cheatsheet-old.dart

import 'package:flutter/material.dart';
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.pink,
      ),
      home: MyHomePage(title: 'Flutter'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: SingleChildScrollView(
        child: Center(
          child: Column(
            // Column is also layout widget. It takes a list of children and
            // arranges them vertically. By default, it sizes itself to fit its
            // children horizontally, and tries to be as tall as its parent.
            //
            // Invoke "debug painting" (press "p" in the console, choose the
            // "Toggle Debug Paint" action from the Flutter Inspector in Android
            // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
            // to see the wireframe for each widget.
            //
            // Column has various properties to control how it sizes itself and
            // how it positions its children. Here we use mainAxisAlignment to
            // center the children vertically; the main axis here is the vertical
            // axis because Columns are vertical (the cross axis would be
            // horizontal).
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Container(
                  width: double.infinity,
                  decoration: BoxDecoration(color: Colors.blue),
                  child: Center(
                    child: Padding(
                        padding: EdgeInsets.all(24),
                        child: Text(
                          "HI VOC",
                          style: TextStyle(
                              color: Colors.white,
                              fontWeight: FontWeight.bold,
                              fontSize: 20),
                        )),
                  )),
              RENDERED_IMAGE,
              RENDERED_IMAGE,
              RENDERED_IMAGE,
              RENDERED_IMAGE,
              RENDERED_IMAGE,
              RENDERED_IMAGE,
              RENDERED_IMAGE,
              RENDERED_IMAGE,
              Card(
                margin: EdgeInsets.all(10),
                child: Container(
                  width: double.infinity,
                  margin: EdgeInsets.all(20),
                  child: Column(
                    children: <Widget>[
                      Text("HOLA"),
                    ],
                  ),
                ),
              ),
              Container(
                width: double.infinity,
                height: 70,
                margin: EdgeInsets.only(top: 10, bottom: 10),
                child: FlatButton(
                  onPressed: runBrowserAction,
                  color: Colors.purple,
                  child: Text(
                    "SUBMIT",
                    style: TextStyle(fontSize: 20, color: Colors.white),
                  ),
                ),
              ),
              Text('You have pushed the button $_counter times:'),
              Text(
                '$_counter',
                style: Theme.of(context).textTheme.display1,
              ),
            ],
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

const RENDERED_IMAGE = Image(
    image: NetworkImage(
        "https://images.unsplash.com/photo-1557246519-f38ee04b918d?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1374&q=80"),
    height: 200,
    width: double.infinity,
    fit: BoxFit.fitWidth);

runBrowserAction() {
  final flutterWebviewPlugin = new FlutterWebviewPlugin();
  flutterWebviewPlugin.launch("https://www.google.com", hidden: true);

  flutterWebviewPlugin
      // .evalJavascript("window.navigator.userAgent")
      .evalJavascript("JSON.stringify({hello:'234'})")
      .then((String val) {
    print("RECEIVED $val");
  });
}

items.dart

import 'package:rxdart/rxdart.dart';

class ItemsBloc {
  List<int> items =
      []; //if the data is not passed by paramether it initializes with 0
  BehaviorSubject<List<int>> _subjectItems;

  ItemsBloc({this.items}) {
    _subjectItems = new BehaviorSubject<List<int>>.seeded(
        this.items); //initializes the subject with element already
  }

  Observable<List<int>> get counterObservable => _subjectItems.stream;

  void pushNew() {
    items.add(items.length);
    _subjectItems.sink.add(items);
  }

  void removeLast() {
    if (items.length <= 0) return;
    items.removeAt(items.length - 1);
    _subjectItems.sink.add(items);
  }

  void dispose() {
    _subjectItems.close();
  }
}

main-items.dart

import 'dart:async';
import 'package:flutter/material.dart';
// import 'bloc/counter.dart';
import 'bloc/items.dart';
import 'util/webruntime.dart';

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new HomePage(title: 'Flutter Demo'),
    );
  }
}

class HomePage extends StatefulWidget {
  HomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _HomePageState createState() => new _HomePageState();
}

class _HomePageState extends State<HomePage> {
  ItemsBloc _itemsBloc = new ItemsBloc(items: []);

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
        appBar: new AppBar(
          title: Text(widget.title),
        ),
        body: new Center(
          child: new Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              new Text('The list has the following items:'),
              new StreamBuilder(
                  stream: _itemsBloc.counterObservable,
                  builder: (context, AsyncSnapshot<List<int>> snapshot) {
                    String txt = snapshot.data != null
                        ? snapshot.data.map((int v) => v.toString()).join((","))
                        : "";
                    return new Text(txt,
                        style: Theme.of(context).textTheme.display1);
                  })
            ],
          ),
        ),
        floatingActionButton: new Column(
            mainAxisAlignment: MainAxisAlignment.end,
            children: <Widget>[
              new Padding(
                  padding: EdgeInsets.only(bottom: 10),
                  child: new FloatingActionButton(
                    onPressed: _itemsBloc.pushNew,
                    tooltip: 'Increment',
                    child: new Icon(Icons.add),
                  )),
              Padding(
                padding: EdgeInsets.only(bottom: 10),
                child: new FloatingActionButton(
                  onPressed: _itemsBloc.removeLast,
                  tooltip: 'Decrement',
                  child: new Icon(Icons.remove),
                ),
              ),
              WebRuntimeHook(),
              new FloatingActionButton(
                onPressed: () {
                  // new Timer(Duration(milliseconds: 1), () => WebRuntime.triggerAction());
                  WebRuntime.triggerAction();
                },
                tooltip: 'Launch',
                child: new Icon(Icons.cast_connected),
              ),
            ]));
  }

