Add a pigeon sample that demonstrates a "realistic" integration scenario with middleware and business logic (#465)

add_to_app/android_books/app/.gitignore

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+/build

add_to_app/android_books/app/build.gradle

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+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+
+android {
+    compileSdkVersion 29
+    buildToolsVersion "29.0.3"
+
+    defaultConfig {
+        applicationId "dev.flutter.example.books"
+        minSdkVersion 16
+        targetSdkVersion 29
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+
+dependencies {
+    implementation fileTree(dir: "libs", include: ["*.jar"])
+    implementation "com.squareup.okhttp3:okhttp:4.7.2"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    implementation 'androidx.core:core-ktx:1.3.0'
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation "androidx.activity:activity-ktx:1.1.0"
+    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+    implementation 'com.google.android.material:material:1.1.0'
+    implementation 'com.google.code.gson:gson:2.8.6'
+    implementation project(path: ':flutter')
+    testImplementation 'junit:junit:4.13'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
+
+}

add_to_app/android_books/app/proguard-rules.pro

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+# 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/android_books/app/src/androidTest/java/dev/flutter/example/books/ExampleInstrumentedTest.kt

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+package dev.flutter.example.books
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class MainActivityTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("dev.flutter.example.books", appContext.packageName)
+    }
+
+    // The app should be hermetic (with offline books JSON) before adding
+    // more tests.
+}

add_to_app/android_books/app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="dev.flutter.example.books">
+
+    <application
+        android:name=".BookApplication"
+        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/AppTheme">
+        <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=".FlutterBookActivity"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:hardwareAccelerated="true"
+            android:windowSoftInputMode="adjustResize" />
+    </application>
+    <uses-permission android:name="android.permission.INTERNET" />
+
+</manifest>

