiple_flutters_android/gradlew

@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"

add_to_app/multiple_flutters/multiple_flutters_android/gradlew.bat

@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

add_to_app/multiple_flutters/multiple_flutters_android/settings.gradle

@@ -0,0 +1,7 @@
+include ':app'
+rootProject.name = "Multiple Flutters"
+setBinding(new Binding([gradle: this]))                                // new
+evaluate(new File(                                                     // new
+        settingsDir.parentFile,                                              // new
+        './multiple_flutters_module/.android/include_flutter.groovy'                         // new
+))

tool/android_ci_script.sh

@@ -18,9 +18,15 @@ pushd add_to_app/fullscreen/flutter_module
 flutter packages get
 popd
 
+echo "Fetching dependencies for 'multiple_flutters/'."
+pushd add_to_app/multiple_flutters/multiple_flutters_module
+flutter packages get
+popd
+
 declare -ar ANDROID_PROJECT_NAMES=(
     "add_to_app/fullscreen/android_fullscreen" \
     "add_to_app/plugin/android_using_plugin" \
+    "add_to_app/multiple_flutters/multiple_flutters_android" \
     "add_to_app/prebuilt_module/android_using_prebuilt_module" \
 )