  @override
  void dispose() {
    _itemsBloc.dispose();
    super.dispose();
  }
}

main.dart

  import 'package:flutter/material.dart';
  import 'util/web-runtime.dart';

  WebRuntime webRuntime = new WebRuntime();

  // MAIN

  void main() => runApp(MyApp());

  class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: MyHomePage(title: 'Flutter Demo'),
      );
    }
  }

  class MyHomePage extends StatefulWidget {
    MyHomePage({Key key, this.title}) : super(key: key);

    final String title;

    @override
    _MyHomePageState createState() => _MyHomePageState();
  }

  class _MyHomePageState extends State<MyHomePage> {
    int _counter = 0;

    @override
    Widget build(BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Text(
                'Web Runtime Test',
              ),
              // Text(
              //   '$_counter',
              //   style: Theme.of(context).textTheme.display1,
              // ),
            ],
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () async {
            webRuntime.triggerAction();
          },
          tooltip: 'Increment',
          child: Icon(Icons.add),
        ),
      );
    }
  }

pubspec.yaml

name: myapp2
description: A new Flutter project.

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.1.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  flutter_inappbrowser: ^1.1.3

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.2

dev_dependencies:
  flutter_test:
    sdk: flutter


# For information on the generic Dart part of this file, see the
# following page: https://www.dartlang.org/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  assets:
    - assets/runtime.html
  #  - images/a_dot_burr.jpeg
  #  - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

runtime.html

<!DOCTYPE html>
<html>

<head>
    <meta charSet="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <script>
        function sendMessage(payload = {}) {
            window.flutter_inappbrowser.callHandler("JS_HANDLER", payload);
            return null;
        }
        function action1() {
            fetch("https://www.google.com")
                .then(response => response.json())
                .then(data => sendMessage({ data: data.substr(0, 1000) }))
                .catch(err => sendMessage({ error: err.message }))
        }
        function action2() {
            Promise.resolve("HELLO WORLD")
                .then(data => sendMessage({ data }))
                .catch(err => sendMessage({ error: err.message }))
        }
    </script>
</head>

<body>
    <h1>RUNTIME</h1>
</body>

</html>

web-runtime.dart

import 'dart:async';
import 'package:flutter_inappbrowser/flutter_inappbrowser.dart';

// BROWSER

class WebRuntime extends InAppBrowser {
  Completer _init;

  Future init() async {
    if (_init == null) {
      _init = new Completer();
    } else if (_init.isCompleted) {
      return;
    }

    await this.openFile("assets/runtime.html", options: {
      "useShouldOverrideUrlLoading": true,
      "useOnLoadResource": true,
      "hidden": true
    });
    await _init.future;

    // listen for post messages coming from the JavaScript side
    this
        .webViewController
        .addJavaScriptHandler("JS_HANDLER", onMessageReceived);
  }

  // @override
  // void onBrowserCreated() async {
  //   print("\n\nBrowser Ready!\n\n");
  //   _init.complete();
  // }

  // @override
  // void onLoadStart(String url) {
  //   print("\n\nStarted $url\n\n");
  // }

  @override
  onLoadStop(String url) {
    _init.complete();
  }

  @override
  void onLoadError(String url, int code, String message) {
    // print("\n\nCan't load $url.. Error: $message\n\n");
    _init.completeError("Unable to initialize the Web Runtime");
  }

  // @override
  // void onExit() {
  //   print("\n\nBrowser closed!\n\n");
  // }

  @override
  void shouldOverrideUrlLoading(String url) {
    // IGNORE ALL NAVIGATION REQUESTS
  }

  // @override
  // void onLoadResource(
  //     WebResourceResponse response, WebResourceRequest request) {
  //   print("Started at: " +
  //       response.startTime.toString() +
  //       "ms ---> duration: " +
  //       response.duration.toString() +
  //       "ms " +
  //       response.url);
  // }

  @override
  void onConsoleMessage(ConsoleMessage consoleMessage) {
    print("""
    console output: ${consoleMessage.message}
    """);
  }

  // RUN CODE ON THE BROWSER

  triggerAction() async {
    await this.init();
    await this.webViewController.injectScriptCode('''
      // sendMessage({a: 1, hello: "world"});
      action1();
      action2();
    ''');
    // "window.flutter_inappbrowser.callHandler('JS_HANDLER', 1, 5,'string', {'key': 5}, [4,6,8]);"
  }

  // GOT A MESSAGE FROM THE BROWSER

  onMessageReceived(arguments) async {
    print(arguments);
  }
}