add_to_app/android_books/app/src/main/java/dev/flutter/example/books/Api.java

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+// Autogenerated from Pigeon (v0.1.0), do not edit directly.
+// See also: https://pub.dev/packages/pigeon
+
+package dev.flutter.example.books;
+
+import java.util.HashMap;
+
+import io.flutter.plugin.common.BasicMessageChannel;
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugin.common.StandardMessageCodec;
+
+/** Generated class from Pigeon. */
+public class Api {
+
+  /** Generated class from Pigeon that represents data sent in messages. */
+  public static class Book {
+    private String title;
+    public String getTitle() { return title; }
+    public void setTitle(String setterArg) { this.title = setterArg; }
+
+    private String subtitle;
+    public String getSubtitle() { return subtitle; }
+    public void setSubtitle(String setterArg) { this.subtitle = setterArg; }
+
+    private String author;
+    public String getAuthor() { return author; }
+    public void setAuthor(String setterArg) { this.author = setterArg; }
+
+    private String description;
+    public String getDescription() { return description; }
+    public void setDescription(String setterArg) { this.description = setterArg; }
+
+    private String publishDate;
+    public String getPublishDate() { return publishDate; }
+    public void setPublishDate(String setterArg) { this.publishDate = setterArg; }
+
+    private Long pageCount;
+    public Long getPageCount() { return pageCount; }
+    public void setPageCount(Long setterArg) { this.pageCount = setterArg; }
+
+    HashMap toMap() {
+      HashMap<String, Object> toMapResult = new HashMap<String, Object>();
+      toMapResult.put("title", title);
+      toMapResult.put("subtitle", subtitle);
+      toMapResult.put("author", author);
+      toMapResult.put("description", description);
+      toMapResult.put("publishDate", publishDate);
+      toMapResult.put("pageCount", pageCount);
+      return toMapResult;
+    }
+    static Book fromMap(HashMap map) {
+      Book fromMapResult = new Book();
+      fromMapResult.title = (String)map.get("title");
+      fromMapResult.subtitle = (String)map.get("subtitle");
+      fromMapResult.author = (String)map.get("author");
+      fromMapResult.description = (String)map.get("description");
+      fromMapResult.publishDate = (String)map.get("publishDate");
+      fromMapResult.pageCount = (map.get("pageCount") instanceof Integer) ? (Integer)map.get("pageCount") : (Long)map.get("pageCount");
+      return fromMapResult;
+    }
+  }
+
+  /** Generated class from Pigeon that represents Flutter messages that can be called from Java.*/
+  public static class FlutterBookApi {
+    private BinaryMessenger binaryMessenger;
+    public FlutterBookApi(BinaryMessenger argBinaryMessenger){
+      this.binaryMessenger = argBinaryMessenger;
+    }
+    public interface Reply<T> {
+      void reply(T reply);
+    }
+    public void displayBookDetails(Book argInput, Reply<Void> callback) {
+      BasicMessageChannel<Object> channel =
+          new BasicMessageChannel<Object>(binaryMessenger, "dev.flutter.pigeon.FlutterBookApi.displayBookDetails", new StandardMessageCodec());
+      HashMap inputMap = argInput.toMap();
+      channel.send(inputMap, new BasicMessageChannel.Reply<Object>() {
+        public void reply(Object channelReply) {
+          callback.reply(null);
+        }
+      });
+    }
+  }
+
+  /** Generated interface from Pigeon that represents a handler of messages from Flutter.*/
+  public interface HostBookApi {
+    void cancel();
+    void finishEditingBook(Book arg);
+
+    /** Sets up an instance of `HostBookApi` to handle messages through the `binaryMessenger` */
+    static void setup(BinaryMessenger binaryMessenger, HostBookApi api) {
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<Object>(binaryMessenger, "dev.flutter.pigeon.HostBookApi.cancel", new StandardMessageCodec());
+        if (api != null) {
+          channel.setMessageHandler(new BasicMessageChannel.MessageHandler<Object>() {
+            public void onMessage(Object message, BasicMessageChannel.Reply<Object> reply) {
+              HashMap<String, HashMap> wrapped = new HashMap<String, HashMap>();
+              try {
+                api.cancel();
+                wrapped.put("result", null);
+              }
+              catch (Exception exception) {
+                wrapped.put("error", wrapError(exception));
+              }
+              reply.reply(wrapped);
+            }
+          });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<Object>(binaryMessenger, "dev.flutter.pigeon.HostBookApi.finishEditingBook", new StandardMessageCodec());
+        if (api != null) {
+          channel.setMessageHandler(new BasicMessageChannel.MessageHandler<Object>() {
+            public void onMessage(Object message, BasicMessageChannel.Reply<Object> reply) {
+              Book input = Book.fromMap((HashMap)message);
+              HashMap<String, HashMap> wrapped = new HashMap<String, HashMap>();
+              try {
+                api.finishEditingBook(input);
+                wrapped.put("result", null);
+              }
+              catch (Exception exception) {
+                wrapped.put("error", wrapError(exception));
+              }
+              reply.reply(wrapped);
+            }
+          });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
+    }
+  }
+  private static HashMap wrapError(Exception exception) {
+    HashMap<String, Object> errorMap = new HashMap<String, Object>();
+    errorMap.put("message", exception.toString());
+    errorMap.put("code", null);
+    errorMap.put("details", null);
+    return errorMap;
+  }
+}

add_to_app/android_books/app/src/main/java/dev/flutter/example/books/BookApplication.kt

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+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package dev.flutter.example.books
+
+import android.app.Application
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.embedding.engine.FlutterEngineCache
+import io.flutter.embedding.engine.dart.DartExecutor
+
+class BookApplication: Application() {
+    companion object {
+        const val ENGINE_ID = "book_engine"
+    }
+
+    private lateinit var flutterEngine: FlutterEngine
+
+    override fun onCreate() {
+        super.onCreate()
+        // This application reuses a single FlutterEngine instance throughout.
+        // Create the FlutterEngine on application start.
+        flutterEngine = FlutterEngine(this).apply{
+            dartExecutor.executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault())
+        }
+        FlutterEngineCache.getInstance().put(ENGINE_ID, flutterEngine)
+    }
+}

add_to_app/android_books/app/src/main/java/dev/flutter/example/books/FlutterBookActivity.kt

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+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package dev.flutter.example.books
+
+import android.app.Activity
+import android.content.Context
+import android.content.Intent
+import dev.flutter.example.books.BookApplication.Companion.ENGINE_ID
+import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+import java.util.HashMap
+
+/**
+ * This {@link FlutterActivity} class repackages Kotlin-Dart interop using the Pigeon IPC mechanism.
+ * It repackages Flutter/Dart-side functionalities in standard Android API style, passing
+ * arguments in and out of the activity using 'startActivityForResult' intents and
+ * 'onActivityResult' intents.
+ */
+class FlutterBookActivity: FlutterActivity() {
+    companion object {
+        const val EXTRA_BOOK = "book"
+
+        /**
+         * Static intent factory to start {@link FlutterBookActivity} with the singleton
+         * {@link FlutterEngine} the application started.
+         *
+         * The activity launched from this intent shows the details of the {@link Api.Book}
+         * supplied.
+         */
+        fun withBook(context: Context, book: Api.Book): Intent {
+            // In a more realistic app, there should be some dependency injection mechanism to
+            // determine which engine to use.
+            return CachedEngineBookIntentBuilder(ENGINE_ID)
+                .build(context)
+                .putExtra(
+                    // The Pigeon data class is useful not only between Kotlin/Java and Dart
+                    // but also within Kotlin/Java where activities must communicate with
+                    // each other via serializable data. The Pigeon data class is a
+                    // serializable class by definition.
+                    EXTRA_BOOK,
+                    // TODO(gaaclarke): the Pigeon generated data class should just implement
+                    // Serializable so we won't need 'toMap()' here
+                    // https://github.com/flutter/flutter/issues/58909
+                    book.toMap()
+                )
+        }
+
+        /**
+         *  A static helper method to parse a result intent from this activity into a {@link Book}.
+         *
+         * @param resultIntent an {@link Intent} that must be the data intent returned by this
+         *                     activity's {@code onActivityResult}.
+         */
+        fun getBookFromResultIntent(resultIntent: Intent): Api.Book {
+            return Api.Book.fromMap(resultIntent.getSerializableExtra(FlutterBookActivity.EXTRA_BOOK) as HashMap<*, *>);
+        }
+    }
+
+    // Intent builder class to build a FlutterBookActivity instance instead of the default FlutterActivity.
+    class CachedEngineBookIntentBuilder(engineId: String): CachedEngineIntentBuilder(FlutterBookActivity::class.java, engineId) { }
+
+    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+        // Called shortly after the activity is created, when the activity is bound to a
+        // FlutterEngine responsible for rendering the Flutter activity's content.
+        super.configureFlutterEngine(flutterEngine)
+
+        // The book to give to Flutter is passed in from the MainActivity via this activity's
+        // source intent getter. The intent contains the book serialized as on extra.
+        val bookToShow = Api.Book.fromMap(intent.getSerializableExtra(EXTRA_BOOK) as HashMap<*, *>)
+
+        // Register the HostBookApiHandler callback class to get results from Flutter.
+        Api.HostBookApi.setup(flutterEngine.dartExecutor, HostBookApiHandler())
+
+        // Send in the book instance to Flutter.
+        Api.FlutterBookApi(flutterEngine.dartExecutor).displayBookDetails(bookToShow) {
+            // We don't care about the callback
+        }
+    }
+
+    // This {@link Api.HostBookApi} subclass will be called by Pigeon when the corresponding
+    // APIs are invoked on the Dart side.
+    inner class HostBookApiHandler: Api.HostBookApi {
+        override fun cancel() {
+            // Flutter called cancel. Finish the activity with a cancel result.
+            setResult(Activity.RESULT_CANCELED)
+            finish()
+        }
+
+        override fun finishEditingBook(book: Api.Book?) {
+            if (book == null) {
+                throw IllegalArgumentException("finishedEditingBook cannot be called with a null argument")
+            }
+            // Flutter returned an edited book instance. Return it to the MainActivity via the
+            // standard Android Activity set result mechanism.
+            setResult(Activity.RESULT_OK, Intent().putExtra(EXTRA_BOOK, book.toMap()))
+            finish()
+        }
+    }
+}

add_to_app/android_books/app/src/main/java/dev/flutter/example/books/MainActivity.kt

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+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package dev.flutter.example.books
+
+import android.app.Activity
+import android.content.Intent
+import androidx.appcompat.app.AppCompatActivity
+import android.os.Bundle
+import android.view.View
+import android.widget.LinearLayout
+import android.widget.ProgressBar
+import android.widget.TextView
+import com.google.android.material.button.MaterialButton
+import com.google.gson.GsonBuilder
+import com.google.gson.JsonParser
+import okhttp3.Call
+import okhttp3.Callback
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.Response
+import java.io.IOException
+import java.lang.Exception
+import java.lang.RuntimeException
+
+class MainActivity : AppCompatActivity() {
+    companion object {
+        const val BOOKS_QUERY = "https://www.googleapis.com/books/v1/volumes?q=greenwood+tulsa&maxResults=15"
+    }
+
+    private lateinit var books: MutableList<Api.Book>
+    private lateinit var list: LinearLayout
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+        list = findViewById<LinearLayout>(R.id.list)
+
+        // OkHttp is arbitrarily chosen here to represent an existing middleware constraint that's
+        // already present in an existing application's infrastructure.
+        val httpClient = OkHttpClient()
+        val bookRequest = Request.Builder()
+            // Retrieve data from Google Books API (arbitrarily chosen). This represents existing
+            // data sources that an existing application is already interfacing with.
+            .url(BOOKS_QUERY)
+            .build()
+
+        httpClient.newCall(bookRequest).enqueue(object : Callback {
+            override fun onFailure(call: Call, e: IOException) {
+                throw e
+            }
+
+            override fun onResponse(call: Call, response: Response) {
+                response.use {
+                    if (!response.isSuccessful) throw IOException("Unexpected code $response")
+                    books = parseGoogleBooksJsonToBooks(response.body!!.string())
+
+                    val spinner = findViewById<ProgressBar>(R.id.spinner)
+
+                    runOnUiThread {
+                        // Showed a spinner while network call is in progress. Remove it when
+                        // response is received.
+                        spinner.visibility = View.GONE
+                        populateBookCards()
+                    }
+                }
+            }
+        })
+    }
+
+    // Take a top level Google Books query's response JSON and create a list of Book Pigeon data
+    // classes that will be used both as a model here on the Kotlin side and also in the IPCs
+    // to Dart.
+    private fun parseGoogleBooksJsonToBooks(jsonBody: String): MutableList<Api.Book> {
+        // Here we're arbitrarily using GSON to represent another existing middleware constraint
+        // that already exists in your existing application's infrastructure.
+        val jsonBooks = JsonParser.parseString(jsonBody).asJsonObject.getAsJsonArray("items")
+        val books = mutableListOf<Api.Book>()
+        for (jsonBook in jsonBooks.map { it.asJsonObject }) {
+            try {
+                // Here we're using GSON to populate a Pigeon data class directly. The Pigeon data
+                // class can be used not just as part of your IPC API's signature but also as a
+                // normal data class in your existing application.
+                //
+                // We could either push the Pigeon data class usage higher into the existing GSON
+                // "middleware" or lower, closer to the IPC.
+                val book = Api.Book()
+                val volumeInfoJson = jsonBook.getAsJsonObject("volumeInfo")
+                book.title = volumeInfoJson.get("title").asString
+                book.subtitle = volumeInfoJson.get("subtitle")?.asString
+                // Sorry co-authors, we're trying to keep this simple.
+                book.author = volumeInfoJson.getAsJsonArray("authors")[0].asString
+                book.description = volumeInfoJson.get("description").asString
+                book.publishDate = volumeInfoJson.get("publishedDate").asString
+                book.pageCount = volumeInfoJson.get("pageCount").asLong
+                books.add(book)
+            } catch (e: Exception) {
+                println("Failed to parse book:")
+                println(GsonBuilder().setPrettyPrinting().create().toJson(jsonBook))
+                println("Parsing error:")
+                println(e)
+            }
+        }
+        return books
+    }
+
+    // Given a populated books list, create a Material Design card in a scroll view for each book.
+    private fun populateBookCards() {
+        for ((index, book) in books.withIndex()) {
+            val card = layoutInflater.inflate(R.layout.book_card, null)
+            updateCardWithBook(card, book)
+            card.findViewById<MaterialButton>(R.id.edit).setOnClickListener {
+                // When the edit button is clicked in a book's card, launch a Flutter activity
+                // showing the details of the book.
+                startActivityForResult(
+                    // We're using our own 'FlutterActivity' subclass which wraps Pigeon API usages
+                    // into an idiomatic Android activity interface with intent extras as input and
+                    // with activity 'setResult' as output.
+                    //
+                    // This lets activity-level feature developers abstract their Flutter usage
+                    // and present a standard Android API to their upstream application developers.
+                    //
+                    // No Flutter-specific concepts are leaked outside the Flutter activity itself
+                    // into the consuming class.
+                    FlutterBookActivity
+                        // Re-read from the 'books' list rather than just capturing the iterated
+                        // 'book' instance since we change it when Dart updates it in onActivityResult.
+                        .withBook(this, books[index]),
+                    // The index lets us know which book we're returning the result for when we
+                    // return from the Flutter activity.
+                    index)
+            }
+            list.addView(card)
+        }
+    }
+
+    // Given a Material Design card and a book, update the card content to reflect the book model.
+    private fun updateCardWithBook(card: View, book: Api.Book) {
+        card.findViewById<TextView>(R.id.title).text = book.title
+        card.findViewById<TextView>(R.id.subtitle).text = book.subtitle
+        card.findViewById<TextView>(R.id.author).text = resources.getString(R.string.author_prefix, book.author)
+    }
+
+    // Callback when the Flutter activity started with 'startActivityForResult' above returns.
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        super.onActivityResult(requestCode, resultCode, data)
+
+        // The Flutter activity may cancel the edit. If so, don't update anything.
+        if (resultCode == Activity.RESULT_OK) {
+            if (data == null) {
+                throw RuntimeException("The FlutterBookActivity returning RESULT_OK should always have a return data intent")
+            }
+
+            // If the book was edited in Flutter, the Flutter activity finishes and returns an
+            // activity result in an intent (the 'data' argument). The intent has an extra which is
+            // the edited book in serialized form.
+            val returnedBook = FlutterBookActivity.getBookFromResultIntent(data)
+            // Update our book model list.
+            books[requestCode] = returnedBook
+
+            // Refresh the UI here on the Kotlin side.
+            updateCardWithBook(list.getChildAt(requestCode), returnedBook)
+        }
+    }
+}

add_to_app/android_books/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/android_books/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/android_books/app/src/main/res/layout/activity_main.xml

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <com.google.android.material.appbar.AppBarLayout
+        android:id="@+id/appbar"
+        app:liftOnScroll="true"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content">
+
+    </com.google.android.material.appbar.AppBarLayout>
+
+    <androidx.core.widget.NestedScrollView
+        android:id="@+id/nestedScrollView"
+        android:layout_width="match_parent"
+
+
+        android:layout_height="match_parent"
+        app:layout_behavior="com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior">
+
+        <LinearLayout
+            android:id="@+id/list"
+            android:orientation="vertical"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            tools:context=".MainActivity" />
+
+    </androidx.core.widget.NestedScrollView>
+
+    <ProgressBar
+        android:id="@+id/spinner"
+        style="?android:attr/progressBarStyle"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:indeterminate="true"
+        app:layout_anchor="@+id/nestedScrollView"
+        app:layout_anchorGravity="center" />
+
+
+</androidx.coordinatorlayout.widget.CoordinatorLayout>

add_to_app/android_books/app/src/main/res/layout/book_card.xml

@@ -0,0 +1,69 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    >
+
+    <com.google.android.material.card.MaterialCardView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="21dp"
+        android:layout_marginStart="21dp"
+        android:layout_marginEnd="21dp"
+        android:layout_marginBottom="2dp">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:padding="16dp">
+
+            <TextView
+                android:id="@+id/title"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:textAppearance="?attr/textAppearanceHeadline5"
+                tools:text="Title" />
+
+            <TextView
+                android:id="@+id/subtitle"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:textAppearance="?attr/textAppearanceSubtitle1"
+                android:textColor="?android:attr/textColorSecondary"
+                tools:text="subtitle" />
+
+            <TextView
+                android:id="@+id/author"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="16dp"
+                android:textAppearance="?attr/textAppearanceBody1"
+                android:textColor="?android:attr/textColorSecondary"
+                tools:text="Author" />
+
+            <LinearLayout
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_margin="8dp"
+                android:orientation="horizontal"
+                android:layout_gravity="end">
+                <com.google.android.material.button.MaterialButton
+                    android:id="@+id/edit"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="@string/edit"
+                    style="?attr/borderlessButtonStyle"
+                    />
+            </LinearLayout>
+
+        </LinearLayout>
+
+    </com.google.android.material.card.MaterialCardView>
+
+</FrameLayout>
+

add_to_app/android_books/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/android_books/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/android_books/app/src/main/res/values/colors.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="colorPrimary">#6200EE</color>
+    <color name="colorPrimaryDark">#3700B3</color>
+    <color name="colorAccent">#03DAC5</color>
+</resources>

add_to_app/android_books/app/src/main/res/values/strings.xml

@@ -0,0 +1,5 @@
+<resources>
+    <string name="app_name">Books</string>
+    <string name="edit">Edit</string>
+    <string name="author_prefix">By: %1$s</string>
+</resources>

add_to_app/android_books/app/src/main/res/values/styles.xml

@@ -0,0 +1,10 @@
+<resources>
+    <!-- Base application theme. -->
+    <style name="AppTheme" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Customize your theme here. -->
+        <item name="colorPrimary">@color/colorPrimary</item>
+        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
+        <item name="colorAccent">@color/colorAccent</item>
+    </style>
+
+</resources>